Stochastic resonance in Gaussian and uniform noise

Abstract

The improvement in threshold of a 2.0 kHz tone in the presence of low levels of uniform and Gaussian noise is compared to tonal threshold measured in quiet. Uniform noise was created using a rectangular amplitude distribution. The noises were low-pass filtered at 12.0 kHz and were presented continuously throughout a run at spectrum levels ranging from 0 to −30 dB/Hz. Pure-tone signals were 400 ms in duration including 10 ms raised cosine onset and offset ramps. Thresholds were obtained using a 3-interval, forced-choice procedure with correct answer feedback in conjunction with a two down, one up adaptive tracking paradigm that targets 70.7% correct on the psychometric function. Subjects were instructed to select the interval that was different from the others. Preliminary results for the Gaussian noise conditions are similar to earlier results [Zeng et al., Brain Res. 869, 251–255 (2000)]. Initial results for the uniform noise indicate that it produced equivalent or slightly lower thresholds than those measured in the presence of Gaussian noise.