The variation across time of sensitivity to interaural disparities: Behavioral measurements and quantitative analyses

Zurek (1980) measured listeners' sensitivities to interaural disparities co nveyed by a 5-ms "probe" segment embedded within a 50-ms burst of otherwise diotic broadband noise [P. M. Zurek, J. Acoust. Soc. Am. 67, 952-964 (1980 )]. He found that thresholds for interaural time delay (ITD) and interaural intensitive difference (IID) were markedly elevated when the onset of the probe segment occurred between 1 and 5 ms after the onset of the burst. Zur ek postulated that this occurred because the leading portion of the noise b riefly inhibited sensitivity to subsequent binaural information. If such in hibition were the primary factor responsible for the elevation in threshold s, then the omission of the portion of the noise trailing the probe segment would be expected to have little, if any, influence on performance. In ord er to test this hypothesis, listeners' sensitivities to ITD and IID were me asured using a paradigm similar to that employed by Zurek. The results reve aled that the omission of either the leading or the trailing portions of th e diotic noise led to substantial reductions in threshold ITDs and IIDs. Th e data were successfully accounted for by a model based upon a combination of a temporal window with an equivalent rectangular duration of approximate ly 10 ms and a weighting function representing a brief loss of binaural sen sitivity just after the onset of a sound. (C) 2001 Acoustical Society of Am erica.