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Rinne test: does the tuning fork position affect the sound amplitude at the ear? Butskiy, Oleksandr; Ng, Denny; Hodgson, Murray; Nunez, Desmond A Mar 24, 2016

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ORIGINAL RESEARCH ARTICLE Open AccessRinne test: does the tuning fork positionaffect the sound amplitude at the ear?Oleksandr Butskiy1,3,5*, Denny Ng2, Murray Hodgson2,4 and Desmond A. Nunez1,3,5AbstractBackground: Guidelines and text-book descriptions of the Rinne test advise orienting the tuning fork tines inparallel with the longitudinal axis of the external auditory canal (EAC), presumably to maximise the amplitude ofthe air conducted sound signal at the ear. Whether the orientation of the tuning fork tines affects the amplitude ofthe sound signal at the ear in clinical practice has not been previously reported. The present study had two goals:determine if (1) there is clinician variability in tuning fork placement when presenting the air-conduction stimulusduring the Rinne test; (2) the orientation of the tuning fork tines, parallel versus perpendicular to the EAC, affectsthe sound amplitude at the ear.Methods: To assess the variability in performing the Rinne test, the Canadian Society of Otolaryngology – Headand Neck Surgery members were surveyed. The amplitudes of the sound delivered to the tympanic membranewith the activated tuning fork tines held in parallel, and perpendicular to, the longitudinal axis of the EAC weremeasured using a Knowles Electronics Mannequin for Acoustic Research (KEMAR) with the microphone of a soundlevel meter inserted in the pinna insert.Results: 47.4 and 44.8 % of 116 survey responders reported placing the fork parallel and perpendicular to the EACrespectively. The sound intensity (sound-pressure level) recorded at the tympanic membrane with the 512 Hztuning fork tines in parallel with as opposed to perpendicular to the EAC was louder by 2.5 dB (95 % CI: 1.35,3.65 dB; p < 0.0001) for the fundamental frequency (512 Hz), and by 4.94 dB (95 % CI: 3.10, 6.78 dB; p < 0.0001) and3.70 dB (95 % CI: 1.62, 5.78 dB; p = .001) for the two harmonic (non-fundamental) frequencies (1 and 3.15 kHz),respectively. The 256 Hz tuning fork in parallel with the EAC as opposed to perpendicular to was louder by 0.83 dB(95 % CI: −0.26, 1.93 dB; p = 0.14) for the fundamental frequency (256 Hz), and by 4.28 dB (95 % CI: 2.65, 5.90 dB;p < 0.001) and 1.93 dB (95 % CI: 0.26, 3.61 dB; p = .02) for the two harmonic frequencies (500 and 4 kHz) respectively.Conclusions: Clinicians vary in their orientation of the tuning fork tines in relation to the EAC when performing theRinne test. Placement of the tuning fork tines in parallel as opposed to perpendicular to the EAC results in a highersound amplitude at the level of the tympanic membrane.Keywords: Tuning fork, Physical examination, Rinne testBackgroundHistorically, up to 20 tuning fork tests were used in thediagnosis of hearing loss [1]. Anecdotally only two tests,Webber and Rinne, continue to be routinely taught inmedical schools and used clinically by otologists and pri-mary care physicians. The Rinne test is recommended aspart of an otological physical exam to detect conductivehearing loss [2]. In patients with otosclerosis, the Rinnetest is used to determine stapes surgery candidacy [3].Olotaryngologists have advocated for further study ofthe sources of variation in performing the Rinne testgiven its widespread clinical use [4].Audiology society recommendations [5] instructionsaimed at medical student and non-specialist on perform-ing the Rinne test in general and otolaryngology text-books [6], instructions intended for otolaryngologyresidents in speciality textbooks [7], and peer reviewed* Correspondence: butskiy.alex@gmail.com1Division of Otolaryngology – Head and Neck Surgery, Vancouver GeneralHospital, Vancouver, BC, Canada3Department of Surgery, University of British Columbia, Vancouver, BC,CanadaFull list of author information is available at the end of the article© 2016 Butskiy et al. Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, andreproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link tothe Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver(http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.Butskiy et al. Journal of Otolaryngology - Head and Neck Surgery  (2016) 45:21 DOI 10.1186/s40463-016-0133-7publications [4, 8] all describe placing the vibrating tun-ing fork tines in parallel with the longitudinal axis of ex-ternal auditory canal (or parallel to the frontal plane ofthe skull). In comparison to perpendicular placement ofthe tines, placement of the tines parallel to the ear canalis thought to result in higher sound intensities (i.e.,sound pressure levels) at the patient’s eardrum [5].Mathematical calculations and sound field recordingsconclude that a higher amplitude sound is delivered tothe ear when the fork is placed parallel to as opposed toperpendicular to the EAC [9, 10]. These lines of evi-dence show a 5 dB difference in the sound intensity pro-duced by the two different positions of the tuning fork[10]. However, there are several known tuning fork vi-bration modes, and these mathematical models and ex-perimental studies have only tested the individualvibration modes. A tuning fork activated by a physicianlikely produces a sound that is a product of at leastseven known vibration modes [11]. The sound inten-sities of a tuning fork placed parallel to and perpendicu-lar to the EAC during the Rinne test have not beencompared before.The present study had two goals: To determine if (1)Canadian otolaryngologists demonstrate variability inperformance of the Rinne test, specifically focusing onthe tuning fork placement during air conduction testing;(2) orientation of the tuning fork tines, parallel to ascompared to perpendicular to the EAC, affects the amp-litude of sound (at fundamental and harmonic frequen-cies) at the level of the tympanic membrane.MethodsTo assess the variability in performance of the Rinne testamongst Canadian otolaryngologists, we conducted ane-mail survey through the Canadian Society of Otolaryn-gology – Head and Neck Surgery member e-mail list.Prior to conducting the survey, ethics approval from ourinstitution was sought, but was deemed unnecessary bythe research ethics board. The survey was e-mailed outonce to the member list on April 22nd, 2015 and the re-sults were collected until June 2nd, 2015. The surveyconsisted of four multiple-choice questions and a com-ment section.An experimental simulation of the air conductioncomponent of the Rinne test was used to measure thesound intensity at the level of the tympanic membranefor both parallel and perpendicular positions of the tun-ing fork. Two aluminum tuning forks (512 Hz and256 Hz) of the same design were used in the experiment(Fig. 1).The experimental design is summarized in Fig. 2. Theprotocol for tuning fork activation and placement wasbased on the most common responses from the emailsurvey. One of the testers was blinded to the studyquestion. A visual reference was used to train the testersto consistently place the edge of the vibrating tuningfork 30–49 mm lateral to the ear canal (Fig. 3a, c). Inaddition, the testers were trained to align the middle oftuning fork with the EAC viewed in the coronal plane(Fig. 3b, d). To ensure consistent tuning fork placementthroughout the experiment, the placement of the tuningfork was re-checked using a visual reference after eachof 50 consecutive activations.The sound intensities produced by the tuning forkduring individual activations were recorded with a RIONNA-28 Sound Level Meter (RION Co., Ltd., Tokyo,Japan) with its microphone inserted into the EAC holein the pinna insert of a KEMAR Manikin Type 45BA(G.R.A.S. Sound & Vibration, Holte, Denmark). Thesound spectra of the tuning forks were measured in 1/3octave bands. Each measurement was triggered whenthe 1/3 octave band of interest (256 or 512 Hz) exceededFig. 1 256 Hz (left) and 512 Hz (right) tuning forks used inthe experimentButskiy et al. Journal of Otolaryngology - Head and Neck Surgery  (2016) 45:21 Page 2 of 8Protocol1. Activate the fork by a strike on the knee2.  Place the fork 30-49mm away from the mannequin ear3.  