UBC Theses and Dissertations

UBC Theses Logo

UBC Theses and Dissertations

Wideband reflectance in adults : normative data and a case series of otosclerosis Bork, Karin T. 2004

Your browser doesn't seem to have a PDF viewer, please download the PDF to view this item.

Item Metadata

Download

Media
831-ubc_2004-0378.pdf [ 14.74MB ]
Metadata
JSON: 831-1.0091503.json
JSON-LD: 831-1.0091503-ld.json
RDF/XML (Pretty): 831-1.0091503-rdf.xml
RDF/JSON: 831-1.0091503-rdf.json
Turtle: 831-1.0091503-turtle.txt
N-Triples: 831-1.0091503-rdf-ntriples.txt
Original Record: 831-1.0091503-source.json
Full Text
831-1.0091503-fulltext.txt
Citation
831-1.0091503.ris

Full Text

W I D E B A N D R E F L E C T A N C E IN A D U L T S : N O R M A T I V E D A T A A N D A C A S E SERIES O F O T O S C L E R O S I S by K A R T N T. B O R K  B . S c , The University of Alberta, 2001  A T H E S I S S U B M I T T E D IN P A R T I A L F U L F I L M E N T OF T H E REQUIREMENTS FOR T H E D E G R E E OF M A S T E R OF SCIENCE in T H E F A C U L T Y O F G R A D U A T E STUDIES (School of Audiology and Speech Sciences)  We accept this thesis as conforming to the required standard  T H E UNIVERSITY O F BRITISH C O L U M B I A October 2004 © Karin T . Bork, 2004  JUBCl THE UNIVERSITY OF BRITISH COLUMBIA  FACULTY OF GRADUATE STUDIES  Library Authorization  In presenting this thesis in partial fulfillment of the requirements for an advanced degree at the University of British Columbia, I agree that the Library shall make it freely available for reference and study. I further agree that permission for extensive copying of this thesis for scholarly purposes may be granted by the head of my department or by his or her representatives. It is understood that copying or publication of this thesis for financial gain shall not be allowed without my written permission.  ?/io/  Name of Author (please print)  ™ e of Thesis:  W.'L.Lui  7001  Date (dd/mm/yyyy)  ft,£lec\«Mte.  L ALll< se  Degree:  ; /[lor^c 'b&rle.i dr  <L)« * J oroide.  Year:  Department of The University of British Columbia Vancouver, BC  Canada  grad.ubc.ca/forins/?formlD=THS  page 1 of-1  last updated:  '20-JUI-04  Abstract For years immittance has been used in order to help diagnose middle ear pathologies. Specifically, multi-frequency tympanometry is able to relate information to clinicians regarding the mechano-acoustical characteristics of the middle ear system. In the past two decades a new method o f middle ear measurement, wideband reflectance ( W B R ) , has been discovered. Wideband reflectance is the ratio o f energy reflected from the surfaces of the ear canal and middle ear on its way to the cochlea in relation to the energy that reaches the surface, or incident energy. This ratio is known as energy reflectance and can be manipulated to give values of power absorption, admittance, susceptance, and conductance. There are numerous advantages to W B R over multi-frequency tympanometry, including its objectiveness, speed, and wide frequency range. However, as of yet, few normative studies have been published to guide clinicians in the practical uses of W B R and their ability to assess middle ear pathologies, such as otosclerosis. In this regard, this thesis adds to the limited normative data available, as well as explores whether these normative data have a clinical utility in the diagnosis of otosclerosis. Taking into consideration possible gender and race differences, normative data were collected for both genders in Chinese and Caucasian populations. Mean, 5th, and 95th percentiles were gathered from 128 subjects (240 ears) for these groups as well as in seven patients (seven ears) with otosclerosis. The four W B R parameters assessed were power absorption, admittance, susceptance, and conductance. Analysis consisted of: (1) a repeated measures analysis o f variance including the within subject factor of level of frequency and the between subject factors of gender, race, and ear, and (2) a visual comparison o f graphically presented normative group data, as well as individual patient data graphically compared with appropriate normative values. Combining statistical analysis and visual observations, this study strongly suggests the need for  implementation o f gender and race specific normative values for W B R . Differences in graphic representation o f patient data plotted against normative values are found for some W B R measures. Further research is needed in this area.  T A B L E OF CONTENTS Abstract  ii  Table of Contents  iv  List of Tables  ix  List of Figures  xi  List of Abbreviations  xix  Acknowledgements  xx  C H A P T E R I Introduction  1  C H A P T E R II Literature Review  5  2.1  Clinical issues of otosclerosis  5  2.2  Diagnostic approach to otosclerosis  8  2.3  Theory and clinical use of middle ear assessment measures  12  2.3.1  Immittance  12  2.3.2  Low frequency tympanometry  15  2.3.3  Multi-frequency tympanometry  16  2.3.4  Wideband reflectance  16  2.4  Normative data 2.4.1  2.5  26  Justification for developing gender and race specific normative data based upon previous middle ear studies  26  2.4.2  Normative values for wideband reflectance  29  2.4.3  Normative data obtained from unpublished data  34  Goals of this thesis  35  2.5.1  Underlying hypothesis of the total project  35  2.5.2  Objectives of this thesis  35  iv  2.5.3  Specific research questions addresses by this thesis  C H A P T E R HI Methods  35 37  3.1  Research design  37  3.2  Subjects  37  3.2.1  Inclusion criteria for normal subjects  37  3.2.2  Inclusion criteria for study subjects  37  3.2.3  Exclusion criteria for normal subjects  38  3.2.4  Exclusion criteria for study subjects  38  3.2.5  Description of normal subjects  38  3.2.5.1 Caucasian normal subjects  38  3.2.5.2 Chinese normal subjects  39  Description of study subjects  39  3.2.6 3.3  3.4  3.5  3.6  Recruitment  40  3.3.1  Recruitment of normal subj ects  40  3.3.2  Recruitment of study subjects  40  Ethics approval  41  3.4.1  Ethics approval  41  3.4.2  Consent retention  41  Instrumentation  41  3.5.1  Inspection, audiometry, and transient-evoked otoacoustic emissions  41  3.5.2  Tympanometry  41  3.5.3  Wideband reflectance  42  Procedure  48  3.6.1  48  Testing done prior to subject inclusion in this study  v  3.6.2  Testing done after subject inclusion in this study  49  3.6.3  Background tympanometric testing used in this study  49  3.7  Data handling  50  3.8  Data analysis  50  C H A P T E R IV 4.1  Results and Discussion Power Absorption  53  4.1.1  Procedure  53  4.1.2  Between gender and race statistical analysis  55  4.1.3  Collected normative values  56  4.1.3.1 Normative data comparing Chinese males and females  57  4.1.3.2 Normative data comparing Caucasian males and females  59  4.1.3.3 Normative data comparing Chinese and Caucasian males  60  4.1.3.4 Normative data comparing Chinese and Caucasian females  62  Discussion o f power absorption results  64  4.1.4 4.2  Admittance  65  4.2.1  Procedure  65  4.2.2  Between gender and race statistical analysis  65  4.2.3  Collected normative values  66  4.2.3.1 Normative data comparing Chinese males and females  66  4.2.3.2 Normative data comparing Caucasian males and females  67  4.2.3.3 Normative data comparing Chinese and Caucasian males  69  4.2.3.4 Normative data comparing Chinese and Caucasian females  69  Discussion of admittance results  71  4.2.4 4.3  52  Susceptance  72 vi  4.3.1  Procedure  72  4.3.2  Between gender and race statistical analysis  72  4.3.3  Collected normative values  73  4.3.3.1 Normative data comparing Chinese males and females  73  4.3.3.2 Normative data comparing Caucasian males and females  74  4.3.3.3 Normative data comparing Chinese and Caucasian males  75  4.3.3.4 Normative data comparing Chinese and Caucasian females  76  Discussion o f susceptance results  77  4.3.4 4.4  Conductance  78  4.4.1  Procedure  78  4.4.2  Between gender and race statistical analysis  78  4.4.3  Collected normative values  79  4.4:3.1 Normative data comparing Chinese males and females  79  4.4.3.2 Normative data comparing Caucasian males and females  80  4.4.3.3 Normative data comparing Chinese and Caucasian males  81  4.4.3.4 Normative data comparing Chinese and Caucasian females  82  Discussion of conductance results  83  4.4.4 4.5  Summary o f the results  84  4.6  Discussion of normative data  86  4.7  Case histories o f patients with otosclerosis  88  4.7.1  Case history of an otosclerotic male: O M 1  89  4.7.2  Case history of an otosclerotic female: OF1  94  4.7.3  Case history o f an otosclerotic female: O F 2  99  4.7.4  Case history of an otosclerotic female: OF3  104  vii  4.8 CHAPTER V  4.7.5  Case history of an otosclerotic female: O F 4  109  4.7.6  Case history of an otosclerotic female: O F 5  114  4.7.7  Case history of an otosclerotic female: O F 6  119  Discussion of case studies of otosclerosis General discussion  124 126  5.1  Summary  126  5.2  Limitations  128  5.3  Sources of differences  129  5.4  Implications  130  5.5  Future research  132  References  135  Appendix I Requested Raw Data from Feeney and Sanford (2004)  143  Appendix II Confirmation of Diagnosis  147  Appendix UI Telephone Questionnaire  148  Appendix IV Email Questionnaire  149  Appendix V Consent Form for Otosclerotic Subjects  150  Appendix V I Analysis of Variance ( A N O V A ) Tables for Power Absorption, Admittance, Susceptance, and Conductance Data with regard to Normal Subjects  154  vm  List of Tables T A B L E 2.1: Constants used for admittance-reflection formula calculations. Adapted from Voss and Allen (1994)  19  T A B L E 2.2: Procedural variables for measuring wideband reflectance in published studies. N / A = information not available. Full investigator names include: Feeney, Grant, & Marryott (2003); Keefe, Bulen, Arehart, & Burns (1993); and Margolis, Saly, & Keefe (1999). * Custom-made wideband reflectance machine by Keefe, Ling, Bulen (1992); modified and used by Keefe, et al. (1993); used by Margolis, et al. (1999) and Feeney, et al. (2003)  30  T A B L E 4.1: Statistical and visual findings for within and between race comparisons for power absorption (PA), admittance (Y), susceptance (B), and conductance (G). L o w frequency cutoff = 1500 Hz; High frequency cutoff = 4000 Hz; N S = Not significant; M = Male; F = Female; C = Caucasian; A = Chinese. A n alpha level o f .05 was used for all statistical tests  85  T A B L E A l : Mean, 5th, and 95th percentile energy reflectance data from Feeney and Sanford (2004)  143  T A B L E A2: Mean, 5th, and 95th percentile admittance data from Feeney and Sanford (2004)  144  T A B L E A 3 : Mean, 5th, and 95th percentile susceptance data from Feeney and Sanford (2004)  145  T A B L E A 4 : Mean, 5th, and 95th percentile conductance data from Feeney and Sanford (2004)  146  ix  T A B L E A 5 : Results from operative reports and surgical confirmation of diagnosis. N A = Not available. * Skeeter drill was also used to remove sclerotic growth anteriorly over the footplate  147  T A B L E A 6 : Summary o f A N O V A for power absorption data  154  T A B L E A 7 : Summary of A N O V A for admittance data  154  T A B L E A 8 : Summary o f A N O V A for susceptance data  155  T A B L E A 9 : Summary o f A N O V A for conductance data  155  x  List o f Figures F I G U R E 2.1: Graphical representation of admittance terminology  13  F I G U R E 2.2: Compensated admittance vectors in relation to frequency. Adapted from Margolis & Shanks, 1991  14  F I G U R E 2.3: Comparison o f adult normative data of energy reflectance (ER) as a function of frequency in three different studies. Data are given as one-twelfth octave E R . Full authors are as follow: Present Study is by Feeney, Grant, and Marryott (2003); Keefe, Bulen, Arehart, and Burns (1993); and Margolis, Saly, and Keefe (1999). From Feeney, Grant, and Marryott (2003), Figure 1, p. 904  21  F I G U R E 2.4: Energy reflectance as a function o f frequency for two ears with otosclerosis. P 5 R represents the right ear o f one participant. P6R represents the right ear o f a second participant. The shaded area represents the 5th to 95th percentile range of normal hearing sensitivity participants. From Feeney, Grant, and Marryott (2003)  23  F I G U R E 2.5: Normalized power absorption curves for 30 normal middle ears o f children ages 2.5 to 5 years (upper panel). Mean normalized power absorption curve from the above panel with ± 1 standard deviation (dotted lines; lower panel). From Jeng, Levitt, Lee, & Gravel, 1999  24  F I G U R E 2.6: Average energy reflectance as a function of frequency. Adapted from Margolis, Saly, & Keefe, 1999, Figure 6c, p. 273  32  F I G U R E 2.7: Power absorption graph as seen before testing begins. The shaded area represents normative adult values provided by Mimosa Acoustics. From Mimosa Acoustics R M S system version 4.0.4.4  33  F I G U R E 3.1: Components of the Mimosa Acoustics (RMS-system v4.0.4.4) wideband reflectance machine  43  xi  F I G U R E 3.2: Organization of data graphs during testing using the Mimosa Acoustics ( R M S system v4.0.4.4) wideband reflectance machine. The shaded area represents normative data provided by Mimosa Acoustics  45  F I G U R E 3.3: Graphical view of the four variables used in this study: Power absorption, Admittance (Magn), Admittance (Imag Part), and Admittance (Real Part). The shaded area refers to normative data provided by Mimosa Acoustics. O f these, only the power absorption curve was visualized during testing. The admittance variables were calculated automatically by the Mimosa software after testing was completed. Frequency is represented in linear format  46  F I G U R E 3.4: Measurement data collection screen used to acquire subject results from Mimosa Acoustics (RMS-system v4.0.4.4) wideband reflectance machine. The above shaded region represents the signal level, while the below shaded region the noise level  47  F I G U R E 3.5: Visual measure of test-retest reliability using the power absorption curve  48  F I G U R E 4.1: Comparison of power absorption as a function of frequency. Mean, 5th, and 95th percentile values are plotted. Data are from Feeney and Sanford (2004) and combined race and gender normative values from this study  55  F I G U R E 4.2: Power absorption as a function of frequency comparing normative data from Chinese males and females. A M refers to Chinese males; A F refers to Chinese females  58  F I G U R E 4.3: Power absorption as a function of frequency comparing normative data from Caucasian males and females. C M refers to Caucasian male; C F refers to Caucasian female  60  F I G U R E 4.4: Power absorption as a function of frequency comparing normative data from Chinese and Caucasian males. C M refers to Caucasian males; A M refers to Chinese males  61  F I G U R E 4.5: Power absorption as a function of frequency comparing normative data from Chinese and Caucasian females. C F refers to Caucasian females; A F refers to Chinese females  63  F I G U R E 4.6: Admittance as a function of frequency comparing normative data from Chinese males and females. A M refers to Chinese males; A F refers to Chinese females. Admittance values are dimensionless as they are normalized using characteristic impedance of the ear canal  67  F I G U R E 4.7: Admittance as a function of frequency comparing normative data from Caucasian males and females. C M refers to Caucasian males; C F refers to Caucasian females. Admittance values are dimensionless as they are normalized using characteristic impedance of the ear canal  68  F I G U R E 4.8: Admittance as a function of frequency comparing normative data from Chinese and Caucasian males. C M refers to Caucasian males; A M refers to Chinese males. Admittance values are dimensionless as they are normalized using characteristic impedance of the ear canal  69  F I G U R E 4.9: Admittance as a function of frequency comparing normative data from Chinese and Caucasian females. A F refers to Chinese females; C F refers to Caucasian females. Admittance values are dimensionless as they are normalized using characteristic impedance of the ear canal  71  F I G U R E 4.10: Susceptance as a function of frequency comparing normative data from Chinese males and females. A M refers to Chinese males; A F refers to Chinese females. Susceptance values are dimensionless as they are normalized using characteristic impedance of the ear canal  74  F I G U R E 4.11: Susceptance as a function o f frequency comparing normative data from Caucasian males and females. C M refers to Caucasian males; C F refers to Caucasian females. Susceptance values are dimensionless as they are normalized using characteristic impedance of the ear canal  7f  F I G U R E 4.12: Susceptance as a function of frequency comparing normative data from Chinese and Caucasian males. A M refers to Chinese males; C M refers to Caucasian males. Susceptance values are dimensionless as they are normalized using characteristic impedance of the ear canal  It  F I G U R E 4.13: Susceptance as a function of frequency comparing normative data from Chinese and Caucasian females. A F refers to Chinese females; C F refers to Caucasian females. Susceptance values are dimensionless as they are normalized using characteristic impedance of the ear canal  7'  F I G U R E 4.14: Conductance as a function of frequency comparing normative data from Chinese males and females. A M refers to Chinese males; A F refers to Chinese females. Conductance values are dimensionless as they are normalized using characteristic impedance of the ear canal  8(  F I G U R E 4.15: Conductance as a function of frequency comparing normative data from Caucasian males and females. C M refers to Caucasian males; C F refers to Caucasian females. Conductance values are dimensionless as they are normalized using characteristic impedance of the ear canal  81  F I G U R E 4.16: Conductance as a function of frequency comparing normative data from Chinese and Caucasian males. A M refers to Chinese males; C M refers to Caucasian males. Conductance values are dimensionless as they are normalized using characteristic impedance of the ear canal  82  F I G U R E 4.17: Conductance as a function of frequency comparing normative data from Chinese and Caucasian females. A F refers to Chinese females; C F refers to Caucasian females. Conductance values are dimensionless as they are normalized using characteristic impedance of the ear canal  83  F I G U R E 4.18: Pre-operative audiometric results of otosclerotic male O M 1  90  F I G U R E 4.19: Power absorption as a function of frequency in otosclerotic male patient O M 1 . C M refers to Caucasian male  91  F I G U R E 4.20: Admittance as a function of frequency in otosclerotic male O M 1 . C M refers to Caucasian male. Admittance values are dimensionless as they are normalized using characteristic impedance o f the ear canal  92  F I G U R E 4.21: Susceptance as a function of frequency in otosclerotic male O M 1 . C M refers to Caucasian male. Susceptance values are dimensionless as they are normalized using characteristic impedance of the ear canal  93  F I G U R E 4.22: Conductance as a function of frequency in otosclerotic male O M 1 . C M refers to Caucasian male. Conductance values are dimensionless as they are normalized using characteristic impedance of the ear canal  94  F I G U R E 4.23: Pre-operative audiometric results of otosclerotic female OF1  95  F I G U R E 4.24: Power absorption as a function o f frequency for otosclerotic female O F 1 . C F refers to Caucasian female  96  xv  F I G U R E 4.25: Admittance as a function of frequency for otosclerotic female OF1. C F refers to Caucasian female. Admittance values are dimensionless as they are normalized using characteristic impedance of the ear canal  97  F I G U R E 4.26: Susceptance as a function o f frequency for otosclerotic female OF1. C F refers to Caucasian female. Susceptance values are dimensionless as they are normalized using characteristic impedance of the ear canal  98  F I G U R E 4.27: Conductance as a function of frequency for otosclerotic female O F 1 . C F refers to Caucasian female. Conductance values are dimensionless as they are normalized using characteristic impedance o f the ear canal F I G U R E 4.28: Pre-operative audiometric results of otosclerotic female O F 2  99 101  F I G U R E 4.29: Power absorption as a function o f frequency for otosclerotic female OF2. C F refers to Caucasian female  101  F I G U R E 4.30: Admittance as a function o f frequency for otosclerotic female OF2. C F refers to Caucasian female. Admittance values are dimensionless as they are normalized using characteristic impedance o f the ear canal  102  F I G U R E 4.31: Susceptance as a function of frequency for otosclerotic female OF2. C F refers to Caucasian female. Susceptance values are dimensionless as they are normalized using characteristic impedance of the ear canal  103  F I G U R E 4.32: Conductance as a function o f frequency for otosclerotic female OF2. C F refers to Caucasian female. Conductance values are dimensionless as they are normalized using characteristic impedance of the ear canal F I G U R E 4.33: Pre-operative audiometric results of otosclerotic female O F 3  104 106  F I G U R E 4.34: Power absorption as a function of frequency for otosclerotic female OF3. C F refers to Caucasian female  106  xvi  F I G U R E 4.35: Admittance as a function o f frequency for otosclerotic female OF3. C F refers to Caucasian female. Admittance values are dimensionless as they are normalized using characteristic impedance o f the ear canal  107  F I G U R E 4.36: Susceptance as a function of frequency for otosclerotic female OF3. C F refers to Caucasian female. Susceptance values are dimensionless as they are normalized using characteristic impedance of the ear canal  108  F I G U R E 4.37: Conductance as a function o f frequency for otosclerotic female OF3. C F refers to Caucasian female. Conductance values are dimensionless as they are normalized using characteristic impedance of the ear canal F I G U R E 4.38: Pre-operative audiometric results o f otosclerotic female O F 4  109 Ill  F I G U R E 4.39: Power absorption as a function o f frequency in otosclerotic female OF4. C F refers to Caucasian female  Ill  F I G U R E 4.40: Admittance as a function of frequency in otosclerotic female OF4. C F refers to Caucasian female. Admittance values are dimensionless as they are normalized using characteristic impedance o f the ear canal  112  F I G U R E 4.41: Susceptance as a function of frequency in otosclerotic female OF4. C F refers to Caucasian female. Susceptance values are dimensionless as they are normalized using characteristic impedance of the ear canal  113  F I G U R E 4.42: Conductance as a function of frequency in otosclerotic female OF4. C F refers to Caucasian female. Conductance values are dimensionless as they are normalized using characteristic impedance of the ear canal F I G U R E 4.43: Pre-operative audiometric results of otosclerotic female OF5  114 116  F I G U R E 4.44: Power absorption as a function o f frequency in otosclerotic female OF5. C F refers to Caucasian female  116  xvii  F I G U R E 4.45: Admittance as a function of frequency in otosclerotic female OF5. C F refers to Caucasian female. Admittance values are dimensionless as they are normalized using characteristic impedance o f the ear canal  117  F I G U R E 4.46: Susceptance as a function of frequency in otosclerotic female OF5. C F refers to Caucasian female. Susceptance values are dimensionless as they are normalized using characteristic impedance of the ear canal  118  F I G U R E 4.47: Conductance as a function o f frequency in otosclerotic female OF5. C F refers to Caucasian female. Conductance values are dimensionless as they are normalized using characteristic impedance of the ear canal F I G U R E 4.48: Pre-operative audiometric results of otosclerotic female O F 6  119 121  F I G U R E 4.49: Power absorption as a function of frequency in otosclerotic female OF6. C F refers to Caucasian female  121  F I G U R E 4.50: Admittance as a function of frequency in otosclerotic female OF6. C F refers to Caucasian female. Admittance values are dimensionless as they are normalized using characteristic impedance o f the ear canal  122  F I G U R E 4.51: Susceptance as a function of frequency in otosclerotic female OF6. C F refers to Caucasian female. Susceptance values are dimensionless as they are normalized using characteristic impedance o f the ear canal  123  F I G U R E 4.52: Conductance as a function of frequency in otosclerotic female OF6. C F refers to Caucasian female. Conductance values are dimensionless as they are normalized using characteristic impedance of the ear canal  124  List o f Abbreviations  AGC  Definition Automatic gain control  B  Susceptance (admittance)  Abbreviation  B  m  Mass susceptance (admittance) Stiffness susceptance (admittance)  B B,  Total susceptance (admittance)  daPa  dekaPascal  ECV ER  Ear canal volume Energy reflectance  F45°  Frequency corresponding to an admittance phase angle of 4 5 °  G HL  Hearing level  Hz  Hertz  mmhos MFT  millimhos Multi-frequency tympanometry  PA  Power absorption  R  Resistance (impedance)  RF  Resonant frequency  TW TEOAE  Tympanometric width Transient evoked otoacoustic emission  SA  Static admittance  SF  Sweep frequency  SP SPL  Sweep pressure  Y  Admittance  Z  Impedance  s  Conductance (admittance)  Sound pressure level  +B  Positive compensated susceptance  -B  Negative compensated susceptance  xix  Acknowledgements Completing a thesis is not to be taken lightly, as is evident by the weight of this book. It takes countless hours of procedural set up, data collection, analysis, and writing, not to mention editing. None of these tasks can be accomplished alone. I would like to thank my thesis supervisor, Dr. Navid Shahnaz, for his vision of extensive middle ear studies that made my thesis possible. His willingness to share new knowledge and his enthusiasm for cutting edge discoveries gave me the drive to continue. I greatly appreciate the time and effort he devoted to my thesis. I would also like to thank my thesis committee, Drs. Sipke Pijl and Brian Westerberg, for their insightful comments and excellent advice. I particularly wish to thank Dr. Westerberg and Marleen for their organization o f patient assessment, making it possible for me to obtain clinical data. I also wish to thank Drs. M . P. Feeney and C . A . Sanford for providing normative data for comparison, as well as, Drs. J. Meyer and J. Allen for their expertise in the interpretation of the data. A n d last, but definitely not least, I would like to thank my family and friends, without whom this thesis would never have been completed. Their many hours of patient listening to my concerns of the day were sincerely appreciated.  xx  Chapter I Introduction Wideband reflectance ( W B R ) is a relatively new measure for middle ear evaluation. It uses a wide range of sound frequencies to establish a ratio of sound energy reflected on its way to the cochlea in relation to the sound that reaches the cochlea. Wideband reflectance has the potential to exceed the clinical utility of commonly used tympanometric measures for the diagnosis o f middle ear pathologies. In addition to expanding the understanding o f middle ear conditions through the use of W B R , examination of pathological middle ear systems will add to the knowledge about W B R . One o f the common middle ear pathologies that could benefit from the examination by a sound stimulus of a wide range o f frequencies is that of otosclerosis. Examination of this common disorder with tympanometric measures has lead to the improved understanding o f the relative contributions of mass, stiffness, and resistance to middle ear pathologies (Shahnaz & Polka, 2002). B y further examining otosclerotic ears with W B R , significant advancement of the audiologists' ability to diagnose and monitor middle ear disease is expected. In the fifth edition of the  Handbook of Clinical Audiology (Rappaport and Provencal,  2002), otosclerosis, a disorder o f the otic capsule leading to symptoms o f progressive hearing loss, is described as "the most intriguing o f all otologic diseases" (p. 21). Descriptions of this common disorder have been in the literature for almost 300 years. In 1735, Valsalva reported that ankylosis or fixation of the stapes could cause hearing loss (Ginsberg & White, 1985). This observation was repeated by others and by 1893, Adam Politzer of Vienna, determined that this ankylosis was due to a disease o f the bone that is responsible for forming the otic capsule and the surrounding area and not due to chronic middle ear catarrh as had been previously thought (Ginsberg & White, 1985). Over time, the understanding o f the pathophysiology of otosclerosis  1  has evolved. It is now understood as a fixation of the stapedial footplate (Gelfand, 2001). This fixation results in reduced ability o f the ossicular chain to transmit signals to the cochlea. Audiological techniques for the diagnosis and assessment of otosclerosis are based on the concepts that otosclerosis typically increases the stiffness o f the middle ear system (Shahnaz & Polka, 2002). Therefore, it is classed as a high impedance (low admittance) pathology (Shahnaz & Polka, 2002). The most effective measures for diagnosing otosclerosis are those that evaluate the relative contributions of mass, stiffness, and resistance (Shahnaz & Polka, 2002; Shanks & Shelton, 1991). For some time, clinical audiologists have relied upon traditional single component, low frequency tympanometry mainly static admittance (SA) in diagnosis of otosclerosis (Alberti, & Kristensen, 1970; Browning, Swan, & Gatehouse, 1985; Dempsey, 1975; Jerger, 1970; Jerger, Anthony, Jerger, & Mauldin, 1974; Liden, Peterson, & Bjorkman, 1970; and Muchnik, Hildesheimer, Rubinstein, & Glettman, 1989). There have also been suggestions that otosclerosis is associated with narrower tympanometric width ( T W ) (Dieroff, 1978; Ivey, 1975; Koebsell, Shanks, Cone-Wesson, & Wilson, 1988; Shahnaz & Polka, 1997). In recent years multi-frequency tympanometry ( M F T ) has shown diagnostic utility in otosclerosis (Shahnaz & Polka, 2002), as described in chapter two in the following literature review. However, there is still a significant overlap between healthy and otosclerotic ears on all measures obtained by tympanometry. More information is needed about middle ear characteristics in patients with otosclerosis. This study will provide a more detailed picture of the mechano-acoustical properties of the middle ear using W B R . B y charting how much energy is transferred into the system across a wide range o f frequencies, W B R can evaluate the relative contribution of mass, stiffness, and resistance. Ultimately, the study hopes to show that W B R can provide an objective means of predicting the conductive involvement in otosclerosis. If this is accomplished, the study will  2  confirm Keefe, Bulen, Arehart, & Burns (1993) study that W B R expands the presently available measure of M F T . Thus, W B R can potentially be used both to diagnose otosclerosis and to evaluate different surgical procedures and the efficiency o f various prosthetic devices for the treatment of otosclerosis. Wideband reflectance provides this potential as it measures how the middle ear reflects or absorbs sounds across a range o f frequencies much greater than that o f MFT. Surgical techniques for otosclerosis have been in the literature for more than 125 years. Currently, there are two techniques in use: stapedectomy (the removal of the ankylosed stapes and footplate) and stapedotomy (where a hole is bored in the footplate rather than removing it). Surgery is discussed further in the following literature review (Chapter IT). Research about otosclerosis is active today on many fronts. Audiologists, otolaryngologists, genetists, histologists, epidemiologists, and others, are exploring ways to advance understanding o f the causes, varying population distributions, audiological evaluation, and treatments o f otosclerosis. The aspect o f critical concern for audiologists and otolaryngologists alike is the advancement o f audiological techniques to improve diagnostic accuracy o f otosclerosis prior to surgery and to explore objective means to assess and advance treatment options. This can be achieved by a series o f steps, some of which are addressed in this study. The steps include: (1) understanding the limitations of current clinical measures o f middle ear pathology and investigating new technologies that may improve the understanding o f both normal and pathological middle ear dynamic characteristics, (2) obtaining normative values for new measures of middle ear function in accordance with the confounding variables that can affect normative data, such as, age, gender, and race, (3) testing subjects with otosclerosis on these new measures and compare results with normative values, and (4) using audiometric, operative, and histological descriptions o f otosclerosis to establish grading systems for  3  comparison with the measurements in order to expand knowledge both of the pathophysiology of otosclerosis and the clinical utility of the new diagnostic tests. This study focuses on establishing adult normative values for W B R including the examination of gender and race effects to see whether gender and race specific normative data should be used. The second stage is an exploratory study to investigate the potential clinical utility of W B R in otosclerosis.  