International Graduate School Neurosensory Science and Systems, Carl-von-Ossietzky-Universitat Oldenburg, 26111 Oldenburg, Germany.
J Acoust Soc Am. 2009 Dec;126(6):3188-98. doi: 10.1121/1.3243307.
In the bandwidening experiment with a diotic noise masker, an apparently wider critical bandwidth has often been reported when a dichotic signal (Spi) is used instead of a diotic signal (So). Two competing across-channel processes were proposed to account for this apparently wider critical bandwidth: (i) A detrimental across-channel effect reducing the binaural masking-level difference (BMLD) for broadband maskers and (ii) a beneficial integration of information across channels for narrowband maskers. The two hypotheses result in different predictions of the BMLD in the notched-noise experiment: According to the first hypothesis, the change in BMLD with notch width is determined by the level-dependence of the BMLD for a narrowband masker centered at the signal frequency, whereas the second hypothesis predicts that it is determined by the level-dependence of the BMLD for a broadband masker. To test the hypotheses, masked thresholds of a diotic or dichotic 500-Hz signal were measured for a diotic notched-noise masker as a function of notch width. In addition, thresholds were measured for a diotic broadband and narrowband masker as a function of masker level. The data indicate that neither of the two hypotheses is able to predict the continuous decrease in the BMLD as the notch width increases.
在使用双声道噪声掩蔽的带宽扩展实验中，当使用双声道信号 (Spi) 而不是单声道信号 (So) 时，通常会报告一个明显更宽的临界频带宽度。有两种相互竞争的跨通道过程被提出来解释这种明显更宽的临界频带宽度：(i) 一种有害的跨通道效应，降低了宽带掩蔽的双耳掩蔽级差 (BMLD)，以及 (ii) 窄带掩蔽器的信息跨通道的有益整合。这两个假设对缺口噪声实验中的 BMLD 产生了不同的预测：根据第一个假设，BMLD 随缺口宽度的变化由窄带掩蔽器的 BMLD 对信号频率中心的带宽依赖性决定，而第二个假设预测它由宽带掩蔽器的 BMLD 对带宽的依赖性决定。为了检验这些假设，用单声道缺口噪声掩蔽器作为函数，测量了单声道或双声道 500Hz 信号的掩蔽阈值，作为缺口宽度的函数。此外，还测量了双声道宽带和窄带掩蔽器作为掩蔽器水平的函数的阈值。数据表明，这两个假设都不能预测随着缺口宽度的增加，BMLD 的连续下降。
