Physiologically plausible and implausible interaural time difference distributions and the dominance of the 700-Hz frequency region

Low-frequency (<1500 Hz) interaural time differences (ITDs) are the primary horizontal-plane sound localization cue for humans. Because of the frequency dispersion occurring when sound travels around the head, the physical ITDs experienced by humans increase with decreasing frequency in this region for a given azimuth. The frequency dependency from the head dispersion appears to have little functional consequence to sound localization; it does not appear to lead to changes in source width and produces modest effects on lateralization that can be explained by the ITD of the sound in the auditory filter near 700 Hz [Constan and Hartmann, J. Acoust. Soc. Am. 114., 998–1008 (2003)]. This talk discusses experiments by Hartmann and colleagues, and recent experiments inspired by them, that use physiologically plausible and implausible ITD distributions across frequency to probe across-frequency processing in human sound-localization. The results of these studies suggest that robust broadband sound localization is primarily dominated by ITD information in the frequency region around 700 Hz.