ASA 125th Meeting Ottawa 1993 May

3pPP5. Evaluation of a linear interpolation scheme for approximating HRTFs.

Abhijit Kulkarni

H. Steven Colburn

Dept. of Biomed. Eng., Boston Univ., 4 Cummington St., Boston, MA 02215

As part of a study of virtual acoustical environments, the ability of subjects to distinguish interpolated HRTFs from empirical HRTFs in the horizontal plane was investigated. Each interpolated HRTF was obtained by averaging empirical HRTFs from two positions chosen symmetrically about the location of interest. Empirical HRTFs were measured from the KEMAR mannequin in anechoic space. Subjects were tested using a 4I, 2AFC paradigm for several angles of interpolation using lowpass noise stimuli. Theoretical analysis predicted a useful lateralization cue for large interpolation angles. For a 2.2-kHz lowpass stimulus, subjects reported the use of such a cue and performed at 96% correct (averaged across four subjects) for a 30-deg angle. For a 10-deg angle, subjects reported no lateralization cue and performed near chance (53% correct), until they discovered a spectral cue increasing performance significantly (69% correct). Monaural performance was comparable to binaural performance, consistent with predictions for the use of spectral information. Results for combinations of interpolation angles and stimulus bandwidth will be presented, and implications for both basic and applied contexts will be discussed. [Work supported by NIDCD.]