Discrimination of brief interaural temporal disparities embedded within diotic bursts of broadband noise

Abstract

Zurek (1980) measured listeners’ sensitivity to interaural disparities conveyed by a 5-ms segment of 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) were markedly elevated when their onset was between 1 to 5 ms following the onset of the noise. Zurek postulated that the leading portion of the diotic burst of noise briefly inhibited sensitivity to subsequent binaural information and, in that manner, linked his findings to the ‘‘precedence effect.’’ In our view, one implication of that reasoning is that the trailing portion of the diotic burst should have little, if any, effect on threshold ITDs. In order to test this hypothesis, we employed Zurek’s general paradigm and included conditions in which we omitted either leading or trailing portions of the diotic burst of noise. We found that omitting either the leading or the trailing portion of the diotic noise greatly reduced the elevation in threshold ITDs observed in the original paradigm. Consequently, it appears that Zurek’s original data, although interesting and important, may reflect effects and mechanisms apart from those responsible for the ‘‘precedence effect.’’ [Work supported by NIH DC 04073.]