Interaural time and amplitude discrimination in noise

Abstract

Just‐noticeable differences (jnds) of interaural time delay (ITD) and interaural amplitude differences (IAD) were measured for 50‐dB SPL 500‐Hz binaural tones in the presence of 100–1000 Hz broadband markers. Data were collected using maskers with various combinations of ITD and IAD. The time and amplitude jnds exhibit similar dependencies on target‐to‐masker ratio, and they vary with masker type in a fashion previously described by Cohen [J. Acoust. Soc. Am. Suppl. 1 64, S35 (1978)] and Ito et al. [J. Acoust. Soc. Am. Suppl. 1 65, S121 (1979)]. Many of these data trends are consistent with the predictions of simple models based on the instantaneous interaural time and amplitude differences of the stimuli and their variability. Our model that generates lateral position estimates from operations on auditory nerve activity [Stern and Colburn, J. Acoust. Soc. Am. 64, 127–140 (1978)] does not accurately describe these results, for reasons at least partly related to inadequacies in its description of the auditory‐nerve response to these stimuli. [Supported by NIH.]