Buss Emily, Hall Joseph W
Department of Otolaryngology/Head and Neck Surgery, University of North Carolina School of Medicine, Chapel Hill, North Carolina 27599, USA.
J Acoust Soc Am. 2008 Oct;124(4):1905-8. doi: 10.1121/1.2968685.
Detection threshold for a pure tone signal centered in a narrow band of noise may be reduced by inclusion of additional flanking masker bands, provided that they share coherent amplitude modulation (AM) across frequency. This comodulation masking release (CMR) associated with coherent AM across frequency is often much smaller if the signal and on-signal masker are presented to one ear and the flanking masker band(s) are presented contralaterally. An experiment was carried out to explore the role of peripheral effects (e.g., suppression) and central effects (e.g., grouping) in this finding. As frequently reported, CMR was smaller when two or more flanking maskers were presented contralaterally to the signal than when presented ipsilaterally. An intermediate condition, where a subset of flanking maskers was presented to each ear, provided comparable benefit to presenting all flankers ipsilateral to the signal. This result suggests that central effects may play a significant role in the reduced dichotic CMR under some conditions.
如果窄带噪声中心的纯音信号包含额外的侧翼掩蔽带，其检测阈值可能会降低，前提是这些掩蔽带在频率上共享相干幅度调制（AM）。如果信号和信号上的掩蔽声呈现给一只耳朵，而侧翼掩蔽带呈现给对侧耳朵，那么与频率上的相干AM相关的这种共调制掩蔽释放（CMR）通常会小得多。进行了一项实验来探究外周效应（如抑制）和中枢效应（如分组）在这一发现中的作用。正如经常报道的那样，当两个或更多侧翼掩蔽声与信号对侧呈现时，CMR比同侧呈现时小。一种中间条件，即向每只耳朵呈现一部分侧翼掩蔽声，与将所有侧翼掩蔽声同侧呈现给信号相比，能提供相当的益处。这一结果表明，在某些条件下，中枢效应可能在双耳CMR降低中起重要作用。
