Temporal integration of dynamic binaural events

Events occurring in different sensory dimensions (e.g., modalities) and within an interstimulus interval (ISI) of few hundred milliseconds typically appear simultaneous. The temporal “window” of sensory integration can be estimated by increasing the ISI until events appear discrete. Here, we adapt the simultaneity-judgment paradigm to investigate the integration of binaural events within and across dimensions of interaural time and level difference (ITD and ILD). Noise bands (353.5–707 Hz) of 2s duration were presented over headphones to normal-hearing listeners. Each stimulus contained two 10-ms binaural-change events, during which the ITD or ILD changed by 500 µs or 6 dB. Events could occur in the same or different cue dimensions (ITD or ILD), but always agreed in direction (leftward or rightward). ISI varied over the range ±600 ms. Listeners indicated the number and direction of each perceived shift in the lateral image, e.g., one (left-to-right) at short ISI, or two (left-to-center, center-to-right) a...