THE ELECTRIC RESPONSE OF THE COCHLEA

Publisher Website
Google Scholar
Abstract
When sound waves fall upon the ear of an anesthetized cat, an electric response, distinct from nervous action currents, is generated in the cochlea. When amplified and transformed again into sound it reproduces with great fidelity spoken words and pure tones. Previous observations upon this phenomenon are confirmed. The upper limit of frequency is over 8000 per sec. The response measured at the round window may amount to 1 millivolt. Positive pressure on the ear drum causes a fall and negative pressure a rise in the electrical potential of the round window. The opposite relation holds for the oval window. The latency of the beginning of the cochlear response following the arrival of a sound wave at the ear drum is about 0.1[sigma], while that of the action currents in the eighth nerve is about 1.0[sigma]. The introduction of higher harmonics and of "difference tones" give evidence of non-linear distortion in the ear. The intensity of the cochlear response plotted as a function of the logarithm of the stimulus (sound pressure) yields a sigmoid curve, reaching its maximum at approximately the intensity which causes discomfort in the human ear. The curve relating threshold stimulus to frequency closely resembles the human audibility curve. The cochlear response and also action currents were absent from the ear of a cat showing congenital absence of the organ of Corti, and from a congenitally deaf guinea-pig showing merely partial degeneration of the sensory hair cells of the cochlea. The cochlear response is interpreted as arising in these sensory cells as a result of mechanical deformation. It differs fundamentally from nervous action currents.

This publication has 8 references indexed in Scilit: