Abstract:

Auditory localization performance has been measured for a point- source stimulus within 1 m of a listener's head. Broadband noise bursts, roved in intensity to eliminate loudness as a distance cue, were presented at random locations ranging from 0(degrees)--180(degrees) in azimuth, 60(degrees)--60(degrees) in elevation, and 15 cm--1 m in distance. The listeners responded to these stimuli by moving a response wand to the perceived location of the sound. Response errors were then calculated in azimuth, elevation, and distance. Directional localization error for nearby sources was comparable to that previously reported in localization experiments at distances greater than 1 m. Distance accuracy was found to depend on source azimuth, with best performance to the listener's side and worst performance directly in front of the listener. Distance judgments were slightly more accurate when the amplitude of the stimulus was not randomized to eliminate distance effects. The improvement in accuracy for the fixed-amplitude stimulus was greater in front than to the side of the listener. Distance accuracy was substantially degraded when one of the listener's ears was occluded by an earplug and muff. These results suggest the importance of binaural cues to near-field distance perception. [Work supported by AFOSR.]