Simultaneous masked thresholds as a function of masker bandwidth for different signal delays.

Abstract

The improvement in signal detectability as signal onset is delayed relative to masker onset was measured as a function of masker bandwidth for notched and unnotched maskers. The signal was a 250-Hz-wide noise band centered at 2500 Hz. In two conditions, the 20-ms signal was gated 1 ms or 250 ms after the onset of a 420-ms masker. Signal thresholds were higher in the short-delay than in the long-delay condition. This difference generally increased as masker bandwidth increased and was similar in magnitude across the two masker types. Further, this difference was greatest for maskers whose spectra were symmetric about the signal frequency, and was smaller, and similar, for maskers that extended exclusively above or below the signal frequency. In a third condition, the signal was gated 1 ms after the onset of a 23-ms masker. Thresholds were highest in this condition, and varied differently as a function of masker bandwidth than in the other two conditions, particularly for the notched maskers. [Work supported by NIDCD award to Dennis McFadden.]<ep;balance>