ASA 127th Meeting M.I.T. 1994 June 6-10

3pPP13. Binaural spectral interference effects measured with masking and with discrimination paradigms.

Leslie R. Bernstein

Constantine Trahiotis

Ctr. for Neurolog. Sci., Surgical Res. Ctr. and Dept. of Surgery Otolaryngol.), Univ. of Connecticut Health Ctr., Farmington, CT 06030

This study concerned binaural spectral interference. First, detection thresholds were measured for a 125-ms, 4-kHz tonal signal masked by a 145-ms, 100-Hz-wide band of noise (centered at 4 kHz) in NoS(pi) or NoSo configurations. These thresholds were compared to those obtained when a spectrally-remote ``interferer'' consisting of a 100-Hz-wide band of noise centered at 500 Hz accompanied the masker. Interferers were either diotic or were interaurally uncorrelated and were presented either continuously or were gated on and off simultaneously with the masker. About 7 dB of interference was obtained (i.e., thresholds increased) in the presence of the uncorrelated, gated interferer and about 5.5 dB of interference was obtained with the diotic, gated interferer. Interference was reduced substantially when the interferer was presented continuously. Reversing the roles of the spectral regions containing the signal and interferer (i.e., measuring detectability of a 500-Hz tone) yielded little interference. That is, interference effects were spectrally asymmetric. Comparable results were obtained when interference was assessed for detection of interaural temporal disparities. In contrast, very little interference was measured for detection of interaural intensitive disparities. [Work supported by NIH and AFOSR.]