Kidd Gerald, Mason Christine R, Arbogast Tanya L, Brungart Douglas S, Simpson Brian D
Hearing Research Center, Sargent College, Boston University, 635 Commonwealth Avenue, Boston, Massachusetts 02132, USA.
J Acoust Soc Am. 2003 Mar;113(3):1594-603. doi: 10.1121/1.1547440.
Although informational masking is thought to reflect central mechanisms, the effects are generally much stronger when the target and masker are presented to the same ear than when they are presented to different ears. However, the results of a recent study by Brungart and Simpson [J. Acoust. Soc. Am. 112, 2985-2995 (2002)] indicated that a speech masker that is presented contralateral to a speech signal can produce substantial amounts of informational masking when a second speech masker is played simultaneously in the same ear as the signal. In this study, we conducted a series of experiments that paralleled those of Brungart and Simpson but used a pure-tone signal and multitone informational maskers in a detection task. Both the signal and the maskers were played as sequences of short bursts in each observation interval. The maskers were arranged in two types of spectrotemporal patterns. One type of pattern, called "multiple-bursts same" (MBS), has previously been shown to produce very large amounts of informational masking while the other type of pattern, called "multiple-bursts different" (MBD), has been shown to produce very small amounts of informational masking. Several conditions of ipsilateral, contralateral, and combined presentation of these maskers were tested. The results showed that presentation of the MBS masker in the contralateral ear produced a substantial amount of informational masking when the MBD masker was simultaneously presented to the ipsilateral ear. The results supported the earlier findings of Brungart and Simpson indicating that listeners are unable to selectively focus their attention on a single ear in some complex dichotic listening conditions. These results suggest that this contralateral masking effect is not restricted to speech and may reflect more general limitations on processing capacity. Further, it was concluded that the magnitude of the contralateral masking effect was related both to the informational masking value of the contralateral masker and the complexity of the stimulus and/or task in the ear in which the signal was presented.
虽然信息掩蔽被认为反映了中枢机制，但通常情况下，当目标和掩蔽声呈现给同一只耳朵时，其效应要比呈现给不同耳朵时强得多。然而，Brungart和Simpson [《美国声学学会杂志》112, 2985 - 2995 (2002)] 最近的一项研究结果表明，当一个语音掩蔽声与语音信号对侧呈现，且第二个语音掩蔽声与信号在同一只耳朵中同时播放时，会产生大量的信息掩蔽。在本研究中，我们进行了一系列实验，这些实验与Brungart和Simpson的实验类似，但在检测任务中使用了纯音信号和多音信息掩蔽声。在每个观察间隔中，信号和掩蔽声都以短脉冲序列的形式播放。掩蔽声被安排成两种类型的频谱时间模式。一种模式称为“多脉冲相同”（MBS），此前已被证明会产生大量的信息掩蔽，而另一种模式称为“多脉冲不同”（MBD），已被证明会产生少量的信息掩蔽。测试了这些掩蔽声同侧、对侧和联合呈现的几种情况。结果表明，当MBD掩蔽声同时呈现给同侧耳朵时，对侧耳朵中呈现的MBS掩蔽声会产生大量的信息掩蔽。这些结果支持了Brungart和Simpson早期的研究发现，即表明在某些复杂的双耳分听条件下，听众无法将注意力选择性地集中在一只耳朵上。这些结果表明，这种对侧掩蔽效应并不局限于语音，可能反映了处理能力上更普遍的限制。此外，得出的结论是，对侧掩蔽效应的大小既与对侧掩蔽声的信息掩蔽值有关，也与呈现信号的耳朵中刺激和/或任务的复杂性有关。
