Lau Joseph C Y, Wong Patrick C M, Chandrasekaran Bharath
Department of Linguistics and Modern Languages, The Chinese University of Hong Kong, Shatin, Hong Kong SAR, China.
Brain and Mind Institute, The Chinese University of Hong Kong, Shatin, Hong Kong SAR, China.
Atten Percept Psychophys. 2019 May;81(4):1020-1033. doi: 10.3758/s13414-018-1621-9.
Speech processing is highly modulated by context. Prior studies examining frequency-following responses (FFRs), an electrophysiological 'neurophonic' potential that faithfully reflects phase-locked activity from neural ensembles within the auditory network, have demonstrated that stimulus context modulates the integrity of speech encoding. The extent to which context-dependent encoding reflects general auditory properties or interactivities between statistical and higher-level linguistic processes remains unexplored. Our study examined whether speech encoding, as reflected by FFRs, is modulated by abstract phonological relationships between a stimulus and surrounding contexts. FFRs were elicited to a Mandarin rising-tone syllable (/ji-TR/, 'second') randomly presented with other syllables in three contexts from 17 native listeners. In a contrastive context, /ji-TR/ occurred with meaning-contrastive high-level-tone syllables (/ji-H/, 'one'). In an allotone context, TR occurred with dipping-tone syllables /ji-D/, a non-meaning-contrastive variant of /ji-TR/. In a repetitive context, the same /ji-TR/ occurred with other speech tokens of /ji-TR/. Consistent with prior work, neural tracking of /ji-TR/ pitch contour was more faithful in the repetitive condition wherein /ji-TR/ occurred more predictably (p = 1) than in the contrastive condition (p = 0.34). Crucially, in the allotone context, neural tracking of /ji-TR/ was more accurate relative to the contrastive context, despite both having an identical transitional probability (p = 0.34). Mechanistically, the non-meaning-contrastive relationship may have augmented the probability to /ji-TR/ occurrence in the allotone context. Results indicate online interactions between bottom-up and top-down mechanisms, which facilitate speech perception. Such interactivities may predictively fine-tune incoming speech encoding using linguistic and statistical information from prior context.
语音处理受到语境的高度调节。先前研究频率跟随反应（FFRs），这是一种电生理“神经音”电位，能忠实地反映听觉网络中神经集合的锁相活动，研究表明刺激语境会调节语音编码的完整性。依赖语境的编码在多大程度上反映一般听觉属性或统计与高级语言过程之间的相互作用仍未得到探索。我们的研究考察了由FFRs反映的语音编码是否受到刺激与周围语境之间抽象语音关系的调节。对17名以普通话为母语的听众，在三种语境下，将一个普通话升调音节（/ji-TR/，“第二”）与其他音节随机呈现，从而引出FFRs。在对比语境中，/ji-TR/与意义对比的高调音节（/ji-H/，“第一”）一起出现。在异调语境中，TR与降调音节/ji-D/一起出现，/ji-D/是/ji-TR/的非意义对比变体。在重复语境中，相同的/ji-TR/与/ji-TR/的其他语音片段一起出现。与先前研究一致，在重复条件下，/ji-TR/音高轮廓的神经跟踪比在对比条件下更准确，在重复条件下/ji-TR/出现的可预测性更高（p = 1），而在对比条件下（p = 0.34）。至关重要的是，在异调语境中，/ji-TR/的神经跟踪相对于对比语境更准确，尽管两者具有相同的过渡概率（p = 0.34）。从机制上讲，非意义对比关系可能增加了/ji-TR/在异调语境中出现的概率。结果表明自下而上和自上而下机制之间的在线相互作用有助于语音感知。这种相互作用可能利用先前语境中的语言和统计信息对传入的语音编码进行预测性微调。
