Effects of correlated and uncorrelated interfering noise on interaural time delay (ITD) detection

Results are reported from two binaural discrimination experiments. The first measured ITD discrimination threshold for broadband noise in the presence of interaurally correlated interfering noise. Six listeners performed an adaptive 2I‐2AFC discrimination task with 100‐ms stimuli composed of delayed and diotic noises (0–3 kHz) mixed in various proportions (1, 0.75, 0.563, 0.422, 0.316, 0.237, and 0.178). A regression analysis showed that thresholds doubled for every halving of the proportion of delayed noise power in the stimulus. The second experiment measured ITD discrimination thresholds for a range of interaural correlations obtained by mixing correlated and uncorrelated noise before applying the delay. Three listeners performed 2I‐2AFC discrimination tasks at correlations of 1, 0.75, 0.5, 0.25, 0.2, 0.15, 0.1, and 0.05, and durations of 100, 500, and 1000 ms. Seventy‐one percent of the threshold were obtained using psychometric functions. Thresholds more than doubled for each halving of the correlation at all three stimuli durations tested.