Translational Research IUsing Acoustic Modeling to Understand Middle-Ear Pathologies and Improve Diagnosis and Treatment This talk summarizes impedance-based acoustic models that characterize the middle ear under normal and pathological conditions. These models provide a basis for understanding how middle-ear impedance and sound transmission are altered by distinct pathologies and by surgical reconstruction, how the impedance changes can affect clinical measures such as audiograms, and how this modeling approach can inform treatment of hearing loss associated with middle-ear disease. Lumped-element models use electrical-circuit analogies to represent acoustic behavior, relating pressure and volume velocity within the middle ear. In the early 1960s, Møller and Zwislocki independently developed lumped-element models of the normal middle ear, which have since been expanded. This lumped-element-model approach provides a description of middle-ear sound transmission up to roughly 3–4 kHz. It highlights the roles of specific middle-ear components in shaping sound flow and enables predictions of how structural changes, whether from disease or surgery, modify sound transmission. These predictions generate hypotheses that can be tested and refined, facilitating our understanding of the hearing loss associated with specific middle-ear states. They also support a model-informed approach to developing reconstructive strategies that maximize hearing, as demonstrated in the extensive work of Merchant, Rosowski, and colleagues. This talk will describe a general lumped-element model of the normal middle ear adapted to represent several common conditions: tympanic-membrane perforation, tympanostomy tube, middle-ear fluid, middle-ear pressure changes, ossicular disarticulation, otosclerosis, and the effects of mastoid surgery and reconstruction. The models will be used to predict how such conditions influence sound transmission and hearing, as well as how the associated impedance changes can affect audiologic measurements in ways often overlooked, leading to inaccurate audiograms when the ear’s impedance is substantially reduced from normal – such as with tympanic-membrane perforations or tympanostomy tube placements or after some mastoid surgeries. Comparisons between model predictions and measurements from human subjects and cadaveric temporal bone preparations will be presented, demonstrating consistency between the modeling and experimental results. Overall, these modeling approaches provide a powerful translational bridge between basic auditory mechanics and clinical care – enhancing diagnostic accuracy, refining interpretation of audiometric measures, and informing the design of surgical and rehabilitative strategies to restore optimal hearing outcomes. Supported by: R15 DC014129-03A1 from the NIDCD
Susan Voss is the Achilles Professor of Engineering within the Picker Engineering Program at Smith College. Voss is an electrical engineer and scientist in the field of speech and hearing. Her research focuses on sound transmission in normal and diseased ears. Voss received her B.S. in Engineering from Brown University (1991), her M.S. in EECS from MIT (1995), and her Ph.D. from the Harvard-MIT Division of Health Sciences and Technology (1998) in Speech and Hearing Sciences. Voss teaches engineering and pursues research with undergraduates within the areas of middle-ear sound transmission with a focus on WAI measurements for middle-ear diagnostic approaches.
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