Observer weighting of interaural delays in source and echo clicks

A correlational analysis was used to assess the relative weight given to th e interaural differences of time (IDTs) of source and echo clicks for echo delays ranging from 1-256 ms. In three different experimental conditions, l isteners were instructed to discriminate the IDT of the source, the IDT of the echo, or the difference between the IDTs of the source and echo. The ID T of the target click was chosen randomly and independently from trial-to-t rial from a Gaussian distribution (mu = 0 mu s, sigma = 100 mu s). The IDT of the nontarget click was either fixed at 0 mu s or varied in the same man ner as the IDT of the target. The data show that for echo delays of 8 ms or less, greater weight was given to the IDT of the source than to that of th e echo in all experimental conditions. For echo delays from 16-64 ms, the I DT of the echo was weighted slightly more than that of the source and the w eights accounted for a greater proportion of the responses when the echo wa s the target, indicating that the binaural information in the echo was domi nant over the binaural information in the source. The data suggested the po ssibility that for echo delays from 8-32 ms, listeners were unable to resol ve the temporal order of the source and echo IDTs. Listeners were able to w eight the binaural information in the source and echo appropriately for a g iven task only when the echo delay was 128 ms or greater. (C) 1999 Acoustic al Society of America. [S0001-4966(99)01601-X].