Effects of flanking band proximity, number, and modulation pattern on comodulation masking release.
Effects of flanking band proximity, number, and modulation pattern on comodulation masking release.
复制标题
侧翼带接近度、数量和调制模式对共调制掩蔽释放的影响。
DOI：
10.1121/1.399294
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发表时间：
1989
期刊：
影响因子：
--
通讯作者：
M. Haggard
中科院分区：
文献类型：
--
作者：
J. Hall;J. Grose;M. Haggard
研究了700赫兹纯音信号的解调掩蔽释放与20赫兹宽的共调侧翼频带的数目和光谱位置的函数关系。在第一个实验中，所有的刺激都是有向呈现的。在频带围绕信号频率对称排列、低于信号频率或高于信号频率的条件下，作为存在的侧翼频带数量的函数来检查CMR。侧翼条带的数目从1到8个不等，分频CMR的大小大约在5-16分贝之间。结果表明：(1)距离信号越近的频段，掩蔽释放量越大；(2)频带越多，CMR越大(但两侧频段以上的回报递减)。检查了另外两组条件，并将其与存在所有八个共调侧翼带的条件进行比较：在一组条件中，八个侧翼带中的两个被移除；在另一组条件中，八个侧翼带中的两个被相对于其他带未共调的带(被称为“偏离”带)所取代。即使当去除的频带相对接近信号频率时，将8个频带减少到6个的效果也很小；然而，当引入偏差频带时，特别是当偏差频带放置在相对接近信号频率时，CMR显著降低。当每个偏差频带具有独特的调制模式(双偏差频带)时，CMR的这些降低比当两个偏差频带本身共享相同的调制模式(协变频带)时略大。在第二个实验中，研究了非信号耳的侧翼频带的数目和光谱位置不同的二分法条件(信号耳只接收到以信号频率为中心的20赫兹宽的噪声频带)。视情况而定，双眼CMR的大小约为2-10分贝。邻近性和侧翼条带的数量的影响与在二倍体条件下获得的效果相似。对于二分和二分数据，邻近度的影响与基于跨通道处理的解释比基于通道内交互的解释更一致。使用异常频带获得的结果表明，听觉系统很难忽略不同于开信号频带的调制模式的侧翼频带的调制模式，特别是当这些频带接近信号频率时。
Comodulation masking release for a 700-Hz pure-tone signal was investigated as a function of the number and spectral positions of 20-Hz-wide comodulated flanking bands. In the first experiment, all stimuli were presented diotically. CMR was examined as a function of the number of flanking bands present, in conditions where the bands were arranged symmetrically around the signal frequency, were below the signal frequency, or were above the signal frequency. The number of flanking bands ranged from one to eight, and the magnitude of the diotic CMR ranged from approximately 5-16 dB. The results indicated: (1) bands closer to the signal resulted in larger masking release, and (2) more bands gave rise to larger CMR (but with diminishing returns above two flanking bands). Two additional sets of diotic conditions were examined and compared to the condition where all eight comodulated flanking bands were present: In one set of conditions, two of the eight flanking bands were removed; in the other set of conditions, two of the eight flanking bands were replaced with bands (termed "deviant" bands) that were not comodulated with respect to the other bands. There was very little effect of reducing eight bands to six, even when the removed bands were relatively near the signal frequency; however, CMR was substantially reduced when deviant bands were introduced, particularly when the deviant bands were placed relatively near the signal frequency. These reductions in CMR were slightly greater when each of the deviant bands had a unique modulation pattern (bideviant bands) than when the two deviant bands themselves shared the same modulation pattern (codeviant bands). In the second experiment, dichotic conditions were examined where the number and spectral positions of the flanking bands in the nonsignal ear were varied (the signal ear received only a 20-Hz-wide noise band centered on the signal frequency). The magnitude of the dichotic CMR ranged from approximately 2-10 dB, depending on condition. Effects of proximity and the number of flanking bands were similar to the effects obtained in diotic conditions. For both the diotic and the dichotic data, the effects of proximity were more consistent with an interpretation based upon across-channel processing than upon a within-channel interaction. The results obtained using deviant bands indicate that it is difficult for the auditory system to disregard the modulation pattern of flanking bands that differ from the modulation pattern of the on-signal band, particularly if such bands are proximal to the signal frequency.