Discrimination of reproducible noise as a function of bandwidth and duration

The discriminability of reproducible noise bursts was studied as a function of bandwidth and duration. Listeners discriminated between trials consisting of two identical noise waveforms or two independent noise waveforms. New noise waveforms were generated each trial. In general, discrimination improved with increasing bandwidth. However, discrimination improved with increasing duration only up to about 25 msec, beyond which it decreased. Additional experiments examined discriminability with (1) forward or backward maskers, which intervened or did not intervene temporally between the comparison stimuli, (2) two noise waveforms fixed over 50 or 300 trials, and (3) high- or low-frequency noise bands. Results suggested that the decrease in discriminability beyond 25 msec was due primarily to sensory interactions of a central origin but with some effect of peripheral masking, memory interference, and attentional limitations. Information at the offset was discriminated best, and low-frequency information was better discriminated than high-frequency information. The results also indicated that envelope cues were used in certain conditions.