This is the first research to address the effect of race on W B R .  This thesis follows standard format of literature review o f otosclerosis, current diagnostic testing methods, W B R testing; details of subjects, methods and procedure, and results; discussion, summary, implications, and applications and ideas for future research. Searches for the literature review were conducted through PubMed. The keywords entered were tympanometry, multi-frequency tympanometry, and wideband reflectance. were later combined with otosclerosis.  These  Well-known authors were also searched for by name,  such as Margolis, Feeney, and Keefe. Search results were then limited to the English language and human subjects. References were also found by visually scanning articles available in the Reference Library of the Middle Ear Laboratory, located on the University of British Columbia campus.  4  Chapter II Literature Review 2.1 Clinical issues of otosclerosis Otosclerosis is a term used to describe "a disease of the temporal bone in which normal bone is progressively reabsorbed and replaced with  spongy bone that may harden to become  sclerotic" (Gelfand, 2001, p. 196). While otosclerosis develops at isolated locations, hearing loss occurs when it involves the oval window and the stapedial footplate, commonly called stapedial  otosclerosis (Gelfand, 2001). This may result in complete ankylosis or fixation of the stapedial footplate (Gelfand, 2001). A s the ossicular chain can no longer transmit signals as efficiently to the cochlea a progressive conductive hearing loss develops, causing  clinical otosclerosis  (Gelfand, 2001). Should the pathological process be observed at surgery to obliterate the footplate, the term  obliterated otosclerosis is used (Lippy, et al., 1999). When the disease  process involves the inner ear, sensorineural hearing loss may occur which is called  cochlear  otosclerosis (Gelfand, 2001). Otosclerosis and its associated disabilities of tinnitus (Gros, Vatovec, Sereg-Bahar, 2003), conductive hearing loss (Gros, et al., 2003), and eventually sensorineural hearing loss (Gros, et al., 2003), with or without vestibular symptoms (Gros, et al., 2003) are common and strike healthy adolescents and adults in their prime. The disease has a large personal, societal and economic cost, making early, accurate diagnosis and effective treatment important to patients. Otosclerosis is the single most common cause of hearing impairment amongst Caucasians, regardless of their geographic distribution with a calculated clinical probability using histological information from autopsy data of 0.3% (Declau, V a n Spaendonck, Tommermons, Liang, Qiu, & van de Heyning, 2001). The estimated prevalence of clinical otosclerosis among Caucasians is two to ten per 1000 (Chen, Campbell, Green, et al., 2002). It is twice as common among females as males (Ginsberg & White, 1985). Clinical otosclerosis  5  with the onset or progression of otosclerosis in or just following pregnancy has been linked to increased estrogen stimulatory effect of osteocytic activity resulting in greater ossification of osteosclerotic foci (Menger & Tange, 2003). The average age of onset of hearing loss is 36 years (Ginsberg & White, 1985), with the age range including children as young as 12 years (Gros, et al., 2003). About 50% of persons with otosclerosis have a known affected family member (Wang, Merchant, McKenna, Glynn, & Nadol, 1999). While causal factors such as metabolic, vascular, and infectious have been considered, today's research focuses on the genetics of otosclerosis.  Epidemiological studies suggest autosomal dominant inheritance with  incomplete penetrance (Chen, et al., 2002) o f approximately 40% (Menger & Tange, 2003). Discoveries of genome loci for hearing loss are rapidly progressing. A t least three loci have been mapped for otosclerosis (Chen, et a l , 2002). These include, O T S C 1 on chromosome 15q26.1 as described in 1998 in an Indian family, O T S C 2 on chromosome 7q34-q36 as described in 2001 in Belgian and Dutch families where 25% of otosclerosis is linked to this gene, and O T S C 3 on chromosome 6p21.3-t22.3 as described in 2000 in Cyprus (Chen, et al., 2002). A m o n g Caucasians there is no indication that the prevalence of otosclerosis and its complications will decrease. Once diagnosed, otosclerosis may be treated with amplification, sodium fluoride, or surgery. Although the use of amplification (i.e. hearing aids) does not alter the progression of the disease, there is also no chance of damaging hearing as a result of surgery. Another alternative is sodium fluoride, an oral medication which may arrest the progression in 80% of patients, but is unlikely to improve hearing loss already present (Gelfand, 2001). Surgery is effective in improving hearing in 90-95% of patients (Rappaport & Provencal, 2002). Surgery is the treatment o f choice for otosclerosis (Gelfand, 2001). Stapedectomy was developed by Shea in 1956. Stapedectomy removes the ankylosed stapes and footplate and seals the oval window  6  with connective tissue or vein graft (Gelfand, 2001). The stapes may be replaced with various prostheses of wire, strut, or piston of various materials (Gelfand, 2001). A partial stapedectomy removes the anterior footplate leaving the posterior eras to transmit signals to the cochlea (Gelfand, 2001). Stapedotomy, where a hole is bored through the stapedial footplate with a drill or laser came to the forefront in the 1980s (Lippy, Berenholz, Burkey, 1999). Stapedotomy has been considered to give similar results to the stapedectomy (Levy, Shvero, & Hadar, 1990), and to have similar long-term pure tone average improvement (Aarnisalo, Vasama, Hopsu, & Ramsay, 2003). Today this is the preferred method. Several authors have now reported that stapedotomy gives less risk of profound hearing loss and is more effective in preserving high frequency hearing than stapedectomy (House, Hansen, A l Dakhail, & House, 2002; Kursten, Schneider, & Zrunek, 1994; and Moller, 1992). There may be a slight, but progressive loss of hearing after surgery and revision stapedectomies may be needed (Gelfand, 2001). Long-term post-surgical outcomes are affected not only by the surgical procedure but by the choice of prostheses (deBruijn, Tange, & Dreschler, 1999). Evaluation of the treatments of otosclerosis has been strongly recommended (Monsell, Balkany, Gates, Goldenberg, Meyerhoff, & House, 1995), and the importance of the choice of outcome measures reinforced (Goldenberg & Berliner, 1995). Recommended outcome measures included four frequency pure-tone average, and the closure of air-bone gap (Monsell, et al., 1995; deBruijn, Tange, & Dreschler, 2001) as well as word recognition scores (Lippy, Burkey, & Arkis, 1998). Functional outcome measures and satisfaction questionnaires are also recommended (Aarnisalo, et al., 2003; Stewart, Jenkins, Coker, Jerger, & Loiselle, 1997). There is potential to expand the evaluation of treatments for otosclerosis through the use of new, objective, and easy to use measures, such as W B R , as experience with this measure increases.  7  2.2 Diagnostic approach to otosclerosis Audiologists or otolaryngologists are generally the first medical professionals to suspect the diagnosis o f clinical otosclerosis.  Generally patients, in their third or fourth decade o f life,  often women, complain of a slowly progressive hearing loss, often accompanied by tinnitus, or an abnormal perception of sounds for which there is no external stimulus (Gelfand, 2001). From the patient, the audiologist seeks family history, unilateral or bilateral involvement and suggestions of conductive loss. In conductive disorders, patients often complain of a loss of intensity, not clarity. That is, they may say that speech is too quiet. "Relatively intense sounds are generally less bothersome to patients with conductive hearing losses because these sounds are reduced in level before entering the cochlea" (Gelfand, p. 176). Good word recognition suggests the hearing loss is conductive and not yet sensorineural. Otoscopic examination may reveal Schwartze's sign, a reddish or pinkish discolouration seen through the tympanic membrane and reflective of vascularization of the cochlear promontory seen in otosclerosis (Gelfand, 2001). Occasionally radiological imaging is considered in the diagnosis of otosclerosis.  High  resolution computerized tomography is the gold standard diagnostic imaging test for otosclerosis (Shin, Calvas, Deguine, Charlet, Cognard, & Fraysse, 2001). This allows for determination of the presence of bilateral disease with clinical otosclerosis only on one side, for completing familial studies, and examining the size of the thickened footplate (Shin, et al., 2001). It should be mentioned that the detection of otosclerosis using imaging techniques is dependent on the quality of the scans, thickness of the sections, and experience of the radiologist. Familial otosclerosis tends to be more extensive within the otic capsule than that which does not occur in families. In familial otosclerosis there is an increased association between anterior foci, a thickened footplate, and pericochlear foci (Shin, et al., 2001). While confirmation of the  8  diagnosis could be accomplished by this testing, it is expensive, contains irradiation, and is unnecessary in most cases. It is possible that with the correct diagnostic audiological battery the presence of bilateral disease with clinical otosclerosis on one side could be diagnosed, and familial studies could be done without imaging. Pure tone audiometric testing with air- and bone-conduction is the main test usually performed by audiologists when otosclerosis is suspected.  The size of the hearing loss depends  on the progression of the disease at the time of testing and may be mild to severe (Gelfand, 2001). Initially, the loss is worse in the lower frequencies, but becomes flatter with disease progression. This is because the disease increases the stiffness effect which is more evident at low frequencies. The degree of conductive hearing loss appears to be determined by the stage of pathological changes at the stapes footplate (Cherukupally, Merchange, & Rosowski, 1998). A n air-bone gap is usually greatest in the lower frequencies and may decrease at 2000 H z to about 30 dB H L and increases again at 4000 H z . This finding is called Carhart's notch and is not a true sensorineural component. It is "thought to occur because the mechanical advantage provided by the 2000-Hz resonance of the ossicular chain is altered by the ankylosis, which prevents the ossicles from vibrating normally" (Gelfand, 2001, p. 197). If the disease has progressed to include sensorineural hearing loss, this latter component is not reversed by surgery. Information provided by a standard 226 H z tympanogram is typically inadequate for distinguishing a normal middle ear from an ear with otosclerosis (Browning, et al. 1985; Colletti, 1976; Shahnaz & Polka, 1997; Shahnaz & Polka, 2002). Standard tympanometry often fails to distinguish otosclerosis because the status of the tympanic membrane dominates the tympanogram and overshadows conditions of more medial structures (Shahnaz & Polka, 1997). Also, low frequency tympanometry forces the middle ear to behave as a stiffness dominated  9  system (Shahnaz & Polka, 1997). Two parameters from standard low-frequency tympanometry have been found to be somewhat different in otosclerosis than normal subjects. The first of these, and the one still commonly used, is static admittance (SA). Studies have shown a trend for lower S A in patients with stapes fixation, although there is overlap with normal subjects (Alberti & Kristensen, 1970; Browning, et al., 1985; Jerger, 1970; Liden, et al., 1970; Shahnaz & Polka, 1997). The second is tympanometric width (TW) as an index for quantifying steepness of the tympanometric peak. A narrower T W in ears with otosclerosis as compared with normal ears has been reported (Koebsell, et al., 1988; Shahnaz & Polka, 1997). In current audiologic practice both for diagnosis and follow-up of otosclerosis, standard tympanometry could be used more effectively when used in combination with other parameters, such as, M F T . In recent years, M F T has been shown to have diagnostic utility in surgically proven otosclerosis (Shahnaz & Polka, 1997; 2002). In their paper, Shahnaz and Polka (2002) confirmed the advantages of higher probe tone frequencies over standard low probe tone frequency in distinguishing otosclerotic ears from normal ears. The receiver operating characteristic curves obtained at the higher probe tone frequencies of 630 H z and 710 H z were statistically better in distinguishing otosclerotic ears than the standard low probe tone frequency which was operating at a chance level (Shahnaz & Polka, 2002). High-frequency tympanometry is not yet routinely used by audiologists when testing patients suspected of having otosclerosis. Shahnaz and Polka (1997) have shown that optimal test performance to improve the diagnostic utility of tests distinguishing otosclerotic patients was achieved by combining F 4 5 ° derived from sweep frequency recordings and T W . They did this by combining standard tympanometry results of S A and T W with M F T results including resonant frequency (RF) and frequency corresponding to admittance phase angle of 4 5 ° ( F 4 5 ° ) . Routine practice has not yet included these tests in the diagnosis of otosclerosis, in part related to their shortcomings. Multi-frequency  10  tympanometry cannot test beyond 2000 H z , although it does provide testing of a much wider range than standard low frequency tympanometry. However, tests that improve the diagnostic accuracy for otosclerosis are being developed. More specifically, it is thought that the success of acoustic ear canal tests (i.e. O A E s ) in predicting cochlear hearing loss can be extended to acoustic immittance tests to predict conductive hearing losses (Piskorski, Keefe, Simmons, & Gorga, 1999). In addition to the use of M F T for the diagnosis of otosclerosis, W B R may be helpful to distinguish between normal-hearing ears and those with otosclerosis.  Wideband reflectance is a  relatively new middle ear analysis technique involving the use of ambient static pressure across a much wider frequency range than M F T (Jeng, Levitt, Lee, & Gravel, 1999; Keefe, Folsom, Gorga, Vohr, Bulen, & Norton, 2000). Advantages of W B R are that the location of the probe in the ear canal is no longer as critical, for both standing waves and ear canal compliance; recent studies have shown W B R to be a fast, sensitive, and non-invasive test for middle ear disease (Jeng, et al., 1999; Keefe, et al., 2000); and W B R can measure more than one resonant frequency allowing for further analysis of middle ear function. Using multivariate analysis, Piskorski, et al. (1999) showed admittance reflectance at 2 and 4 k H z increased sensitivity to 90% and specificity to 94% when predicting conductive hearing loss in children. In 2003, Keefe and Simmons reported the test performance of a wideband acoustic transfer function to give greater sensitivity in predicting the presence of conductive hearing loss; with pressurized wideband acoustic transfer function sensitivity reached 94%. Presently, there are few studies giving normative data on W B R and none reporting on the effect of gender and race. There are no published studies focusing on the results of W B R in otosclerosis.  Scattered reports on patients with middle ear disease have included some patients  with otosclerosis.  Feeney, Grant, & Marryott (2003) reported on two patients with otosclerosis.  11  They found that W B R , as measured in energy reflectance (ER), was more sensitive than a standard probe tone of 226 H z to the presence of otosclerosis.  These clinical case histories are  outlined in section 2.3.4. 2.3 Theory and clinical use of middle ear assessment measures The following sections provide a brief description of immittance terminology and principles as well as a brief overview of standard low probe tone frequency tympanometry and M F T . This will assist in the interpretation of the results of the otosclerotic case studies and increase the understanding of the underlying principles of W B R . This background will also assist in the interpretation of collected W B R normative data.  2.3.1 Immittance The term immittance includes admittance and impedance. Admittance (Y) is measured in acoustic millimhos (mmhos) and is defined by the ease o f energy flow into the middle ear system. Reciprocally, impedance (Z) is measured in acoustic ohms (ohms) and is defined by the opposition of energy flow into the middle ear system. Modern immittance audiometry machines measure energy flow in admittance; hence, for the purpose of this study admittance will be used whenever possible. Within the term admittance there are three elements: stiffness, mass, and friction. In the middle ear system these elements each work along a specific vector to determine admittance. The stiffness component is referred to as stiffness susceptance (B ) and works along the positive s  vertical vector. The mass component is referred to as mass susceptance ( B ) and works along m  the negative vertical vector. Together stiffness susceptance and mass susceptance are referred to as total susceptance (B ). That is: t  (B ) = (B ) + ( B ) t  s  m  (1)  12  Admittance |Y)  8  Bs  »  Conductance (G) •Bm  Figure 2.1: Graphical representation of admittance terminology.  When B is positive the middle ear system is stiffness dominated. When B is negative the t  t  middle ear system is mass dominated. The third element of admittance is friction which either dissipates or absorbs acoustical energy. This component is referred to as conductance (G) and works along the positive horizontal vector. In M F T it is important to understand the relationship between these admittance components and frequency in the normal middle ear system. The frictional component or acoustic conductance is independent of frequency, whereas the stiffness component, or B is s  inversely proportional to frequency, and the mass component, or B  m  is directly proportional to  frequency. That is, with increasing frequency the total susceptance (B ) moves from being t  positive or stiffness dominated (+B), toward zero or resonance, to negative or mass dominated (B). When stiffness susceptance and mass susceptance are equal, resonance of the middle ear system is reached ( B = 0 mmhos). A t R F the only component that contributes to admittance is t  conductance. Using M F T , it has been found that the R F in a normal adult ear varies from 630  13  H z to 2000 H z (Margolis & Goycoolea, 1993), and in various pathologies shifts lower (mass dominating pathologies, e.g. ossicular discontinuity; Feeney, et al., 2003) or higher (stiffness dominating pathologies e.g. otosclerosis; Shahnaz & Polka, 1997). These shifts result from the relationship between R F and middle ear mechanical properties. Thus, R F is directly proportional to stiffness and inversely proportional to mass within the middle ear system. This results in a higher R F in a stiffness dominated middle ear system. Another important measure occurs when, as the frequency increases, susceptance decreases and conductance increases. Figure 2.2 depicts these concepts.  -90° 0  1  2  3  4  5  C O N D U C T A N C E (G) mmho Figure 2.2: Compensated admittance vectors in relation to frequency. Adapted from Margolis & Shanks, 1991.  14  2.3.2 Low frequency tympanometry Clinical measurement of admittance of the middle ear system is ordinarily done using standard low probe tone tympanometry. B y presenting a tone at either 220 or 226 H z and measuring admittance magnitude as a function of the ear canal pressure, a graphical representation of the middle ear system is formed. There is one major problem with standard tympanometry. B y using a low probe tone frequency, the middle ear system in normal individuals is stiffness dominated and thus the stiffness component contributes a much greater part to the admittance measurement than the conductance, or frictional component. This, in effect, often conceals pathological middle ears from detection, especially in ossicular chain abnormalities (Colletti, 1975, 1976; Lilly, 1984). A s seen in figure 2.2, probe tone frequency increase relates directly to a reduction in stiffness dominated middle ear systems. This is particularly relevant to W B R as a larger frequency range allows for better detection of middle ear pathologies. This difficulty of detecting some middle ear pathologies may lie with the anatomy of the middle ear as the structures involved are medial to the tympanic membrane, or with our lack of understanding about such ossicular dysfunctions on tympanometric results. Knowing this and understanding how different ossicular chain pathologies affect the stiffness or mass of the middle ear system leading to an increase or decrease in the R F of the middle ear, researchers have realized that using higher probe tone frequencies, closer to the R F of the middle ear will be more likely to distinguish normal and pathological middle ears (Colletti, 1977; Feldman, 1976; Shahnaz & Polka, 2002). This is particularly true of those affecting the ossicular chain (Shanks, 1984). This leads to an explanation of why tympanometry using higher probe tone frequencies, especially those frequencies close to resonant frequencies of the middle ear, are thought to give a  15  greater distinction between normal and abnormal middle ears, such as those with stapes fixation (Colletti, 1977; Liden, et al., 1974).  2.3.3 Multi-frequency  tympanometry  Historically, low probe tone frequency of 220 or 226 H z was used due to its ease of calibration (Terkildsen & Thomson, 1959; Margolis & Shanks, 1995). With the advancement o f technology related to higher probe tone frequencies, it is realized that more clinically useful information can be collected when using multiple frequencies (226-2000 Hz). Resonant frequency can be defined as the frequency at which total susceptance is zero. Resonance is directly proportional to the stiffness and inversely proportional to the mass of the middle ear system. For example, in otosclerosis there is an increased stiffness in the system which correspondingly relates to an increase in R F (Figure 2.2). The M F T have become useful tools in assisting clinicians and researchers alike in their understanding of middle ear pathologies; however, there are disadvantages to M F T as well. A pressure seal is needed for M F T to be functional. Multi-frequency tympanometry is also limited in its ability to measure frequencies above 2000 H z leading to a restricted view of the middle ear system.  2.3.4 Wideband reflectance A new measure of middle ear evaluation has been developed called W B R . In order for humans to hear, sound must pass through the external ear canal, the tympanic membrane, the middle ear, and into the cochlea. In doing so, some o f this sound is absorbed by these structures and some is reflected back out of the ear canal. Wideband reflectance is the ratio of energy reflected from the surfaces on its way to the cochlea in relation to the energy that reaches the surface, or incident energy. This ratio is called energy reflectance (ER) and varies from zero, where all sound energy is absorbed, to one, where all sound energy is reflected.  16  Energy Reflectance =  Reflected Energy Incident Energy  (2)  Energy reflectance is derived from wideband impedance measures using a chirp as a probe stimulus. In general, when a middle ear pathology is present that increases the susceptance (i.e. stiffness) of the middle ear, E R at lower frequencies should increase, i.e. more energy is reflected. With middle ear pathologies, such as tympanic membrane perforation, that decrease the stiffness susceptance of the middle ear, E R at low frequencies should decrease, i.e. more energy is absorbed (Jeng, et al., 1999). Following this conclusion, E R at lower frequencies should increase in otosclerosis due to increased stiffness. It has been shown (Shahnaz & Polka, 2002) that otosclerosis affects conductance (i.e. resistance) more than stiffness. In a mechanical system this resistance will result in a rapid decay of vibration. Another measure used in W B R is power absorption (PA). This measure is the reciprocal of E R in that P A is a ratio of incident energy to reflected energy. Power absorption varies from zero, where all sound energy is reflected, to one, where all sound energy is absorbed.  Power Absorption =  Incident Energy Reflected Energy  (3)  Contrary to measures using tympanometry, W B R uses a measure of acoustical immittance as a function of frequency at a constant pressure, usually ambient pressure. The components of both tympanometry and W B R , however, are similar:  Y(/) = G(/)+yB(/)  (4)  17  where Y or complex acoustic admittance is equal to G or conductance (real part) plus B or susceptance (imaginary part, j), at a specific frequency. Piskorski, et al. (1999) chose the three variables o f conductance, equivalent volume, and energy reflectance to represent the acoustic response o f the ears they tested. Conductance, as defined in Piskorski, et al. (1999) by power absorption (II), is expressed as follows:  n(/) = y G(/)| (/)| 2  2  P  (5)  where |p(/)| represents the squared magnitude of pressure at frequency/ Equivalent volume 2  (V), in terms of susceptance, is expressed as follows:  where p is the density o f air, c is the phase velocity o f sound, B is susceptance, and f is frequency. The third variable, energy reflectance, is defined here in terms o f admittance (Y) as follows:  2  lf)  R  l ^(/>  (7)  + Z  where Z = pc/S and Z represents the characteristic impedance o f a cylindrical tube of area S c  c  (i.e. an estimate of the ear canal area). A l l constants are shown in Table 2.1. It is important to note that in W B R machines a normalization factor is implemented, i.e. the characteristic impedance of the ear canal. Due to this normalization factor, admittance values are dimensionless (Shahnaz, 2004). This is discussed further in methods section (3.5.3). 18  A s well, W B R instrumentation does not yet compensate for the effect of the ear canal; thus, results are a combined measure of the ear canal, middle ear, and inner ear (Shahnaz, 2004). Researchers are currently working on ways of compensating for the ear canal.  Units  Constant  Value  Speed of sound  c  33480  cm/s  Density of air  P  0.001223  g/cm  Ear canal diameter  d  0.75  cm  Ear canal area  S  0.43  cm  Specific impedance  pc  40.946  g/s*cm  95.2  g/s'cm  Name  Characteristic impedance  Z =^ e  c  3  2  4  s  Table 2.1: Constants used for admittance-reflection formula calculations. Adapted from Voss and Allen (1994).  