TIME-FREQUENCY DISTRIBUTIONS OF CLICK-EVOKED OTOACOUSTIC EMISSIONS

Emissions evoked by broad-band stimuli, such as clicks, show a 'freque ncy dispersion' reminiscent of the place-frequency distribution along the cochlea. Analysis of the time-frequency properties of transiently evoked otoacoustic emissions (TEOAEs) is therefore of considerable int erest due to their close relation with cochlear mechanisms. In particu lar, since OAEs in response to click stimuli are expected to evoke a c umulative response from the whole cochlea, the analysis of click-evoke d OAEs can yield a global view of cochlear function. Wavelet analysis is performed to obtain time-frequency distributions of click-evoked OA Es at various intensity levels from normal ears. By means of the inver se wavelet transform, the recorded responses are decomposed into eleme ntary components representing the contribution within a narrow frequen cy band to the cumulative OAE. The relationship between the frequency of the elementary components, latency and level of stimulation is desc ribed.