How does temporal diffusion affect the ongoing precedence effect?

Abstract

In room acoustic scenarios, listeners' localization is often dominated by the sound propagating directly from the its source despite numerous reflections that present different spatial cues only milliseconds later. This is called the precedence effect (PE). Most studies have simulated the PE by presenting one sound (the lead) followed by a copy of the lead that is delayed and presented with different interaural cues (the lag). These simulations assume that reflective surfaces are flat, yet interior surfaces are often far more complex and variable, resulting in spatially and temporally diffuse reflections. The effect of the temporal aspect of this diffusion on listeners' localization of lead/lag, 200-ms duration, noise stimuli filtered to 100–900 Hz and presented over headphones is investigated. Lag stimuli are convolved with a Hanning-windowed 2-ms noise burst to simulate temporal effects of uneven reflective surfaces. Results show that listeners' localization is dominated by the interaural cues of the lead, even when gating onsets/offsets are windowed out. Modeling analyses based on those in Pastore and Braasch (2019) suggest that interaural time differences in the ongoing stimulus portion can be extracted from rising slopes of the envelopes of neural output, even when lead and lag envelopes are decorrelated.