Record the amplitudes of the fundamental and non-fundamental frequencies Tester 1Fork Parallel N=50Fork Perpendicular N=50Tester 2Fork Parallel N=50Fork Perpendicular N=50Tester 3Fork Parallel N=50Fork Perpendicular N=50Fundamental FrequencyFork Parallel (N=150) vs Perpendicular (N=150)Non-Fundamental FrequenciesFork Parallel (N=150) vs Perpendicular (N=150)Fig. 2 The experimental designa bc dFig. 3 Simulation of the Rinne Test: placement of the 512 Hz tuning fork parallel (a, b) and perpendicular (c, d) to the ear canalButskiy et al. Journal of Otolaryngology - Head and Neck Surgery  (2016) 45:21 Page 3 of 870 dB. This helped reduce variability associated with dif-ferent excitations, and positionings, of the tuning fork.Once triggered, the measurements were taken over 3 sand averaged.An independent-samples t-test was used to comparethe parallel and perpendicular placements of the tuningfork with respect to the measured amplitudes of the fun-damental frequencies (512 and 256 Hz) and dominantharmonic frequencies. The dominant harmonic frequen-cies were identified by visual inspection of the averagedsound spectrum of each tuning fork activation.Results(1) Email surveyOut of 512 active members of the CSO-HNS, 116 physi-cians responded to the survey for a response rate of23 % (Tables 1, 2, 3, and 4). 113 responders reportedpracticing in Canada. The highest proportion of the re-sponders reported using a 512 Hz tuning fork (73 %; 85responders), activating the fork by a strike on the knee(45.7 %; 55 responders), and holding the fork 3 to 4 cmaway from the ear (44.8 %; 52 responders). 55 (47.4 %)of the surveyed physicians reported placing the fork par-allel, and 52 (44.8 %) reported placing the fork perpen-dicular to the ear canal.(2) Simulation of the Rinne air conduction testingThe average amplitudes of the sound spectra producedby 512 and 256 Hz tuning forks placed parallel and per-pendicular to the ear canal are presented in Fig. 4. Visualinspection of the sound spectra of each tuning fork iden-tified two dominant harmonic frequencies for the512 Hz tuning fork (1 and 3.15 kHz) and three dominantharmonic frequencies for the 256 Hz tuning fork(500 Hz, 1.6, and 4 kHz).The statistical comparison of parallel and perpendicu-lar placements of the 512 and 256 Hz tuning forks withrespect to the amplitude of the fundamental frequenciesand dominant harmonic frequencies are summarized inTables 5 and 6. The sound intensity recorded at the tym-panic membrane with the 512 Hz tuning fork tines inparallel with as opposed to perpendicular to the EACwas louder by 2.5 dB (95 % CI: 1.35, 3.65 dB; p < 0.0001)for the fundamental frequency (512 Hz), and by 4.94 dB(95 % CI: 3.10, 6.78 dB; p < 0.0001) and 3.70 dB (95 %CI: 1.62, 5.78 dB; p = .001) for the two harmonic fre-quencies (1 and 3.15 kHz) respectively (Table 5). The256 Hz tuning fork in parallel with the EAC as opposed toperpendicular to was louder by 0.83 dB (95 % CI: −0.26,1.93 dB; p = 0.14) for the fundamental frequency (256 Hz),and by 4.28 dB (95 % CI: 2.65, 5.90 dB; p < 0.001) and1.93 dB (95 % CI: 0.26, 3.61 dB; p = .02) for the two har-monic frequencies (500 and 4 kHz) respectively (Table 6).For the 1.6 kHz harmonic frequency of the 256 Hz tuningfork, the perpendicular placement of the tuning fork waslouder than parallel placement of the tuning fork by0.11 dB (95 % CI: −1.58, 1.8 dB; p = 0.89).DiscussionThe results of the e-mail survey show that despite theuse of the Rinne test by the majority of the respondingotolaryngologists, the air conduction testing techniquesin use are not uniform. The survey suggests that the ma-jority of Canadian otolaryngologists prefer the 512 Hztuning fork, activate the fork by the strike of the knee,and place the fork approximately 3 to 4 cm away fromthe ear canal when testing air conduction. Despite thetraditional teaching on the placement of the tuning forktines during air conduction testing, the results of thesurvey show a roughly equal use of parallel and perpen-dicular tuning fork placement amongst the responders.Whilst some of the responders did not understand whatwas meant by parallel and perpendicular placement ofthe fork, these findings suggest that Canadian Otolaryn-gologists vary in their orientation of the tuning forktines.The results of the survey