The precedence effect with increased lag level.

When a pair of sounds arrive from different directions with a sufficiently short delay between them, listeners hear a perceptually fused image with a perceived location that is dominated by the first arriving sound. This is called the precedence effect. To test the limits of this phenomenon, 200-ms noise stimuli were presented over headphones to model a temporally overlapping direct sound (lead) with a single reflection (lag) at inter-stimulus intervals (ISIs) of 0-5 ms. Lag intensity exceeded that of the lead by 0-10 dB. Results for 16 listeners show that lateralization shifted from the position of the lead towards the lag as lag level increased. Response variability also increased with lag level. An oscillatory pattern emerged across ISIs as lag level increased, to a degree that varied greatly between listeners. Analysis of modeled binaural cues suggests that these oscillatory patterns are correlated with ILDs produced by the physical interference of lead and lag during the ongoing portion of the stimulus, especially in the 764-Hz frequency band. Different listeners apparently weighted cues from the onset versus ongoing portions of the stimulus differently, as evidenced by the varying degree of influence the ongoing ILD cues had on listeners' perceived lateralization.