Middlebrooks John C
Department of Otolaryngology, University of California at Irvine, Irvine, California 92697-5310, USA.
J Acoust Soc Am. 2017 Dec;142(6):3362. doi: 10.1121/1.5014053.
In a complex auditory scene, signals of interest can be distinguished from masking sounds by differences in source location [spatial release from masking (SRM)] and by differences between masker-alone and masker-plus-signal envelopes. This study investigated interactions between those factors in release of masking of 700-Hz tones in an open sound field. Signal and masker sources were colocated in front of the listener, or the signal source was shifted 90° to the side. In Experiment 1, the masker contained a 25-Hz-wide on-signal band plus flanking bands having envelopes that were either mutually uncorrelated or were comodulated. Comodulation masking release (CMR) was largely independent of signal location at a higher masker sound level, but at a lower level CMR was reduced for the lateral signal location. In Experiment 2, a brief signal was positioned at the envelope maximum (peak) or minimum (dip) of a 50-Hz-wide on-signal masker. Masking was released in dip more than in peak conditions only for the 90° signal. Overall, open-field SRM was greater in magnitude than binaural masking release reported in comparable closed-field studies, and envelope-related release was somewhat weaker. Mutual enhancement of masking release by spatial and envelope-related effects tended to increase with increasing masker level.
在复杂的听觉场景中，可通过声源位置差异[空间掩蔽释放（SRM）]以及仅掩蔽声与掩蔽声加信号包络之间的差异，将感兴趣的信号与掩蔽声区分开来。本研究调查了开放声场中700赫兹纯音掩蔽释放时这些因素之间的相互作用。信号源和掩蔽声源位于听众前方同一位置，或者信号源向一侧偏移90°。在实验1中，掩蔽声包含一个25赫兹宽的信号频段加上侧翼频段，其包络要么相互不相关，要么是共调制的。在较高掩蔽声声级时，共调制掩蔽释放（CMR）在很大程度上与信号位置无关，但在较低声级时，对于侧向信号位置，CMR会降低。在实验2中，一个短暂信号被置于一个50赫兹宽的信号掩蔽声的包络最大值（峰值）或最小值（谷值）处。仅对于90°信号，在谷值条件下的掩蔽释放比在峰值条件下更多。总体而言，开放声场中的SRM幅度大于可比的封闭声场研究中报道的双耳掩蔽释放，且与包络相关的释放稍弱。随着掩蔽声声级增加，空间和与包络相关的效应在掩蔽释放上的相互增强倾向于增加。
