Hall J W, Grose J H, Hartmann W M
Division of Otolaryngology/Head & Neck Surgery, University of North Carolina Medical School, Chapel Hill 27599-7070, USA.
J Acoust Soc Am. 1998 May;103(5 Pt 1):2573-7. doi: 10.1121/1.422778.
In experiment 1 NoSo and NoS pi thresholds for a 500-Hz pure tone were obtained in a low-fluctuation masking noise and a high-fluctuation masking noise for six normal-hearing listeners. The noise bandwidth was 10 Hz. In agreement with previous investigations, the NoSo thresholds were lower in low-fluctuation noise than in high-fluctuation noise. For three listeners, NoS pi thresholds were similar for the two types of noise, while for the other three listeners, Nos pi thresholds were higher for low-fluctuation noise than for high-fluctuation noise. In experiment 2, the masker was created by amplitude modulating a 500-Hz pure tone by a 0-10-Hz low-pass noise. The degree of masker fluctuation was controlled by adjusting the average modulation depth (100%, 63%, 40%, and 25%). The signal was a 10-Hz-wide noise centered on 500 Hz. Results were similar to those of experiment 1: for the NoSo conditions, signal detection improved with decreasing degree of fluctuation, and for NoS pi conditions, the results were subject dependent. For three listeners, NoS pi thresholds were again similar in the two types of noise, while for the other three listeners, NoS pi thresholds were again higher in low-fluctuation noise than in high-fluctuation noise. The results showed that a high degree of masker fluctuation sometimes facilitates NoS pi detection. It is possible that the binaural detection mechanism utilizes the relatively good signal-to-noise ratios that occur in the low power or "dip" regions of fluctuating masker waveforms.
在实验1中，针对6名听力正常的受试者，分别在低波动掩蔽噪声和高波动掩蔽噪声条件下，获取了500赫兹纯音的NoSo和NoS pi阈值。噪声带宽为10赫兹。与之前的研究一致，低波动噪声中的NoSo阈值低于高波动噪声中的NoSo阈值。对于3名受试者，两种噪声类型下的NoS pi阈值相似，而对于另外3名受试者，低波动噪声下的Nos pi阈值高于高波动噪声下的Nos pi阈值。在实验2中，掩蔽音通过用0 - 10赫兹的低通噪声对500赫兹纯音进行幅度调制来产生。通过调整平均调制深度（100%、63%、40%和25%）来控制掩蔽音的波动程度。信号是一个以500赫兹为中心、带宽为10赫兹的噪声。结果与实验1相似：对于NoSo条件，随着波动程度降低，信号检测得到改善；对于NoS pi条件，结果因受试者而异。对于3名受试者，两种噪声类型下的NoS pi阈值再次相似，而对于另外3名受试者，低波动噪声下的NoS pi阈值再次高于高波动噪声下的NoS pi阈值。结果表明，高度的掩蔽音波动有时会促进NoS pi检测。有可能双耳检测机制利用了波动掩蔽音波形低功率或“波谷”区域中出现的相对较好的信噪比。
