Influence of Pulsed Masking on the Threshold for Spondees
作者:
Richard H. Wilson,
Raymond Carhart,
期刊:
The Journal of the Acoustical Society of America
(AIP Available online 1969)
卷期:
Volume 46,
issue 4B
页码: 998-1010
ISSN:0001-4966
年代: 1969
DOI:10.1121/1.1911820
出版商: Acoustical Society of America
数据来源: AIP
摘要:
The changes in masking for spondee words that result from varying both the level and the interruption rate of a white‐noise masker were studied with 14 normal hearing subjects and 14 subjects with sensorineural hearing loss diagnosed as resulting from cochlear otosclerosis. The masker was a white noise and was presented monaurally at either 90 dB sound‐pressure level (SPL) or 30 dB sensation level (SL). It was either continuous or was pulsed at rates of 1, 10, or 100/sec with 50% duty cycle. During the burst‐off half of each cycle, the noise was either dropped 14 dB in level or was fully interrupted. The masked speech reception threshold (SRT) was not improvedrethe masked SRT in continuous noise when the 30 dB SL masker was pulsed 100 times/sec. Reduction in masking was observed under all other circumstances of cycling the noise. This reduction was more pronounced when the noise was completely interrupted rather than only modulated by 14 dB, when the masker was at its higher level (90 dB SPL as opposed to 30 dB SL), and when the masker was interrupted at the slowest rate [1 interruption per second (ips)]. During equivalent conditions, the reduction in masking was greater for normal‐hearing subjects than for those with cochlear otosclerosis. Appreciable residual masking (reSRT in quiet) persisted across the range of all parameters of noise level, modulation depth, cycling rate, and type of subject encompassed during the present study. This last finding appears to be contradictory to some of the results from earlier studies but not to others. This discrepancy, along with other aspects of the present findings, are discussed.
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