Physiological masking in the peripheral auditory system. 3. Effect of varying test-click intensity.

Abstract

Masking recovery and the "masking-duration effect" were studied at different test-click intensities. When "masking" was expressed as the difference between control and recovering A. P. [auditory potential] amplitudes, the following were observed: When masking intensity is below 75-85 db, amount of masking is increased as test-click intensity is increased. However, above a certain click-intensity level, amount of masking remains constant (the "difference plateau"). The difference plateau disappears above the 75-85 db masking-intensity level. Varying click intensity has no direct effect on the time course of masking recovery. However, increasing click intensity increases the slowing effect of masking duration. These finding are discussed in terms of the concept that masking is determined by the "overlap" of the responses to the masked and masking stimuli. Masking increases A. P. latency, but not as much as lowering click intensity. This effect is independent of masking frequency up to 7,000 cycles/sec. The possible mechanism of this latency increase is discussed.