Spectral dominance in sensitivity to interaural delay for broadband stimuli

Abstract

Just-noticeable differences (jnds) in interaural delay of a target band were measured in the presence of a diotic spectral fringe. Stimuli were clicks or 100-ms bursts of noise with flat spectra from 0.1 to 9 kHz. The bandwidth of the target band was 0.4 times the center frequency. With either clicks or noise, the jnds for target bands having center frequencies between 0.5 and 1 kHz were roughly unaffected by the presence of the fringe: They were on the order of tens of microseconds. In contrast, the jnds for target bands at high frequencies were greatly degraded by the presence of the fringe: They increased from approximately 100 μs to greater than 600 μs. With noise, delaying a low-frequency target band causes the image of that band to separate from the image of the fringe. With clicks, delaying a low-frequency band (with about 3% of the total energy) causes the entire wideband image to lateralize. In general, the results suggest that the degree of the dominance region described by Bilsen and Raatgever [Acustica 28, 131–132 (1973)] is virtually total and that interaural delays at high frequencies are insignificant compared to those at low frequencies. [Work supported by NIH.]