Phase effects in masking: within- versus across-channel processes.
The effects of bandwidth and component phase on masking were investigated using 200-ms narrowband (1-ERB(N)) and broadband (5-ERB(N)) cosine-phase (CP) and random-phase (RP) harmonic complex maskers, centered at 1 or 6 kHz. A continuous notched-noise was used to restrict off-frequency listening. The masker fundamental frequency (F0) was 25 Hz. In experiment 1, thresholds were measured for sinusoidal signals at 1 and 6 kHz, gated with the maskers. Thresholds were lower in the CP than in the RP masker, for both bandwidths, but the effect was markedly greater for the wider bandwidth. For the CP maskers, thresholds were markedly lower for the 5-ERB(N) than for the 1-ERB(N) bandwidth; for the RP maskers, there was a small effect in the opposite direction. Experiment 2 used 1- and 6-kHz CP maskers. The masker components in the ERB(N) around the signal frequency were presented to one ear, and the remaining components were presented contralaterally. Thresholds were much higher than when all components were presented to the same ear, and were higher than for the 1-ERB(N) masker alone, suggesting that the low thresholds for broadband monaural presentation do not depend on "high level" across-channel comparisons. Simultaneous masked thresholds could be predicted well using a model based on a simulated auditory filter, a level-dependent compressive nonlinearity, and a sliding temporal integrator; it was not necessary to assume the involvement of across-channel processes or of selective listening in the masker dips.
Department of Experimental Psychology, University of Cambridge, Downing Street, Cambridge CB2 3EB, England. jia10@cus.cam.ac.uk
José I
JI
Alcántara
Brian C J
BC
Moore
Brian R
BR
Glasberg
Alex J K
AJ
Wilkinson
Urszula
U
Jorasz
D000328:Adult; D001309:Auditory Threshold; D007839:Functional Laterality; D006801:Humans; D008144:Loudness Perception; D008297:Male; D008875:Middle Aged; D010470:Perceptual Masking; D010897:Pitch Discrimination; D011571:Psychoacoustics; D013018:Sound Spectrography