Characterization of acoustic head-related transfer functions for nearby sources

Abstract

Head Related Transfer Functions (HRTF) for nearby sources were characterized for human subjects and the Knowles Electronics Manikin for Acoustic Research (KEMAR). The HRTFs were measured in several reverberant room conditions for sound source positions at 0, 45, and 90 degrees in azimuth and 15cm and 1m from the center of the head using maximum-length sequences. The effects of reverberation on interaural time difference, interaural level difference, magnitude response, and spectral content were examined. Results were consistent with acoustic theory. Reverberation was found to decrease ILD, cause comb-filtering, and to distort and add frequency-to-frequency variations to acoustic cues. These affects were most pronounced in room positions with the most reverberant energy.