Department of Communication Sciences and Disorders, Northwestern University, 2240 Campus Drive, Evanston, Illinois 60201, USA.
J Acoust Soc Am. 2013 Sep;134(3):2136-47. doi: 10.1121/1.4816410.
Dynamic range compression is widely used to reduce the difference between the most and least intense portions of a signal. Such compression distorts the shape of the amplitude envelope of a signal, but it is unclear to what extent such distortions are actually perceivable by listeners. Here, the ability to distinguish between compressed and uncompressed versions of a noise vocoded sentence was initially measured in listeners with normal hearing while varying the threshold, ratio, attack, and release parameters. This narrow condition was selected in order to characterize perception under the most favorable listening conditions. The average behavioral sensitivity to compression was highly correlated to several acoustical indices of modulation depth. In particular, performance was highly correlated to the Euclidean distance between the modulation spectra of the uncompressed and compressed signals. Suggesting that this relationship is not restricted to the initial test conditions, the correlation remained largely unchanged both (1) when listeners with normal hearing were tested using a time-compressed version of the original signal, and (2) when listeners with impaired hearing were tested using the original signal. If this relationship generalizes to more ecologically valid conditions, it will provide a straightforward method for predicting the detectability of compression-induced distortions.
动态范围压缩被广泛用于减少信号中最强和最弱部分之间的差异。这种压缩会改变信号幅度包络的形状，但不清楚听众实际上能察觉到这种失真的程度。在这里，在正常听力的听众中，通过改变阈值、比率、攻击和释放参数，最初测量了噪声变码句子的压缩和未压缩版本之间的区分能力。选择这种狭窄的条件是为了在最有利的听力条件下描述感知。对压缩的平均行为敏感性与调制深度的几个声学指标高度相关。特别是，性能与未压缩和压缩信号的调制谱之间的欧几里得距离高度相关。这表明这种关系不仅限于初始测试条件，当使用原始信号的时间压缩版本测试正常听力的听众时，以及当使用原始信号测试听力受损的听众时，相关性基本保持不变。如果这种关系推广到更符合生态有效性的条件，它将为预测压缩引起的失真的可检测性提供一种直接的方法。
