Simultaneous Trans-Tympanic and Electrophysiological Indices of the Acoustic Reflex Activity in the Cat

Abstract

The middle ear muscle contractions of the awake cat were monitored simultaneously by changes in cochlear microphonic response and changes in the output of a microphone sealed, along with a carrier-tone source, in the animal's ear canal. A comparison of the two methods showed the cochlear microphonic attenuation caused by muscle contraction to be more sensitive, but the difference was often only 10–15 db for stimulus/carrier frequencies between about 1.2 and 2.5 Kc. This observation is taken as evidence that the difference in sensitivity of the acoustic reflex of man and cat is not primarily due to differences in the sensitivity of the measurement method employed.