Effects of the Temporal Properties of a Masker upon Simultaneous-Masking Patterns

Abstract

Fletcher’s (1940) critical band hypothesis suggests that maskers with equal power within a critical band around the signal frequency ought to produce equal amounts of masking. Simultaneous-masking patterns (SMP’s) for pure-tone and narrowband-noise maskers of equal power and similar center frequency (Egan and Hake, 1950; Carter and Kryter, 1962) indicate that the critical band hypothesis is an over-simplification. At masker levels above 60 dB SL filtered, narrowband-noise and pure-tone maskers were found to mask differently as a function of frequency. Pure-tone maskers were found to be more effective when the probe was 1/2 octave or more above the masker frequency while narrowband-noise maskers were more effective when the probe was at or very near the masker frequency. In the frequency region below the masker, pure-tone and narrow-band noise maskers produced nearly equivalent amounts of masking. More recently, Buus (1985) has shown that pure-tone and broadband-noise maskers, which produced nearly equivalent amounts of masking, produced more masking on the high-frequency side of the masking pattern than did narrowband-noise.