Temporal cueing effects in backward change masking

Abstract

In a simple monaural yes‐no paradigm observers were asked to detect a 20‐ms segment of a 3000‐Hz sinusoid under two types of masking conditions both with and without contralateral temporal cues. Backward change masking was produced by a postsignal change in the frequency centroid of the masking noise in which both spectrum level of the noise within the critical band of the signal and its total power remained constant. The change masking was produced by an alternation between two masking noises which were classified as “high” and “low,” corresponding to the perceived pitch of each. Relative to the continuous (no change) conditions, results show a differential masking effect from backward change masking out to a 300‐ms delay between signal offset and change onset in the noncued experimental conditions. A timing cue was then provided by a gap in an otherwise continuous, uncorrelated noise in the contralateral ear. The gap cue led the signal by 5 ms and was switched off simultaneously with signal offset. Results show the cue to be effective in reducing backward change masking, thus implicate temporal uncertainty as a factor in backward change masking. These results parallel those reported at previous meetings for standard backward masking conditions [J. S. Puleo and R. E. Pastore, J. Acoust. Soc. Am. 60, S49(A) (1976)]. [Research supported by a grant from NINCDS.]