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Beneficial effects of notched noise on intensity discrimination in the region of the “severe departure”

 

作者: Christopher J. Plack,  

 

期刊: The Journal of the Acoustical Society of America  (AIP Available online 1998)
卷期: Volume 103, issue 5  

页码: 2530-2538

 

ISSN:0001-4966

 

年代: 1998

 

DOI:10.1121/1.422774

 

出版商: Acoustical Society of America

 

数据来源: AIP

 

摘要:

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-band 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.

 

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