The W B R instrumentation consists of a probe system, signal processing board, a compatible laptop computer, and a calibration device. More information about the instrumentation for W B R is given in the Methods section (3.5.3). A probe stimulus is presented from low, usually 250 H z , to high, usually 8000 to 10 000 H z and measures are obtained seconds later using computer averaging. Although research on W B R is limited, early studies have been promising. Keefe, et al. (1993) and Voss and Allen (1994) have studied normal middle ear function in adults using W B R . A m o n g adult patients with middle ear pathologies, research is beginning to discover the diagnostic applications of using W B R to assist in distinguishing middle ear pathologies from 19  normal middle ears and other middle ear pathologies (Feeney, et al., 2003). With regard to children, W B R shows promising results in discriminating children with otitis media from normal hearing children (Jeng, et al., 1999; Piskorski, et al., 1999). Results of W B R measures for middle ear pathologies in adults are scarce. A n article by Feeney, et al. (2003) studied E R in ten adult participants with ages ranging from 21 to 65 years (mean of 42 years) who had a variety of hearing impairments. They compared the E R results of these ten participants to 40 normal hearing individuals with ages ranging from 19 to 24 years (mean of 22 years). In this article, normative data were presented graphically; hence, the mean, S D , and 90% range values were not published. Data have also been obtained from Feeney & Sanford (2004) and is referred to in section 2.4.3. Figure 2.3 shows the group mean data averaged across 75 ears of the 40 normal hearing participants in Feeney, et al.'s (2003) study. Estimate comparisons are also made to normative data from Keefe, et al. (1993) and Margolis, Saly, & Keefe (1999). The general shape is consistent with that seen in children (Jeng, et al., 1999), albeit reciprocal to Jeng, et al.'s (1999) power absorption curve due to the y-axis variable. That is, E R is high in the low frequencies and decreases as a function of frequency to a minimum near 4.0 k H z , and then increases once again until 8.0 k H z .  20  0.2  — — Present Study (n = 75) Keefe etal. 1993(n = 10) Margolis et al. 1999 (n = 20)  0 100  1000 Frequency (Hz)  10000  Figure 2.3: Comparison of adult normative data of energy reflectance (ER) as a function of frequency in three different studies. Data are given as one-twelfth octave ER. Full authors are as follow: Feeney, Grant, and Marryott (2003; Present Study); Keefe, Bulen, Arehart, and Burns (1993); and Margolis, Saly, and Keefe (1999). From Feeney, Grant, and Marryott (2003).  Of the participants with hearing impairments (Feeney, et al. 2003), two patients had otosclerosis. One subject, P5, a 49-year-old woman had an eight-year history of right ear mixed hearing loss. Air conduction demonstrated a moderate loss (40-50 dB HL) from 250-8000 Hz. Bone conduction showed a loss at 2000 Hz of 40 dB HL. Using 226 Hz tympanometry, her SA was 0.4 mmhos and T W was 65 daPa. Wideband E R exceeded the 95th percentile from 250 to 944 Hz but results were within normative values at higher frequencies (Feeney, et al., 2003) as seen in Figure 2.4. The second patient, P6, a 26-year-old woman with bilateral otosclerosis had had previous otosclerotic surgery with slipped prosthesis and disarticulation on the left. The right, nonoperated ear, had air conduction from 25 to 50 dB HL, greater in the lower frequencies, and a slight sensorineural hearing loss notch at 1000 and 2000 Hz. The 226 Hz tympanogram was characterized by an abnormally low SA of 0.2 mmhos and a TW of 110 daPa at the high end of  the normal range. Compared with normative values, the wideband E R was above the 95th percentile from 250 to 1189 H z and 5993 to 7551 H z and lower than the 5th percentile at 4757 H z as seen in Figure 2.4. Together these cases suggest a higher than normal E R for frequencies below 1000 H z for the otosclerotic ears. A s this occurred in both cases, while 226 H z tympanometry was abnormal in only one patient, this suggests increased sensitivity of wideband E R in the presence o f otosclerosis (Feeney, et al., 2003). While Feeney, et al. (2003) present just two cases of otosclerosis, their results are very informative. While these are only case studies, not lending themselves to statistical analysis, these results suggest more research should be done in this area. These two cases o f otosclerosis as seen in Figure 2.4 are o f special interest to this thesis. For the right ear o f P5 (P5R) the tympanometric findings were within the normal limits. Wideband reflectance results, however, picked up a difference, where the E R data exceeded the 95th percentile between 250 and 944 H z . For the right ear o f P6 (P6R) the tympanometric results show an abnormally low S A and a T W approaching the high end of the normal range. Similar W B R results o f P5 show that E R exceeds the 95th percentile between 250 and 1189 H z . In addition, E R for "higher frequencies was mostly within the normal range except for higher than normal E R between 5993 and 7551 H z , and lower than normal E R at the one-twelfth octave centered at 4757 H z . Figure 2.4 depicts these results o f higher than normal E R at frequencies below 1000 H z . Due to the fact that tympanometric results for P5 were considered within normal limits, it has been suggested that the " E R pattern . . . was more sensitive to the presence of otosclerosis than was the 226-Hz tympanometry" (Feeney, et al, 2003, p. 900). A s previously mentioned, the low sample size detracts from the accuracy o f these results, but the overall patterns will likely remain the same, which will hopefully lead to greater diagnostic accuracy for  22  otosclerosis. Feeney, et al. (2003) also point out that the large difference in mean age between the participant groups may be a confounding variable.  3i 100  1000  1—,—r-» Frequency(Hz)  10000  Figure 2.4: Energy reflectance as a function of frequency for two ears with otosclerosis. P5R represents the right ear of one participant. P6R represents the right ear of a second participant. The shaded area represents the 5th to 95th percentile range of normal hearing sensitivity participants. From Feeney, Grant, and Marryott (2003).  While Feeney, et al. (2003) focus on measures of ER, Jeng, et al. (1999) and Voss and Allen (1994) show measures using PA. The results obtained for ER are the reciprocal of those for PA. Thus, the normal pattern of graphed data expected for P A would increase in the lower frequencies and decrease in the higher frequencies, i.e. the peak corresponds to the range that energy is most effectively transmitted to the middle ear. Jeng, et al. (1999), studying children, and Voss and Allen (1994), studying adults, have come to similar conclusions. Only a small amount of acoustic power is absorbed by the ear at low frequencies due to eardrum stiffness, but as frequency increases, the power absorption also increases "such that at 1.0 kHz, just over half of the acoustic power entering the ear canal is absorbed by the middle ear and cochlea" (Jeng, et al., 1999, pp 195-96) and by 3.0 to 5.0 kHz  almost all of the acoustic power is absorbed (Jeng, et al., 1999; Voss & Allen, 1994). That is, the location o f the peak corresponds to the range that energy is most effectively transmitted to the middle ear. Although there are large variations among subjects, Figure 2.5 shows that a general shape is clearly present in the power absorption curve. Other researchers have also observed this pattern in normal middle ears o f adults (Keefe, Ling, & Bulen, 1992; Keefe, et al., 1993; and Voss & Allen, 1994).  c o a. o  j  1r  ...j..:.:,.;  ;  i  \ "  \  <  \1 \ \ ' J.1A 1 . :i  10.5 o CL  1  _  ;  : :  L f  o  10  '  ' •  '. 1  '  ' " " •  z  \  "  \-\:\ i \ v  -  4  l 2  10  10  Frequency in H z  Figure 2.5: Normalized power absorption curves for 30 normal middle ears of children ages 2.5 to 5 years (upper panel). Mean normalized power absorption curve from the above panel with ± 1 standard deviation (dotted lines; lower panel). From Jeng, Levitt, Lee, & Gravel, 1999.  Piskorski, et al. (1999) conducted a study using clinical decision theory to discover whether results from acoustic ear canal responses can predict conductive hearing loss. Using 161 ears from children two to 10 years of age, they classified the ears as normal or impaired with 24  air-bone gap measurements as a 'gold standard'. A multivariate analysis of Y R responses proved that the presence of conductive hearing loss can be predicted, with areas under the response operating curve of up to 0.97 (Piskorski, et al, 1999). Also, they confirmed that the 2.0 to 4.0 k H z frequency range is a "particularly sensitive indicator of middle-ear status" (Piskorski, et al., 1999, p. 1749) and agree with Keefe, et al. (1993) that W B R is a useful clinical tool. Wideband reflectance has a number of advantages and limitations. First, W B R is fast, objective, and non-invasive. Second, contrary to M F T , W B R can measure frequencies exceeding 2000 H z which allows a better 'view' of the middle ear system. Third, with this increased frequency range, W B R provides more precise frequency specific information about the conductive portion of the peripheral auditory system. Fourth, again with relation to the increased frequency range, information can be related from the type of hearing loss to the frequency response of speech. Fifth, when measures of acoustic power flow are used, the problem of standing waves in the ear canal is eliminated (Jeng, et al, 1999). That is, W B R measurements are not "critically dependent on the location of the probe in the ear canal as is the case with pressure measurements" (Jeng, et al., 1999). Sixth, the lack of need for a pressure seal allows for diagnostic use when other measures may harm, or interfere with a middle ear or inner ear disorder. Because of this lack of need of a pressure seal, W B R should be a safe measure to use after surgery for otosclerosis or ossicular discontinuity. A s well, W B R reduces the concern over ear canal compliance in infants (Keefe, et al, 2000). Seventh, there is a possibility to measure more than one resonant frequency in the middle ear system. There are three limitations of W B R . First, W B R is not yet in clinical use. Second, few clinical norms have yet been published for either normal or pathological ears. Third, W B R results must correlate to surgical findings in order for W B R to be deemed diagnostically accurate. A l l of these above limitations may be overcome given time. Research is increasing in  25  this field which can only lead to a better understanding of W B R and a broader usage of this measure. From information known about W B R this should be a very useful measure to diagnose and evaluate treatment in otosclerosis.  It is known that otosclerosis increases stiffness o f the  middle ear system and is classed as a high impedance pathology (Shahnaz & Polka, 2002; Shanks & Shelton, 1991). A s E R drops in the range of 4000 to 6000 H z indicating a stiffness system, then W B R should be abnormal in otosclerosis below 6000 H z . The only published study available using W B R with otosclerotic patients is the two case studies by Feeney, et al. (2003) as described above. Since this study only contained two ears from two different subjects, this author does not believe it justified to try to look beyond a basic pattern for such a limited sample size. Patients of Feeney, et al. (2003), as seen in Figure 2.4, show a basic pattern of higher than normal E R at frequencies below 1000 H z . Wideband reflectance patterns may vary with the degree of otosclerosis; however, there is currently no data to support this premise. 2.4 Normative data Unfortunately, there are no tables available from published studies on W B R to extract precise normative values; thus, estimates taken from published graphs showing normative data are used for comparison purposes. Published normative values are presented mainly as E R graphic data. Graphic presentation of normative data for adults are not given for Y , B , and G in the literature. Recording the data in various formats, e.g. P A , Y , B , and G , allows a more complete view o f the data. This may enhance available information when comparing groups or make the data more comparable to M F T results for further analysis.  2.4.1 Justification for developing gender and race specific normative data based upon previous middle ear studies  26  The effect of gender on normative values obtained from standard low probe tone tympanometry has been evaluated by a number of authors with conflicting results. Comments below are limited to those used in this study as background and supporting measures. While the differences outlined below are marginal, they are sufficient for the current recommendation to be that gender specific normative values be used when completing tympanometric measurements in adults (Shahnaz & Davies, 2004). Margolis and Heller (1987) using a Welch Allen microtymp machine with a pump speed of 200 daPa/s and a pressure range of+200 to -300 daPa found no gender differences for S A or T W . However, Roup, et al. (1998) using a G S I 3 7 machine with a pump speed o f 600/200 daPa/s and a pressure range o f +200 to -300 daPa and Wiley, et al. (1996) using a Virtual 310 and pressure range of +250 to -300 daPa found males to have a larger mean S A than females, but with similar lower margins o f the 90% range. Shahnaz and Davies (2004), using the Virtual 310, pump speed o f 125 daPa/s and pressure range of +250 to -300 daPa found no gender effect for S A , but the lower margin of the 90% range was 0.30 mmhos for males and 0.36 mmhos for females. Both Shahnaz and Davies (2004) and W a n and Wong (2002); using a GSI 33 machine, with a pump speed o f 600/200 daPa/s and pressure range o f +200 to -200 daPa, showed no significant statistical difference between mean or 90% range results for S A among Chinese males and females. While there were differences in procedure from study to study, each used the same procedure for males and females within an individual study. Some differences in S A according to gender appear to be present. Fewer authors have studied gender effect for M F T . The measures o f particular interest for this study are R F . Margolis & Goycoolea (1993) and Shahnaz & Polka (1997) demonstrated a trend for higher R F in Caucasian males over females, whereas Wiley, et al. (1999) found female results to be higher. Shahnaz and Davies (2004) found no differences for R F by either  27  recording method or compensation method in either Caucasians or Chinese. However, the 90% range differed regardless of the method used suggesting the need for male and female normative values. Most published normative data for middle ear measures do not mention the racial background of their subjects. T o accomplish such studies definitions of race are necessary. Shahnaz and Davies (2004) used the following definitions that are also used in this study. Chinese participants were primarily immigrants from mainland China, Hong Kong, and Taiwan, i.e. both grandparents and parents were from these areas. This is similar to the definition of W a n and Wong (2002) for tympanometric measurements. Their Chinese youth were descendants of immigrants from mainland China without traceable foreign decent. Using the Statistics Canada (2002) definition, Shahnaz & Davies (2004) defined Caucasian as non-Hispanic, non-Aboriginal, non-Arab/West Arab, non-Black, non-East/South/South-East Asian, with white or light skin and of European descent. Race was determined by self report. From low frequency tympanometric measures, Chinese subjects were found to have lower S A than Caucasians (Shahnaz & Davies, 2004). Similarly, from M F T measures, Chinese subjects have higher mean R F than Caucasians thought to be associated with increased stiffness in the middle ear transmission system (Shahnaz & Davies, 2004). These findings lead Shahnaz and Davies (2004) to recommend race specific normative data for all tympanometric measures. The results are convincing and future studies and clinical work should consider race specific normative data. A s yet there are no data specifically linking S A and R F measurement results to those o f W B R . However, in view of the gender and racial differences just discussed, these variables must be taken into consideration in this study.  28  2.4.2 Normative values for wideband reflectance Normative values for W B R are few and there are significant difficulties in comparing them. A s seen in Table 2.2, instrumentation and procedures differ among the studies available giving normative values for adults. In addition, normative information is given graphically. This is likely due to the complexity of addressing the numerous frequencies tested. The numbers of subjects in each study are relatively few. A s described by Voss and Allen (1994) considerable variability is noted. While there are a number of ways that W B R measures can be expressed, most studies report E R or P A . Race is not mentioned in these papers.  29  No. of Measure  Age Investigator  Machine  M/F  Adults  Chirp signal  Frequency recorded  (years) (ears) Briiel and Kjaer 4157 Voss & and Industrial 10  Allen  18-24  1024-point,  100-15000  12.8 ms  Hz  2048-point,  125-10700  40 ms  Hz  ER, impedance  N/A  Research (1994) Products, Inc. DB-100  One-third Keefe, et al. custom made*  10  N/A  octave averaged  N/A  (1993)  ER  Margolis, et custom made*  20  20-53  10/10  al. (1999) Feeney, et custom made* al. (2003)  40 (75)  19-24  20/20  125-11310  ER at 0, +300  Hz  and -300 daPa  200-10000  One-twelfth  Hz  octave ER  40 ms at 12.5/s  40 ms at 12.5/s  Table 2.2: Procedural variables for measuring wideband reflectance in published studies. N / A = information not available. Full investigator names include: Feeney, Grant, & Marryott (2003); Keefe, Bulen, Arehart, & Burns (1993); and Margolis, Saly, & Keefe (1999). * Custom-made wideband reflectance machine by Keefe, Ling, Bulen (1992); modified and used by Keefe, et al. (1993); used by Margolis, et al. (1999) and Feeney, et al. (2003).  In their 1994 paper, Voss and Allen present case study data o f 10 normal adult subjects, 18-24 years. Their work establishes E R and impedance patterns. Graphical representation of means and standard deviations is shown for reflectance. The series of graphs show considerable 30  variability. The variability was believed to be due to subject cochlear and middle ear impedance differences. Voss and Allen (1994) replicated their own individual subject data. Static air pressure was not measured. They found the reflectance patterns to be highest in the lower frequencies, dropping at 2000 to 4000 Hz and then rising. Similar E R patterns have been since found. In their 1993 paper, Keefe, et al. examined young children as well as healthy adults. For this study only information from the 10 healthy adults is reviewed. The instrument was custom made based on earlier work by Allen (1985) used to measure eardrum impedance of cats. This instrument differs from Voss and Allen (1994), but is used or modified by the three authors with published normative values, i.e. Keefe, et al., 1993; Margolis, et al., 1999; and Feeney, et al., 2003. The results o f Keefe, et al. (1993) were reported as third-octave averaged E R with a pattern similar to those o f Voss and Allen (1994). For the 10 adult subjects the mean and standard deviation for the minimum value o f E R was 0.35 ± 0.20 at 3200 Hz, and a maximum value of 0.73 ± 0.18 at 8000 Hz. Variations between subjects were noted. T o a lesser extent than subject variability, measurement errors of E R related to ear canal volume and were noted mainly under 2000-3000 Hz. In 1999, Margolis, et al. studied 20 normal subjects using W B R tympanometry, with the majority of the data collected above or below ambient pressure, but not at static ambient pressure. The results as published are not strictly comparable to other results. Gender differences were noted for middle ear impedance, but not mentioned for E R . Reflectance as a function o f frequency at 0 daPa is given in F i g 2.6, (Margolis, et al, 1999, Figure 6c, p. 273). The curve of this graph is in standard numeric format, decreasing from the low frequencies to about 3000 Hz and then increasing. This is the same pattern o f the normal E R as previously described.  31  Ul 0.3 4 0.2 0.1 Q  #  Q  .J >—— | —I j—j—| +  o C4  IA  n  o o  1—t—t— ) • >••. i - . - t — r — | - - 4 — t — t — 4 — f - t — ( — ^ - H - 4 - - + - f - 4 — - H r  f O  ^ O  O T  O -  O O  o cv  O  O  O  O  a  O U  C J  J O  O O  <0  CM  FREQUENCY (Hz) Figure 2.6: Average energy reflectance as a function o f frequency. Adapted from Margolis, Saly, & Keefe, 1999, Figure 6c, p. 273.  A s seen in Figure 2.3, Feeney, et al. (2003) incorporate their own data and those of Keefe, et al. (1993) and Margolis, et al. (1999) each on their own curve, now using logarithmic x-axis. The latter has the effect of accentuating the values for the higher frequencies. It is likely that Feeney, et al. (2003) used the raw data from these authors to construct the figure. Feeney, et al. (2003) had 75 ears obtained from 40 young adults subjects. Data were derived from wideband impedance measures at ambient pressure. The normative values, including graphing presentation of the mean and 5th and 95th percentile, are presented as E R . Subsequently, individual data from Feeney, et al.'s (2003) series of case studies were superimposed on the 90% range graphic data. Data from individual cases falling outside this range or cutoff were considered abnormal. Only one paper, Piskorski, et al., (1999) gives normal data on conductance in children, confirming high resistance in the lower frequencies with a gradual decline to 8000 H z . 32  With regard to gender and ear differences using WBR, the only study found to statistically account for these variables was by Keefe, et al. (2000). Findings from neonatal ears state that the "left ear was acoustically stiffer than the right ear, and that the female ear was acoustically stiffer than the male ear" (Keefe, et al., 2000, p. 461). This was thought to be related to neonatal specific factors, i.e. vernix fluid. As such, W B R ear differences would be unlikely among adults. Normative data accompanying the Mimosa Acoustics RMS-System v4.0.4.4, that is the instrument used for this study, is shown graphically below in Figure 2.7 as PA. (The reciprocal, ER, is also available by Mimosa.) Mimosa literature does not give the race, gender, age, or number of subjects used to obtain this normative data. It is assumed that this Mimosa data combines the genders. Normative values from this study will be visually compared with these normative values and differences discussed in the results section.  | Power Absorption  A  ^ I smooth: no •  100 80  -  60  CN  cr +  40 20 0  1000  2000 3000 4000 frequency [Hz]  5000  Figure 2.7: Power absorption graph as seen before testing begins. The shaded area represents normative adult values provided by Mimosa Acoustics. From Mimosa Acoustics R M S system version 4.0.4.4.  33  The above descriptions demonstrate how little normative data for adults tested using W B R are available. The primary concern is a lack of consistency or known comparability among studies in the instrumentation. This concern is extended to the present study where the Mimosa Acoustics RMS-System v4.0.4.4 differs from Keefe, et al.'s (1992) custom machine and its successor used by Feeney, et al. (2003). Other concerns include small sample sizes, not to mention lack of stratification by race and gender. In addition, the primary mode of publication is by graphing which does not lend itself to comparison with the present data. Another problem is the lack of detailed description of the subjects of the normative database o f Mimosa Acoustics and a failure of information regarding gender. Some corrections could make up for the deficits of the published normative data on W B R . T o attempt to overcome this, data from Feeney and Sanford (2004) were obtained and are discussed in section 2.4.3. The most important correction this study can make to this literature is to describe the collected normative data clearly by gender and race. Given the differences found in tympanometric data as described in 2.4.1 and the recommendations by Shahnaz and Davies (2004), failure to analyze this normative data by the important variables of gender and race would diminish its value for both research and clinical purposes.  2.4.3 Normative data obtained from unpublished data A s raw data values, and actual mean, standard deviation, or 90% range are not given in the previously mentioned publications of Feeney, et al. (2003), Margolis, et al. (1999), or Keefe, et al. (1993), a request was made to Dr. M . P . Feeney for more information. Data prepared for a soon to be published paper by Feeney and Sanford (2004) were received for W B R consisting of 15 frequencies representative of the test frequencies between 250 to 6000 H z . Data were from 40 subjects (20 males and 20 females), with a mean age of 21 years. The race of the subjects is unknown. N o gender specific data are given. Data were received for four variables, E R , Y , B ,  34  and G presented as mean, 5th, and 95th percentile. These data are presented in Tables A l , A 2 , A 3 , and A 4 in Appendix I. Data for the variable o f E R were transformed into its reciprocal P A . The mean and 90% range of this P A data can be found in the results section (Figure 4.1) presented with the data from this study on the same graph. A s expected from the previously mentioned graphic normative data, a steep rise in percent P A is noted in the lower frequencies under about 1200 H z and a decline in percent P A after 4000 H z . In frequencies around 2000 H z a flattening effect is seen. 2.5 Goals of this thesis  2.5.1 Underlying hypothesis of the total project Differences between normal and otosclerotic ears are more evident at frequencies above 226 H z which are rarely tested in routine clinical practice. Wideband reflectance will provide a more detailed picture of the mechano-acoustical properties of normal and otosclerotic middleears across a much wider frequency range than standard middle ear analysis techniques.  2.5.2 Objectives of this thesis The primary objective objective o f this study is to determine gender and racial differences within the normative values for power absorption, admittance, susceptance, and conductance of W B R measures measures in Chinese and Caucasian adults. The second objective is to explore i f W B R is clinically useful in measuring predictable differences from normative population data in a group of patients with surgically confirmed otosclerosis.  2.5.3 Specific research questions addressed by this thesis There are three specific research questions addressed by this thesis. They are as follow: 1. Are there differences in collected normative W B R data in relation to gender and race?  35  2. H o w does the normative data collected on W B R measures compare with those in the literature? 3. H o w does the collected data on otosclerotic ears compare with normative W B R data collected for this thesis?  36  Chapter UI Methods 3.1 Research design The study was a cross-sectional, group comparison study of a sample of normal hearing subjects and a consecutive group of patients with surgically confirmed otosclerosis. This was exploratory, such that, the number of study subjects with otosclerosis is inadequate for definitive statistical comparison of audiological parameters with those of the normal subjects; however, it will provide significant contribution with regard to potential clinical applicability of W B R . 3.2 Subjects  3.2.1 Inclusion criteria for normal subjects. 1. Chinese or Caucasian as defined in section 2.4.1. 2. Age of between 18 to 34 years. 3. Normal otoscopic examination. 4. Pure tone audiometric thresholds lower than 25 dB H L at octave frequencies between 250-8000 H z with no air-bone gap greater than 10 dB at any frequency. 5. Normal hearing status as determined by passing a transient-evoked otoacoustic emissions ( T E O A E ) . T E O A E s provide a screening for normal middle ear and cochlear function and are quite sensitive to conductive hearing loss (Koivunen, Uhari, Laitakari, Alho, & Luotonen, 2000).  3.2.2 Inclusion criteria for study subjects. 1. Normal otoscopic examination with the exception of Schwartze's sign. 2. Pure tone audiometric thresholds assessed, but there no cut-off limit for abnormal functioning. 3. T E O A E s used to verify pure tone results in otosclerotic patients. N o criteria set.  37  4. Otosclerosis confirmed at surgery. 5. Able to give informed consent.  3.2.3 Exclusion criteria for normal subjects 1.  Evidence of eardrum abnormalities excludes a subject. The exclusion of subjects with tympanic membrane abnormalities is necessary because the associated low impedance masks the more medially significant high impedance pathology of otosclerosis (Feldman, 1974).  2.  If more than one-third of the tympanic membrane could not be seen, the ear was excluded.  3.  A history of head trauma or recurrent otitis media.  3.2.4 Exclusion criteria for study subjects 1.  If any evidence of eardrum abnormalities (with the exception of Schwartze's sign) is present, the subject's results were excluded.  2.  If more than one-third of the tympanic membrane could not be seen, then ears were cleaned by an otolaryngologist before testing, or results were excluded.  3.  A history o f head trauma or recurrent otitis media.  4.  Known previous ear surgery, including surgery for otosclerosis in the ear under study.  3.2.5 Description of normal subjects Two populations were used for the collection of normative data for a total of 128 subjects (240 ears).  3.2.5.1 Caucasian normal subjects A s otosclerosis occurs more frequently in Caucasian subjects, Caucasian normative data were collected. Sixty-two subjects volunteered. Twenty-eight Caucasian male subjects (51 ears)  38  with a mean age o f 27.3 ± 4.7 years participated in this study. Thirty-four Caucasian female subjects (64 ears) with a mean age o f 24.4 ± 3.9 years participated in this study. Data from another nine Caucasian ears were omitted due to wax, failure to meet T E O A E inclusion criteria, or incompletion of testing.  3.2.5.2 Chinese normal subjects Racial differences in normative data were sought in this study. Chinese make up a significant proportion of the population o f Greater Vancouver. O f note, otosclerosis is infrequent among Chinese (Declau, et al., 2001). Sixty-six subjects volunteered. Twenty-four Chinese male subjects (46 ears) with a mean age of 24.1 ± 4.5 years participated in this study. Forty-two Chinese female subjects (79 ears) with a mean age of 23.4 ± 4.6 years participated in this study. Seven ears were omitted due to wax, failure to meet T E O A E inclusion criteria, or incompletion of testing.  