Wideband Analysis of Otoacoustic Intermodulation

Nonlinear interaction between close tones in the cochlea has been examined in gerbil via the multiple otoacoustic emissions this interaction generates. Tonal stimuli of near equal level yield a wide spread of up to 20 otoacoustic sidebands. The amplitude and relative phase of these components have been measured and these have provided new insights into cochlear mechanical nonlinearity and data on the reverse transmission of distortion products. Otoacoustic intermodulation and suppression characteristics differ in detail from those of the simple saturating nonlinear model presented. Demodulation of the wideband emissions reveals temporal attributes of the cochlear interaction to be the major difference from the model.