The influence of pinnae-based spectral cues on sound localization

Abstract

The role of pinnae-based spectral cues was investigated by requiring listeners to locate sound, binaurally, in the horizontal plane with and without partial occlusion of their external ears. The main finding was that the high frequencies were necessary for optimal performance. When the stimulus contained the higher audio frequencies, e.g., broadband and 4.0-kHz high-pass noise, localization accuracy was significantly superior to that recorded for sitmuli consisting only of the lower frequencies (4.0- and 1.0-kHz low-pass noise). This finding was attributed to the influence of the spectral cues furnished by the pinnae, for when the stimulus composition included high frequencies, pinnae occlusion resulted in a marked decline in localization accuracy. Numerous front-rear reversals occurred. The ability to distinguish among sounds originating within the same quadrant also suffered. Performance proficiency for the loss-pass stimuli was not further degraded under conditions of pinnae occlusion. The 4.0-kHz high-pass noise was located when both, neither, or only 1 ear was occluded; the pinna-based cues of the near ear contributed powerfully toward localization accuracy.