Slow Component of Evoked Otoacoustic Emissions

Abstract

Input-output functions for the slow component of evoked otoacoustic emissions (EOAEs) were studied on six normal ears with typical slow and fast components. The slow component was found to saturate at the stimulus level of about 60 dBpeSPL and at the response level of about 25 dBpeSPl. Computer simulation of EOAEs was then performed to reproduce the data using an active nonlinear model of the cochlea. The followings were inferred from the simulation: (1) irregularity of the damping of basilar membrane in a few arrayed sections such as 1.5 times higher than surrounding sections was enough to produce realistic EOAEs and (2) the saturation of EOAEs came from the nonlinearity of the active feedback mechanism of the cochlea.