Effects of masker level and signal delay on forward masking in normal and impaired listeners

Abstract

Forward masking of a brief tonal probe by a long-duration tonal masker of the same frequency is determined primarily by masker level and signal delay. Forward masking was measured in listeners with normal hearing and in those with mild and moderate sensorineural losses as a function of both these variables. Tonal forward masking was also measured in normal listeners in the presence of continuous broadband noise, in an effort to simulate a sensorineural loss. The majority of the impaired listeners showed roughly normal decay of forward masking over time, but abnormal functions relating forward masking to masker level. Less forward masking occurs in impaired listeners than in those with normal hearing at all but the highest masker sound pressure levels. More forward masking occurs in impaired listeners than in normal listeners when maskers are equated in terms of sensation level at all but the lowest sensation levels. Use of background noise in tests of listeners with normal hearing does not provide a good simulation of sensorineural hearing loss. [Work supported by NIH.]