MATHEMATICAL MODELING OF COCHLEAR MECHANICS

DESCRIPTION: (Adapted from the Applicant's Abstract.) The goal of the
proposed research is to improve our basic understanding of the peripheral
auditory system through mathematical analysis and computer simulation of
cochlear mechanics. In recent years, models of cochlear mechanics with
active elements helped to motivate physiologic research on outer hair cell
motility. The motility of outer hair cells and their influence on cochlear
mechanics remains a topic of considerable interest among physiologists. The present proposal will continue research on active and nonlinear models
of cochlear mechanics. The emphasis will be on (1) establishing a physical
basis for active elements in the cochlea which are essential for achieving
sharp tuning and high sensitivity, (2) deriving an explicit representation
for functional nonlinearity in the cochlea which serves to compress the
large dynamic range of inputs to the ear into a smaller dynamic range of
inputs to the auditory nerve, (3) simulating the intensity dependent travel
time of acoustic transients typical of the human cochlea and (4) providing
a framework for understanding independent measures of cochlear function
such as otoacoustic emission and the auditory brainstem response in normal,
impaired, and developing cochleas. Specific objectives are (1) to learn
more about the influence of outer hair cells on cochlear mechanics, (2) to
account for the decrease observed in latency with increasing intensity both
in auditory brainstem responses and in otoacoustic emissions over a wide
range of tone burst frequencies, (3) to simulate the influence of external
tones on spontaneous acoustic emissions, (4) to simulate normal and
abnormal growth of loudness observed in ears with and without functioning
outer hair cells, and (5) to derive algorithms for frequency analysis of
acoustic signals which will produce results similar to cochlear frequency
analysis and provide an alternative to traditional Fourier frequency
analysis.