听觉信息掩蔽的亚成分：基于行为和脑成像研究的证明

听觉掩蔽的机制是解决嘈杂声学环境下对特定目标声音进行加工, 即“鸡尾酒会”问题的关键。听觉掩蔽可以分为能量掩蔽和信息掩蔽两种类型。前者是因为目标和掩蔽声音在听觉外周在时间和频率上的重叠所造成的, 而后者被认为是掩蔽声音在听觉中枢和目标声音竞争加工资源所造成的。长久以来, 信息掩蔽一直被当作一种单一成分的现象, 这一概念框架已经成为制约对其机制进行深入研究的一个瓶颈。信息掩蔽中至少包含有知觉信息掩蔽和认知信息掩蔽两种亚成分, 它们源于不同的中枢机制。多个说话人声音掩蔽的条件下, 总体掩蔽量是能量掩蔽、知觉信息掩蔽和认知信息掩蔽等成分总和的结果。操纵掩蔽和目标声音的知觉空间分离、掩蔽声音的可懂度以及掩蔽和目标声音的知觉相似度, 可以实现对两种信息掩蔽亚成分的双重分离。应用功能性核磁共振成像技术可以发现两者有不同的神经机制。

The Subcomponents of Informational Masking: Evidence from Behavioral and Neural Imaging Studies

The processing of a target speech under noisy environment is influenced by the presence of concurrent sounds, this phenomenon is referred to as auditory masking. Previous research showed that there are two kinds of masking, energetic masking and informational masking. Energetic masking originated from auditory periphery, where the masking sound overlaps with the target sound in time and frequency, resulting in an incomplete representation of the latter. On the other hand, informational masking is believed to occur in the central auditory system. However, for a long time, the concept of informational masking has been used as a “suitcase” or “catchall” word. All the influencing effect that can not be explained by energetic masking is attributed to informational masking, though its underlying mechanism is still largely unknown. In this article, a new conceptual framework of informational masking is proposed. In this framework, informational masking is divided into two subcomponents, perceptual informational masking and cognitive informational masking. Perceptual masking is caused by the competition between the sound stream/object, while cognitive informational masking is caused by the higher cognitive information included in the masking sounds, which could be automatically processed by the auditory or linguistic system. Psychophysical and neural imaging studies are proposed to test the above hypothesis. In behavioral studies, the perceived spatial separation between the target and the masker, the intelligibility and the voice number in the masking sound, as well as the perceptual similarity between the target and masker streams are manipulated to demonstrate that perceptual masking and cognitive masking could be double-dissociated. In the neural imaging study, fMRI technique is used to show that perceptual and cognitive informational masking may have different neural mechanism.