3.2.6 Description  of study subjects  Ten study subjects volunteered. Data from one subject was excluded due to previous ear surgery. One other subject volunteered but was not tested because she had had previous otosclerotic surgery on the ear to be studied. Another subject o f Chinese background was fully tested, but data were excluded due to extreme negative middle ear pressure. Seven study subjects (one male, six females, seven ears) with otosclerosis were tested from June 15 to August 25, 2004. Otosclerosis has been surgically confirmed in two o f these subjects to date (Appendix II). While both ears o f these seven subjects were fully tested, only results from the ears with otosclerosis were used. The mean age o f the study subjects was 41.4 ± 11.4 years (range 24 to 56 years).  39  3.3 Recruitment  3.3.1 Recruitment of normal subjects Subjects were recruited through advertising on the University o f British Columbia campus. Potential subjects were contacted by the investigator and a brief interview was conducted to determine eligibility. See Appendix HI for the telephone questionnaire and Appendix IV for the email questionnaire. Appointments were made at the Middle Ear Laboratory where subjects were tested. Informed consent was obtained before testing.  3.3.2 Recruitment of study subjects Patients with otosclerosis were recruited from consecutive patients awaiting surgery for their ear condition at St. Paul's Hospital (Vancouver). They were recruited through an introductory letter describing the study some months prior to their surgery date. This letter provided details of how to contact the principal investigator should potential subjects have further questions. Patients who agreed to participate in this project were required to remain for approximately 15 minutes longer at an otherwise regularly scheduled pre-operative evaluation in order to complete the additional testing. The purpose and procedures o f this project were discussed in lay terms with those subjects who indicated that they wished to participate. This was done prior to the commencement of the already established pre-operative audiological evaluation which took place at St. Paul's Hospital. This investigator discussed the project and consent form with the subjects and addressed concerns. Informed consent was obtained. A copy of the consent form is found in Appendix V .  40  3.4 Ethics approval  3.4.1 Ethics approval Ethics Board approvals were obtained from the University of British Columbia ( R E B File number C04-0098) and the University of British Columbia/Providence Health Care Office of Research - Research Ethics Board at St. Paul's ( R E B File number P04-0059).  3.4.2 Consent retention A l l signed consent forms are locked in a filing cabinet in the Middle Ear Laboratory. 3.5 Instrumentation  3.5.1 Inspection, audiometry, and transient-evoked otoacoustic emissions Otoscopy was conducted with a Welch-Allyn clinical otoscope with disposable tips. For pure tone audiometry, an O B 802 audiometer was used for the normative subjects and a GSI 10 audiometer was used for the subjects with otosclerosis, both calibrated to A N S I standards (re: S3.6.1989). Supra-aural earphones (TDH-39) were used to test hearing levels in a sound booth. Transient-evoked otoacoustic emissions were tested using an ILO-292 Analyzer (Otodynamics, Ltd., Hatfield, England) calibrated based on the operators manual from the manufacturer. Transient-evoked otoacoustic emissions are used widely within the clinical field and are safe, non-invasive, and risk free for young children, adults (Robinette & Glattke, 2002), as well as newborns (NIH, 1993). A hypoallergenic probe tip containing a microphone was inserted into the outer ear canal. A series of clicks at approximately the loudness of conversational speech (80 dB pe) were presented to each ear. Emissions from the cochlea were measured and averaged by a computer.  3.5.2 Tympanometry The Virtual 310 digital immittance instrument, commercially available and routinely used to test newborn through geriatric patients, was used for this study. This instrument which  41  contains an extended high frequency option, was calibrated before each data collection session using three standard cavities (0.5, 2.0, and 5.0 cm ) as specified in the operation manual 3  provided by the manufacturer. Data obtained through tympanometry is not part of the normative data for this study, but will be used for a larger study and provides background for testing patients with otosclerosis.  3.5.3 Wideband reflectance Wideband reflectance is safe, non-invasive, and extremely efficient, taking only two to three seconds to measure each ear. A Mimosa Acoustics (RMS-system v4.0.4.4) wideband reflectance machine was used for this study. The instruments consist o f an I B M compatible laptop or desktop computer with a Type II P C M C I A slot for audio data acquisition and delivering and for digital signal processing, a probe interface cable which connects the probe to the P C board and functions as the pre-amplifier for the probe, and an E R - 1 0 C P probe (acoustical probe) with two output transducers and one input transducer (microphone). A four-cavity calibration device which is supplied with the W B R instrument is also required. The computer should be placed at least one and one-half meters from the subject while testing occurs. The DSP-Card, with the "Mimosa Acoustics" label up, is inserted into the P C M C I A slot of the computer. The Probe Interface Cable (PIC) then joins the DSP-Card to the probe.  42  Figure 3.1: Components of the Mimosa Acoustics (RMS-system v4.0.4.4) wideband reflectance machine. In order to ensure that there is a proper probe fit for both calibration and testing, it is important to keep the plastic tube of the ear tip flush with the front edge of the ear tip, to properly align the ear tip with the probe, and to roll the ear tip evenly prior to insertion to decrease the diameter of the tip and prevent leakage. The appropriate ear tip size should also be selected for each subject. Both plastic and foam ear tips are available in a variety of sizes for the Mimosa Acoustics instrument. Foam ear tips were used in this study and were calibrated appropriately. Calibration of the W B R machine was completed using the four-cavity calibration device prior to each subject. Once the appropriate ear tip size had been selected and each of the four calibration cavities had been measured individually, an overall calibration was completed. A value of at least 91% was required for testing to proceed. A l l subjects in this study passed with the calibration at or above 91%.  43  The Mimosa W B R machine used in this study, collected data using impedance (i.e. the reciprocal of admittance). Data were then mathematically altered by the instrument to present the other variables. Power absorption was presented automatically in percent; hence, the ratio value from zero to one was multiplied by 100. The admittance variables of Y , B , and G were presented in unitless values as they were normalized by the characteristic impedance of the ear canal. Using an average adult ear canal size of 0.75 cm, the characteristic impedance can be calculated.  Zc = ^ S  (8)  Formula (8) defines Z as the characteristic impedance of the ear canal, p as the density o f air, c c  as the speed o f sound, and S as the area o f the ear canal. Impedance, as measured by the instrument, was then divided by the characteristic impedance in order to obtain the normalized values and attempt to compensate for the effect o f the ear canal. Four data graphs were available for each patient. Each o f these data graphs can be set up to show one of fourteen different y-axis variables: Sound pressure level, Sound pressure level (Group Delay), Power Reflectance, Reflectance (Group Delay), Power Absorption, Impedance (Real Part), Impedance (Imaginary Part), Admittance (Real Part), Admittance (Imaginary Part), Impedance (Magnitude), Impedance (Group Delay), Admittance (Magnitude), Admittance (Group Delay), and Sound intensity level. The variables chosen in this study, as already discussed, are Power Absorption, Admittance (Magnitude), Admittance (Imaginary Part), and Admittance (Real Part), previously referred to as P A , Y , B , and G , respectively. The three admittance variables were chosen because they best approximate tympanometric admittance data to be more comparable for future research. A s well, by evaluating these components, the  44  underlying mechanism of difference between races and normal and diseased groups may be observed. During testing two of the four data graphs were set to power absorption as a function of frequency and the other two were set to power reflectance as a function of frequency. See Figure 3.2. This was done so that the Mimosa Acoustics normative values could be visualized while testing. It was not necessary to run tests for all the variables used in this study as the Mimosa software automatically calculates values for the other variables if they are chosen from the menu. See Figure 3.3. J Left Ear Power Absorption  ~3  smooth: | no  -UElJ-JJJJ-J  3  3  Power Abswption  3]  smooth: jno  *  100 80  100  I« cr  J 40 20 0 10'  10 frequency IHz) D  Power Reflectance  10 frequency [Hzj  3 snwothj-o  Power Reflectance  ao E 60  £ 60 £ 40 20 0 10  10 frequency [Hz]  fc 40 20 0 10  10 frequency [Hzj  Figure 3.2: Organization of data graphs during testing using the Mimosa Acoustics (RMSsystem v4.0.4.4) wideband reflectance machine. The shaded area represents normative data provided by Mimosa Acoustics.  45  3 srnootli |nc  Poww Absorption  smooth: ] no *  Admittance (Imag Pail]  100 80  i»  '"A „  p10  If  o:  J  /  40 20 1000  0  2000 3000 4000 frequency [Hz]  Admittance |Magn)  5000  1000  2000 3000 4000 frequency |Hz]  5000  _»] smoo jthno " tf N.  /  1000  2000 3000 4000 frequency [Hz]  5000  1000  2000 3000 4000 frequency [Hz]  5000  Figure 3.3: Graphical view of the four variables used in this study: Power absorption, Admittance (Magn), Admittance (Imag Part), and Admittance (Real Part). The shaded area refers to normative data provided by Mimosa Acoustics. Of these, only the power absorption curve was visualized during testing. The admittance variables were calculated automatically by the Mimosa software after testing was completed. Frequency is represented in linear format.  The test is then run by selecting the correct type of ear tip used for the subject, the ear to be measured, and the Reflectance Measurement System (RMS) icon. A new window then opens which allows for a single measurement to occur (Figure 3.4). The result can then be accepted or re-measured depending on whether the signal-to-noise ratio is adequate across all frequencies tested. Measurements were accepted only if the signal was visible clearly above the noise value at the lowest measured frequency. The input spectrum should also be as smooth as possible. Up to eight individual measurements can be taken during one testing session.  46  Measurement Data Collection  input spectrum  10'  10 frequency [Hz] Passes= 25; Rejects= 0; A/D-overflows= 0  Commen:t ^htEar,Ti14A No. of averages: j 25 output atenuation(dB): 19E . Cancel | Remeasure Accept P  Figure 3.4: Measurement data collection screen used to acquire subject results from Mimosa Acoustics (RMS-system v4.0.4.4) wideband reflectance machine. The above shaded region represents the signal level, while the below shaded region the noise level.  For each ear, at least two individual measurements were taken in order to judge test-retest reliability. In order to check the test-retest reliability of the measures, at least two of the measures taken must visually approximate the other using the PA curve. This can be seen in Figure 3.5.  47  J J J J J J Power Absorption  \ w £ ZJ  3  smooth: | no J^J  100 60 CN  60  f  40 20 .. 0  /  /  \  ;  1000  J  !  2000 3000 4000 frequency [Hz]  5000  Figure 3.5: Visual measure of test-retest reliability using the power absorption curve.  Once testing was complete, data could be viewed graphically as any of the 14 y-axis variables listed above. See Figure 3.3 for a visualization of the variables used in this study. In order to obtain the numerical results, each saved graph was exported separately from the Mimosa Acoustics software into a text file and then into a Microsoft Excel file where it could be analyzed further. 3.6 Procedure 3.6.1 Testing done prior to subject inclusion in this study Otoscopy was performed on all subjects to rule out excessive cerumen, discharge, or gross tympanometric abnormalities. Appropriate referrals were made when necessary. Pure tone audiometry was performed in a standard sound booth using a 10 dB H L down, 5 dB H L up bracketing technique. Behavioural responses were recorded for the softest tones heard. These above tests are part of the regular pre-operative evaluation for otosclerotic patients and were mandatory; further testing proceeded only with the written consent of the patient. The T E O A E test was conducted in a quiet room using a laptop computer. Results indicate status of the middle ear and cochlea. Testing of TEOAEs was completed after pure tone 48  audiometry in order to avoid researcher bias with prior knowledge of middle ear or cochlear status. Measurements were considered unreliable when the stimulus level in the closed ear canal was less than 71 dB pe. Each of the five frequencies, 1000, 1500, 2000, 3000, and 4000 H z , were estimated separately. Transient-evoked otoacoustic emissions were considered to be present when the amplitude o f the emission was greater than, or equal to 3 dB relative to the noise (i.e. >3 dB signal-to-noise ratio) from frequencies 1000 to 3000 H z .  3.6.2 Testing done after subject inclusion in this study If the subject met the inclusion criteria, as described in section 3.2, tympanometry was performed. Subjects were tested using both standard tympanometry and M F T . For the normal subjects, as both ears were being used, alternate ears were tested first to prevent order effects. For the study subjects, the otosclerotic ear was tested first. For W B R , four parameters were computed: power absorption (PA), admittance magnitude (Y), susceptance (B), and conductance (G). The data were recorded in P A and then exported into text format for the four variables of P A , Y , B , and G . The data from each subject were then imported into a Microsoft Excel spreadsheet. A l l the data from each subject were then transposed and compiled into a database based on variable (i.e. P A , Y , B , and G). In total, data from 248 frequencies, dispersed evenly from 211 to 6000 H z , were collected. These measurements allowed the researcher to evaluate subtle mechano-acoustical changes o f the middle ear across a wide range of frequencies. Each o f the W B R variables was analyzed across the entire frequency range.  3.6.3 Background tympanometric testing used in this study The data obtained using the Virtual 310 system was not analyzed in this study as it was collected in lieu of larger study which is not relevant to the scope this paper. However, both  49  standard tympanometric and multi-frequency tympanometric results were used as background information for the otosclerotic subjects. 3.7 Data handling Graphics give data as mean and 90% range. This range includes those values falling between the 5th and 95th percentiles. Values beyond the 90% range were considered abnormal. The value of the 90% range was useful as it provides cutoff points for differential diagnosis. Normative data from the literature were limited to some variables (i.e. P A and E R ) and were provided in graphic forms showing the 90% range. Similarly normative data from the Mimosa Acoustics machine were provided showing 90% range for P A . Gender and race specific normative data were generated by this study for P A , Y , B , and G . These were given in graphic format using Microsoft Excel to show mean and 90% range. Graphic comparisons between normal subject groups were made. Comparison between otosclerotic subjects as a group and normative data were problematic due to a sample size of seven. Thus, data from a series of otosclerotic case studies were individually plotted alongside appropriate normative data showing the mean and 90% range. This allowed visual determination of the frequencies or ranges of frequencies where the data of the subjects were beyond the cutoff values. 3.8 Data analysis Prior to repeated measures analysis of variance ( A N O V A ) , the data from normal subjects for each of the four variables of the W B R measure was explored using box-plots. The data were observed for asymmetry in empirical distribution and outliers were identified. Square root transformation was done to identify only the extreme outliers. These extreme outliers due to measurement errors were excluded from further analysis e.g. negative values using the P A variable which is measured in percent.  50  For each o f the 248 frequencies from 211 to 6000 H z , four variables were recorded, P A , Y , B , and G . Under these circumstances, repeated measures A N O V A was advantageous as error variance is reduced by decreasing variability among subjects. In repeated measures A N O V A each subject was considered as a block and thus variability among blocks was taken away from the error variance, making the test of significance more sensitive. Another advantage o f repeated measures design was that as the subjects are measured repeatedly, fewer subjects were required for the study to detect a significant difference between groups. Level o f frequency, a continuous variable, was considered to be the within subject factor. Between subject factors for the categorical variables of gender (male and female), race (Chinese and Caucasian), and ear (right and left) were established. Significant effects were further explored using 95% confidence intervals (CI) at each frequency level for the four variables. Significance was determined in two ways: (1) by comparison o f means with values of p < .05 considered significant, and (2) by clear separation o f the 95% CI plots.  51  Chapter IV Results and Discussion This study evaluates the effect of gender and race, Chinese compared with Caucasian, on normative values for four wideband reflectance ( W B R ) measures and presents the pre-operative test results using W B R for seven cases of otosclerosis. These W B R measures include power absorption (PA), admittance (Y), susceptance (B), and conductance (G). In order to effectively use W B R in clinical practice, all sources of subject variability that can affect the outcome of measurement should be considered. These currently known sources of variability include: age, gender, and race. A s age is limited for the normal subjects of this study to healthy young adults and is similar to that of the subjects of Feeney, et al. (2003), age is not evaluated. There are no age-specific normative values for W B R from older adults at this time. The two variables considered as sources of variation for normative values in this study are gender and race. This variation is considered for three reasons. First, it allows for the creation o f gender specific or race specific normative data. Second, previous reports for other measures of middle ear function have suggested gender or racial differences. Margolis, et al. (1987), Roup, et al. (1998), Wiley, et al. (1996), Shahnaz and Davies (2004), and Wan and Wong (2002) have reported differences in normative tympanometric data either by gender or race or both. (See section 2.4). Based on their recent study, Shahnaz and Davies (2004) recommended the use o f gender specific and race specific (Chinese and Caucasian) normative data for both low frequency tympanometry and M F T . Third, this method helps to answer the question whether data by gender and race should be collapsed when normative data are compared with that of different middle ear pathologies. For W B R measures there are seven ears from seven otosclerotic subjects and 240 ears from 128 normal subjects (51 ears from 28 Caucasian males; 64 ears from 34 Caucasian females; 46 ears from 24 Chinese males; and 79 ears from 42 Chinese females). Analyses for gender and '  52  racial differences were completed for each o f the four measures of W B R for normal subjects. A l l seven otosclerotic subjects were Caucasian. Comparisons were made with Caucasian normal subjects, using gender specific data as appropriate. The organization o f this chapter is by section, first according to each of the four measures given above, then by case histories. For each of the four measures, subsections are as follows: (1) procedure, (2) between gender and race statistical analysis for normal subjects to justify whether race and gender specific normative values should be used, (3) graphed normative data by race and gender, and (4) discussion o f normative data. Within the subsection on P A , normative data from this study is plotted alongside normative data from Feeney and Sanford (2004, Figure 4.1). The second section of the results gives the case histories o f the seven otosclerotic subjects with their individual data presented graphically relative to normative data. A s statistical analysis would be problematic due to the small sample size, this method allows for interpretation of the data and formulation of future recommendations. 4.1 Power Absorption  4.1.1 Procedure A commercially available W B R machine developed by Mimosa Acoustics was used for this study. Calibration o f the W B R machine was completed prior to each subject using the fourcavity calibration device. A value o f at least 91% must be obtained in order for testing to proceed. A l l subjects in this study passed with the calibration at or above 91%. Each of the four variables used as part o f the W B R measure in this study were chosen from 14 possible variables within the Mimosa Acoustics W B R machine's software. Power absorption was chosen as the measure that would be visible on the screen while testing was in progress so that each subject's results could be readily compared with Mimosa's normative data collected by Voss and Allen.  53  A broadband chirp stimulus of between 200-6000 H z was presented and data from 248 frequencies (at approximately a 23.3 H z interval) between 211-6000 H z were collected. Once testing was completed, data were saved and exported to a Microsoft Excel spreadsheet where further analysis took place. Each ear took approximately 2-3 seconds to test. Prior to graphing the data by gender and race, the 90% range for 15 frequencies of the combined Caucasian and Chinese groups o f this study was compared with the requested unpublished normative values by Feeney and Sanford (2004). Feeney and Sanford's (2004) data were equally divided by gender and were o f unknown race. It was thus assumed that no selection criteria were made for race when establishing the normative values. A s such, data from this study were averaged across gender and race, and combined for overall mean, 5th, and 95th percentile values. The data, as received, were then transformed into P A . Knowing that E R and P A are reciprocal ratios, Feeney and Sanford's (2004) E R ratio data were converted using simple subtraction from one and then multiplied by 100 in order to gain percent values to be compatible with results from this study. Table A l (Appendix I) gives the E R mean, 5th, and 95th percentile data from Feeney and Sanford (2004). A s seen below in Figure 4.1, the mean and percentile data from Feeney and Sanford (2004) and the combined gender and race data from our study show a fairly steep increase in the percent of P A until about 1200 H z . The values from this study were all substantially higher from 250 to approximately 3500 H z where there was a reversal. These differences may be due to the W B R machine used, race, units o f presentation, or some other, yet unexplained factor. Further comparisons can be done when more specific information from Feeney and Sanford's (2004) data are available.  54  Comparison of Power Absorption as a Function of Frequency  6000 Frequency (Hz)  Present Study - 95th Percentile —  Feeney & Sanford - 95th Percentile  Present Study - Mean ^ ^ ^ F e e n e y & Sanford - Mean  Present Study - 5th Percentile —  Feeney & Sanford -5th Percentile  Figure 4.1: Comparison of power absorption as a function of frequency. Mean, 5th, and 95th percentile values are plotted. Data are from Feeney and Sanford (2004) and combined race and gender normative values from this study.  4.1.2 Between gender and race statistical analysis The data for the variable P A were explored using repeated measures A N O V A . The variables of interest for this analysis were the between subject factors of gender (male or female), race (Chinese or Caucasian), and ear (right or left). The within subject factor was level of frequency. Preliminary box-plots showed that the distribution of P A was symmetrical except for very few outliers. Six extreme outlier observations (ear outliers) o f three subjects, defined by negative values, were eliminated. A s the empirical distribution of the P A data was symmetrical, no transformation was needed. Had this distribution been asymmetrical, a transformation, such  55  as, square root transformation, would have been used to allow for a more normal distribution and to define the most extreme outliers. Table A 6 (Appendix V ) shows the A N O V A summary table. The main effect o f race was significant [ F ( l , 235) = 12.45, p = .001]; however, the effect o f gender and ear were not significant [ F ( l , 235) = 1.53, p = .218], and [ F ( l , 235) = 0.78, p = .377], respectively. There were no significant interactions. Gender differences were not observed within either race. T o find at which frequency differences occurred between different races o f the same gender, 95% CI plots were observed. A s confirmed by 95% CI plots, Chinese and Caucasian females differed at frequencies 422-1805 H z and 4313-6000 H z . Caucasian values were higher in the lower frequencies and lower in the higher frequencies. Similarly Chinese and Caucasian males differed. In the lower frequencies, 352-1266 H z , Caucasian males had higher averages than Chinese males, but at 3891-6000 H z the reverse is true. There were no ear differences. A possible explanation for the above findings is that higher P A in lower frequencies reflects more efficiency within the system. Caucasian males and females demonstrated higher values, suggesting greater efficiency, at lower frequencies. This is presumably due to the anatomical differences of larger middle ear cavities. A t higher frequencies, the Chinese male and female data demonstrated more efficiency than Caucasians. This might be explained by the smaller size of the middle ear o f Chinese, as smaller cavities have higher resonant frequencies.  4.1.3 Collected normative values Given that differences have been found between races for tympanometric measures, two normative groups were established. Chinese and Caucasian normative values were also separated by gender. A s discussed earlier, both the 5th and 95th percentiles were calculated and plotted alongside their corresponding mean value. The range between the 5th and 95th  56  percentile lines, or the 90% range, is often used clinically as a cutoff between normal and abnormal results.  4.1.3.1 Normative data comparing Chinese males and females A s seen in Figure 4.2, the mean, 5th, and 95th percentile lines of the graph showed P A between Chinese males and females did not directly overlap. A s just discussed in section 4.1.2, mean statistical differences in gender data were not seen among Chinese. Despite the lack o f statistical differences, plotting o f the 90%> range was used to compare whether these cutoffs are the same or different between the two genders within a race. Observed differences between males and females suggest that gender specific data is needed. In this graph (Figure 4.2) the 5th percentile lines for Chinese males and females up to about 1400 H z are very close. This may be important as this is the area Feeney, et al. (2003) suggested would be abnormal in otosclerosis. From about 1400 H z to 2350 H z Chinese female scores fall below 5th percentile for males. The reverse is true with Chinese females having greater P A at the 95th percentile than males for frequencies between 2836-5000 H z . In general, visual inspection suggests Chinese females have values above Chinese males in the higher frequencies at the 5th and 95th percentiles and males have higher values in the lower frequencies. These observations suggest that the female Chinese middle ear may be less efficient at lower frequencies and thus is stiffer at those frequencies, as less energy is absorbed compared with the Chinese male middle ear. The data also suggest that at higher frequencies, the middle ears o f Chinese females may be more efficient. These differences may be anatomical, related to middle ear size. Studies have shown that there is a correlation between head size and middle ear size in humans (Huang, et al., 2000). Based on this argument, i f female middle ears are, on average, smaller than male middle ears, then female middle ears should have a higher R F . This higher R F value can be translated into better efficiency of energy transfer at higher frequencies.  This argument is supported by evidence  57  from Shahnaz & Davies (2004) as ear canal volume was found to be significantly different between male and females. Overall, differences noted in the cutoff levels appear sufficient to require gender specific normative data for Chinese adults. Power Absorption in Chinese Males and Females 100 -r  Frequency (Hz)  |—•  95th Percentile - AM  -Mean - AM -  - 5th Percentile - AM  95th Percentile - AF  Mean - AF  5th Percentile - AF |  Figure 4.2: Power absorption as a function of frequency comparing normative data from Chinese males and females. A M refers to Chinese males; A F refers to Chinese females.  Compared with the Mimosa normative values (Figure 2.8), there is no peak around 1250 Hz for the 90% range. As well, there is no drop in the 95th percentile at around 2000 Hz. The values from this study continue to gradually increase throughout the lower frequencies. Visual inspection of Chinese normative values for PA for both genders compared with those of Feeney and Sanford (2004) as seen in Figure 4.1 suggests Chinese data curves do not reveal a relative  58  flattening at approximately 1200-1900 H z and show an overall pattern more like that of the combined normative data o f this study (Figure 4.1).  4.1.3.2 Normative data comparing Caucasian males and females Figure 4.3 displays P A graphic data for Caucasian males and females. A s stated in 4.1.2, gender differences were not statistically significant. However, plotting of the 90% range showed differences in the cutoff values. A s with the Chinese, Caucasian females had lower scores at the 5th and 95th percentile range in lower frequencies than males and higher scores in the frequencies exceeding about 1200 H z . A s mentioned for the Chinese population, this P A data suggests greater stiffness among females than males at lower frequencies and less stiffness at higher frequencies. The Caucasian male middle ear may be more efficient at lower frequencies than the female ear. Anatomical middle ear size likely accounts for much of this difference. This graphic data strongly suggests gender specific data are needed. With the exception of the large 90% range in the low frequencies, the Caucasian group had a more similar overall pattern to the Mimosa normative values o f Voss and Allen than the Chinese group. The pattern of the Caucasian gender combined data was more similar to that o f Feeney and Sanford (2004) data than to the Chinese data of this study.  59  Power Absorption in Caucasian Males and Females  40 30 20 Y II 10 0  /  V  •—  Js *•' f *  ir TT-  Csj  "  »  «.  , . -' *  in rCO  CB N m r*- co o T-  CO  O  CD  CO  CO  CN  CD  CO  co  in  00 O  (S  to O V CO O CO O  ^  C  O  T  CO  J  j c o o ^ c o c o r ^ T - i n c D j j i n c N c o ^ t i - r ^ T j - o c o  -  C  CO  O  C  O  C  D  T  -  C  O  ^  -  C  O  C  O  O  I  Frequency (Hz)  95th Percentile - C M "  •Mean - CM  1  5th Percentile - CM *  -95th Percentile - CF •  - Mean - CF  co  ir-  CO T-  CD CN  CD ^  m  m  in  m  CM CD  OJ  co  rS-  co in  Oi  m m m  5th Percentile - CF  Figure 4.3: Power absorption as a function of frequency comparing normative data from Caucasian males and females. C M refers to Caucasian male; CF refers to Caucasian female.  4.1.3.3 Normative data comparing Chinese and Caucasian males When values of Chinese and Caucasian males were compared, as seen in Figure 4.4, there were significant differences in the patterns of the curves. As just seen in 4.1.2, there were statistical differences in Chinese and Caucasian male values. Visually, Caucasian males had higher mean, 5th and 95th percentiles in the low frequencies than Chinese males. This reversed at higher frequencies. Mean differences were separated by about 15% at approximately 1100 Hz and by a full 20% at 5000 Hz. These results are consistent with statistical findings; hence, it is clear that separate racial normative values are needed for males. Compared with Chinese males, the Caucasian male  60  middle ear is more efficient in transferring power at low frequencies; the Chinese middle ear is better at higher frequencies. Possible reasons for these differences are discussed in section 4.1.4. It is interesting to note that compared with Chinese males, Caucasian males have a larger variation at frequencies below 500 Hz.  Power Absorption in Chinese and Caucasian Males  co co  r*- T o> to  in  in  in in  in  ^  <N  CM ID  o n oo in S  O)  in in  Frequency (Hz) 95th Percentile - CM •  •Mean - CM  5th Percentile - CM  - 95th Percentile - AM  - Mean - AM  5th Percentile - AM  Figure 4.4: Power absorption as a function of frequency comparing normative data from Chinese and Caucasian males. C M refers to Caucasian males; A M refers to Chinese males.  When compared with the Mimosa normative values by Voss and Allen, the overall pattern for the Caucasian males was more similar to these normative values than those of the Chinese males. Mimosa values showed a peak in the low frequencies for the 95th percentile values. This contrasted with the gently sloping Chinese male pattern. As mentioned previously, the rapid acceleration and peak of the percent PA at 1000 H z for Caucasian males revealed a  pattern similar to that of Feeney and Sanford (2004). Both Caucasian and Chinese mean values were higher than those in Feeney and Sanford (2004). Such apparent variations may be due to different calibration, or other such factor, between the different machines used.  4.1.3.4 Normative data comparing Chinese and Caucasian females A s seen in Figure 4.5, the differences observed between Chinese and Caucasian males persist with females. Statistical differences between mean values have been shown (section 4.1.2). Visually, Caucasians had higher mean, 5th, and 95th percentile scores in low frequencies. A s described earlier, the Caucasian middle ear has greater percentage of P A at lower frequencies than the Chinese middle ear and is more efficient. This may relate to increased stiffness in the lower frequencies due to size of the middle ear cavity, or physiological aspects of the annular ligament as is discussed in section 4.1.4.  62  Power Absorption in Chinese and Caucasian Females  100 i  jr^-sy  90  ^^-l^^"  80  i  70  g I  \  —  r  ~  ~  ,  \  60{  \  \  Q.  8 50  a <  % 40  / ' '  (//  • <  30 A  f,  i/j /  /•'..--"' > ,•  j,!* 20 yj / / ..• 10 0  Tt  * -'"  •'*.•' T-  LO  CO  CO  eg CO in r- oo o  CD  LO  CO CM  un  CO 00  CN LO CO  CD  TO  O CO T-  CD  95th Percentile - CF * •Mean - CF  C O C M C D O ^ t c O C M C D O O h - C O O C O C N C D l O C N " O TCO CD 00 CM CO CO CO CO CO CO  Frequency (Hz) 5th Percentile - CF  CO  co -=r  -95th Percentile - AF  CO  TCO  r-~  CO CO O  - Mean - AF  CD  i-  LO  I OJ CN LO  *— CD LO  LO CD CN CO © N O LO LO  CO IO ) LO  5th Percentile - AF  Figure 4.5: Power absorption as a function of frequency comparing normative data from Chinese and Caucasian females. CF refers to Caucasian females; A F refers to Chinese females.  Compared with the Mimosa normative values by Voss and Allen, the results showed a higher power absorption level at 2000 Hz. This can also be said of the other normative values collected in this study. The mean score for Chinese females paralleled most closely the mean scores of Feeney and Sanford (2004). However, unlike the Chinese females, the Caucasian females have a slight peak in PA at approximately 1200 Hz in the 95th percentile curve which is similar to Feeney and Sanford's (2004) combined data under the 95th percentile curve. Thus, the pattern of the curve in Feeney and Sanford's data suggested that they had mainly Caucasian normative subjects. This remains to be seen as Feeney and Sanford's (2004) data have not yet been published; thus, race is unknown.  4.1.4 Discussion ofpower absorption results Power absorption was chosen as a W B R variable since the 90% range from Mimosa normative data, obtained by Voss and Allen, was available in P A and provided a framework to readily compare the data. Power absorption can also be compared, albeit reciprocally to some published data. This was the first attempt to determine i f gender plays a role in the results for either race. N o statistical differences were found in means for gender for either Caucasian or Chinese subjects. However, differences can be seen in the 90% range cutoffs o f the graphic data. Differences in the 90% range between genders are important as these cutoffs are used to separate diseased from non-diseased ears. This suggests that gender specific normative values should be used. Statistical differences in means were found between races for each gender. In addition, 90% range differences were found between Chinese and Caucasian males and Chinese and Caucasian females. Again, these cutoffs were important in separating diseased from healthy ears. Power absorption data showed more efficiency of the middle ear at lower frequencies for the males compared with females and Caucasians compared with Chinese. A s discussed above, differences in percentage o f P A by gender and race are likely related to differences in size o f the middle ear cavity among these groups. Keefe, et al. (1993) studied cross-sectional area of the adult ear canal in relation to E R and showed greater variation o f results in frequencies below 3000 H z . Another reason that has been postulated as a cause o f the variation in low frequencies is due to the physiological response o f the annular ligament. The annular ligament is located around the oval window and footplate and in normal hearing individuals assists in reducing low frequency sounds. If this physiological response is different among groups, this could result in a variation in low frequency efficiency as showed by the percentage o f P A . There is ongoing  64  debate over the cause of high frequency differences. Based on the results found in this study, race specific normative values are required. 4.2 Admittance  4.2.1 Procedure Admittance was chosen as a measure as it was thought to be comparable to tympanometric admittance; thus, future studies would have a base of comparison. Once testing was completed, data were saved and the admittance values exported to a spreadsheet where further analysis took place. A l l admittance variables are in normalized units as discussed in 3.5.3. The normalization factor given by Mimosa Acoustics relates to the characteristic impedance of the ear canal. Due to this normalization process, admittance is dimensionless.  4.2.2 Between gender and race statistical analysis Exploratory analysis using box-plots was completed. Results showed asymmetry o f the distribution o f admittance data. Thus, square root transformation was used to make the data more symmetrical. This resulted in the exclusion of six observations (ear outliers) from three separate subjects. In order to evaluate the effects o f race, gender, and ear, a repeated measure A N O V A was performed. The within subject factor was level o f frequency, while the between subject factors were gender (male or female), race (Chinese or Caucasian), and ear (right or left). These A N O V A results are summarized in Table A 7 (Appendix V ) . The main effect of race was significant [ F ( l , 234) - 12.89, p = .000]. Gender effect was also significant [ F ( l , 234) = 4.64, p = .032], but ear effect was not significant. Race-gender interaction was not significant [ F ( l , 234) = 1.8, p = .18]. The 95% CI plots of male and female values within each racial group were examined. For Y , Caucasian males have higher values than females from 1781 to 2367 H z . Similar 95% CI plots for Chinese show no difference between males and females.  65  Between race-group analysis confirmed a significant statistical difference in means as given above. The 95% CI plots confirmed differences between Caucasian and Chinese male mean values from 281 to 1125 H z with Caucasians having higher values. Similarly, for females, the 95% CI plots showed differences between mean values for Chinese and Caucasian females from 211 to 1313 H z . Caucasian values were higher. These findings were clinically significant. N o differences were found by ear as seen in Table A 7 Appendix V .  4.2.3 Collected normative values 4.2.3.1 Normative data comparing Chinese males and females A s seen in Figure 4.6, showing the mean, 5th, and 95th percentiles of admittance across frequencies from 211 to 6000 H z , Asian males generally have higher results than females. With the exception o f the 5th percentile curve, from about 2500 to 2800 H z , males had a lower cutoff level than females. N o statistical differences were found between genders for Chinese values. However, observation o f the 90% range values support the need for separate cutoff levels for Chinese males and females.  66  Admittance in Chinese Males and Females  1 oo  Frequency (Hz)  ~~  95th Percentile-AM ^"^Mean - AM •  • 5th Percentile - AM -  95th Percentile - AF  Mean - AF  5th Percentile - AF j  Figure 4.6: Admittance as a function of frequency comparing normative data from Chinese males and females. A M refers to Chinese males; A F refers to Chinese females. Admittance values are dimensionless as they are normalized using characteristic impedance of the ear canal.  4.2.3.2 Normative data comparing Caucasian males and females Similar to Chinese males and females for admittance results, there are visual differences in the 90% range between Caucasian males and females (Figure 4.7). Males have higher 5th and 95th percentile values until about 4000 Hz; however, for higher frequencies the mean, 5th and 95th percentile scores all dropped below those of females. As shown in Figure 4.7, it is easier for energy in males (i.e. higher admittance values) to enter the middle ear in lower frequencies than in females. This can be explained by the possible size difference of the middle ear as males have a larger volume behind the eardrum; hence, their middle ear is more compliant in the low  67  frequencies. These Y results support conclusions noted for PA, that at least in the lower frequencies, there is more absorption for Caucasians than Chinese; among Caucasians, there is more absorption among males. This could be due to larger middle ear cavities in these groups which allow less energy reflectance and less stiffness based on the principles of the Helmholtz resonator (Durrant & Lovrinic, 1995). Contrary to Caucasians, Chinese males continue to have higher admittance values across all of the frequencies tested. Perhaps there is a difference in the susceptance and/or conductance at the higher frequencies in Chinese middle ears. Admittance in Caucasian Males and Females 100 -x  -  Pj  t  (D  N  O)  Frequency (Hz) 95th Percentile - C M •  "Mean - CM -  -  5th Percentile - C M  -95th Percentile - C F  - Mean - C F  5th Percentile - C F  Figure 4.7: Admittance as a function of frequency comparing normative data from Caucasian males and females. C M refers to Caucasian males; CF refers to Caucasian females. Admittance values are dimensionless as they are normalized using characteristic impedance of the ear canal.  68  4.2.3.3 Normative data comparing Chinese and Caucasian males As seen in Figure 4.8, Caucasian males had observed higher scores for 95th percentiles for frequencies below about 5200 Hz, higher mean values to about 3600 Hz, and higher 5th percentile values below about 1200 Hz. This suggests that the Caucasian ear is more compliant in the lower frequencies, as with P A data, but is not found for Y across frequencies. Admittance in Chinese and Caucasian Males 100  i  •  1  -o <  0.1  *  r~-<*ococoa>coc\icou-> Frequency (Hz) 95th Percentile - C M •  •Mean - C M  5th Percentile - C M  -95th Percentile-AM  -Mean - A M  5th Percentile - A M  Figure 4.8: Admittance as a function of frequency comparing normative data from Chinese and Caucasian males. C M refers to Caucasian males; A M refers to Chinese males. Admittance values are dimensionless as they are normalized using characteristic impedance of the ear canal.  4.2.3.4 Normative data comparing Chinese and Caucasian females As seen in Figure 4.9, Caucasian females had higher mean and 95th percentile values across all frequencies than Chinese females. Caucasian 5th percentile values were higher in the  69  low frequencies to about 1500 H z . In the lowest frequencies under about 550 H z , the mean for Caucasian females approached the 95th percentile for Chinese females. Chinese female scores dropped well below Caucasian females at about 4000 H z for the 95th percentile curve and 3000 H z for the 5th percentile curve. Admittance observations for Caucasian and Chinese females in the low frequencies supported the P A observations of more efficiency. It can now be said that this increased efficiency is due to the increased ease of energy when entering the Caucasian middle ear, compared to the Chinese middle ear. It is possible that these differences are due to size o f the middle ear cavity. Unlike, the P A findings, however, Caucasians continue to have greater admittance across the frequency range. This may be due to differences in stiffness, possibly imposed by the annular ligament.  70  Admittance in Chinese and Caucasian Females 100  £ •o <  T  -  W  Q  f  O  S  r  W  f  f  l  n  c  o  n  O  O  '  t  (  O  W  (  D  O  *  t  D  f  J  t  D  O  ^  K  )  C  O  N  i  -  t  f  )  0  1  C  O  N  '  -  n  O  )  P  l  •^r^coo<ocorouocNcou^.-co^oi^<r>ococ\ic»inc\ico  Frequency (Hz) 95th Percentile - C F '  •Mean - C F -  -  5th Percentile - C F  95th Percentile - A F  - Mean - A F  5th Percentile - A F  Figure 4.9: Admittance as a function of frequency comparing normative data from Chinese and Caucasian females. A F refers to Chinese females; C F refers to Caucasian females. Admittance values are dimensionless as they are normalized using characteristic impedance o f the ear canal.  4.2.4  Discussion of admittance results  For Y , repeated measures A N O V A confirmed gender differences within the Caucasian race; however, analysis did not confirm gender differences within the Chinese race. Statistical analysis confirmed racial differences within each gender. This is supported by 9 5 % C I plots with Caucasian and Chinese subjects separated across some frequencies for both males and females. There is no doubt that for Y , race specific normative values should be used. Gender specific normative data are suggested for Caucasians. In general, Y data supports the concept o f  71  greater efficiency of the middle ear system in low frequencies for Caucasians over Chinese and Caucasian males over Caucasian females. 4.3  Susceptance  4.3.1 Procedure Susceptance was chosen as a measure as it was thought that it would be most comparable to tympanometric susceptance. Once testing was completed, data were saved and the susceptance values were exported to a spreadsheet where further analysis took place. A s susceptance is one of the elements o f admittance, it is also in normalized units; hence, susceptance is dimensionless (section 3.5.3).  4.3.2 Between gender and race statistical analysis Exploratory box-plots of within subject effect of level o f frequency showed a symmetrical empirical distribution of the data for the variable B . Five outliers were noted and excluded. N o transformation of the data was required. Table A 8 (Appendix V ) shows the results of the repeated measures A N O V A regarding the parameter o f B . A s for the previous analysis, the between subject factors are gender, race, and ear. The main effect o f race was significant [ F ( l , 235) = 17.27, p = .000]. The effect o f gender was significant [ F ( l , 235) = 10.35, p = .001], but the effect o f ear was not significant [ F ( l , 235) = 0.11, p = .918]. The interaction effects were not significant. The 95% C I plots for gender interaction with Caucasian males have higher values at frequencies at 1945-1992 H z . Differences between 95%> CI plots for Chinese by gender, with males having higher values, were at frequencies 4172 to 4383 H z . These short segments of frequencies showed statistically significant differences by gender within races. Between gender and race group analyses showed significant differences in means as given above [ F ( l , 235) = 10.35, p = .001]. The 95% CI plots for Caucasian and Chinese females  72  showed statistical differences from 211 to 867 H z and from 3844 to 5203 H z . This is seen graphically by a widening between means o f Chinese and Caucasian females with Caucasians having higher scores. Repeated measures A N O V A did not find differences between races within male gender. N o differences were found by ear.  4.3.3 Collected normative values The 5th percentile curve for the race and gender graphs appeared irregular for frequencies from about 2500 to 6000 H z . It is unlikely that smoothing would improve these curves. One possible explanation for these findings is the use of a logarithmic scale for the dependent variable.  4.3.3.1 Normative data comparing Chinese males and females For frequencies to about 2500 H z , male Chinese had higher 95th percentile and mean curves than females. For a mid-frequency range, 2800-3100 H z , values were similar and again for high frequency males had higher values. For the lowest frequencies to about 750 H z , Chinese males values were above females, however from about 750-1050 H z males and females had similar scores. It is not possible to determine whether male or female Chinese scores were higher for the 5th percentile from 2500 H z to 5000 H z (Figure 4.10). However, as reported above, mean differences are highly significant with Chinese males having higher values than females. This suggests that the male middle ear system in less stiff than the female middle ear system. Physiological differences likely result in this decreased stiffness.  73  Susceptance in Chinese Males and Females 100  -i  '—'  '  10  Frequency (Hz) 95th Percentile-AM  Mean-AM -  -  5th P e r c e n t i l e - A M - - — - 9 5 t h Percentile-AF  Mean-AF  5th Percentile-AF]  Figure 4.10: Susceptance as a function of frequency comparing normative data from Chinese males and females. A M refers to Chinese males; A F refers to Chinese females. Susceptance values are dimensionless as they are normalized using characteristic impedance of the ear canal.  4.3.3.2 Normative data comparing Caucasian males and females As seen in Figure 4.11, for the 95th percentiles and mean curves, Caucasian male values exceeded female values throughout the low frequencies and up to about 5000 Hz. Values were similar in higher frequencies. For the lower range cutoff, male values appeared above female until 700 Hz. Although this 5th percentile curve was irregular from about 2100- 5000 Hz, male values appeared higher than female.  74  Susceptance in Caucasian Males and Females 1 0 0 -r  10  Frequency (Hz) 95th Percentile - C M  Mean - C M -  -  5th Percentile - C M  95th Percentile - C F  Mean - C F  5th Percentile - C F |  Figure 4.11: Susceptance as a function of frequency comparing normative data from Caucasian males and females. C M refers to Caucasian males; CF refers to Caucasian females. Susceptance values are dimensionless as they are normalized using characteristic impedance of the ear canal.  4.3.3.3 Normative data comparing Chinese and Caucasian males Figure 4.12 displays data for males, comparing Chinese and Caucasian values. In general, the 95th percentile scores overlapped. There were minor differences in mid-frequencies with Caucasian males having higher values. For the lowest frequencies up to 800 Hz, Caucasian males had higher values than Chinese. From about 2000 Hz, Caucasian males had higher values on the 5th percentile curve than Chinese, dropping below Chinese by about 4500 Hz.  75  Susceptance in Chinese and Caucasian Males  100  10  " " " ^  —  ^ — - v ^ ,  0.1  0.01  Frequency (Hz) I"  95th Percentile - C M  Mean - C M -  -  5th Percentile - C M  95th P e r c e n t i l e - A M ~  Mean-AM  5th Percentile-AM |  Figure 4.12: Susceptance as a function of frequency comparing normative data from Chinese and Caucasian males. A M refers to Chinese males; C M refers to Caucasian males. Susceptance values are dimensionless as they are normalized using characteristic impedance of the ear canal.  4.3.3.4 Normative data comparing Chinese and Caucasian females The pattern shown in Figure 4.13 is similar to that of Figure 4.12. Caucasian and Chinese females had similar mean and 95th percentile scores for frequencies below about 3200 Hz. At higher frequencies Caucasian females had higher scores. For frequencies below about 900 Hz Caucasian females had values higher than Chinese females. At frequencies from about 2500-5500 Hz, Caucasian females had values above Chinese females. These differences are likely due to the size of the middle ear cavity with smaller middle ears promoting more  76  reflectance; hence, the middle ear of Chinese females is stiffer. At higher frequencies, the Caucasian mean values were statistically significant, above those of the Chinese females. Susceptance in Chinese and Caucasian Females 100  10  '  *  1  -  *  *  *  0.1 •  '•'  0.01  Frequency (Hz) |^—  95th Percentile -CF  Mean - CF -  -  5th Percentile - CF  95th Percentile-AF  Mean-AF  5th Percentile-AF |  Figure 4.13: Susceptance as a function of frequency comparing normative data from Chinese and Caucasian females. A F refers to Chinese females; CF refers to Caucasian females. Susceptance values are dimensionless as they are normalized using characteristic impedance of the ear canal.  4.3.4 Discussion of susceptance results  The data for susceptance varies from that expected along the 5th percentile curve. This curve is highly irregular after about 2500 Hz. It should be noted that when individual normal subjects were graphed, they had a deep dip or reverse spike within this frequency range. This increased irregularity may reflect more variation at the lower cutoff. There are sufficient differences in the mean and 95th percentile curves to suggest that gender and race specific  77  normative data curves should be established for B . However, the variation of the 5th percentile B values over 2500 H z would make cutoff level determination difficult. Statistical analysis showed significant differences between means for Caucasian and Chinese females in both lower and higher frequencies with the Caucasians having higher values. This low frequency difference suggests less stiffness among Caucasian females compared with Chinese, thus greater efficiency. The findings for Caucasians compared with Chinese males are similar, but without reaching statistical significance. The smaller middle ear of Chinese, whether male or female, may give smaller volume which then increases stiffness. This is similar to the increased stiffness and reduced percentage of P A in Caucasians compared with Chinese already described. The annular ligament may also impose stiffness in the lower frequencies. 4.4 Conductance 4.4.1  Procedure  Conductance, as with admittance and susceptance, was chosen as a measure as it was thought that it would be most comparable to its tympanometric equivalent. Once testing was completed, data were saved and the conductance component was exported to a spreadsheet where further analysis took place. For further information, please refer to section 3.5.3. Conductance, as it is an element of admittance, is dimensionless due to Mimosa Acoustic's normalization procedure. Unfortunately, until further research can be done, these dimensionless variables cannot be compared with tympanometric values. 4.4.2 Between gender and race statistical  analysis  Exploratory box-plots of the within subject effect of level of frequency showed the empirical distribution o f data to be symmetrical except for three observations on two subjects, thus classed as outliers.  78  With respect to differences between means for the between subject effect for gender, race, and ear, a repeated measures A N O V A was performed. Results were summarized in Table A 9 (Appendix V ) . The effect of race was not significant [ F ( l , 237) = 2.58, p = .110]; gender effect was significant [ F ( l , 237) = 4.23, p = .041]. There was no significant ear effect. Racegender interaction was significant [ F ( l , 237) = 5.79, p = .017]. N o other interactions were significant. T o find out the frequencies where the males and females differed within races, 95% CI plots for each frequency were explored. For the Caucasian race, mean gender differences were found at 2016 to 2297 H z with males having higher values. There were no differences between males and females among Chinese. In 95% CI plots, Caucasian females had a higher mean value than Chinese females shown at frequencies 422-1758 H z . This difference in means is seen in Figure 4.15. Caucasian males had higher mean values than Chinese male values as seen in 95%> CI plots for frequencies 539 to 1430 H z , 2063-2250 H z , and 5227-6000 H z . This is reflected in Figure 4.16. There were no significant ear effects found.  4.4.3 Collected normative values 4.4.3.1 Normative data comparing Chinese males and females A s seen in Figure 4.14, Chinese males had higher cutoff levels and higher mean values than females on conductance. Given the consistency across frequencies o f males having higher conductance values than females, anatomical considerations may be contributing to the observed difference. O n average, males have a larger ear canal cavity and middle ear space (Huang, et al. 2000); thus, resistance is less and conductance is higher. It is important to note that conductance is somewhat different from resistance as conductance is the product o f both reactance and resistance.  79  Conductance in Chinese Males and Females  100  10  0.01  TtllJ fl^lti tltJ Jtl tlltfJII [IIIIJIII llll Llll rril rl IIIII III Ll III IIJIIIIL118111 It 11 It IIIJII18 ItlJ llll El ttlltl 11^11118Jtllll lllltllllTIII IJIIlfJI IJJIITJI18 llil llli IIIIJIIIJJIII11BI11B til L J I I J S J I I I I I l E ^ L I B J i  llll tltl ttl llfl I III I till  r < - T - T - i - r N w w w ( N r j ( o n t o n p i n n t ^ ^ ^ ^ ^ i f i i D i o i o i n i o  Frequency (Hz) - -  95th Percentile-AM  Mean-AM -  -  5th Percentile-AM  — - 9 5 t h Percentile-AF  Mean-AF  5th Percentile-AF  Figure 4.14: Conductance as a function of frequency comparing normative data from Chinese males and females. A M refers to Chinese males; A F refers to Chinese females. Conductance values are dimensionless as they are normalized using characteristic impedance of the ear canal.  4.4.3.2 Normative data comparing Caucasian males and females  As seen in Figure 4.15, males had higher values than females for the 95th percentiles for all frequencies up to about 4350 Hz, values then dropped well below female values. By 6000 Hz, male and female mean values were the same as each other and the same as the 95th percentile for males. Mean scores for males exceeded females from about 3800 Hz and below, then dropped below mean values for females. The 90% range was much greater at higher than lower frequencies for females. For the 5th percentile curve, males and females had similar values to about 2400 Hz, then males dropped below females until about 4800 Hz.  80  C o n d u c t a n c e in C a u c a s i a n M a l e s a n d F e m a l e s  100  10  Frequency (Hz) |^—  95th Percentile - C M  'Mean - C M -  -  5th Percentile - C M  95th Percentile - C F  Mean - C F  5th Percentile - C F |  Figure 4.15: Conductance as a function of frequency comparing normative data from Caucasian males and females. C M refers to Caucasian males; CF refers to Caucasian females. Conductance values are dimensionless as they are normalized using characteristic impedance of the ear canal.  4.4.3.3 Normative data comparing Chinese and Caucasian males  Figure 4.16 shows significant shifts with the 90% range being smaller in lower frequencies compared with higher frequencies. In lower frequencies to about 1600 Hz male values for mean, 5th and 95th percentile for Caucasians exceeded Chinese. For frequencies less than 900 Hz, the mean for Caucasian males was approximately the same as the 95th percentile for Chinese males. For the 5th percentile curve, Caucasian males had higher values than Chinese males until about 1600 Hz. By about 3200 Hz the 5th percentile values for the  81  Caucasian males dropped well below Chinese. Indeed, the 95th percentile for Caucasian males approached the mean and the 5th percentile values dropped greatly. Conductance in Chinese and Caucasian Males 100  -i  •  10  Frequency (Hz) |^—  95th Percentile - CM  Mean - CM -  -  5th Percentile - CM  95th Percentile-AM  Mean-AM  5th Percentile-AM |  Figure 4.16: Conductance as a function of frequency comparing normative data from Chinese and Caucasian males. A M refers to Chinese males; C M refers to Caucasian males. Conductance values are dimensionless as they are normalized using characteristic impedance of the ear canal.  4.4.3.4 Normative data comparing Chinese and Caucasian females  Figure 4.17 shows a pattern similar to that of Figure 4.16, in the lower frequencies. That is, as for males, female values showed the mean of Caucasians approximating the 95th percentile for Chinese. The 5th percentile for Caucasian females was significantly above that of Chinese until about 4300 Hz. As for males, the 5th percentile curve for Caucasian females dropped below the Chinese values in higher frequencies.  82  Conductance in Chinese and Caucasian Females 1 0 0 -i  • — •  10  Frequency (Hz) |  95th Percentile - CF — M e a n - CF -  - 5th Percentile - CF  95th Percentile-AF  Mean-AF  5th Percentile-AF |  Figure 4.17: Conductance as a function of frequency comparing normative data from Chinese and Caucasian females. A F refers to Chinese females; CF refers to Caucasian females. Conductance values are dimensionless as they are normalized using characteristic impedance of the ear canal.  4.4.4 Discussion of conductance results  Repeated measures A N O V A found no difference between means for Chinese males and females. Racial differences between means were not confirmed by the repeated measures A N O V A . However, 95% CI plots did confirm short segment differences between races for both genders. Visual inspection confirmed a wide spread between means at the lower frequencies between Chinese and Caucasian groups for both genders (Figure 4.16 and 4.17).  83  Throughout the G data of Caucasian subjects there appears to be an unusual drop o f the 5th percentile scores away from mean scores beginning in the mid-frequencies and continuing through the high frequencies. The curves generated with Chinese male and female data showed a slight widening o f 90% range in higher frequencies over that o f lower frequencies. The approximation of the 95th percentile of values to mean values for Caucasian males remains unexplained (Figure 4.15 and 4.16). The statistical analysis did not confirm mean race differences within G . Only a few differences were seen in small frequency segments suggesting less mean resistance for the Caucasian middle ear. There is greater evidence for less mean resistance o f the male middle ear among Caucasians at least in the range of 2016-2297 H z . This was not noted for Chinese. However, although statistical differences for G reflected only a trend, observations of the 90% range were very informative. These cutoff curves suggest Chinese males had less resistance than females at all frequencies. Caucasian females had less resistance at higher frequencies than males, but this reversed at low frequencies. Caucasian males had less resistance at low frequencies than Chinese and this was reversed at higher frequencies. The findings were similar for Caucasian females over Chinese in the lower frequencies; this was reversed at higher frequencies. 4.5 Summary o f results Repeated measures A N O V A results and visual inspection of graphic results for determined gender and race differences are summarized in Table 4.1 below. From graphically determined cutoff levels for low frequencies, it can be seen that both males and Caucasians have larger values. One likely reason for this finding is the anatomical variations among these groups. A s previously mentioned, Huang, et al. (2000) noted that the size o f middle ear structures in  84  animals is closely associated to body size. This study supports their findings. High frequency findings show much less consistency and deserve further study. Graphically Determined Cutoff Level L o w Frequency Variable  5 th  95 th  5 th  in means (p-value)  Percentile  Percentile  Percentile  Percentile  PA  NS  M >F  M~F  F>M, M >F (>5000 Hz)  F >M  Y  NS  M >F  M >F  M >F  M >F  B  .001  M >F  M >F  M >F  M >F  G  NS  M >F  M >F  M >F  M >F  PA  NS  M >F  M >F  F >M  F > M, M >F (>4800 H z )  Y  .032  M >F  M >F  F >M  F >M  groups  Male vs. Female  Within race Caucasian: Male vs. Female  Between race male: Chinese vs.  B  .001  M >F  M >F  M ~ F  M >F (25004000 Hz), F >M (>4000Hz)  G  .041  M >F  M - F  M>R F >M (>4300 Hz)  F> M, M >F (>4800 Hz)  PA  .001  O A  O A  Chinese vs. Caucasian  A>C O A , A>C (>5500 Hz)  A>C A~C. A > C (>5100 Hz)  Y  .000  O A  O A  B  NS  O A  O A  O A  C>A  G  NS  O A  O A  A>C  A>C  PA  .001  O A  O A  A>C  A > C  Y  .000  O A  O A  O A  O A O A A> C  Caucasian  Between race female:  High Frequency  95th  Comparison  Within race Chinese:  Statistical differences  B  .000  O A  O A  O A  G  NS  O A  O A  O A  Table 4.1: Statistical and visual findings for within and between race comparisons for power absorption (PA), admittance (Y), susceptance (B), and conductance (G). L o w frequency cutoff= 1500 H z ; High frequency cutoff = 4000 H z ; N S = Not significant; M = Male; F = Female; C = Caucasian; A = Chinese. A n alpha level of .05 was used for all statistical tests.  4.6 Discussion of normative data Both statistical analyses and graphic presentation o f data are needed to determine differences within race and gender groups for W B R normative data. The repeated measures A N O V A and 95% CI plots assessed differences for the four variables. The plotted 5th and 95th percentile curves allowed determination of cutoffs as is needed clinically. Within limits, the greater the sample size, the more accurate these percentile curves should become. The data as graphically displayed demonstrates the need for gender and race specific normative data. Throughout the four variables o f the W B R measures there were few occasions where the mean, 5th or 95th percentile curves overlap for gender or race. Most of the curves share separations. The separations that were not statistically significant are the data from Chinese males and females for P A , Y , and G ; Caucasian males and females for P A ; and Chinese and Caucasian males for B . The mean differences for G between Chinese and Caucasians did not show a significant race effect. Moreover, 95% CI plots did not overlap at a number o f frequencies for both males and females, thus, there were segmental level of frequency differences. However, for the rest, statistical differences occurred between males and females and between Chinese and Caucasian subjects. Regardless of the statistical results, where there were differences between the lower and upper margins of the 90% range, cutoff levels would be affected and this could have clinical consequences. Values beyond the 90% range are considered abnormal and serve to distinguish normal from diseased ears. It is a common practice to use the 90% range to define the lowest and highest cutoffs for clinical purposes. However, it is recognized that a few normal subjects could have values below the 5th percentile or above the 95th percentile. There are at least two possible reasons for the differences in males and females, and Chinese and Caucasian subjects. First, mechano-acoustical properties may account for these  86  disparities. It was shown, for instance, using P A , that Caucasian middle ears were more efficient in the lower frequencies than Chinese middle ears. This finding may be due to differences in properties o f the middle ear between the two races. The second alternative, as previously discussed, are anatomical variations. A s gender and race specific curves have been shown to be necessary, the number o f subjects available to create these specific curves is lower than with combined data. Future research comparing race and gender specific normative values to middle ear pathologies encompassing from low to high impedance will determine whether using race and gender specific normative data can improve the overall test performance. The present data show similarities to previous tympanometric data. For admittance, this data found no difference in means for Chinese females and males. Similarly for S A , Shahnaz and Davies (2004) and Wan and Wong (2002) found no differences in means; however, differences within the 90% range were reported by Shahnaz and Davies (2004), but not by W a n and W o n g (2002). The present study also suggests lack o f difference o f means by gender among Chinese for admittance. Differences by gender within Caucasian groups were noted by Shahnaz and Davies (2004) and are found in this study. With regard to R F , Shahnaz and Davies (2004) found no gender effects within the race groups; however, for F 4 5 ° , there was a gender effect within the Chinese group. Although a direct parallel cannot be drawn, in this study the gender effect within the Chinese group was present for B and not present for G . For this study there were gender effects within the Caucasian group for Y , B , and G , but not for P A . From visual inspection of the curves, the pattern o f P A is similar to Voss and Allen normative values included in the W B R machine by Mimosa Acoustics. Comparing the curves to the reciprocal E R curve o f Feeney and Sanford (2004) has been disappointing, particularly in the lower frequencies where the mean o f the present study approaches the 95th percentile o f that o f  87  Feeney and Sanford. This may be related to the use of different machines, calibration, unit presentation, or ear canal compensation. Credible cutoff levels cannot be established for general clinical use unless these levels become more similar. There are no normative data curves for comparison with the Y , B , and G curves of this study. The differences found in this study attributed to gender and race for the W B R measures are likely due, in part, to variations in ear canal and middle ear volume. Keefe, et al. (2003) discussed the effect ear canal volume had on E R measurements and explored curve estimates to account for these differences. Another approach to improve W B R measurements would be establishing actual individual measurements o f ear canal volume. A possible method for measuring ear canal size would be to place distilled water in the ear canal to measure its volume. Obviously, there are concerns with regard to this method, including additional time and patient discomfort. Another alternative would be to measure real ear to coupler differences and then compensate for the specific size of the ear canal. This method could theoretically be incorporated into the Mimosa machine and be used to calculate the characteristic impedance automatically for each individual. This would be extremely beneficial in decreasing the amount of error when testing. 4.7 Case histories of patients with otosclerosis In order to investigate the clinical utility of W B R , seven otosclerotic patients who have been scheduled for surgery were tested. Each case history of an otosclerosisis patient is presented with the accompanying W B R graphic data followed by a general interpretation and discussion. The variable of P A was chosen to compare the otosclerotic subjects with above normative data. Admittance, susceptance, and conductance were chosen as variables as they can be most comparable to tympanometric measures.  88  4.7.1 Case history of an otosclerotic male: 0M1 This 56-year-old Caucasian male patient had a five-year history o f hearing loss in his left ear.  A family history o f unilateral hearing loss was noted on the maternal side. O M 1 had no  memory o f middle ear infections. N o history o f tinnitus or vestibular symptoms was found; a history o f noise exposure was noted. N o evidence of eardrum abnormality was observed through otoscopy. A hearing aid was worn on the left ear, but is no longer o f benefit to the patient. Audiometry results showed a severe-to-profound mixed hearing loss with a large conductive component in the low frequencies as seen in Figure 4.18. T E O A E s were found to be absent from 1000 to 4000 H z in the surgical ear. Standard tympanometry results showed a S A of 0.3 mmhos, at the lower limit of the 90% range o f normative data; and a T W o f 89.3 daPa which was within normal limits. Multi-frequency tympanometry results showed that F 4 5 ° was at 1000 H z , while R F was 1250 and 1400 H z for positive and negative compensations, respectively; these results were at or above the 95th percentile of normative data. Wideband reflectance results were separated into the four variables measured and deviations from the 90% range values were estimated from the graphs. Figure 4.19 shows results from the P A variable in relation to normal hearing Caucasian males. Deviations from the normal cutoff values occurred. Between 398-1219 H z , P A results were below the 5th percentile; between 1594-1875 H z and 2320-2859 H z , P A results were above the 95th percentile. These low frequency results suggest decreased percent o f P A with less efficiency and increased stiffness o f the middle ear system (Figure 4.19). This result is comparable to that found by Feeney, et al. (2003) in subjects with otosclerosis and supports the diagnosis of otosclerosis. One possible explanation of these results in the lower frequencies could be an increase in the imposed stiffness o f the annular ligament. Results from Y are shown in Figure 4.20 and are seen to extend below the normative cutoff values from 211-750 Hz. This suggests that there is more opposition to energy entering the  89  middle ear in this patient than in normal male subjects at these frequencies. Figure 4.21 depicts O M 1 's variation from normative values when using the measure o f B . The frequencies of 211586 H z , 1711-2273 H z , and 3820-3914 H z are all below the 5th percentile. These findings o f B suggest increased stiffness. Frequencies o f between 305-1219 H z were also below the 5th percentile for the G variable, as seen in Figure 4.22, suggesting increased resistance. Figure 4.22 suggests that G contributes more than B at low frequencies in differentiating otosclerotic ears which is consistent with the results of Shahnaz and Polka (2002). O M 1 is scheduled for surgery. At this time his W B R results cannot be compared with surgical findings, but are compatible with his diagnosis of otosclerosis. F R E Q U E N C Y IN S z  1  125  .  250  500 ;  V  i  v.  s.  c  1  20Q&  .  i  >  , 4000  8000.  • .:•  i  TJr. ^ '. ....T >  ! i  !  | •r.  1000  • j  '  1  1-7  1  •1  ' ^  • \  -""^  }  I "1  U  E  r  1  i -J  A  1  i . i-  • .  I  £  I  !  •  !  Figure 4.18: Pre-operative audiometric results of otosclerotic male O M 1 .  90  Power Absorption in an Otosclerotic Male  Figure 4.19: Power absorption as a function of frequency in otosclerotic male patient O M 1 . C M refers to Caucasian male.  Admittance in an Otosclerotic Male 100  Frequency (Hz) 95th Percentile - C M  Mean - CM -  -  5th Percentile - CM  OM1 |  Figure 4.20: Admittance as a function of frequency in otosclerotic male O M 1 . C M refers to Caucasian male. Admittance values are dimensionless as they are normalized using characteristic impedance of the ear canal.  92  Susceptance in an Otosclerotic Male 100  0.01  T - i o c n c o r ^ T - m o i c o T t O C D C O C n C D C S J C O l O < D o o O i T - i N T t c D r ^ c n  T-lOa>rOf^T-lf5CJ)COCOCNCOO T - i ^ c o o c o c o c n i o c N j c o L O T - c o . -  c g m u * ) r ^ o o o T - c o m < D c o O ' - r o i n t D c o  Frequency (Hz) 95th Percentile - CM <  •Mean-CM  -  5th Percentile - CM  -OM1  Figure 4.21: Susceptance as a function of frequency in otosclerotic male O M 1 . C M refers to Caucasian male. Susceptance values are dimensionless as they are normalized using characteristic impedance o f the ear canal.  93  Conductance in an Otosclerotic Male 100  T  10  Frequency (Hz) | —  95th Percentile-CM — — Mean - C M -  -  5th Percentile - C M  OM1 |  Figure 4.22: Conductance as a function of frequency in otosclerotic male O M 1 . C M refers to Caucasian male. Conductance values are dimensionless as they are normalized using characteristic impedance of the ear canal.  4.7.2 Case history of an otosclerotic female: OF1 This 42-year-old Caucasian female had a history of left ear hearing loss beginning during her first pregnancy. Progression of this hearing loss had been gradual, progressing to involving a sensorineural component. A severe mixed hearing loss was present in the surgical ear. Carhart's notch was noted at 2000 H z (Figure 4.23). There was no family history of hearing loss. A positive history of tinnitus was present in her left ear. There was no history of vestibular symptoms or middle ear infections. A hearing aid is worn only on the non-surgical side. Visual inspection of the eardrum through otoscopy revealed no abnormal findings. T E O A E s were found to be absent from 1000 to 4000 H z in the surgical ear. Standard tympanometry showed a 94  SA of 0.6 mmhos and a TW of 98.7 daPa, both within normal range. Multi-frequency tympanometry revealed F45° to be 710 Hz, at the upper limits of normative values for females; while RF was 1000 and 1120 Hz for positive and negative compensations, respectively, and were within normal limits. Results for WBR are shown in Figures 4.24, 4.25, 4.26, and 4.27 below. For PA there was a deviation above of the 95th percentile of normal at frequencies between 2906 and 3492 Hz. This suggests an increase in middle ear efficiency in this frequency range. This is not consistent with Feeney, et al.'s (2003) findings in otosclerotic ears. The reason for this difference is unexplained. Perhaps surgical results may allow for a better understanding of the results. For B, a notch, or reversed spike complex, below the 5th percentile occurred for frequencies between 3961 to 4008 Hz. This deviation is a common occurrence throughout all subjects, both normal and otosclerotic. It is considered to represent the transition between a stiffness dominated middle ear system to a mass dominated middle ear system. For Y and G, results remained within the 90% range of normative values. . . F R E Q U E N C Y I N }A 2<fj  500  "  1  :  •'  if  _  :  i K , '">J•K.  •  i..  .  2000  i !..'  ^krr "  1000  •  \  1  ,,  8000  -  S-  •\ ^ i v < " \ '• '  71  J, r"  .1 •  4000  £ r- •. • j  t——  —  t  1  i  E  I  i  i  .  i  ..:  -, con  Figure 4.23: Pre-operative audiometric results of otosclerotic female OF1.  95  Power Absorption in an Otosclerotic Female 100  Frequency (Hz) | —  95th  Percentile - CF  Mean - CF -  -  5th  Percentile - CF  OF1 |  Figure 4.24: Power absorption as a function of frequency for otosclerotic female OF1. C F refers to Caucasian female.  96  Admittance in an Otoslerotic Female 100 •  0.1  Frequency (Hz) [—  95th Percentile - C F  Mean - C F -  -  5th Percentile - C F  OF1 [  Figure 4.25: Admittance as a function of frequency for otosclerotic female O F 1 . C F refers to Caucasian female. Admittance values are dimensionless as they are normalized using characteristic impedance of the ear canal.  97  Susceptance in an Otosclerotic Female 100  10  0.01 T - L O O i C O r ^ T - L T - r N - C O O t O C O C M C O L O I ^ C O O T -  O O l C O J l O T - C O T - T - x  O C i -  C O C N N C O L n C O O T - T - C  C O D N  D O T O ^ J C  ^ C C N  t O O ^ O L C M  O C N C O O r ^ C O — — -. — — O C O O D O T - C O ^ - C O C O a j T - C O C N C N C N C O C O C O C O C O C O C O  LO CO  IT I'l T T I' IT T I' I'l T I'l TTTT ITT  CD CO  CO CT) CO  CO  .  T-  LO  Oi  CO  OJ CO CN OO LO LO L O IO LO LO IO  Frequency (Hz) 95th Percentile - C F '  •Mean - C F  5th Percentile - C F •  -OF1  i  Figure 4.26: Susceptance as a function of frequency for otosclerotic female O F 1 . C F refers to Caucasian female. Susceptance values are dimensionless as they are normalized using characteristic impedance of the ear canal.  98  Conductance in an Otosclerotic Females 100  -i  10  Frequency (Hz) |^—  95th Percentile - C F  Mean - C F -  -  5th Percentile - C F  OF1 j  Figure 4.27: Conductance as a function o f frequency for otosclerotic female OF1. C F refers to Caucasian female. Conductance values are dimensionless as they are normalized using characteristic impedance of the ear canal.  4.7.3 Case history of an otosclerotic female: OF2 This 35-year-old Caucasian female had a seven-year history of hearing loss in her left ear. There was no family history of hearing loss. N o history of tinnitus, vestibular symptoms, or middle ear infections was evident. N o hearing aids were worn. Visual inspection, using otoscopy, revealed no abnormal findings. A left moderately severe sloping to profound mixed hearing loss was found as seen in Figure 4.28. T E O A E s were found to be absent from 1000 to 4000 H z in the surgical ear. Standard tympanometry revealed a S A value of 1.3 mmhos, at the upper limits of normative of normative values, and a T W of 70.5 daPa was within normal limits.  99  Multi-frequency tympanometry revealed a F 4 5 ° of 560 H z and R F positive and negative compensation values of 800 and 900 H z , respectively; all within normal limits. Wideband reflectance results can be compared with normative values in Figures 4.29, 4.30, 4.31, and 4.32. Power absorption values for O F 2 were above the 95th percentile o f the normative data for frequencies between 1219-1406 H z , indicating increased middle ear efficiency in this frequency region. This does not correspond with Feeney, et al.'s (2003) findings. Admittance values for OF2 were all within the normative range o f Caucasian females. Susceptance values were below the 5th percentile from 3070-3234 H z displaying a typical reverse spike complex, while conductance values were above the 95th percentile from 1195-1336 H z . O f note, for all of the variables O F 2 had a slight sigmoidal shape between 1000-1500 H z . This finding remains unexplained. Within the current limited knowledge of otosclerosis using W B R , these findings remain helpful in the diagnosis, i.e. even though O F 2 had results for tympanometry tests within the normal limits, W B R results were abnormal. A post-operative surgical report was obtained. O F 2 had laser stapedotomy. A significant amount o f bone was noted at surgery. A modified piston bucket prosthesis with vein graft was used. The diagnosis o f left otosclerosis was confirmed. See Appendix H  100  FREQUENCY IN Hz 125  250  500  1000  2000  4000  8000  o 10  >  20 30 40 50 60 70  IS  80 90 100 110  750  1500  3000  6000  Figure 4.28: Pre-operative audiometric results o f otosclerotic female O F 2 .  Power Absorption in an Otosclerotic Female  Figure 4.29: Power absorption as a function o f frequency for otosclerotic female O F 2 . C F refers to Caucasian female.  101  Admittance in an Otoslerotic Female 100 -r  0.1  Frequency (Hz) |  95th Percentile - CF  Mean - CF -  - 5th Percentile - CF  OF2 j  Figure 4.30: Admittance as a function of frequency for otosclerotic female O F 2 . C F refers to Caucasian female. Admittance values are dimensionless as they are normalized using characteristic impedance of the ear canal.  102  Susceptance in an Otosclerotic Female 100  Frequency (Hz) [~^—  95th Percentile-CF  Mean - CF -  - 5th Percentile - CF  OF2  Figure 4.31: Susceptance as a function o f frequency for otosclerotic female OF2. C F refers to Caucasian female. Susceptance values are dimensionless as they are normalized using characteristic impedance of the ear canal.  103  Conductance in an Otosclerotic Female 100  -i  10  Frequency (Hz) |  95th Percentile - CF  Mean - CF -  - 5th Percentile - CF  OF2 |  Figure 4.32: Conductance as a function of frequency for otosclerotic female O F 2 . C F refers to Caucasian female. Conductance values are dimensionless as they are normalized using characteristic impedance o f the ear canal.  4.7.4 Case history of an otosclerotic female: OF3 This 50-year-old Caucasian female has had a slowly progressing history of bilateral hearing loss. N o family history is present. N o history of tinnitus, or vestibular symptoms was present. A history of at least one middle ear infection as a child was recollected. Hearing aids were worn bilaterally. The left ear was chosen for surgery. Visual inspection, using otoscopy, revealed no abnormal findings. Audiological testing showed an upward sloping moderate to mild conductive hearing loss in the left ear (Figure 4.33). Carhart's notch was present at 2000 H z . T E O A E s were found to be absent from 1000 to 4000 H z in the surgical ear. Standard  104  tympanometry revealed a S A value of 1.3 mmhos, at the upper limits of normal range; and a T W of 47 daPa which was below the 5th percentile o f normative values. Multi-frequency tympanometry showed F 4 5 ° to be 500 H z and R F for positive and negative compensation to be 800 H z , which were at or just within the lower limits of normal. Results from W B R show a deviation from the 90% range in all four variables. For P A , deviations above the upper cutoff occurred between 516-1078 H z . These findings do not correspond with those of Feeney, et al. (2003). For Y , deviations occurred above the 95th percentile for frequencies between 281-867 H z and below the 5th percentile for frequencies from 1101-1289 H z . A rapid change from less opposition to significantly more opposition within a small frequency range might indicate an abnormality in sound transfer through the system. This might account for the sigmoidal type curve from approximately 500-1200 H z in all of the variables. For B , deviations occurred between the frequencies o f 281-656 H z where values were above the 95th percentile, and between 844-1195 H z and 4195-4242 H z where values fell below the 5th percentile. The pattern for B for frequencies below 1200 H z parallels the pattern found for Y and suggests a sudden increase in stiffness well below the lower cutoff from normative values. For G , values extended above the 90%> range between 492-984 H z ; a pattern that is similar to that found in Y and B . Figures 4.34 through 4.37 show these results. Left otosclerosis was confirmed at surgery. Sclerotic bone growth anteriorly over the footplate was removed with a special drill prior to laser stapedotomy (Appendix II).  105  F R E Q U E N C Y IN H z ! 250  125  500  1000  o 10  >  1  20  8000  4000  2000  b  3  < k  30  dp —  •  40  „..n.,-mTT  5a  /.  60 70  >  so  c  ^/ .  >r  ,»  s  :— " ^  /"I  £  /J*—  , "- f  ' i*  so 100  1  1  110  Figure 4 . 3 3 : Pre-operative audiometric results of otosclerotic female O F 3 .  Power Absorption in an Otosclerotic Female 100  A 80  70  o  <~ ^ ~ ~~ ^  //'\ X 1/ > • 1/ / \  t1  < O  S o  i—/  /  _  ^ s .  —  *'  *  \  \> *  1  Q_  30  20  10  < — •T— N-LO C D C O IC OL CN C O OO hC -D C O s  CD CO CO CN LO CM CO LO C O I O C D C  O  CD 1O  O CO T -  .  C  O  h-TtOCLD OC C O OLO ^M (L-C COCNCDO^-COCOr^ OC— DDCC OC NO C O C M C O O Or^COOCDCMCDIOCNcO^t ONLOfflLO _ L  .  O  C  D  C  O  O  ^  C  O  ^  C  D  C  O  C  D  T  -  C  O  ^  C  D  C  O  ^ O  J  ^. ^ -  C  M  T-  T - T - T - T - C ^ C N C N C N C N C M C O C O C O C O C O C O C O ^ ^ t ' ^ - T l - ' J j - T j - L O L O  Frequency (Hz) 95th Percentile - C F «  •Mean - C F -  5th Percentile - C F  -OF3  Figure 4 . 3 4 : Power absorption as a function of frequency for otosclerotic female O F 3 . C F refers to Caucasian female.  106  Admittance in an Otoslerotic Female  100  10  Frequency (Hz) | ——  95th Percentile - CF ^—  Mean - CF -  - 5th Percentile - CF  OF3 |  Figure 4.35: Admittance as a function of frequency for otosclerotic female O F 3 . C F refers to Caucasian female. Admittance values are dimensionless as they are normalized using characteristic impedance of the ear canal.  107  Susceptance in an Otosclerotic Female  100  10  - ---~jd£^r -f» * i - * * »  0.1 •  0.01  C M C O LO  C ON-C MC D O OC ? O -C C O C O C O CNCTM MCMCM CMC OCOCOC to  Frequency (Hz) 95th Percentile -CF «  •Mean - CF  r-  hTT  5th Percentile - CF •  C D C O C O C M O) LO lNC OC — C MT— LO COO O C O C O LO LO LO LO LO  - i - io ^  o  CD co — "  CD  Tf  -OF3  Figure 4.36: Susceptance as a function o f frequency for otosclerotic female OF3. C F refers to Caucasian female. Susceptance values are dimensionless as they are normalized using characteristic impedance of the ear canal.  108  Conductance in an Otosclerotic Female  100  10  Frequency (Hz)  |  95th Percentile - CF  Mean - CF -  - 5th Percentile - CF  OF3 |  Figure 4.37: Conductance as a function o f frequency for otosclerotic female O F 3 . C F refers to Caucasian female. Conductance values are dimensionless as they are normalized using characteristic impedance of the ear canal.  