Hill Kevin T, Bishop Christopher W, Miller Lee M
Human Neuroimaging Laboratory, Virginia Tech, Virginia Tech Carilion Research Institue, Roanoke VA, USA.
Front Hum Neurosci. 2012 Jun 8;6:158. doi: 10.3389/fnhum.2012.00158. eCollection 2012.
The human brain uses acoustic cues to decompose complex auditory scenes into its components. For instance to improve communication, a listener can select an individual "stream," such as a talker in a crowded room, based on cues such as pitch or location. Despite numerous investigations into auditory streaming, few have demonstrated clear correlates of perception; instead, in many studies perception covaries with changes in physical stimulus properties (e.g., frequency separation). In the current report, we employ a classic ABA streaming paradigm and human electroencephalography (EEG) to disentangle the individual contributions of stimulus properties from changes in auditory perception. We find that changes in perceptual state-that is the perception of one versus two auditory streams with physically identical stimuli-and changes in physical stimulus properties are reflected independently in the event-related potential (ERP) during overlapping time windows. These findings emphasize the necessity of controlling for stimulus properties when studying perceptual effects of streaming. Furthermore, the independence of the perceptual effect from stimulus properties suggests the neural correlates of streaming reflect a tone's relative position within a larger sequence (1st, 2nd, 3rd) rather than its acoustics. By clarifying the role of stimulus attributes along with perceptual changes, this study helps explain precisely how the brain is able to distinguish a sound source of interest in an auditory scene.
人类大脑利用声学线索将复杂的听觉场景分解为其组成部分。例如，为了改善交流，听众可以根据音高或位置等线索，在拥挤的房间里挑选出一个单独的“声流”，比如一个说话者的声音。尽管对听觉流进行了大量研究，但很少有研究能证明感知的明确相关性；相反，在许多研究中，感知与物理刺激属性的变化（如频率分离）相关。在本报告中，我们采用经典的ABA听觉流范式和人类脑电图（EEG）来区分刺激属性的个体贡献与听觉感知的变化。我们发现，感知状态的变化——即在物理刺激相同的情况下对一个或两个听觉流的感知——以及物理刺激属性的变化在重叠的时间窗口内的事件相关电位（ERP）中独立反映出来。这些发现强调了在研究听觉流的感知效应时控制刺激属性的必要性。此外，感知效应与刺激属性的独立性表明，听觉流的神经相关性反映的是一个音调在更大序列（第一、第二、第三）中的相对位置，而不是其声学特性。通过阐明刺激属性的作用以及感知变化，本研究有助于准确解释大脑如何能够在听觉场景中区分感兴趣的声源。
