EFFECT OF DECORRELATION OF BINAURAL SOUND ON BARN OWL’S ABILITY TO DETECT CHANGE IN INTERAURAL TIME DIFFERENCE UNDER A BAYESIAN PROCESSING MODEL
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Barn Owls (Tyto alba) have an exceptional ability to spatially localize sounds in their environment. Barn owls are able to localize prey using hearing alone (Konishi, 1973). By processing the interaural time and level differences of incoming sound stimuli, owls are able to place sounds in a neural space map. The neural pathway for processing interaural time difference (ITD) is well documented in the literature (Carr & Konishi, 1988; Carr & Konishi, 1990; Wagner, Takahashi, & Konishi, 1987). Recent literature has suggested that the classical place coded model for barn owl sound localization is ineffective in predicting behavior, and a Bayesian model for localization is a more accurate representation neural and behavioral results. (Fischer & Pena, 2011 ). Our research aims to show how owls' ability to detect an ITO is altered by varying levels of binaural correlation of incoming sounds. I hypothesized that decorrelation of binaural sound stimuli would lead to owls' decreased accuracy of detecting an interaural time difference. Results have shown owls' ability to accurately detect a change in ITD of 8μs at 100 percent binaural correlation. Our data also shows that owls are able to detect 8 microsecond changes in ITO at binaural correlation values as low as 60%, leading us to believe that the birds can maintain high behavioral accuracy with low levels of binaural correlation. Future research will require more experiments to build a data set with less variance and to develop a complete model of owls' ITO detection capabilities given a broader range of binaural decorrelation values.