摘要 : Themammalian auditory system includes a brainstem-mediated efferent pathway from the superior olivary complexby way of the media lolivocochlear system, which reduces the cochlear response to sound(Warrand Guinan,1979; Libermanetal... 展开 Themammalian auditory system includes a brainstem-mediated efferent pathway from the superior olivary complexby way of the media lolivocochlear system, which reduces the cochlear response to sound(Warrand Guinan,1979; Libermanetal., 1996).The human medial olivocochlear response has an onset delay of between 25 and 40m sand rise and decay constant sintheregion of 280 and 160ms, respectively (Backus and Guinan,2006). Physiological studies with nonhuman mammals indicate that onset and decay characteristics of efferent activation are dependent on the temporal and level characteristics of the auditory stimulus (Bacon and Smith, 1991; Guinan and Stankovic, 1996). This study uses a novel psychoacoustical masking technique using a precursorsound toobtainame as ureof the efferent effect in humans. This technique avoids confounds currently associated with other psychoacoustical measures. Both temporal and level dependency of the efferent effect was measured,providing a comprehensive measure of the effect of human uditory efferent soncochlear gain and compression. Results indicate that aprecursor (> dBSPL) induced efferent activation, resulting in a decrease in both maximum gain and maximum compression, with linearization of the compressive function for input sound levels between 50 and 70 dB SPL. Estimated gaindecreased as precursor level increased, and increased as the silent interval between the precursorand combinedmasker-signalstimulus increased, consistent with a decay of the efferent effect. Humanauditory efferent activation linearizes the cochlear response for mid-level sounds while reducingmaximumgain. 收起