LAUSR

Detection thresholds tend to be lower when the spectral and/or temporal characteristics of the signal are predictable than unpredictable, particularly in an unpredictable masker. The present study evaluated the detrimental effect of frequency uncertainty and the beneficial effect of temporal coherence for a pure-tone signal presented in a multi-tonal masker with unpredictable frequency sequences. Stimuli were composed of 80-ms tone bursts. The signal was 1, 2, 4, or 8 sequential tone bursts, and burst frequency was either fixed across trials or randomly varied across trials but fixed across bursts. The masker was composed of four streams of tone bursts; the frequency of each burst was randomly drawn from a uniform distribution 250-4000 Hz, with the caveat that synchronous masker and signal bursts were separated by 1/5 oct or more. Signal and masker bursts were synchronously gated, and the masker played continuously throughout a threshold estimation track. Thresholds tended to improve with increasing numbe...