OBSERVER WEIGHTING OF INTERAURAL DELAYS IN FILTERED IMPULSES

Onset dominance in sound localization was examined by estimating obser ver weighting of interaural delays for each click of a train of high-f requency filtered clicks. The interaural delay of each click was a nor mal deviate that was sampled independently on each trial of a single-i nterval design. In Experiment 1, observer weights were derived for tra ins of n=2, 4, 8, or 16 clicks as a function of interclick interval (I CI=1.8, 3.0, or 12.0 msec). For small n and short ICI (1.8 msec), the ratio of onset weight to remaining weights was as large as 10. As ICI increased, the relative onset weight was reduced. For large it and all ICIs, the ongoing train was weighted more heavily than the onset. Thi s diminishing relative onset weight with increasing ICI and n is consi stent with optimum distribution of weights among components. Efficienc y of weight distribution is near ideal when ICI=12 msec and n=2 and ve ry poor for shorter ICIs and larger ns. Further experiments showed tha t: (1) onset dominance involves both within- and between-frequertcy-ch annel mechanisms, and (2) the stimulus configuration (ICI, n, frequenc y content, and temporal gaps) affects weighting functions in a complex way not explained by cross-correlation analysis or contralateral inhi bition (Lindemann, 1986a, 1986b).