Sound pressures in the basal turn of the cat cochlea

Publisher Website
Google Scholar
Abstract
Techniques were developed for measuring sound pressure in the cochlea with calibrated, liquid-filled, piezoelectric probe microphones. Sound pressures were measured in scala vestibuli and scala tympani in the basal turn in 25 cats for tones from 20-10,000 Hz. In controls intracochlear pressures were essentially uninfluenced by the measuring technique and were conducted to the cochlea via the ossicular chain. Intracochlear pressures were linearly related to pressure at the tympanic membrane for tone levels at least as high as 105 dB SPL [sound pressure level] and were relatively independent of depth of probe insertion in the scalae. The transfer ratio of sound pressure in scala vestibuli to the tympanic membrane increased in magnitude over the frequency range 50-1000 Hz to reach a maximum value of 15-30 dB and decreased at higher frequencies. The middle ear apparently provided a frequency-dependent pressure gain. At frequencies below 40 Hz, the pressures in scala vestibuli and scala typani were approximately equal and determined by the round-window membrane compliance. At frequencies above 100 Hz the round-window membrane impedance was small compared to the acoustic input impedance of the cochlea. The pressure in scala vestibuli considerably exceeded that in scala tympani; the pressure difference across the cochlear partition apparently is approximately equal to the pressure in scala vestibuli.

This publication has 2 references indexed in Scilit: