Modeling the precedence effect for multiple echoes.

Abstract

A typical and controlled way to study the precedence effect has been to use two pairs of binaural click stimuli with different lead-lag delays. For lead-lag delays between 1 and 5 ms, interaural differences in the lead click pair are more easily discriminated than those in the lag click pair. This work attempts to move from the classic, but unrealistic, two-source paradigm to a more realistic situation, much like real rooms in which multiple echoes occur. Using a three-source paradigm, listeners were presented three click pairs (lead, lag1, and lag2) via headphones. Discrimination of directional changes in each of the three click pairs was measured with a 2AFC task for delays between 0 and 130 ms. Results show that due to interactions amongst the three sources “echo thresholds” were affected in a non-monotonic way. Temporal order effects were observed for long delays, which led to poorer lead discrimination, and better lag2 discrimination. Summing localization was observed for short delays between lead and lag1, and lag1 and lag2. A simple weighting model [Shinn-Cunningham et al., J. Acoust. Soc. Am. 93, 2923–2932 (1993)] was adapted to include this multiple source data and the complex relationships between the three sources. [Work supported by NIH-NIDCD R01 DC003083—R.Y. L.]