Three-Dimensional Auditory Localization of Nearby Sources

Although the head-related transfer function (HRTF) is known to change substantially with distance when a source is located within 1 m of the listener's head, very little is known about auditory localization performance in this region. In this experiment, an acoustic point source was used to measure auditory localization accuracy in azimuth, elevation and distance. The overall directional error (16.5°) was similar to that measured in previous localization experiments with more distant sources, although the number of front-back reversals increased when the source was near the head. Distance localization was relatively accurate for lateral sources (stimulus-response correlation r>0.80) and relatively inaccurate for sources near the median plane, indicating that binaural difference cues are important to auditory distance perception for nearby sources. These results suggest that distance-dependent HRTFs measured for nearby sources could be used to provide robust binaural distance information in a virtual audio display.