Effect of irregularities in basilar membrane impedance on TEOAEs: theoretical considerations

Transiently evoked otoacoustic emissions (TEOAEs) are believed to be attributed to the presence of impedance discontinuities on the basilar membrane in the cochlea. However, the generation mechanism of TEOAEs has not been clarified. In this study, using the mathematical model of a cochlea, which has the impedance discontinuities on the basilar membrane, TEOAEs were simulated. The results reveal that the TEOAEs are produced by not only the active process associated with the outer hair cell motility, but also the presence of impedance discontinuities at a site of the basilar membrane whose characteristic frequency is close to the stimulus frequency. Therefore, it may be said that the TEOAEs in response to a tone burst stimulus reflect the condition at the specific point of the cochlea.