Sound pressures in the basal turn of the cat cochlea

摘要: Techniques were developed for measuring sound pressure in the cochlea with calibrated, liquid-filled, piezoelectric probe microphones. Sound pressures measured scala vestibuli and tympani basal turn 25 cats tones from 20--10 000 Hz. Control experiments indicated that intracochlear essentially uninfluenced by technique, conducted to via ossicular chain. Intracochlear are linearly related at tympanic membrane tone levels least as high 105 dB SPL, relatively independent of depth insertion scalae. The transfer ratio increases magnitude over frequency range 50--1000 Hz reach a maximum value 15--30 dB, decreases higher frequencies, thus demonstrating middle ear provides frequency-dependent gain. At frequencies below 40 Hz, approximately equal both determined round-window compliance. above 100 impedance is small compared acoustic input cochlea, considerably exceeds tympani; consequently, difference across cochlear partition vestibuli.