4.7.5 Case history of an otosclerotic female: OF4 This 33-year-old Caucasian female has a ten-year history of bilateral hearing loss. A positive history of tinnitus was present. N o history of vestibular symptoms or middle ear infections was present. A s well, there was no family history of hearing loss. Hearing aids were worn bilaterally. The right ear was chosen for surgery. Visual inspection, using otoscopy, revealed no abnormal findings. Audiological testing showed an upward sloping moderate to mild conductive hearing loss in the right ear as seen in Figure 4.38. T E O A E s were found to be absent from 1000 to 4000 H z in the surgical ear. Standard tympanometry revealed a S A value of  109  0.4 mmhos and a T W o f 103.4 daPa, which were within normal limits. Multi-frequency tympanometry showed F 4 5 ° to be 1120 H z and R F at 1400 and 1600 H z for positive and negative compensation, respectively; all above the 95th percentile o f normal values o f Shahnaz & Davies (2004). Wideband reflectance results are shown in figures 4.39 through 4.42. Power absorption results for O F 4 were below the 90% range for frequencies between 938-1219 H z and 3891-4195 H z . These lower frequency findings are similar to O M 1 and to the two cases published by Feeney, et al. (2003). They suggest an increased stiffness and less efficiency of the middle ear system, which is typical of otosclerosis. Admittance results extended above the 90% cutoff range for frequencies between 4547-5766 H z suggesting reduced opposition to energy transfer in this range. For B , frequencies between 4219-4922 H z and 5039-6000 H z are above the 90% range and frequencies between 4992-5016 H z are below the 90% range. These elevations are part of the reverse spike complex. It is interesting to note that both this reverse spike complex and the R F value found through M F T are higher in frequency. This complex is different than similar findings in the normal subjects because: (1) it occurs at higher frequencies and (2) it extends well above the 95th percentile curve. A s well, for conductance, frequencies between 914-1125 H z are below the 5th percentile, while frequencies between 4688-5367 H z are above the 95th percentile. These findings suggest an increased resistance o f the middle ear structure to low frequencies and a decreased resistance in higher frequencies. Results from Y , B , and G suggest a pattern of abnormality occurring in this high frequency range (4500-5700 Hz). It would be worthwhile to carry out further investigation on this finding.  110  FREQUENCY IN Hz 250 ' •  500  1000  2000  4000  8000  1  1  !  H  1<  —  <  *  ,  •.... J.•ri.,**^.......it  cry— c i !  1  |  1  750  1500  1  1 1 i I i 3000 i  6000  Figure 4.38: Pre-operative audiometric results of otosclerotic female O F 4 .  Power Absorption in an Otosclerotic Female  Figure 4.39: Power absorption as a function of frequency in otosclerotic female OF4. C F refers to Caucasian female.  Admittance in an Otoslerotic Female  100  Frequency (Hz) |^—  95th Percentile - CF  Mean - CF -  - 5th Percentile - CF  OF4  Figure 4.40: Admittance as a function of frequency in otosclerotic female O F 4 . C F refers to Caucasian female. Admittance values are dimensionless as they are normalized using characteristic impedance of the ear canal.  112  Susceptance in an Otosclerotic Female  100  10  * w  t »  0.1  *  »  (7* t  mm***  \I  " N *  >mm  m.  #  » « *  ,  »  i  1  in mi n n i n n i n i i i i i i i i m i n i  TT-  CN  m CD co h- co o  CO  LO  h-  CO CO  TCO O  IO CD CO CO CM CD LO CN CO LO i  -  CO  LO  CD CO  mini  I  n  nil n n n n n n i i i n n i mi mi nil i m i i i i m u n i mi l i m n mi un i i i i i i i n i i i i T— LO CD O ^ CO CD CO CM CO LO CO CM 00 CD 00 0 0 CD T t T f r t O l O L O L O L O l O O C O  •^f CO CM CO 00 CM CD O CD CM CD I O CD _ t - c O L O C O C O O t C M C M C M C N J C M C M C O C O C O C O C O C  o  Frequency (Hz) 95th Percentile -CF '  •Mean - C F  1  5th Percentile - C F  -0F4  Figure 4.41: Susceptance as a function of frequency in otosclerotic female OF4. C F refers to Caucasian female. Susceptance values are dimensionless as they are normalized using characteristic impedance o f the ear canal.  113  Conductance in an Otosclerotic Female 100  Frequency (Hz) 95th Percentile - CF  Mean - CF -  - 5th Percentile - CF  OF4 |  Figure 4.42: Conductance as a function of frequency in otosclerotic female O F 4 . C F refers to Caucasian female. Conductance values are dimensionless as they are normalized using characteristic impedance of the ear canal.  4.7.6 Case history of an otosclerotic female: OF5 This 24-year-old Caucasian female had a hearing loss in her right ear since childhood. A positive history of tinnitus was present. No history of vestibular symptoms or middle ear infections was present. A s well, there was no family history of hearing loss. N o hearing aids are worn. Visual inspection, using otoscopy, revealed no abnormal findings. Audiological testing showed a moderate to mild conductive hearing loss in the right ear (Figure 4.43). Carhart's notch was present at 2000 H z . T E O A E s were found to be absent from 1000 to 4000 H z in the surgical ear. Standard tympanometry revealed a S A value of 0.3 mmhos was at the lower limits  114  of normal for normative data, and a T W o f 84.6 daPa was within the normal range. Multifrequency tympanometry showed F 4 5 ° to be 900 H z , well above the 90% range; while R F was 1120 and 1250 H z for positive and negative compensation, respectively, are at or within the upper limits o f normal according to Shahnaz and Davies (2004). Results of W B R are shown in Figures 4.44 through 4.47. For P A , frequencies from 328-1148 H z were below the 90% range. This is the third patient with this finding in this series. Again, a low percent P A in this frequency range suggests poor efficiency o f the middle ear system, likely due to increased stiffness imposed by the annular ligament. This explanation is compatible with the diagnosis of otosclerosis. For Y , frequencies between 3188-3492 H z were above the 90%> range, indicating an ease o f energy transfer in this region. For B , all frequencies are between the 5th and 95th percentiles; hence, they were within the normal range. For G , OF5's values were outside o f the 90%> range for two different frequency ranges: below between 398-1102 H z and above between 3211-3445 H z . The abnormalities seen for Y , B , and G overlap in the same frequency range (i.e. approximately 3100 Hz) and most likely correspond with a R F of the middle ear. Correlation between this finding and M F T R F values bear further investigation. Figure 4.47 also shows increased resistance in the lower frequencies. O F 5 has not yet had surgery.  115  F R E Q U E N C Y IN Hz 125  250  500 ' . -rOOO.  sr /I  /  •  :  — — i 1  ••ry  20  ^  2000  •v..-  4000 "...  K  'c  p» •«  f  SOOO  ••  A  •N  1  ".750  .  1500  3000  6000  Figure 4.43: Pre-operative audiometric results o f otosclerotic female O F 5 .  Power Absorption in an Otosclerotic Female  ,  V.  f / l»I ' m•+ ^  J  r /j if J  ~ > •»  **  f  * »- *_  v  m  ' / 1( t /  >  f  CO CM  o in  4969 {  ^ N  1111111111111111111111 H 111II1111111111111111111111111111111111111111111111 C N C O O ^ - O O C M C D O - ^ - C O C O r ^ c O O C D C N a J L O C N C O ' ^ - ^ C O C O O T - C O ^ f c D C O O i T - C O OJ C N C N C O C O C O C O C O C O C O ^ t - *  CO  -3-  4805 |  ;  I I co  4477 \  o  O  4641 \  CO  1852  T-  2016  CO CO  1688 \  r~  1523  I I o  1359  co  1195  539 !  375 ;  211 ;  i *J y * ii nn 11 in i riTrnn'i'iTTri'ivn'iTTriTTi'n  co  CO TLO  r-CD CM  UO  T CD Tt LO  tr)  CD  co  CM CO LO CD CT) LO LO LO  Frequency (Hz) —  95th Percentile - C F  Mean - C F -  -  5th Percentile - C F  OF5  Figure 4.44: Power absorption as a function o f frequency in otosclerotic female O F 5 . C F refers to Caucasian female.  116  Admittance in an Otoslerotic Female  100  T  10  0.1 Frequency (Hz) |—  95th Percentile - CF  Mean - CF -  - 5th Percentile - CF  OF5 |  Figure 4.45: Admittance as a function of frequency in otosclerotic female O F 5 . C F refers to Caucasian female. Admittance values are dimensionless as they are normalized using characteristic impedance of the ear canal.  117  Susceptance in an Otosclerotic Female 100 -|  — — —  10  Frequency (Hz) 95th Percentile-CF  Mean - C F -  -  5th Percentile - C F  OF5 |  Figure 4.46: Susceptance as a function of frequency in otosclerotic female O F 5 . C F refers to Caucasian female. Susceptance values are dimensionless as they are normalized using characteristic impedance of the ear canal.  118  Conductance in an Otosclerotic Female  100  10  Frequency (Hz) |  95th Percentile - CF  Mean - CF -  - 5th Percentile - CF  OF5 |  Figure 4.47: Conductance as a function of frequency in otosclerotic female O F 5 . C F refers to Caucasian female. Conductance values are dimensionless as they are normalized using characteristic impedance of the ear canal.  4.7.7 Case history of an otosclerotic female: OF6 This 50-year-old Caucasian female had a history of hearing loss in her left ear for the last two years. N o history of tinnitus, vestibular symptoms, or middle ear infections was present. A s well, there was no family history of hearing loss. N o hearing aids are worn. Visual inspection, using otoscopy, revealed no abnormal findings. T E O A E s were found to be absent from 1000 to 4000 H z in the surgical ear. Audiological testing showed a moderate conductive hearing loss in the left ear as seen in Figure 4.48.  Standard tympanometry revealed a S A value of 1.2 mmhos  and a T W of 70.5 daPa, both of which are within normal limits. Multi-frequency tympanometry  119  showed F 4 5 ° to be 630 H z while R F was 800 and 900 H z for positive and negative compensation, respectively; all within normal limits (Shahnaz & Davies, 2004). Results o f W B R are shown in Figures 4.49 through 4.52. Power absorption for O F 6 extends above the 90% range in frequencies 1242-1758 H z and below the 90% range in frequencies 4898-5203 H z . This finding o f better middle ear efficiency in this frequency range is not consistent with Feeney, et al. (2003), but does correspond with some of the other cases in this study. Perhaps the amount of ankylosed bone present around and on the footplate is related to this finding. Admittance also extends above the 90% range for frequencies between 844-1430 H z and 2461-2695 H z indicating an ease of energy transfer in these regions. Susceptance values between 750-1148 H z were above the 95th percentile, while values between 2648-2695 H z were below the 5th percentile. For conductance, O F 6 had three separate frequency regions where her results extended beyond the 90% range normative values: above between 1031-1617 H z and 2461-2695 H z , and below between 5016-5836 H z . These findings suggest an inconsistency in the transfer of energy through the middle ear as shown by the sigmoidal lines throughout P A , Y , B , and G . O f note, both P A and G show decreased values, indicating a less efficient middle ear system in the higher frequencies due to increased resistance.  120  FREQUENCY IN Hz 125  250  500  *1  1000  2000  - / -1  to  V.  k"V. f  V-  '20  0  8000.  "  v  7>  p  y  V  V  60  r  v  p—• I*  30  50  4000  X  0  40  /  70  80 SO J00  1 10  750  .1500  . 3000  6000  Figure 4.48: Pre-operative audiometric results of otosclerotic female OF6.  Power Absorption in an Otosclerotic Female 100  Frequency (Hz) 95th Percentile - CF  Mean - CF  5th Percentile - CF  QFJ]  Figure 4.49: Power absorption as a function of frequency in otosclerotic female OF6. C F refers to Caucasian female. 121  Admittance in an Otoslerotic Female  100  £  3  o>  CM CO IO  CO  o  •<-  LO CO  CO eg  LO  03 co CO  CM -  CD  LO  LO  LO  Frequency (Hz) 95th Percentile - CF '  •Mean - CF  5th Percentile - CF •  -OF6  Figure 4.50: Admittance as a function of frequency in otosclerotic female OF6. C F refers to Caucasian female. Admittance values are dimensionless as they are normalized using characteristic impedance of the ear canal.  122  Susceptance in an Otosclerotic Female 100  -i  —  —  10  Frequency (Hz) —  95th Percentile -CF  Mean - CF -  - 5th Percentile - CF  OF6  Figure 4.51: Susceptance as a function of frequency in otosclerotic female OF6. C F refers to Caucasian female. Susceptance values are dimensionless as they are normalized using characteristic impedance of the ear canal.  123  Conductance in an Otosclerotic Female  100  tT—  eg  Ifl  O)  \— CO  co LO  Frequency (Hz) 95th Percentile - CF <  •Mean - CF  5th Percentile - CF •  -OF6  Figure 4.52: Conductance as a function of frequency in otosclerotic female O F 6 . C F refers to Caucasian female. Conductance values are dimensionless as they are normalized using characteristic impedance of the ear canal.  4.8 Discussion of case studies of otosclerosis In view of the small sample size of otosclerotic study subjects in this exploratory report, formal statistical analyses are not done. From Feeney, et al.'s (2003) paper there is an expectation that subjects with otosclerosis will have values below the 5th percentile for P A at frequencies below 1000 H z . From the graphic information, cases O M 1 , O F 4 , and OF5 have P A values below the 5th percentile curve of normative values. In view of the common occurrence o f lower percent P A values in the low frequencies among subjects, it is likely that otosclerotic patients will have low values in this region with a larger sample size.  124  It is important to note that all of the otosclerotic patients in this study deviated from the normative values on at least one of the four W B R parameters, even when their M F T results were within normal limits. Although only seven patients were tested, these results provided evidence in favour of the utility of W B R for diagnosis of otosclerosis.  Further research should be  conducted in this regard to replicate these findings. O f special interest was the reverse spike complex that is present in B . A s previously mentioned, this complex is present in individual results in both the normal and otosclerotic groups. It is thought that the reverse spike complex in B shows a transition between the stiffness dominated middle ear system and the mass dominated middle ear system. There is a suggestion from the review of the otosclerotic cases that there is a positive relationship between the R F value and a higher frequency location of the reverse spike complex. Although data from only seven otosclerotic subjects has been reviewed, the pattern produced using W B R variables is sufficiently different from normal subjects. This suggests that evaluation of qualitative factors should be considered. This approach has worked well in M F T using Vanhuyse patterns. In summary from this section, information about middle ear dynamic characteristics in otosclerosis from this study can be obtained from the graphic presentation given the small sample size. A s experience is gained from more patients with otosclerosis, W B R patterns will develop that can be correlated with surgical findings. Results may become highly important in the understanding of the clinical utility of W B R in otosclerosis and in understanding middle ear pathologies. The final interpretation of this with regard to diagnosis of otosclerosis or with regard to understanding mechano-acoustical events in the middle ear system awaits clarification of this data.  125  Chapter V General Discussion 5.1 Summary Wideband reflectance (WBR) is a new measure for middle ear evaluation that uses a wide range of sound frequencies to establish the ratio of sound energy reflected on its way to the cochlea in relation to the incident energy, or sound that reaches the cochlea. The objectives of this descriptive, cross-sectional, group comparison study were to establish normative data for W B R by gender using Chinese and Caucasian normal hearing adults, and to explore the potential clinical utility o f W B R in otosclerosis, a common adult middle ear pathology. The subjects included 66 Asian and 62 Caucasian young adults providing 125 and 115 normal middle ears, respectively; and seven ears from seven Caucasian patients with otosclerosis. The objectives were addressed by measuring four parameters of W B R for each ear tested. These parameters included power absorption (PA), admittance (Y), susceptance (B), and conductance (G). Three types of analyses were undertaken. First, repeated measures analysis o f variance ( A N O V A ) assessed the frequency as a within subject factor and gender (male or female), race (Chinese or Caucasian), and ear (left or right) as between subject factors. Significance was determined in two ways: (1) by comparison of means of p < .05, and (2) by clear separation o f the 95% confidence intervals. Second, graphic visual comparisons of mean and 90% range values between race and gender combinations of normal subjects were made for all parameters. Third, data from each individual otosclerotic patient were plotted against appropriate normative curves. A s summarized in Table 4.1, statistical differences in means were found for P A and Y between male Chinese and Caucasian subjects, and female Chinese and Caucasian subjects, with Caucasians having higher values. Similarly, for B , female Caucasians have statistically higher mean values than Chinese. For G , there were no statistical differences. For gender differences  126  within race, only B showed gender differences among Chinese with males having higher values than females. Among Caucasians, males have higher values for Y , B , and G . These differences in mean values are likely based on anatomical differences with Caucasians having larger middle ear volumes than Chinese, and males having larger middle ear volumes than females. This is consistent with Shahnaz and Davies (2004) finding o f larger ear canal volumes in these groups. Differences between all race/gender combinations (i.e. Chinese males and females, Caucasian males and females, Chinese and Caucasian males, and Chinese and Caucasian females) were found by visual exploration o f the graphed parameters data. In view of the importance o f the cutoff levels in clinical practice and lack o f similarity o f these levels for all race/gender combinations, it was concluded that for W B R gender and race specific normative data are needed. For patients with otosclerosis, visual inspection was the analysis method used. When compared to appropriate normative data, all otosclerotic ears had values beyond the 90% range in at least one o f the four W B R variables. While there was not one consistent pattern of results for the otosclerotic ears, three main trends were evident: (1) values using the P A variable tended to vary in the frequencies below 1200 H z , with values lower than the 5th percentile curve indicating less efficient transfer of energy and an increase in stiffness possibly due to growth o f spongy tissues around the annular ligament; (2) the reverse spike complex, as visualized using the B variable, seems to advance in frequency in relation to increasing R F as measured by M F T ; and (3) conductance measures indicate that there is an increase in resistance in some otosclerotic ears. This latter trend is consistent with Shahnaz and Polka's (2002) finding that conductance plays an important role in otosclerosis. Wideband reflectance results were found to be abnormal in all seven of the otosclerosis patients tested, including in four cases where both standard and M F T measures were within  127  normal limits. This suggests the possibility of greater sensitivity of W B R than M F T to the diagnosis of otosclerosis. Further studies should be done to affirm these results. 5.2 Limitations Given that research in the area of W B R is still in its infancy, preferred graphing variables, as well as their units are, as of yet, still inconsistent. This poses considerable difficulty when organizing collected data to fit with already published normative values. When establishing normative values, the sample size should be reasonably large to enhance the power of statistical analysis. Although repeated measures A N O V A took these issues into consideration, a larger sample size o f normal subjects would still benefit this study, and W B R research in general. It would also have been helpful to have a larger patient group, but given time constraints, this was not possible. One important variable that was not taken into consideration by this study was age. The normative population in this study was made up of normal, healthy young adults. The subjects with otosclerosis, on the other hand, had a mean age of 41 years. It is unknown whether this age difference would be enough to influence the patient groups' results. There is some evidence that W B R normative distribution is different among various age populations (Feeney, et al., 2003; Keefe, et al., 2000). In the future, this potential confounding variable should be addressed with age-specific normative data. Other researchers have discussed the effect of ear canal size on results (Voss & Allen, 1994; Keefe, et al., 1993). Controlling for this variable would reduce much of the inter-subject variability seen. Ear canal variation was a limitation to this study. Methods used to reduce the effect of ear canal volume on W B R measurements are recommended as a future research project. Possible methods of measuring ear canal volume include water displacement and using real ear to coupler differences.  128  5.3 Sources o f differences Within the procedure o f this study there were few sources o f differences. The protocol was strictly followed for all normal and otosclerotic subjects. The same instrument, the Mimosa Acoustics R M S v4.0.4.4 machine was used for all subjects. It should be noted, however, that the Mimosa Acoustics software was updated part way through this study. Data obtained prior and after this change should be compared for any significant differences. Instruments could be another source of difference between the results o f this study and those of other authors, including Feeney, et al. (2003) and Feeney and Sanford (2004). There has not been a comparison study done using the same test subjects on both the Mimosa Acoustics and the custom-made instrument o f Keefe, et al., (1993).  Machine variability is a  likely source o f difference between studies due to possible variations in calibration, units, or methods to calculate variables. This study has shown differences between racial and gender groups for W B R which is consistent with previous findings reported using both standard and M F T tympanometry (Shahnaz & Davies, 2004; Wan & Wong, 2002). These variations may be due to anatomical differences as discussed previously in section 4.6. Huang, et al. (2000) noted that there were correlations between the volume of the middle ear of animals and their size. This supports the finding of this study o f apparent anatomical differences affecting test results. That is, i f the middle ear cavity is smaller, there would be increased stiffness in the middle ear system allowing a more efficient transfer o f energy at higher frequencies. Consideration must be given to sources of differences among otosclerotic subjects. A s this exploratory study had only one male, male/female differences within race could not be tested. However, it is likely that gender differences would contribute to differences in study  129  subjects. Similarly, the greater mean age o f the otosclerotic patients relative to the normative subjects may contribute to differences in results. Another source o f difference among otosclerotic subjects is the degree, or stage, o f otosclerosis. Clinically otosclerosis is a progressive disorder. Even after the diagnosis o f clinical otosclerosis is made, progression occurs. A way of determining the degree of stapes fixation, which is a measure o f the amount or stage o f otosclerosis, is by the degree of conductive hearing loss present. A s the new bone growth fixes the stapes further, the conductive hearing loss increases. Differences may also relate to the amount o f stiffness present in different subjects with otosclerosis. Although otosclerosis is a middle ear pathology that is considered to increase stiffness, there have been some exceptions to this in the literature. In some cases otosclerosis could be present with less or no stiffness, possibly related to less bone accumulation. Based on R F tests, Zhao, Wada, Koike, Ohyama, Kawase, and Stephens (2002) found 44.4% of 36 ears with otosclerosis had high stiffness, but 13.9 % had low stiffness and the remaining had normal stiffness status. The occurrence of low or normal stiffness in otosclerotic ears has often been thought to be due to low diagnostic accuracy o f the test used. It is possible that low stiffness occurs in otosclerosis particularly in earlier stages. The degree of otosclerosis as well as the test measure used may both be sources of difference. While it is not clear that stiffness as determined by R F relates to W B R testing, nonetheless differences in amount of stiffness among subjects needs to be considered. 5.4 Implications While W B R is still in early clinical application development, it has so far shown great promise. It has many advantages over conventional middle ear measures in both technical and practical aspects o f testing. Wideband reflectance allows testing o f a larger range of frequencies,  130  giving the clinician more information about the middle ear; concern over ear canal compliance is reduced; a pressure seal is not needed; and dependency on the location of the probe tip in the ear canal is not as critical. In addition, W B R testing is extremely time efficient, both in the testing phase, as well as in the analysis of results as it can be readily represented in Y , B , and G , as well as 11 other parameters as needed. Wideband reflectance is objective, non-invasive, and safe. These latter attributes are particularly important in post-operative otosclerosis, where pressure changes, as induced with tympanometric measures, can potentially damage middle ear structures. One problem that has yet to be resolved is the issue of how the W B R data will be commonly represented (i.e. E R , P A , Y , B , G , etc.). Before the establishment universally clinical normative values, this issue must be resolved. Closely related to this issue is the fact that the most useful measure of W B R has yet to be determined. It may be proven that different pathologies will have preferred measures for diagnosis and/or differential diagnosis. Once these issues have been resolved, it seems likely that W B R will become a promising diagnostic tool. Wideband reflectance has potential clinical utility in a number of middle ear pathologies beyond otosclerosis.  In addition to its usefulness as a diagnostic tool, W B R may become  important in the post-operative evaluation of middle ear surgeries due to its safety. Thus, various surgical procedures and different prosthetic devices could be accurately evaluated. The present evaluation methods of surgery for otosclerosis include direct or indirect measures of the hearing level, such as, pure tone average including 4000 H z and air-bone gap (Goldenberg & Berliner, 1995); word recognition scores (Lippy, et al., 1998); questionnaires of improvement (Aarnisalo, et al., 2003); and quality of life measures (Stewart, et al., 1997). Should a more direct discriminating test be available post-operatively, treatment evaluation would be enhanced. With the ease of administration and safety of W B R testing, this could become an excellent tool for measuring outcomes.  131  The race and gender specific normative values established in this study are vitally important as the basis for further studies of W B R use in middle ear pathologies. These studies require accurate and reliable cutoff levels. Ultimately, these normative data may provide the basis for clinically useful cutoff levels for W B R in adults. This could be further refined by formulating cutoff levels at specific frequencies for individual middle ear disorders. The results of this study have wide implications for further understanding of middle ear functioning and middle ear pathologies.  Specifically, with regard to otosclerosis, W B R is likely  to have greater potential than low frequency tympanometric measurements, as is the case with M F T . Low frequency tympanometry forces the middle ear system to behave as a stiffness dominated system. A s frequency increases, as occurs with W B R , middle ear stiffness is reduced and the middle ear system is less stiffness dominated. B y charting how much energy is transferring into the middle ear system across a wide range of frequencies, the relative contribution of mass, stiffness, and resistance can be evaluated. In the past, the general consideration in otosclerosis has been that B is the component most affected. Thus, both stiffness and mass have been considered. Shahnaz and Polka (2002) have suggested that G may be more affected than B . That is, in otosclerosis conductance (resistance) may be more affected than stiffness. Thus, findings of increased resistance in the middle ear system may assist in a better understanding of the underlying mechanisms of otosclerosis.  More otosclerotic subjects  need to be studied before these findings can be clarified. 5.5 Future research Findings from this study suggest that it is critical to have both gender and race specific normative data. These results should be replicated to assist in generalization and confirmation of the differences found. Measurements of body size, i.e. height, weight, and head circumference, may be useful in determining normative data. In addition, the confounding variable of age  132  should be addressed. A preliminary study to investigate the effect of age on W B R data should be conducted. This is especially important when comparing to middle ear pathologies, such as otosclerosis, as the diseased group is very likely to have a higher average age. If age is discovered to influence W B R parameters, age specific normative data should be sought. This would allow for better diagnostic capability of the W B R measures. This study was limited by its exploratory nature. A larger sample size of subjects with otosclerosis would allow for meaningful statistical analysis and reliable results. Such further studies of otosclerosis using W B R measures would be enhanced by several changes in approach. These include: (1) surgical confirmation of the degree and exact location of otosclerosis as the amount of ankylosed growth present at the time of surgery, would be exceedingly helpful in allowing researchers to correlate gradations o f otosclerosis with W B R findings. This would allow researchers to narrow in on the precise measurement that would be most clinically and diagnostically beneficial; and (2) testing of subjects both before and after surgery would allow monitoring o f treatment effects and changes in the W B R measure. Variations between this study and others (Feeney & Sanford, 2004) should be explored. One way of doing this would be to test the same subjects using both the Mimosa Acoustics and custom made machines. This would allow for differences between the two machines to be monitored, such as, output stimulus and recording filters, while other confounding variables are minimized. Once differences in instrumentation and nomenclature have been overcome, further gender and race specific normative data collection would allow for comparisons between different researchers as well as for clinical purposes. Finally, once ample normative data have been gathered, it is essential to complete test performance analysis on the results to calculate both the clinical utility of W B R , as well as its ability to provide a differential diagnosis.  