Auditory processing of interaural timing information: New insights

AbstractDifferences in the time‐of‐arrival of sounds at the two ears, or interaural temporal disparities (ITDs), constitute one of the major binaural cues that underlie our ability to localize sounds in space. In addition, ITDs contribute to our ability to detect and to discriminate sounds, such as speech, in noisy environments. For low‐frequency signals, ITDs are conveyed primarily by “cycle‐by‐cycle” disparities present in the fine‐structure of the waveform. For high‐frequency signals, ITDs are conveyed by disparities within the time‐varying amplitude, or envelope, of the waveform. The results of laboratory studies conducted over the past few decades indicate that ITDs within the envelopes of high‐frequency are less potent than those within the fine‐structure of low‐frequency stimuli. This is true for both measures of sensitivity to changes in ITD and for measures of the extent of the perceived lateral displacement of sounds containing ITDs. Colburn and Esquissaud (1976) hypothesized that it is differences in the specific aspects of the waveform that are coded neurally within each monaural (single ear) channel that account for the greater potency of ITDs at low frequencies rather