should be interpreted withcaution. Only a limited number of physicians respondedto the survey (23 % response rate). Furthermore, thequestion design only allowed for a limited number of re-sponses. Therefore, the complete variability in air con-duction testing by Canadian otolaryngologists has likelynot been captured by the survey. Despite these limita-tions, the survey provided useful information for design-ing the experimental part of the study.To our knowledge, the sound spectra for the 512 and256 Hz tuning forks activated in clinical practice for theTable 1 Canadian Society of Otolaryngology - Head and NeckSurgery e-mail survey results (116 Responders)What Frequency of tuning fork do you use to administer the Rinne test?256 Hz 512 Hz Other16 83 17Table 2 Canadian Society of Otolaryngology - Head and NeckSurgery e-mail survey results (116 Responders)How do you mostly activate the tuning fork for the Rinne test?ElbowStrikeKneeStrikeStriking a soft coatedsurfaceFingerPinchOther38 53 10 3 12Table 3 Canadian Society of Otolaryngology - Head and NeckSurgery e-mail survey results (116 Responders)How far from the ear do you hold the tuning fork?12 cm 3–4 cm 5–6 cm 7–8 cm 9–10+ cm other45 52 11 4 0 4Butskiy et al. Journal of Otolaryngology - Head and Neck Surgery  (2016) 45:21 Page 4 of 8purposes of the Rinne test have not been documentedpreviously. The sound spectra (Fig. 4) and the know-ledge of the dominant harmonic frequencies are valuablefor interpreting Rinne test results for patients with dif-ferent levels of hearing loss across the frequencyspectrum.The experimental findings support the traditionalteaching that parallel placement of tuning fork tines withrespect to the EAC produces higher sound amplitude atTable 4 Canadian Society of Otolaryngology - Head and NeckSurgery e-mail survey results (116 Responders)During the Rinne test, are the tines of the fork parallel or perpendicularto the auditory canal?Parallel Perpendicular Other55 52 9010203040506070809010012.5 Hz16 Hz20 Hz25 Hz31.5 Hz40 Hz50 Hz63 Hz80 Hz100 Hz125 Hz160 Hz200 Hz250 Hz315 Hz400 Hz500 Hz630 Hz800 Hz1 kHz1.25 kHz1.6 kHz2 kHz2.5 kHz3.15 kHz4 kHz5 kHz6.3 kHz12.5 Hz16 Hz20 HzAmplitude (dB)512 Hz ForkAverage Amplitudes of Parallel (N=150) and Perpendicular (N=150) ActivationsParallel Perpendicular010203040506070809010012.5 Hz16 Hz20 Hz25 Hz31.5 Hz40 Hz50 Hz63 Hz80 Hz100 Hz125 Hz160 Hz200 Hz250 Hz315 Hz400 Hz500 Hz630 Hz800 Hz1 kHz1.25 kHz1.6 kHz2 kHz2.5 kHz3.15 kHz4 kHz5 kHz6.3 kHz8 kHz10 kHz12.5 kHz16 kHz20 kHzAmplitude (dB)256 Hz ForkAverage Amplitudes of Parallel (N=150) and Perpendicular (N=150) ActivationsParallel PerpendicularFundamentalFrequencyFundamentalFrequencyFig. 4 Average amplitudes obtained by activating 512 and 256 Hz tuning forks in parallel (shaded bars) and perpendicular (solid bars). Thefundamental frequencies are marked with solid arrow heads; the main non-fundamental frequencies are marked with empty arrow headsButskiy et al. Journal of Otolaryngology - Head and Neck Surgery  (2016) 45:21 Page 5 of 8the level of the tympanic membrane than perpendicularplacement of the tines. For the 512 Hz tuning fork, thedifference between the two positions of the tuning forkwas measured to be 2.5 dB for the fundamental fre-quency. This is less than the 5 dB difference predictedby the mathematical models [10]. The smaller than ex-pected difference could be due to the complex interac-tions of the tuning fork vibration modes not accountedfor by the mathematical models. Alternatively, thissmaller difference could be explained by the inherentvariability in activations of the tuning fork by a strike onthe knee.The measured 0.83 dB fundamental frequency ampli-tude difference between the parallel and perpendicularplacement of the 256 Hz tuning fork was smaller thanthe 2.5 dB difference measured for the 512 Hz tuningfork. Even though the amplitude for the parallel place-ment of the 256 Hz tuning fork was again greater thanfor the perpendicular placement, this difference did notreach statistical significance. The explanation for thelack of statistical significance likely lies in the differenceof geometry between the 512 and 256 Hz fork. Due tothe need to keep