Theoretical Analysis of Otoacoustic Emissions and the Cochlear Amplifier

Abstract

Otoacoustic emissions (OAEs) are assumed to be the byproducts of power amplification of the acoustic wave on the basilar membrane. This power amplification has been called the cochlear amplifier. But there was no convincing evidence for the cochlear amplifier. The present study reports a computational model of OAEs, assuming that there is no cochlear amplifier. The slow component of evoked OAE (EOAE) was assumed to be explained by a second harmonic of Bragg reflection in a human cochlear model. The amplitude of distortionproduct OAE (DPOAE) at 2f₁-f₂ was estimated by computing the summation of the two primary wavelets. There was a good agreement between the theoretical predictions and the experimental results for the level behavior of DPOAE. However, the non-monotonicity in the frequency ratio function of the experimental DPOAE data was unaccountable in this meodel.