Forward masking by sinusoidal and noise maskers.

A 2-kHz sinusoid and a narrow-band noise centered at 2 kHz, with the same total power, served as maskers for a 2-kHz sinusoidal signal. We compare the forward masking produced by these two maskers (1) as a function of offset--offset time for 5- and 35-ms signals, (2) as a function of signal duration for a fixed offset--onset time, and (3) as a function of signal duration for a fixed offset--offset time. In all these comparisons, we find that the noise and sinusoid not only produce different amounts of masking for the same experimental condition, but they also show different trends for the same manipulation. The important relations in these results are demonstrated in an additional set of conditions with a 1-kHz signal. In order to account for the differences observed in both experiments, we argue that forward masking is determined by at least two factors. We suggest signal energy as one factor and the presence or absence of differences in quality between masker and signal as another.