The effect of DC polarization on the magnitude and phase of the CM harmonics

Abstract

Rectification processes must play an important role in the mechanical to neural transduction process in the auditory system since intracellular recording has demonstrated large DC receptor potentials for sinusoidal acoustic stimuli in inner haircells [I. J. Russell, and P. M. Sellick, Nature 267, 858–860 (1977)]. Any rectification process would not only generate DC potentials but also would generate even harmonic distortion. The magnitude and phase of the CM fundamental and harmonics were measured in scale media of the first turn of the guinea pig cochlea using digital signal‐processing techniques. The data suggest that the even order harmonics are the sum of two separate components which are 180° out of phase at low acoustic frequencies. One component dominates at low SPL and the other at high SPL. Positive DC polarization shifts the transition of the two components to lower SPL and a reverse current shifts the transition to higher SPL. The results are consistent with our recent hypothesis that the hairc...