Masking-Level Differences with Continuous and Burst Masking Noise

Abstract

Psychometric functions were obtained for several interaural phase combinations with both continuous and burst masking noise. In the burst conditions, the signal (400 cps, 125 msec) and the wide-band masker (45 dB/cycle) were gated simultaneously; in the continuous conditions, only the signal was gated. Performance on burst N0-S0 was only about 0.5 dB worse than on continuous N0-S0, but the masking-level differences (MLD's) for N0-Sπ, Nπ-S0, N0-Sm, and Nπ-Sm were 4–6 dB smaller with burst than with continuous noise. In an additional experiment, the noise burst (N0) was gated 0, 75, 150, 250, 400, 600, and 1000 msec before the onset of the signal (Sπ). These MLD's increased gradually between 0 and 600 msec and then leveled off at approximately the value obtained with a continuous masker. A single-interval, yes-no procedure was used in these experiments. When two-alternative, forced choice was used, the difference between continuous and burst noise was considerably diminished. [Research supported by the U. S. Air Force Office of Scientific Research and by the Public Health Service, U. S. Department of Health, Education, and Welfare.]