Middle ear muscle effects on cochlear responses to bone-conducted sound.

Abstract

AbstractContractions of the stapedius and tensor tympani muscles were elicited by electrical stimulation of their motor nerves or of the muscles themselves in anesthetized cats. The effects of these contractions on cochlear microphonic responses to air‐ and bone‐conducted sound were examined. Stapedius contractions that produced changes in air conduction similar to those observed under physiological conditions had almost identical effects on bone conduction. Tensor tympani effects on bone conduction were of similar magnitude but greater complexity than those on air, and varied as a function of the location of the bone conductor on the skull. Control observations established that the effects were attributable to the middle ear muscles and not to other consequences of the experimental procedures, and that they did not reflect modification of an air‐conduction component of the bone‐conduction stimulus. The functional significance of these effects is discussed in terms of protection against masking of environmental sounds by self‐generated bone‐conducted sound.