Richards V M, Buss E, Tian L
Department of Psychology, University of Pennsylvania, Philadelphia 19104, USA.
J Acoust Soc Am. 1997 Jul;102(1):468-76. doi: 10.1121/1.419719.
In an effort to evaluate the importance of across-frequency comparisons of envelope patterns in comodulation masking release (CMR) experiments and to compare joint effects of target-masker frequency separation for both CMR and modulation detection interference (MDI) tasks, thresholds were measured for three tasks. These tasks were: (a) the detection of sinusoidal amplitude modulation (SAM) of a tone, (b) the detection of a reduction in the modulation depth of a fully modulated SAM tone, and (c) the detection of a tone added to a narrow band of noise. Thresholds were obtained for the target alone and for the target presented with two maskers. For the detection of SAM, thresholds did not depend on whether the modulation patterns of the target and masker elements were the same or random. For the latter two tasks, modulator phase effects were apparent for target-masker frequency separations less than 1-2 oct. In contrast, past work has shown that observers can compare modulator envelope phases across frequency separations larger than 1-2 oct [Strickland et al., J. Acoust. Soc. Am. 86, 2160-2166 (1989); Yost and Sheft, J. Acoust. Soc. Am. 85, 848-857 (1989)]. In a second experiment, thresholds for the detection of SAM were obtained after prolonged exposure to a fully modulated SAM tone. For four of the five observers, modulation-rate specific adaptation was obtained for test/adapting carrier-frequency separations approaching 2 oct below and 1 oct above the adaptor.
为了评估在共调制掩蔽释放（CMR）实验中包络模式跨频率比较的重要性，并比较CMR和调制检测干扰（MDI）任务中目标-掩蔽器频率分离的联合效应，对三项任务进行了阈值测量。这些任务分别是：（a）检测纯音的正弦幅度调制（SAM）；（b）检测完全调制的SAM纯音调制深度的降低；（c）检测添加到窄带噪声中的纯音。分别获得了单独目标以及目标与两个掩蔽器同时呈现时的阈值。对于SAM检测，阈值并不取决于目标和掩蔽器成分的调制模式是相同还是随机。对于后两项任务，当目标-掩蔽器频率分离小于1 - 2倍频程时，调制器相位效应明显。相比之下，过去的研究表明，观察者能够在大于1 - 2倍频程的频率分离上比较调制器包络相位[斯特里克兰等人，《美国声学学会杂志》86, 2160 - 2166（1989）；约斯特和谢夫特，《美国声学学会杂志》85, 848 - 857（1989）]。在第二个实验中，在长时间暴露于完全调制的SAM纯音后，获得了SAM检测的阈值。对于五名观察者中的四名，在测试/适应载波频率分离接近低于适应器2倍频程和高于适应器1倍频程时获得了调制速率特异性适应。
