Sound-localization experiments with barn owls in virtual space: influence of broadband interaural level difference on head-turning behavior

Interaural level differences play an important role for elevational sound l ocalization in barn owls. The changes of this cue with sound location are c omplex and frequency dependent. We exploited the opportunities offered by t he virtual space technique to investigate the behavioral relevance of the o verall interaural level difference by fixing this parameter in virtual stim uli to a constant value or introducing additional broadband level differenc es to normal virtual stimuli. Frequency-specific monaural cues ill the stim uli were not manipulated. We observed an influence of the broadband interau ral level differences on elevational, but not on azimuthal sound localizati on. Since results obtained with our manipulations explained only part of th e variance in elevational turning angle, we conclude that frequency-specifi c cues are also important. The behavioral consequences of changes of the ov erall interaural level difference in a virtual sound depended on the combin ed interaural time difference contained in the stimulus, indicating an indi rect influence of temporal cues on elevational sound localization as well. Thus, elevational sound localization is influenced by a combination of many spatial cues including frequency-dependent: and temporal features.