同时掩蔽效应的实验研究

Experiments on simultaneous mask effect

不同声压级下窄带噪声对纯音同时掩蔽效应的实验结果表明:掩蔽曲线可以用两段直线来近似。当掩蔽声压级为60dB时,上升直线的平均斜率为21.6dB/Bark,而下降直线的平均斜率为-20.7dB/Bark。随着声压级的增加,上升直线的斜率增加,而下降直线的斜率变化不大。但在临界带内,掩蔽效果作用的范围越来越宽,即掩蔽峰越来越圆缓。而且在高频一侧,曲线的边缘在高声压级下变得比较缓慢。因此,双直线近似有一定的局限性。另外,掩蔽曲线的斜率不会随频率升高而显著上升或下降。产生上述结果的主要原因是听觉神经传导和双音信号的互相抑制机理。

Experiments on simultaneous mask effect where tones were masked by narrow-band noises with different SPL showed that the masking curve could be approximated as two segments of straight line. When SPL of the masker was 60dB, the average slope of the up-line was 21.6 dB/Bark, and that of the down-line was -20.7dB/Bark. With increasing SPL of the masker, the average slope of the up-line increases while the down-line almost keeps unchanged. However, the scope of the mask effect expanded within a critical band, meaning that the mask peak becomes rounder. At high frequencies the slope of the lines becomes shallower towards high levels. So, the two segments straight-line approximation has its limitation. Additionally, the slope does not increase or decrease significantly with frequency. This can be considered as a consequence of sound propagation in nerves and two-tone suppression.