Figure 1.

Schematic representation of three mechanisms that could enhance the amplitude modulation cues in speech. A, Basilar membrane velocity versus sound pressure level with and without MOC efferent activation (adapted from Cooper and Guinan, 2006). B, Auditory nerve rate-level functions in quiet and in noise with and without MOC efferent activation (adapted from Guinan, 2006). C, Dynamic range adaptation of auditory neurons to the most frequently occurring level (adapted from Wen et al., 2009). Each panel illustrates the internal representation (ordinate) of the acoustic envelope depth (abscissa) associated with each mechanism. See main text for further details.