133  A s previously discussed, W B R is a ratio of the sound energy reflected on its way to the cochlea in relation to the sound that reaches the cochlea. Theoretically, then i f the impedance of the cochlea were higher in certain pathologies, i.e. Meniere's disease, then this would be observed in the test results. Extending this further, other situations where cochlear fluid pressure changes occur, as with cerebral spinal fluid pressure changes, may affect impedance results. Thus, it might be possible that W B R could be used as a measurement o f a change in the pressure, or density of cochlear fluids. Hence, W B R could become a useful diagnostic tool in Meniere's disease, or other similar diseases. This remains to be seen. Future research using W B R may also be expanded to include other middle ear pathologies. This will increase understanding of the mechano-acoustical properties o f the middle ear system and continue to expand knowledge o f the relative contribution o f mass, stiffness, and resistance to these pathologies. This basic understanding will assist in the development of better diagnosis and treatment of middle ear diseases.  134  References Aarnisalo, A . , Vasama, J., Hopsu, E . , & Ramsay, H . (2003). Long-term hearing results after stapes surgery.  Otology & Neurotology, 24, 567-571.  Allen, J. (1985). Measurement of eardrum acoustic impedance. In J. Allen, J. Hall, A . Hubbard, S. Neely, & A . Tubis (eds).  Peripheral Auditory Mechanisms. New York: Springer-  Verlag. A N S I (1989). Specifications for instruments to measure aural acoustic impedance and admittance (aural acoustic immittance). A N S I S3.39-1989.  New York: American  National Standards Institute. Browning, G . , Swan, I., & Gatehouse, S. (1985). The doubtful value of tympanometry with diagnosis of otosclerosis.  Journal of Auditory Research, 10, 52-58.  Chen, W . , Campbell, C , Green, G . , V a n Dan Bogaert, K . , Komodikis, C , Manolidis, L . , Aconomon, E . , Kyamides, Y . , Christodoulou, K . , Faghel, C , Giguere, C , Alford, R., Manolidis, S., V a n Camp, G . , & Smith, R. (2002). Linkage o f otosclerosis to a third locus ( O T S C 3 ) on human chromosome 6p21.3-22.3.  Journal ofMedical Genetics, 39(7),  473-477. Cherukupally, S., Merchant, S., Rosowski, J. (1998). Correlations between pathologic changes in the stapes and conductive hearing loss in otosclerosis.  Annals of Otology, Rhinology,  & Laryngology, 107, 319-326. Colletti, V . (1976). Tympanometry from 200 to 2000 H z probe tone.  Audiology, 15, 106-119.  de Bruijn, A . , Tange, R., Dreschler, W . (1999). Comparison of stapes prostheses: A retrospective analysis of individual audiometric results obtained after stapedotomy by implantation o f a gold and a teflon piston.  American Journal of Otology, 20, 573-580.  135  de Bruijn, A . , Tange, R., & Dreschler, W . (2001). Efficacy of evaluation of audiometric results after stapes surgery in otosclerosis. I. The effects of using different audiologic parameters and criteria on success rates.  Otolaryngol Head Neck Surg, 124, 76-83.  Declau, F . , V a n Spaendonck, M . , Tommermons, J., Liang, M . , Q i u , J., & van de Heyning, P. (2001). Prevalence of otosclerosis in an unselected series of temporal bones. Otology  and Neurotology, 22, 595-602. DeJonge, R. R. (1986). Normal tympanometric gradient: A comparison o f three methods.  Audiology, 25, 299-308. Dempsey, C . (1975). Static compliance. In J.F. Jerger (ed.). Handbook of clinical impedance audiometry (pp.71-84). New York: American Electromedics. Dieroff, H . (1978). Differential diagnostic value of tympanometry in adhesive processes and  otosclerosis. Audiology, 77,77-86. Durrant, J. D . , & Lovrinic, J. H . (1995).  Bases of hearing science (3rd ed.). Baltimore, M D :  Williams and Wilkins. Feeney, M . P., Grant, I. L . , & Marryott, L . P. (2003). Wideband energy reflectance measurements in adults with middle-ear disorders.  Journal of Speech, Language, and  Hearing Research, 46, 901-911. Feeney, M . P., & Keefe, D . H . (2001). Estimating the acoustic reflex threshold from wideband measures of reflectance, admittance and power. Ear and Hearing, 22, 316-332. Feeney, M . P., & Sanford, C . A . (2004). Age effects in the human middle ear: Wideband acoustical measures.  Journal of the Acoustical Society of America. (In press.)  Feldman, A . (1974). Eardrum abnormality and the measurement of middle ear function.  Archives of Otolaryngology, 99, 211-217. Gelfand, S. (2001).  Essentials ofAudiology (2nd ed.). N Y : Thieme Medical Publishers, Inc.  136  Ginsberg, I. A . , & White, T . P. (1985). Otologic considerations in audiology. In: Katz, J.  Handbook of Clinical Audiology (3rd ed.). Baltimore: Williams and Wilkins. Goldenberg, R., & Berliner, K . (1995). Reporting operative hearing results: Does choice o f outcome measure make a difference? The American Journal of Otology, 16, 128-135. Gros, A . , Vatovec, J., & Sereg-Bahar, M . (2003). Histologic changes on stapedial footplate in otosclerosis. Otology and Neurotology, 24, 43-47. House, P., Hansen, M . , A l Dakhail, A . , & House, J. (2002). Stapedectomy versus stapedotomy: Comparison of results with long-term follow-up. Laryngoscope, 112(11), 2046-50. Huang, G . T . , Rosowski, J. J., Peake, W . T . (2000). Relating middle-ear acoustic performance to body size in the cat family: Measurements and models. Journal of Comparative  Physiology, 186, 447-465. Ivey, R. (1975). Tympanometric curves and otosclerosis. Journal of Speech and Hearing  Research, 18, 554-558. Jeng, P., Levitt, H . , Lee, W . , & Gravel, J. (1999). Reflectance measures for detecting O M E in children: preliminary findings. In D . L i m (Ed.), Abstracts o f the Seventh International Symposium on Recent Advances in Otitis Media, (p. 217). Fort Lauderdale, Florida. Jerger, J. (1970). Clinical experience with impedance audiometry. Archives of Otolaryngology, 96, 311-324. Jerger, J., Anthony, L . , Jerger, S., & Mauldin, L . (1974). Studies in impedance audiometry: HI Middle ear disorders. Archives of Otolaryngology, 99, 165-171. Keefe, D . H . , Bulen, J. C , Arehart, K . H . , & Burns, E . M . (1993). Ear-canal impedance and reflection coefficient in human infancts and adults. Journal of the Acoustical Society of  America, 94, 2617-2638.  137  Keefe, D . H . , Folsom, R. C , Gorga, M . P., Vohr, B . R., Bulen, J. C , & Norton, J. S. (2000). Identification o f neonatal hearing impairment: ear-canal measurements of acoustic admittance and reflectance in neonates,  Ear & Hearing, 21(5), 443-61.  Keefe, D . , Ling, R., & Bulen, J. (1992). Method to measure acoustic impedance and reflection coefficient.  Journal of the Acoustical Society ofAmerica, 91(1), 470-485.  Keefe D . H . , & Simmons J. L . (2003). Energy transmittance predicts conductive hearing loss in older children and adults.  Journal of the Acoustical Society ofAmerica, 114(6 Pt 1),  3217-38. Kemp, D . T., & Souter, M . (1988). A rapid new component in the cochlear response to brief electrical efferent stimulation: C M and otoacoustic observations. Hearing Research,  34(1), 49-62. Koebsell, K . , Shanks, J . , Cone-Wesson, B . , & Wilson, R. (1988). Tympanometric width measures in normal and pathologic ears.  ASH A, 30,99.  Koivunen, P., Uhari, M . , Laitakari, K . , Alho, O . , & Luotonen, J. (2000). Otoacoustic emissions and tympanometry in children with otitis media.  Ear and Hearing, 21(3), 212-217.  Kursten, R., Schneider, B . , & Zrunek, M . (1994). Long-term results after stapedectomy versus stapedotomy.  American Journal of Otolaryngology, 6, 804-6.  Lilly, D . (1984). Multiple frequency, multiple component tympanometry: New approaches to an old diagnostic problem.  Ear and Hearing, 5, 300-308.  Levy, R., Stvero, J., Hadar, T. (1990). Stapedotomy technique results: Ten years experience and comparative study with stapedectomy. Laryngoscope, 100, 1-7. Liden, G . , Peterson, J . L . , & Bjorkman, G . (1970). Tympanometry.  Archives of Otolaryngology,  92, 248-257.  138  Lippy, W . , Berenholz, L . , & Burkey, J. (1999). Otosclerosis in the 1960s, 1970s, 1980s, and 1990s. Laryngoscope,  109(S), 1307-1309.  Lippy, W . , Burkey, J., & Arkis, P. (1998). Word recognition score changes after stapedectomy for far advanced otosclerosis. The American Journal of Otology, 19, 56-58. Margolis, R. H . , & Goycoolea, H . G . (1993). Multifrequency tympanometry in normal adults. Ear and Hearing,  74,408-413.  Margolis, R. H . , & Heller, J. W . (1987). Screening tympanometry: Criteria for medical referral. Audiology,  26, 197-208.  Margolis, R. H . , & Hunter, L . (1999). Tympanometry: Basic principles and clinical applications. In W . F . Rintelmann, & F . Musiek (Eds.), Hearing assessment, (pp. 89-130). Boston: A l l y n & Bacon. Margolis, R. H . , Saly, G . L . , & Keefe, D . H . (1999). Wideband reflectance tympanometry in normal adults. Journal of the Acoustical  Society of America,  106(1), 265-280.  Margolis, R. H . , & Shanks, J. E . (1985). Tympanometry. In J Katz (Ed.), Handbook of audiology: 3  rd  clinical  edition (pp. 438-475). Baltimore: Williams & Wilkins.  Margolis, R. H . , & Shanks, J. E . (1991). Tympanometry: Principles and procedures. In W . F . Rintelmann (Ed.), Hearing assessment (pp. 179-246). Texas: Pro-Ed. Margolis, R. H . , V a n Camp, K . J., Wilson, R. H . , & Creten, W . L . (1985). Multifrequency tympanometry in normal ears. Audiology,  24(1), 44-53.  Menger, D . J . , & Tange, R. A . (2003). The aetiology of otosclerosis: A review of the literature. Clinical  Otolaryngology,  28, 112-120.  Moller, P. (1992). Stapedectomy versus stapedotomy. Review of Laryngology  Otology  Rhinology (Bord), 113(5), 397-400.  139  Monsell, E . , Balkany, T . , Gates, G . , Goldenberg, R., Meyerhoff, W . , & House, J. (1995). Committee on hearing and equilibrium: Guidelines for the evaluation o f results of treatment of conductive hearing loss.  Otolaryngology, Head and Neck Surgery, 113,  186-187. Muchnik, C , Hildesheimer, M . , Rubinstein, M . , & Glettman, Y . (1989). Validity o f tympanometry in cases of confirmed otosclerosis.  Journal of Laryngology &  Otolaryngology, 103, 36-38. NTH Consensus Statement Online. (1993). Early identification o f hearing impairment in infants and young children. Retrieved September, 2004 from http://odp.od.nih.gov/consensus/cons/092/092  statement.htm  Piskorski, P., Keefe, D . , Simmons, J., & Gorga, M . (1999). Prediction o f conductive hearing loss based on acoustic ear-canal response using a multivariate clinical decision theory.  Journal of the Acoustic Society of America, 105, 1749-1764. Rappaport, J., & Provencal, C . (2002). Neuro-otology for audiologists. In: Katz, J.  Handbook of  Clinical Audiology (5th ed.). New York: Lippincott, Williams & Wilkins. Robinette, M . S., & Glattke, T. J. (2002). Otoacoustic emissions: Clinical applications. New York: Thieme Medical Publishers, Inc. Roup, C . M . , Wiley, T . L . , Safady, S. H . , and Stoppenbach, D . T . (1998). Tympanometric screening norms for adults.  American Journal of Audiology, 7, 55-60.  Shahnaz, N . (2001). Distinguishing otosclerotic ears from healthy ears using multifrequency and multicomponent tympanometry.  Unpublished doctoral dissertation, McGill University,  Montreal, Quebec. Shahnaz, N . (2004). Through personal communication with Patrick Feeney and Jens Meyer. September 21.  140  Shahnaz, N . , & Davies, D . (2004). Standard and multi-frequency tympanometric norms for Caucasian and Chinese young adults. Submitted for  publication.  Shahnaz, N . , & Polka, L . (1997). Standard and multifrequency tympanometry in normal and otosclerostic ears. Ear and Hearing,  18(4), 326-341.  Shahnaz, N . , & Polka, L . (2002). Distinguishing healthy from otosclerotic ears: Effect of probetone frequency on static immittance. Journal of the American Academy of  Audiology,  13(1), 345-355. Shanks, J. E . (1984). Tympanometry. Ear and Hearing, 5, 268-280. Shanks, J. E . , & Shelton, C . (1991). Basic principles and clinical applications of tympanometry. Otolaryngology  Clinics of North America, 24, 299-328.  Shea, J. J. (1998). A personal history of stapedectomy.  The American Journal of Otology, 19,  S2-S12. Shin, Y . J . , Calvas, P., Deguine, O . , Charlet, J-P., Cognard, C , & Fraysse, B . (2001). Correlations between computed tomography findings and family history in otosclerosis patients. Otology and Neurotology, 22, 461-464. Statistics Canada (2002). Retrieved September, 2004 from http://www.statcan.ca/english/concepts/definitions/ethnicitv01.htm. Stewart, M . & Jenkins, H . , Coker, N . , Jerger, J., & Loiselle, L . (1997). Development of a new outcomes instrument for conductive hearing loss. American Journal of Otology, 18, 413420. Terkildsen, K . , & Thomson, K . (1959). The influence of pressure variations on the impedance of the human ear drum. Journal of Laryngology  and Otolaryngology,  73, 409-418.  Voss, S. E . & Allen, J. B . (1994). Measurement of acoustic impedence and reflectance in the human ear canal. Journal of the Acoustical  Society of America,  95, 372-384.  141  Wan, I. K . & Wong, L . L . (2002). Tympanometric norms for Chinese young adults. Ear and  Hearing, 23(5), 416-421. Wang, P . C , Merchant, S. N . , McKenna, M . J., Glynn, R. J., & Nadol, J. B . (1999). Does otosclerosis occur only in the temporal bone? The American Journal of Otology,  20,  162-165. Wiley, T . L . , Cruickshanks, K . J., Nondahl, D . M . , & Tweed, T . S. (1999). Aging and middle ear resonance. Journal of the American Academy of Audiology,  10, 173-179.  Wilson, R. H . , Shanks, J. E . , & Kaplan, S. K . (1984). Tympanometric changes at 226 Hz and 678 Hz across 10 trials and for two directions o f ear canal pressure change. Journal of Speech and Hearing Research, 27(2), 257-266. Zhao, F . , Wada, H . , Koike, T . , Ohyama, K . , Kawase, T . , & Stephens, D . (2002). Middle ear dynamic characteristics in patients with otosclerosis. Ear & Hearing, 23(2), 150-158.  142  Appendix I Requested Raw Data from Feeney and Sanford (2004).  Energy Reflectance (%) Frequency (Hz)  Mean  5th Percentile  95th Percentile  250  96.3  92.3  99.1  315  95.1  89.5  98.7  397  92.6  86.2  98.0  500  88.1  77.9  96.8  630  81.8  63.2  93.9  794  75.8  54.2  92.0  1000  68.8  45.1  89.2  1260  63.2  32.3  86.1  1587  60.3  27.1  81.6  2000  58.1  30.0  79.8  2520  48.9  26.2  71.7  3175  35.0  8.3  55.8  4000  23.9  5.3  46.1  5040  32.9  7.2  70.2  Table A l : Mean, 5th, and 95th percentile energy reflectance data from Feeney and Sanford (2004).  143  Admittance Frequency (Hz)  Mean  5th Percentile  95th Percentile  250  1.45  1.06  2.05  315  1.77  1.26  2.53  397  2.24  1.63  3.24  500  2.82  2.06  4.09  630  3.46  2.58  4.95  794  4.21  3.07  6.46  1000  5.00  3.66  7.93  1260  5.87  4.16  9.32  1587  7.04  4.67  11.64  2000  9.21  5.88  14.76  2520  13.33  7.53  24.09  3175  18.18  8.34  36.72  4000  26.23  6.64  45.76  5040  30.92  3.95  63.87  Table A 2 : Mean, 5th, and 95th percentile admittance data from Feeney and Sanford (2004).  144  Susceptance Frequency (Hz)  Mean  5th Percentile  95th Percentile  250  1.44  1.05  2.04  315  1.75  1.26  2.49  397  2.21  1.63  3.17  500  2.75  2.03  4.03  630  3.30  2.48  4.82  794  3.93  2.94  6.22  1000  4.55  3.26  6.85  1260  5.21  3.44  8.01  1587  6.19  3.78  9.60  2000  8.05  4.93  13.32  2520  9.67  -1.89  18.76  3175  11.70  -6.30  21.46  4000  6.51  -18.82  23.15  5040  -5.71  -25.0  33.22  Table A 3 : Mean, 5th, and 95th percentile susceptance data from Feeney and Sanford (2004).  145  Conductance Frequency (Hz)  Mean  5th Percentile  95th Percentile  250  0.151  0.029  0.291  315  0.213  0.050  0.393  397  0.343  0.099  0.660  500  0.578  0.213  1.035  630  0.957  0.430  1.729  794  1.390  0.568  2.522  1000  1.963  1.093  4.047  1260  2.543  1.171  4.925  1587  3.113  1.710  6.562  2000  4.001  1.969  7.017  2520  6.678  3.168  17.015  3175  11.279  3.809  27.530  4000  20.837  2.214  44.684  5040  23.140  1.508  51.200  Table A 4 : Mean, 5th, and 95th percentile conductance data from Feeney and Sanford (2004).  146  Appendix U Confirmation of Diagnosis  Post-  PreStudy  Surgical  Amount o f  Prosthesis  Window  procedure  bone  type  closure  operative  operative subject  diagnosis  diagnosis  OF2  OF3  Left  Laser  otosclerosis  stapedotomy  Left  Laser  otosclerosis  stapedotomy*  Significant  N/A  Modified  V e i n graft  from  Left  piston bucket  patient's left  handle  hand  Lippy  V e i n graft from  Left  modified  patient's left  otosclerosis  piston bucket  hand  otosclerosis  handle  Table A 5 : Results from operative reports and surgical confirmation of diagnosis. N A - Not available, * Skeeter drill was also used to remove sclerotic growth anteriorly over the footplate.  147  Appendix III Telephone Questionnaire  Name:  Contact info: Phone: Email:  Time that they are available:  H o w they heard about the study:  To book subjects, the following criteria must be met: 1.  Are between the ages of 18-34 years.  2.  They have normal hearing (to the best o f their knowledge).  3.  Have had no middle ear disease/infection.  4.  Have had no head trauma.  5.  O f Chinese or Caucasian descent: a) Have parents and grandparents from mainland China, Taiwan, or Hong Kong, or b) Have parents and grandparents o f European descent (i.e. non-Hispanic, nonAboriginal, non-Arab/West Arab, non-Black, and non-East/South/South-East Asian, with white or light skin).  Location of M E L : Woodward Biomedical Library/IRC building R o o m B28 Phone: 822-9474  148  Appendix IV Email Questionnaire  Thank you for your interest in our study. The study is, in part, investigating i f there are differences between the middle ears of Chinese and Caucasian young adults. The other part is to compare normal hearing subjects to patients with otosclerosis (a type of hearing loss). To be a participant in the study I need to confirm that: (1) you are either Caucasian or Chinese (with parents and grandparents from mainland China, Taiwan, or Hong Kong), (2) you have no history of head trauma or middle ear infections, (3) you are between the ages of 18-34, and (4) you have normal hearing to the best of your knowledge. If you meet these criteria, I can arrange a time for you to participate in the study. Participation involves a hearing test to confirm that you have normal hearing, followed by some middle ear measurement tests. A l l of the tests are easy to participate in and are not invasive or painful. There is a $10 honorarium for 1 hour o f participation. Testing takes place in room B28 of the Woodward IRC building on U B C campus. Please let me know when you will be available for the study so that I can set up an appointment with you. If you need more information or have any questions, please contact the Middle Ear Lab at (604) 822-9474, or email at mel@audiospeech.ubc.ca. Thank you, Middle Ear Lab Researchers  149  Appendix V Consent Form for Otosclerotic Subjects  T H E UNIVERSITY O F BRITISH C O L U M B I A  & PROVIDENCE H E A L T H C A R E  H i  A i t M  . C A'-tt E  St. Paul's Hospital Rotary Hearing & E N T  School of Audiology & Speech Sciences Faculty o f Medicine 5804 Fairview Avenue  1081 Burrard St.  Vancouver, B C , Canada V 6 T 1Z3  Vancouver, B C Canada V 6 Z 1Y6  nshahnaz@audiospeech.ubc.ca  Tel: (604) 684-6532  Tel: (604) 822-5591 Fax: (604) 822-6569  Consent Form Project Title: Wide Band Reflectance in Surgically Confirmed Otosclerosis Principal Investigator: Dr. Navid Shahnaz Assistant Professor, School of Audiology & Speech Sciences University of British Columbia Phone: 604-822-5953 Email: nshahnaz@audiospeech.ubc,ca  Dr. Brian Westerberg Clinical Associate Professor Rotary Hearing & E N T Clinic Providence 2, St. Paul's Hospital Phone: (604) 806-8540 Email: BrianWesterberg(a>telus.net  Co-investigators: Dr. Sipke Pijl Director of Audiology Rotary Hearing & E N T Providence 2, St. Paul's Hospital Phone: (604) 682-2344 ext 62514 Email: spijl@providencehealth.be.ca  Karin Bork Graduate Student School of Audiology & Speech Sciences University of British Columbia Phone: (604) 822-9474 Email: karin@audiospeech.ubc.ca  Purpose: Y o u have been invited to participate in this research project because we are studying patients with otosclerosis who have been booked for surgery. W e want to improve how we test for otosclerosis (the fixation of the third ear bone in your middle ear) that causes hearing loss.  150  The usual hearing test that is done before surgery includes a measure of your hearing in a sound room. This test is called pure-tone audiometry. The usual measurement of the eardrum and middle-ear will be done with standard tympanometry. These are both safe and routine tests. Y o u may remember that you may feel some pressure with the tympanometry test as well as a low volume tone. For this study, we want to learn more about newer tests of middle ear function. These tests are called multi-frequency tympanometry and wide band reflectance.  These tests measure a  much wider frequency range than the regularly used tests. This provides a more detailed picture of your middle ear. We expect to find two main results: 1.  The new tests will show a difference between normal middle ears and ears of patients  2.  Used together, these tests will diagnose otosclerosis better than the old tests.  with otosclerosis.  Your participation in these extra tests is voluntary. If you do not take part, your care will continue normally. If you choose to volunteer, you may stop the tests at any time. Withdrawal will not change your care.  Study Procedures: If you do choose to volunteer to participate in this research study, all testing will be conducted by Dr. N . Shahnaz, Ph.D., who is a certified audiologist, or by his co-investigator Karin Bork under his supervision. The tests will be done as part of your pre-operative evaluation in the Rotary Hearing and E N T clinic at St. Paul's Hospital. Should there be any findings from this study that may be useful to your doctor, this information will be communicated to him/her with your permission. Before the tests start we will look at your eardrum and ear canal. A n Ear, Nose & Throat physician will clean your ear canal i f necessary. The tests for this research study are: 1) Transient-evoked otoacoustic emissions, 2) Multi-frequency tympanometry, and 3) Wide band reflectance. The three tests together take approximately fifteen minutes. This will be in addition to the 20-30 minutes required for the usual tests before surgery. In each of the three tests, a small earphone will be placed into the entrance of your ear canal using a soft and delicate plastic or sponge tip. It is designed not to cause any allergic reactions. The presence of the earphone may be a bit uncomfortable to some patients, but not painful. The earphone and the attached tip pose no danger to your ear or hearing and has been used widely in the testing of newborns, children, and adults. The first test, transient-evoked otoacoustic emissions, is commonly used in clinics to detect hearing loss. Y o u will hear a clicking sound through a small earphone placed at the entrance of your ear canal. The level of sound is the same as normal talking. Echoes to the sound come back out of your ear. These echoes are measured by a computer. This test will give us information about your middle and inner ear. It will take 2-3 minutes in each ear. 151  The second test, multi-frequency tympanometry, presents a pure tone while the air pressure in the ear canal is changed. W e will test at the frequencies o f speech. It will take about 4 minutes in each ear. The third test, wide band reflectance, presents chirping sounds. This helps us see how well the middle ear reacts to sounds that span the human speech range. This test will take about 2-3 seconds for each ear.  Advantages These are tests of middle ear function. They are not treatments. W e hope these tests will better help us to check middle ears.  We hope to improve the diagnosis and treatment of  otosclerosis in the future. There are no direct benefits to you.  Disadvantages The tympanometry tests give small pressure changes in the ear.  A l l tones that are  presented during the testing are safe.  Pressure changes are well below any level that could  damage your eardrum or middle ear.  However, as a safety measure, the tester will carefully  examine each ear before beginning. If you choose to end your participation in this study, we will stop the testing at any time. There will be no change in the care you would normally receive.  How your information will be used Y o u r test results will be compared with test results from adults with no middle ear disease.  W e will find out i f these new tests are better to separate normal and diseased middle  ears. Your results will also be compared to the observations of your doctor during the surgery on your ear. This will show i f the tests are correct in what they tell us about otosclerosis.  Confidentiality: Your identity will be coded using a code known only to the researchers. A l l information that is collected from you will remain confidential.  Only group results or coded individual  results will be given in any reports about the study. Coded results only will be kept in computer files on a password protected hard drive. N o personal information will be kept in these files. N o private or confidential information that discloses your identity will be released or published, unless required by law, without your specific consent. However, research records and medical records identifying you may be inspected in the presence of the investigator or his designate by representatives of Health Canada, and the U B C Research Ethics Board for the purpose of monitoring the research. N o records which identify you by name or initials will be allowed to leave the Investigators' offices.  Compensation for Injury: Signing this consent form in no way limits or restricts your legal rights against the investigators, or anyone else.  Consent: I,  , have read the above test protocol and I consent to  participate in this study undertaken by Dr. Navid Shahnaz, Dr. Brian David Westerberg, Dr. Sipke Pijl, and Karin Bork at St. Paul's Hospital. The researcher tells me that my participation 152  in this study is completely voluntary. The researcher also assures me that I may withdraw from this research at any time without consequences. If I have any question or desire further information with respect to this study, I may contact Dr. Navid Shahnaz at 604-822-5953. If I have any concerns about my treatment or rights as a research subject, I may contact the Director at the Office o f Research Services at the University  of British  Columbia,  at  604-822-8598,  or Dr. Stephan Shalansky, Chair  -  UBC/Providence Health Care Research Ethics Board, at (604) 682-2355 local 62325. I have received a copy of this consent form for my records.  Subject signature  Date  Subject name (please print)  Signature of principle/co- investigator  Date  Name o f principle/co-investigator (please print)  153  Appendix V Analysis of Variance ( A N O V A ) Tables for Power Absorption, Admittance, Susceptance, and Conductance Data with regard to Normal Subjects.  Source RACE GENDER EAR R A C E * GENDER RACE * EAR GENDER* EAR RACE*GENDER* EAR Error  Type III Sum of Squares 238507.602 29303.929 15017.481 41062.205 5684.753 270.822 1269.102  df  Mean Square  F  Significance  1 1 1 1 1 1 1  238507.602 29303.929 15017.481 41062.205 5684.753 270.822 1269.102  12.439 1.528 0.783 2.141 0.296 0.014 0.066  .001 .218 .377 .145 .587 .905 .797  4506021.287  235  19174.559  Table A6: Summary o f A N O V A for power absorption data.  Source RACE GENDER EAR RACE * GENDER RACE * EAR GENDER*EAR RACE*GENDER* EAR Error  Type III Sum of Squares 83.346 30.016 0.215 11.698 20.024 1.077 3.344E-02  df  Mean Square  F  Significance  1 1 1 1 1 1 1  83.346 30.016 0.215 11.698 20.024 1.077 3.344E-02  12.896 4.644 0.033 1.810 3.098 0.167 0.005  .000 .032 .856 .180 .080 .683 .943  1512.308  234  6.463  Table A 7 : Summary o f A N O V A for admittance data.  154  Source RACE GENDER EAR R A C E * GENDER RACE * EAR G E N D E R * EAR R A C E * GENDER* EAR Error  Type III Sum of Squares 113.275 67.912 6.929E-02 4.332 17.912 0.133 1.086E-02  df  Mean Square  F  Significance  1 1 1 1 1 1 1  113.275 67.912 6.929E-02 4.332 17.912 0.133 1.086E-02  17.270 10.354 0.011 0.660 2.731 0.020 0.002  .000 .001 .918 .417 .100 .887 .968  1541.389  235  6.559  Table A 8 : Summary of A N O V A for susceptance data.  Source RACE GENDER EAR RACE*GENDER RACE * EAR GENDER* EAR RACE * GENDER* EAR Error  Type III Sum of Squares 9.131 14.999 4.907 20.531 11.877 0.319 0.148  df  Mean Square  F  Significance  1 1 1 1 1 1 1  9.131 14.999 4.907 20.531 11.877 0.319 0.148  2.578 4.234 1.385 5.796 3.353 0.090 0.042  .110 .041 .240 .017 .068 .764 .838  839.487  237  3.542  Table A 9 : Summary of A N O V A for conductance data.  155  

Cite

Citation Scheme:

        

Citations by CSL (citeproc-js)

Usage Statistics

Share

Embed

Customize your widget with the following options, then copy and paste the code below into the HTML of your page to embed this item in your website.
                        
                            <div id="ubcOpenCollectionsWidgetDisplay">
                            <script id="ubcOpenCollectionsWidget"
                            src="{[{embed.src}]}"
                            data-item="{[{embed.item}]}"
                            data-collection="{[{embed.collection}]}"
                            data-metadata="{[{embed.showMetadata}]}"
                            data-width="{[{embed.width}]}"
                            async >
                            </script>
                            </div>
                        
                    
IIIF logo Our image viewer uses the IIIF 2.0 standard. To load this item in other compatible viewers, use this url:
http://iiif.library.ubc.ca/presentation/dsp.831.1-0091503/manifest

Comment

Related Items