Beneficial effects of notched noise on intensity discrimination in the region of the "severe departure". 1998

C J Plack
Laboratory of Experimental Psychology, University of Sussex, Brighton, England.

Intensity discrimination for a 6-kHz sinusoidal pedestal was measured in quiet and in the presence of a noise background. In the first experiment, the level of a 30-ms pedestal was fixed at 45 dB SPL and presented in the temporal and spectral center of a 110-ms notched noise. For a noise spectrum level of between 0 and 15 dB the noise produced a substantial reduction in the Weber fraction, i.e., an improvement in detectability, compared to the condition without the noise. The second experiment showed that, unlike the situation with notched noise, narrow-noise produced no performance improvement, suggesting that the effect is dependent on noise frequency components outside the critical band of the pedestal. The third experiment showed that the improvement also occurred for a 6-ms pedestal presented in a 10-ms gap between two bursts of notched noise. The experiment rules out an explanation for the effect of the noise in terms of suppression on the basilar membrane. Finally, the effect was shown to decrease as the gap between the noise bursts was increased, in a manner at least broadly consistent with the decay of the temporal excitation pattern. It is suggested that the improvement in intensity discrimination in notched noise is due to an across-frequency comparison mechanism similar to "profile analysis," perhaps operating on a temporally smoothed central representation of the stimulus.

UI MeSH Term Description Entries
D009622 Noise Any sound which is unwanted or interferes with HEARING other sounds. Noise Pollution,Noises,Pollution, Noise
D011601 Psychophysics The science dealing with the correlation of the physical characteristics of a stimulus, e.g., frequency or intensity, with the response to the stimulus, in order to assess the psychologic factors involved in the relationship. Psychophysic
D006801 Humans Members of the species Homo sapiens. Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man
D001307 Auditory Perception The process whereby auditory stimuli are selected, organized, and interpreted by the organism. Auditory Processing,Perception, Auditory,Processing, Auditory
D013997 Time Factors Elements of limited time intervals, contributing to particular results or situations. Time Series,Factor, Time,Time Factor

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