The effect of angular disparity between sound source sequences on the perceptual organization of auditory objects

Abstract

Within auditory scene analysis is a well-known streaming phenomenon which is observed when listeners group several sounds into “auditory objects” in complex auditory scenes. When two auditory sequences consist of similar sounds, these sequences tend to be perceived as a single stream, but can form segregated streams when the sounds are presented from disparate angles. This study investigated the tolerance thresholds for the angular disparity at which the sound sources would segregate rather than group together into single auditory objects, when 50-ms one-third octave bands of noise were presented in the horizontal plane with changing azimuth angle. Listeners were asked to judge whether the presented noise sequences were perceived as a single stream or not. The results revealed that listeners tend to perceive the presented sequences as a single stream when the angular disparity between noises was small; however, these tolerance thresholds depended on the spatial region within which the sequences were presented. Tolerance thresholds became large when the noise sequences were presented from the side, in comparison to the situation when sequences were presented from in front of the listeners. Results were consistent with the minimum audible angle on the horizontal plane.