Middle-ear disease is the most common cause of hearing loss. Otologic surgeons repair thousands of middle ears each year, with mixed success, especially after severe middle-ear disease. Knowledge of structure-function relations is crucial to improving reconstructive techniques. In the past, we developed physiology-based models that relate structure and function in normal ears, pathological ears and reconstructed ears. We focus now on four new clinically-relevant structure-function issues: (1) We quantify the contribution of the middle ear to the shape of the auditory threshold curve by (a) comparing middle-ear inputs and outputs to quantify the power transfer efficiency of the middle-ear in individual animals, (b) comparing estimates of middle-ear output at physiologic threshold in live animals. Near constant levels of middle-ear output at threshold would imply the middle ear plays a dominant role in shaping normal auditory thresholds. (2) We investigate the contribution of the round window and natural or pathologic `third windows'to normal, pathological and aided middle-ear function. Normal and pathologic inner-ear windows are potential pathways for stimulating the cochlea as well as potential shunt paths for directing sound power away from the cochlea. This work will determine how the round window and different `third windows'into the inner ear affect sensitivity to airborne sound and assess their potential as pathways for cochlear stimulation. (3) We will quantify the relative contributions of different bone-conduction pathways. Recent reports come to contradictory conclusions on the clinical significance of compressive bone conduction, and point to a sensitivity of this mechanism to inner-ear conductive pathology. We quantify the contribution of cochlear compression relative to other bone-conduction mechanisms and test whether changes in bone-conducted thresholds with `third-window'pathologies are explained by cochlear compression. (4) We test methods, including laser-Doppler vibrometry and bone-conduction stimulation, to separate `conductive'and `sensory-neural'hearing loss phenotypes in animal models of hearing loss. This separation is critical in understanding the mechanisms of various genetic models of hearing loss. Middle-ear disease is the most common form of hearing loss, and otologic surgeons routinely repair middle ears but with variable success. This proposal is designed to answer questions on the mechanisms of middle- and inner-ear conductive losses that result from middle and inner-ear abnormalities. It will also investigate the pathways for bone-conduction hearing and use bone conduction to define measures that better distinguish between middle-ear and inner- ear related hearing losses.

Public Health Relevance

Middle-ear disease is the most common form of hearing loss, and otologic surgeons routinely repair middle ears but with variable success. This proposal is designed to answer questions on the mechanisms of middle- and inner-ear conductive losses that result from middle and inner-ear abnormalities. It will also investigate the pathways for bone-conduction hearing and use bone conduction to define measures that better distinguish between middle-ear and inner- ear related hearing losses.

Agency
National Institute of Health (NIH)
Institute
National Institute on Deafness and Other Communication Disorders (NIDCD)
Type
Research Project (R01)
Project #
5R01DC000194-26
Application #
7689936
Study Section
Auditory System Study Section (AUD)
Program Officer
Miller, Roger
Project Start
1983-01-01
Project End
2013-08-31
Budget Start
2009-09-01
Budget End
2010-08-31
Support Year
26
Fiscal Year
2009
Total Cost
$320,875
Indirect Cost
Name
Massachusetts Eye and Ear Infirmary
Department
Type
DUNS #
073825945
City
Boston
State
MA
Country
United States
Zip Code
02114
Rosowski, John J; Bowers, Peter; Nakajima, Hideko H (2018) Limits on normal cochlear 'third' windows provided by previous investigations of additional sound paths into and out of the cat inner ear. Hear Res 360:3-13
Ravicz, Michael E; Rosowski, John J (2017) Chinchilla middle ear transmission matrix model and middle-ear flexibility. J Acoust Soc Am 141:3274
Chhan, David; McKinnon, Melissa L; Rosowski, John J (2017) Identification of induced and naturally occurring conductive hearing loss in mice using bone conduction. Hear Res 346:45-54
Chhan, David; Bowers, Peter; McKinnon, Melissa L et al. (2016) Middle-ear and inner-ear contribution to bone conduction in chinchilla: The development of Carhart's notch. Hear Res 340:144-152
Ravicz, Michael E; Rosowski, John J (2013) Inner-ear sound pressures near the base of the cochlea in chinchilla: further investigation. J Acoust Soc Am 133:2208-23
Chhan, David; Röösli, Christof; McKinnon, Melissa L et al. (2013) Evidence of inner ear contribution in bone conduction in chinchilla. Hear Res 301:66-71
Ravicz, Michael E; Rosowski, John J (2013) Middle-ear velocity transfer function, cochlear input immittance, and middle-ear efficiency in chinchilla. J Acoust Soc Am 134:2852-65
Röösli, Christof; Chhan, David; Halpin, Christopher et al. (2012) Comparison of umbo velocity in air- and bone-conduction. Hear Res 290:83-90
Puria, Sunil; Rosowski, John J (2012) Bekesy's contributions to our present understanding of sound conduction to the inner ear. Hear Res 293:21-30
Ravicz, Michael E; Rosowski, John J (2012) Chinchilla middle-ear admittance and sound power: high-frequency estimates and effects of inner-ear modifications. J Acoust Soc Am 132:2437-54

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