The addition of a second lag to the lead-lag precedence effect paradigm for temporally overlapping noise stimuli

Abstract

In reverberant conditions, humans routinely perceive sound sources in the direction of the first wavefront despite competing directional information presented by a host of reflections arriving soon after—the so-called “Precedence Effect.” This is often tested over headphones using a “direct sound” (lead) with a single delayed copy (lag) serving as a modeled reflection. Previously, we employed this common experimental paradigm to investigate the lateral extent of the precedence effect using temporally overlapping noise stimuli. The current study extends this inquiry towards the multiple reflections encountered in room-acoustic scenarios by presenting a second lag. Lead and lag stimuli are 200-ms Gaussian noise (500-Hz center frequency, 800-Hz bandwidth) presented dichotically with a programmable amount of delay for both lags. Relative to the intensity of the lead, the two lags are presented at 0, −3, and −6 dB. The lead is presented at the midline, with an ITD of 0 μs. The two lags are delayed by between 1 and 7 ms, with opposing ITDs of ±300 μs. Listeners indicate the lateralization of their auditory event with an acoustic pointer.