ASA 125th Meeting Ottawa 1993 May

3pPP1. Binaural masking and lateralization of click trains with alternating interaural time delays.

Uma Balakrishnan

Richard L. Freyman

Dept. of Commun. Disord., 6 Arnold House, Univ. of Massachusetts, Amherst, MA 01003

Broadband click trains were used to investigate the effect of onset and ongoing interaural time delays (ITDs) on lateralization and binaural masking. Within a train, successive click pairs had ITDs that were either identical or alternated between two values. The interclick interval was 2 ms and the total duration of each train was 250 ms. Perceived intracranial position of the signals was estimated using an acoustic pointer. Detection thresholds for the same trains were obtained in the presence of a continuous white noise masker with a fixed interaural delay. It was found that lateralization generally followed the ITD of the very first click pair in the train. Masked thresholds were dependent upon the proximity of one or both signal ITDs to the masker ITD, but were independent of the perceived lateral position of the signal relative to that of the masker. These results suggest that while the onset ITD may dominate lateralization for click trains, it has no influence on masked binaural detection of the same signals. [Work supported by NIDCD Grant No. DC01625.]