the design of the 512 and 256 Hz tun-ing forks consistent, the 256 Hz tuning fork was largerthan the 512 Hz tuning fork (Fig. 1). Given, its larger di-mensions, the difference in the amplitude between theparallel and perpendicular placement of the 256 Hz tun-ing fork was likely negated by the wider vibration fieldof the larger tines: when testing the parallel position ofthe tuning fork, placing the edge of the 256Hz fork 30to 49 cm away from the EAC positions the centre of thetuning fork further away from the EAC as compared tothe same placement of the smaller 512Hz tuning fork(Fig. 5). We tested this explanation by performing a sep-arate experiment with a different design of the 256 Hztuning fork, where the dimensions of the 256 Hz forkwere similar to the 512 Hz fork. In this separate experi-ment, not presented in this report, a statistically signifi-cant difference of 3.7 dB in favour of the parallelplacement of the tuning fork was found.Loudness perception is a complicated psychoacousticphenomenon influenced not only by the amplitude butalso by the frequency of the sound, its spectral distribu-tion, its duration and time structure, and by its overallacoustic environment [12]. Assuming that all other vari-ables influencing the perception of loudness are keptconstant, a normal hearing individual should be able todiscriminate a difference in amplitude as small as 1.5 dB[13, 14]. The amplitude resolution of 1.5 dB is preservedin hearing-impaired patients with most types of conduct-ive and sensorineural hearing loss. The only apparentexception is the lower amplitude resolution seen in pa-tients with acoustic neuroma (4.5 dB) [13, 14]. Thesefacts suggest that the amplitude difference between inparallel and perpendicular to the EEC tuning fork place-ment observed in this study can be perceived by mostpatients undergoing the Rinne test. Thus, the position ofthe tuning fork with respect to the EAC during theRinne test represents a significant variable that can po-tentially influence the sensitivity and specificity of thetest. Further investigation is needed to test whether theposition of the tuning fork during the Rinne test affectsthe its results in patients with hearing loss.ConclusionsDespite widespread use of the Rinne test by Canadianotolaryngologists, the Rinne test techniques practicedare non-uniform. Orientation of the tuning fork tineswith respect to the EAC during air conduction testing isan important source of variation in performing theTable 5 Sound amplitudes produced by parallel and perpendicular placement of 512Hz fork at the selected frequenciesFrequencyMeasuredMean Amplitude (±SD) Mean Difference(95 % CI)p-valueParallel (N = 150) Perpendicular (N =150)500 Hz 90.04 dB (±4.46 dB) 87.53 dB (±5.63 dB) 2.50 dB (±1.15 dB) <0.00011 kHz 57.86 dB (±7.64 dB) 52.92 dB (±8.50 dB) 4.94 dB (±1.84 dB) <0.00013.15 kHz 64.76 dB (±7.32 dB) 61.05 dB (±10.69 dB) 3.70 dB (±2.08 dB) .001SD Standard Deviation, CI Confidence IntervalTable 6 Sound amplitudes produces by parallel and perpendicular placement of 256Hz fork at the selected frequenciesFrequency Measured Mean Amplitude (±SD) Mean Difference(95 % CI)p-valueParallel (N = 150) Perpendicular (N =150)250 Hz 91.14 dB (±4.06 dB) 90.30 dB (±5.47 dB) 0.83 dB (±1.09 dB) .14500 kHz 68.67 dB (±7.30 dB) 64.39 dB (±6.99 dB) 4.28 dB (±1.62 dB) <0.0011.6 kHz 58.80 dB (±7.13 dB) 58.92 dB (±7.73 dB) −0.11 dB (±1.69 dB) .894 kHz 42.35 dB (±8.52 dB) 40.42 dB (±6.05 dB) 1.93 dB (±1.67 dB) .02SD Standard Deviation, CI Confidence IntervalButskiy et al. Journal of Otolaryngology - Head and Neck Surgery  (2016) 45:21 Page 6 of 8Rinne test. Placement of the tuning fork tines in parallelas opposed to perpendicular to the ear canal produces asound of higher amplitude at the level of the tympanicmembrane. Physicians are encouraged to pay attentionto the orientation of tuning fork’s tines with respect tothe long axis of the EAC when testing air conductionduring the Rinne test.AbbreviationsEAC: external ear canal.Competing interestsThe authors declare that they have no competing interests.Authors’ contributionsOB: study conception, literature search, study design, data collection, dataanalysis, manuscript drafting and revision. DN: study design, acousticexperiment set up, and data collection. MH: study design, acousticexperiment set up. DN: study design, literature search, financial support,manuscript revision. All authors read and approved the final manuscript.AcknowledgementsWe thank Dr. Lorienne M. Jenstad for the use of her laboratory space andequipment.Author details1Division of Otolaryngology – Head and Neck Surgery, Vancouver GeneralHospital, Vancouver, BC, Canada. 