Detection of Auditory Signal in Restricted Sets of Reproducible Noise

Abstract

The detectability of auditory signals in reproducible random noise was studied under 2 conditions: a single noise used throughout a block of 288 trials, and 12 noises occurring at random, but with equal frequency, throughout a block of trials. Both 2-interval forced-choice judgments and judgments of the presence or absence of the signal in single-noise samples were obtained in separate blocks of trials. On individual trials of the forced-choice judgments, the same noise ap- peared in both intervals. Signal detectability was found to be significantly better when a single noise was present in a block of trials. Introducing variability in the stimulus by altering the number of different signal levels presented during a block of trials did not affect detection. The results support the importance of memory for the noise to trial in the detection process.