Cochlear mechanics, nonlinearities, and cochlear potentials

Cochlear microphonic (CM) magnitude functions are shown from various turns of the cochlea at constant sound pressure level (SPL), constant stapes displacement, and constant stapes velocity. The similarities of these curves with basilar membrane displacement functions are considered. The influence of CM nonlinearity on the shape of the plots is discussed, and it is demonstrated that the response is extremely nonlinear in a narrow frequency range above the best frequency of the electrode location, while at other frequencies it is much more linear. All nonlinear phenomena that are demonstrable in cochlear potentials, namely harmonic distortion, summating potential generation, and interference effect, are primarily concentrated in the aforementioned nonlinear frequency region.