Shen Yi, Lentz Jennifer J
Department of Speech and Hearing Sciences, Indiana University, Bloomington, Indiana 47405-7000, USA.
J Acoust Soc Am. 2010 Jun;127(6):3654-65. doi: 10.1121/1.3418684.
To determine the effects of hearing loss and fast-acting compression on auditory grouping based on across-frequency modulation, modulation detection interference (MDI) was measured in listeners with normal hearing and hearing loss. MDI, the increase in the amplitude-modulation detection threshold of a target presented with an interferer distant in frequency, was measured using a 500-Hz target and a 2140-Hz interferer, both modulated with narrow-band noises of the same bandwidth. The two modulated tones were presented at equal loudness levels to listeners with normal hearing and hearing loss in the absence (Exp. 1) and in the presence (Exp. 2) of fast-acting compression applied to the interferer. Modulation detection thresholds increased with increasing modulation depth of the interferer by similar amounts for the two groups of listeners, suggesting that across-frequency grouping based on amplitude modulation is not altered by hearing impairment. Compression provided an additional increase in thresholds for both groups, indicating that compression algorithms might alter across-frequency grouping cues. Partial support for an idea that compression's effect of sharpening the onsets after each envelope valley is provided by a third experiment which found somewhat greater interference produced by square-wave modulation than sine-wave modulation at larger interferer modulation depths.
为了确定听力损失和快速作用压缩对基于跨频率调制的听觉分组的影响，我们在听力正常和听力损失的听众中测量了调制检测干扰（MDI）。MDI是指在频率上与目标相距较远的干扰音出现时，目标的调幅检测阈值的增加量，我们使用一个500赫兹的目标音和一个2140赫兹的干扰音进行测量，二者均由相同带宽的窄带噪声进行调制。在不存在快速作用压缩（实验1）和存在快速作用压缩（实验2）的情况下，将这两个调制音以相等的响度水平呈现给听力正常和听力损失的听众，其中快速作用压缩应用于干扰音。两组听众的调制检测阈值均随着干扰音调制度深度的增加而以相似的幅度增加，这表明基于调幅的跨频率分组不会因听力障碍而改变。压缩使两组听众的阈值进一步增加，这表明压缩算法可能会改变跨频率分组线索。第三个实验为压缩在每个包络谷之后锐化起始点的作用这一观点提供了部分支持，该实验发现在较大的干扰音调制度深度下，方波调制产生的干扰比正弦波调制产生的干扰略大。
