EFFECTS OF INTERAURAL DECORRELATION ON NEURAL AND BEHAVIORAL DETECTION OF SPATIAL CUES

The detection of interaural time differences (ITDs) for sound localiza tion critically depends on the similarity between the left and right e ar signals (interaural correlation). We show that, like humans, owls c an localize phantom sound sources well until the correlation declines to a very low value, below which their performance rapidly deteriorate s. Decreasing interaural correlation also causes the response of the o wl's tectal auditory neurons to decline nonlinearly, with a rapid drop followed by a more gradual reduction. A detection-theoretic analysis of the statistical properties of neuronal responses could account for the variance of behavioral responses as interaural correlation is decr eased. Finally, cross-correlation analysis suggests that low interaura l correlations cause misalignment of cross-correlation peaks across di fferent frequencies, contributing heavily to the nonlinear decline in neural and ultimately behavioral performance.