Effects of Signal Duration and Masker Duration on Detectability under Diotic and Dichotic Listening Conditions

Abstract

The detectability of a 500-Hz tone of either 32- or 256-msec duration in a broad-band 50-dB spectrum level noise was measured as a function of the duration of the noise. The noise was continuous or was gated 0, 125, or 250 msec before the onset of the signal. For the gated noise conditions, the noise was terminated approximately 5 msec after termination of the signal. With a homophasic condition (N0-S0), the three noise conditions led to approximately the same detectability as did the continuous masher. In an antiphasic condition (N0-Sπ), detectability was poorest when signal and masker began together and improved as the delay between noise onset and signal onset increased. The difference between the simultaneous onset and the continuous noise condition was about 9 dB for the 32-msec signal and about 3 dB for the 256-msec signal. These results will be compared to those reported by McFadden (1966) and discussed in terms of theories of binaural signal detectability. [Research supported by a grant from the National Science Foundation.]