On the continuous control of the middle ear muscles activity in cat.

Abstract

Middle ear muscle activity in response to clicks was quantitatively evaluated by electronic integration of electromyography. An integrator capable of dealing linearly with succesive short bursts of electromyographic acitivity was developed. If the same click was applied repeatedly the EMG response varied and for quantitative evaluation it was necessary to establish average responses using an on-line average computor on 25–30 responses obtained at an interval of 10 seconds. Interactions between two clicks applied with intervals varying from 5 msec to 500 msec were studied using this technique. These studies indicate that:A) Interaction between succesive stimuli occurs both in the form of facilitation and inhibition.B) Facilitation and inhibition do not run parallel in the two middle ear muscles, indicating that these muscles are not true synergists.C) Small differences in sound pressure (2 dB at a level of 80 dB HL) are capable of changing the middle ear muscle response, indicating that the middle ear musc...