Université de Bordeaux, Bordeaux, France.
Adv Exp Med Biol. 2013;787:175-82. doi: 10.1007/978-1-4614-1590-9_20.
The threshold for detecting a tone in a multitone masker is lower when the masker-plus-signal stimulus is preceded by a copy of the masker. One potential explanation of this "enhancement" phenomenon is that the -precursor stimulus acts as a "template" of the subsequent masker, thus helping listeners to segregate the signal from the masker. To assess this idea, we measured enhancement for precursors that were perceptually similar to the masker and for precursors that were made dissimilar to the masker by gating their components asynchronously. We found that the two types of precursor produced similar amounts of enhancement. This was true not only when the precursor and the subsequent test stimulus were presented to the same ear but also when they were presented to opposite ears. In a second experiment, we checked that the precursors with asynchronously gated components were perceptually poor templates of the subsequent maskers. Listeners now had to discriminate between test stimuli -containing the same components as the precursor and test stimuli containing all but one of the precursor components. We found that in this experimental situation, where enhancement could play no role, gating the precursor components asynchronously disrupted performance. Overall, our results are inconsistent with the hypothesis that precursors producing enhancement are beneficial because they are used as perceptual templates of the masker. Our results are instead consistent with an -explanation of enhancement based on selective neural adaptation taking place at a central locus of the auditory system.
当多频掩蔽器加信号刺激之前有掩蔽器的副本时，检测音调的阈限会降低。这种“增强”现象的一个潜在解释是，前导刺激充当了后续掩蔽器的“模板”，从而帮助听众将信号与掩蔽器分离。为了评估这个想法，我们测量了对与掩蔽器在感知上相似的前导刺激和对通过异步门控使其与掩蔽器不同的前导刺激的增强。我们发现这两种类型的前导刺激产生了相似的增强效果。这不仅适用于前导和后续测试刺激同时呈现给同一耳朵的情况，也适用于它们呈现给相对耳朵的情况。在第二个实验中，我们检查了具有异步门控成分的前导刺激是否是后续掩蔽器的感知不佳模板。现在，听众必须在包含与前导刺激相同成分的测试刺激和包含除前导刺激成分之外的所有成分的测试刺激之间进行区分。我们发现，在这种增强不能发挥作用的实验情况下，异步门控前导刺激成分会干扰表现。总的来说，我们的结果与前导刺激产生增强是因为它们被用作掩蔽器的感知模板这一假设不一致。我们的结果与基于在听觉系统的中央位置发生的选择性神经适应的增强解释一致。
