Bader Maria, Schröger Erich, Grimm Sabine
Institute of Psychology, Leipzig University, Leipzig, Germany.
PLoS One. 2017 May 4;12(5):e0176981. doi: 10.1371/journal.pone.0176981. eCollection 2017.
The recognition of sound patterns in speech or music (e.g., a melody that is played in different keys) requires knowledge about pitch relations between successive sounds. We investigated the formation of regularity representations for sound patterns in an event-related potential (ERP) study. A pattern, which consisted of six concatenated 50 ms tone segments differing in fundamental frequency, was presented 1, 2, 3, 6, or 12 times and then replaced by another pattern by randomly changing the pitch of the tonal segments (roving standard paradigm). In an absolute repetition condition, patterns were repeated identically, whereas in a transposed condition, only the pitch relations of the tonal segments of the patterns were repeated, while the entire patterns were shifted up or down in pitch. During ERP measurement participants were not informed about the pattern repetition rule, but were instructed to discriminate rarely occurring targets of lower or higher sound intensity. EPRs for pattern changes (mismatch negativity, MMN; and P3a) and for pattern repetitions (repetition positivity, RP) revealed that the auditory system is able to rapidly extract regularities from unfamiliar complex sound patterns even when absolute pitch varies. Yet, enhanced RP and P3a amplitudes, and improved behavioral performance measured in a post-hoc test, in the absolute as compared with the transposed condition suggest that it is more difficult to encode patterns without absolute pitch information. This is explained by dissociable processing of standards and deviants as well as a back propagation mechanism to early sensory processing stages, which is effective after less repetitions of a standard stimulus for absolute pitch.
识别语音或音乐中的声音模式（例如，以不同调演奏的旋律）需要了解连续声音之间的音高关系。我们在一项事件相关电位（ERP）研究中调查了声音模式规律性表征的形成。呈现一个由六个连续的50毫秒音调片段组成的模式，这些片段的基频不同，该模式出现1、2、3、6或12次，然后通过随机改变音调片段的音高被另一个模式取代（移动标准范式）。在绝对重复条件下，模式完全相同地重复，而在转调条件下，仅模式的音调片段的音高关系被重复，而整个模式在音高上向上或向下移动。在ERP测量期间，参与者未被告知模式重复规则，但被指示辨别很少出现的较低或较高声音强度的目标。模式变化（失配负波，MMN；和P3a）和模式重复（重复正波，RP）的ERP结果表明，即使绝对音高变化，听觉系统也能够从不熟悉的复杂声音模式中快速提取规律性。然而，与转调条件相比，在绝对条件下，后测中增强的RP和P3a振幅以及改善的行为表现表明，在没有绝对音高信息的情况下编码模式更困难。这可以通过标准刺激和偏差刺激的可分离处理以及向早期感觉处理阶段的反向传播机制来解释，对于绝对音高，该机制在标准刺激较少重复后有效。
