2016 Volume 59 Issue 6 Pages 615-622
Sounds in natural environments, including speech sounds, vary over time. The auditory system extracts information embedded in the temporal variations to recognize speech and environment. This review pertains to methods to evaluate evaluation of the auditory sensitivities to temporal information and the possible auditory mechanisms involved in the analysis of the information. Temporal variation of a sound can be decomposed into an amplitude envelope and a temporal fine structure. The amplitude envelope conveys important information for speech understanding. The gap detection threshold and temporal modulation transfer function are widely used as indices of the auditory sensitivities to the amplitude envelope. The modulation spectrum can be used to describe envelope information. Modulation filter bank is a possible auditory mechanism involved in the analysis of the modulation spectrum. The temporal fine structure contributes to pitch perception and sound localization, as well as to recognition of speech in noisy environments. Alterations of the detailed responses of the basilar membrane and/or reduction of auditory nerve function can significantly degrade auditory sensitivity to the temporal fine structure.