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

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 of middle ear measurement, wideband reflectance (WBR), has been discovered. Wideband reflectance is the ratio of 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 WBR 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 WBR 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 WBR parameters assessed were power absorption, admittance, susceptance, and conductance. Analysis consisted of: (1) a repeated measures analysis of 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 of 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 of gender and race specific normative values for WBR. Differences in graphic representation of patient data plotted against normative values are found for some WBR measures. Further research is needed in this area.

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