Alain Claude, Quan Jessica, McDonald Kelly, Van Roon Patricia
Rotman Research Institute, Baycrest Centre for Geriatric Care, Toronto, Ontario, Canada.
Eur J Neurosci. 2009 Jul;30(1):132-42. doi: 10.1111/j.1460-9568.2009.06792.x. Epub 2009 Jun 25.
Noise is usually detrimental to auditory perception. However, recent psychophysical studies have shown that low levels of broadband noise may improve signal detection. Here, we measured auditory evoked fields (AEFs) while participants listened passively to low-pitched and high-pitched tones (Experiment 1) or complex sounds that included a tuned or a mistuned component that yielded the perception of concurrent sound objects (Experiment 2). In both experiments, stimuli were embedded in low or intermediate levels of Gaussian noise or presented without background noise. For each participant, the AEFs were modeled with a pair of dipoles in the superior temporal plane, and the effects of noise were examined on the resulting source waveforms. In both experiments, the N1m was larger when the stimuli were embedded in low background noise than in the no-noise control condition. Complex sounds with a mistuned component generated an object-related negativity that was larger in the low-noise condition. The results show that low-level background noise facilitates AEFs associated with sound onset and can be beneficial for sorting out concurrent sound objects. We suggest that noise-induced increases in transient evoked responses may be mediated via efferent feedback connections between the auditory cortex and lower auditory centers.
噪声通常对听觉感知有害。然而，最近的心理物理学研究表明，低水平的宽带噪声可能会改善信号检测。在此，我们在参与者被动聆听低音调和高音调（实验1）或包含一个调谐或失谐成分从而产生同时存在的声音对象感知的复杂声音（实验2）时，测量了听觉诱发电位（AEFs）。在这两个实验中，刺激被嵌入低或中等水平的高斯噪声中，或者在无背景噪声的情况下呈现。对于每个参与者，AEFs用一对位于颞上平面的偶极子进行建模，并研究噪声对所得源波形的影响。在这两个实验中，当刺激被嵌入低背景噪声中时，N1m比在无噪声对照条件下更大。带有失谐成分的复杂声音产生了与对象相关的负电位，在低噪声条件下更大。结果表明，低水平背景噪声促进了与声音起始相关的AEFs，并且可能有利于区分同时存在的声音对象。我们认为，噪声引起的瞬态诱发反应增加可能是通过听觉皮层与较低听觉中枢之间的传出反馈连接介导的。
