Further modeling of temporal effects in two-tone suppression

Abstract

Two-tone suppression, a nearly instantaneous reduction in cochlear gain and a by-product of the active process, has been extensively studied both physiologically and psychoacoustically. Some physiological data suggest that the medial olivocochlear reflex (MOCR), which reduces the gain of the active process in the cochlea, may also reduce suppression. The interaction of these two gain reduction mechanisms is complex and has not been widely studied or understood. Therefore, a model of the auditory periphery that includes the MOCR time course was used to systematically investigate this interaction of gain reduction mechanisms. This model was used to closely examine two-tone suppression at the level of the basilar membrane using suppressors lower in frequency than the probe tone. Results were compared both with and without elicitation of the MOCR. Preliminary results indicate that elicitation of the MOCR reduces two-tone suppression when measured as the total basilar membrane response at the characteristic frequency (CF) of the probe. The purpose of this study was to investigate further by separating the frequency components of the basilar membrane response at CF to determine the excitation produced by the probe and by the suppressor with and without MOCR elicitation. [Research supported by NIH(NIDCD)R01 DC008327 and T32 DC00030.]