ASA 129th Meeting - Washington, DC - 1995 May 30 .. Jun 06

2pPP59. Binaural profile analysis: On the comparison of interaural time difference and interaural correlation across frequency.

William S. Woods

Univ. Oldenburg, FB8/Medizinische Physik, D-26111 Oldenburg, Germany

Andrew R. Brughera

H. Steven Colburn

Boston Univ., Boston, MA 02215

Experiments are reported on that were aimed at determining if a ``profile-analysis'' process is performed in the binaural domain, specifically with interaural time difference (ITD) and interaural correlation (IC). Sensitivity to variations in these parameters across frequency was investigated by roving the parameters across intervals and requesting subjects to choose the interval containing an incrementally different parameter value in a target band. The size of the increment needed to identify the target interval was measured for several bandwidths of the total stimulus. In the ITD experiments, tone complexes were used and the target was a tone at 500 Hz. For harmonic complexes (100-Hz spacing), the addition of reference tones (out to 4 kHz) does not aid detection of the target interval but usually degrades performance. For logarithmic complexes (spacing factor 1.3) performance improved at the widest (4 kHz) bandwidth. In the IC experiment, spectrally continuous noise was used, with a 115-Hz wide target band at 500 Hz. Adding fringe bands increased thresholds significantly for a narrow stimulus bandwidth (354 Hz), and performance returned to that measured for the target alone for wide bandwidths. These results are discussed in terms of possible binaural contributions to auditory grouping. [Work supported by NIDCD (Grant DC00100).]