Detection of Modulated Tones in Modulated Noise by Non-human Primates
Detection of Modulated Tones in Modulated Noise by Non-human Primates
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DOI：
10.1007/s10162-014-0467-7
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发表时间：
2014-10-01
影响因子：
2.4
通讯作者：
Ramachandran, Ramnarayan
中科院分区：
文献类型：
--
作者：
Bohlen, Peter;Dylla, Margit;Ramachandran, Ramnarayan
在自然环境中，许多声音都是调幅的。调幅被认为是一种有助于听觉客体形成的信号。先前对噪声中信号检测的研究发现，当音调或噪声被调幅时，噪声的掩蔽效果较差，并且噪声中音调的检测阈值降低。这些结果表明，调制噪声中调制信号的检测将得到增强。本文描述了在信号和噪声都被调幅的情况下如何改进检测的实验结果。两只猴子（猕猴）被训练去检测连续的、调幅的宽带噪声中的调幅音调。当其他类似幅度调制的音调和噪声的相位差发生变化时，当调制为同相时检测阈值最高，当调制为反相时检测阈值最低。当音调或噪声的调制深度变化时，如果调制是反相位的，则检测阈值降低。当调制同相时，增加音调调制深度会增加音调检测阈值，而增加噪声调制深度对音调检测阈值没有影响。改变音调或噪声的调制频率，使阈值发生变化，在高于20hz的调制频率处达到饱和；当音调和噪声调制为同相时，阈值降低，当它们为反相时，阈值降低。反应时间和音调水平之间的关系不受信号或噪声的时间变化性质的影响。行为阈值的变化与大脑从信号中减去噪声的模型相一致。这些结果表明，信号调制和掩模的参数以非常可预测的方式严重影响检测。这些结果与人类和鸟类的一些结果一致，并为噪声检测机制的神经生理学研究奠定了基础。
In natural environments, many sounds are amplitude-modulated. Amplitude modulation is thought to be a signal that aids auditory object formation. A previous study of the detection of signals in noise found that when tones or noise were amplitude-modulated, the noise was a less effective masker, and detection thresholds for tones in noise were lowered. These results suggest that the detection of modulated signals in modulated noise would be enhanced. This paper describes the results of experiments investigating how detection is modified when both signal and noise were amplitude-modulated. Two monkeys (Macaca mulatta) were trained to detect amplitude-modulated tones in continuous, amplitude-modulated broadband noise. When the phase difference of otherwise similarly amplitude-modulated tones and noise were varied, detection thresholds were highest when the modulations were in phase and lowest when the modulations were anti-phase. When the depth of the modulation of tones or noise was varied, detection thresholds decreased if the modulations were anti-phase. When the modulations were in phase, increasing the depth of tone modulation caused an increase in tone detection thresholds, but increasing depth of noise modulations did not affect tone detection thresholds. Changing the modulation frequency of tone or noise caused changes in threshold that saturated at modulation frequencies higher than 20 Hz; thresholds decreased when the tone and noise modulations were in phase and decreased when they were anti-phase. The relationship between reaction times and tone level were not modified by manipulations to the nature of temporal variations in the signal or noise. The changes in behavioral threshold were consistent with a model where the brain subtracted noise from signal. These results suggest that the parameters of the modulation of signals and maskers heavily influence detection in very predictable ways. These results are consistent with some results in humans and avians and form the baseline for neurophysiological studies of mechanisms of detection in noise.