The Influence of Different Acoustical Stimuli on the Threshold of the Contralateral Ear: a Possible Index of Attenuation by the Intratympanic Reflex

A previous attempt to assess the attenuation produced by the intratympanic muscle reflex involved determination of the increase in absolute threshold following contralateral pure tone stimulation. This estimate was considerably smaller than estimates of reflex attenuation obtained by other means. In the present study a 110-db SL sine wave, square wave, narrow band noise, or broad band noise was introduced in one ear and the resultant threshold shift in the contralateral ear was measured. The smallest changes were produced by the square wave and pure tone stimuli. Appreciably larger threshold increases were elicited by the broad band and narrow band noises, especially the latter. Possible explanations of the obtained differences are discussed.