2Department of Mechanical Engineering,University of British Columbia, Vancouver, BC, Canada. 3Department ofSurgery, University of British Columbia, Vancouver, BC, Canada. 4School ofPopulation and Public Health, University of British Columbia, Vancouver, BC,Canada. 5Gordon & Leslie Diamond Health Care Centre, 4th. Fl. 4299B-2775Laurel Street, Vancouver, BC V5Z 1M9, Canada.Received: 5 January 2016 Accepted: 15 March 2016References1. Ng M, Jackler RK. Early history of tuning-fork tests. Am J Otol. 1993;14:100–5.2. Burkey JM, Lippy WH, Schuring AG, Rizer FM. Clinical utility of the 512-HzRinne tuning fork test. Am J Otol. 1998;19:59–62.3. Shea PF, Ge X, Shea JJ. Stapedectomy for far-advanced otosclerosis. Am JOtol. 1999;20:425–9.4. MacKechnie CA, Greenberg JJ, Gerkin RC, McCall AA, Hirsch BE, Durrant JD, RazY. Rinne revisited: steel versus aluminum tuning forks. Otolaryngol–Head NeckSurg Off J Am Acad Otolaryngol-Head Neck Surg. 2013;149:907–13.5. British Society of Audiology. Recommended procedure for Rinne andWeber tuning-fork tests. British Society of Audiology. Br J Audiol. 1987;21:229–230. http://www.tandfonline.com/doi/abs/10.3109/03005368709076410.6. Bickley L. Bates’ Guide to Physical Examination and History-Taking. 11th ed.Philadelphia: Lippincott Williams & Wilkins; 2012.7. Bunni J, Nunez D, Shikowitz M. The Essential Clinical Handbook for ENTSurgery: The Ultimate Companion for Ear, Nose and Throat SurgeryIncluding a Chapter on Facial Plastic Surgery …. London: BPP LearningMedia; 2013.8. Sheehy JL, Gardner G, Hambley WM. Tuning fork tests in modern otology.Arch Otolaryngol Chic Ill 1960. 1971;94:132–8.9. Rossing TD, Russell DA, Brown DE. On the acoustics of tuning forks. Am JPhys. 1992;60:620–6.10. Russell DA. On the sound field radiated by a tuning fork. Am J Phys. 2000;68:1139–45.ABC512 HzPerpendicular512 HzParallel256 HzParallel256 HzPerpendicularLegend:Red Dash–middle of the tuning fork dipole (themathematical center from which soundemanates)A– distance from the edge of the tuning fork tothe ear canal (30–49 mm in the experiment)B–Perpendicular placement. Distance from thecenter of the dipole (red dash) to the ear canalC–Parallel placement. Distance from the centerof the dipole (red dash) to the ear canalFig. 5 The influence of tuning fork size on the distance from thecentre of the tuning fork dipole to the ear canal. Parallel orientationproduces a louder sound and when this is coupled with placementof the vibrating dipole closer to the ear canal in the smaller 512 Hztuning fork the effect is most markedButskiy et al. Journal of Otolaryngology - Head and Neck Surgery  (2016) 45:21 Page 7 of 811. Vibrational Modes of a Tuning Fork. [http://www.acs.psu.edu/drussell/Demos/TuningFork/fork-modes.html]12. Florentine M. Loudness. In: Florentine M, Popper AN, Fay RR, editors.Loudness. New York: Springer; 2011. p. 1–15. Springer Handbook ofAuditory Research, vol. 37.13. Zwicker E, Fastl H. Psychoacoustics: Facts and Models, Springer Science &Business Media. 2013.14. Fastl H, Schorn K. Discrimination of level differences by hearing-impairedpatients. Audiol Off Organ Int Soc Audiol. 1981;20:488–502.•  We accept pre-submission inquiries •  Our selector tool helps you to find the most relevant journal•  We provide round the clock customer support •  Convenient online submission•  Thorough peer review•  Inclusion in PubMed and all major indexing services •  Maximum visibility for your researchSubmit your manuscript atwww.biomedcentral.com/submitSubmit your next manuscript to BioMed Central and we will help you at every step:Butskiy et al. Journal of Otolaryngology - Head and Neck Surgery  (2016) 45:21 Page 8 of 8

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