Measurement of the binaural temporal window using a lateralisation task

Binaural temporal resolution was measured using the discrimination of brief interaural time delays (ITDs). In experiment 1, three listeners performed a 2I-2AFC, ITD-discrimination procedure. ITD changes of 8 to 1024micros were applied to brief probe noises. These probes, with durations of 16 to 362ms, were placed symmetrically in time within a 500-ms burst of otherwise interaurally uncorrelated noise. Psychometric functions were measured to obtain thresholds and temporal windows fitted to those thresholds. The best-fitting window was a symmetric roex shape (equivalent rectangular duration=197ms), an order of magnitude longer than monaural temporal windows and differed substantially from windows reported by Bernstein et al. [Bernstein, L.R., Trahiotis, C., Akeroyd, M.A., Hartung, K., 2001. Sensitivity to brief changes of interaural time and interaural intensity. J. Acoust. Soc. Am. 109, 1604-1615]. Experiment 2, replicated their main experiment, comparing their ITD-detection task with a similar discrimination procedure. Thresholds in the detection conditions were significantly better than those in the discrimination condition, particularly for short probe durations, indicating the use of an additional cue at these durations for the detection task and thus undermining the assumptions made in their window fit.