Effects of the stimulus spectrum on temporal weighting of binaural differences

The influence, or "perceptual weight" of binaural information typically varies over the duration of a brief sound, as characterized by the temporal weighting function (TWF). Here, TWFs were measured for binaural lateralization of Gabor click trains (GCT) varying in carrier frequency from 1 to 8 kHz, and of broadband noise-burst trains (NBT) with repeated ("frozen") or newly-sampled ("fresh") noise across bursts. Interclick intervals (ICI) ranged 2-10 ms. On each of many trials, listeners judged the lateral position of a singly presented GCT or NBT. Lateral positions varied with the overall interaural time (ITD, ranging +/- 500 μs) and level (ILD, ranging +/-5 dB) differences applied to each stimulus. Additional random variation in ITD (+/- 100 μs) and ILD (+/- 2dB) was applied independently to each click within a train. TWFs were calculated by multiple linear regression of normalized position judgments onto the individual click ITD and ILD values, and indicated large ICI-dependent weights on the initial click, elevated weights near offset, and lower weights for interior clicks. Flatter TWFs were observed for "fresh" NBT stimuli than for GCT or "frozen" NBT stimuli. Results corroborate previous reports of temporal asymmetries in binaural processing of periodic stimuli across frequency.