Acoustic Reflexes of the Human Musculus Tensor Tympanh

Abstract

In a previous report a method was described, which allows the demonstration of intra-aural muscle reflexes through small concomitant movements of the ear drum, the direction of which is different for contractions in either of the two muscles involved. In some patients a stapedius muscle reflex was found, while in others there were movements which could only be ascribed to the tensor muscle. The method has been improved so that movements of the eardrum can be determined at any pressure in the external ear canal. Through this modification muscle reflexes could be demonstrated in 95% of ears that were strictly normal. Both tensor and stapedius reflexes were found in 40%, while in 33% and 22% respectively only stapedius or tensor reflexes were evident. Considering the physiological conditions involved in this method it seems warranted to assume that both muscles are acoustically active in all human ears.