Serniclaes Willy, López-Zamora Miguel, Bordoy Soraya, L Luque Juan
Institute of Neuroscience and Cognition, CNRS, UMR 8002, Université Sorbonne Paris Cité, Paris, France.
Unité de Recherche en Neurosciences Cognitives, Centre de Recherches en Cognition et Neurosciences, Université Libre de Bruxelles, Bruxelles, Belgium.
Brain Behav. 2021 Jun;11(6):e02194. doi: 10.1002/brb3.2194. Epub 2021 May 21.
Previous studies have evidenced a different mode of speech perception in dyslexia, characterized by the use of allophonic rather than phonemic units. People with dyslexia perceive phonemic features (such as voicing) less accurately than typical readers, but they perceive allophonic features (i.e., language-independent differences between speech sounds) more accurately.
In this study, we investigated the perception of voicing contrasts in a sample of 204 Spanish children with or without dyslexia. Identification and discrimination data were collected for synthetic sounds varying along three different voice onset time (VOT) continua (ba/pa, de/te, and di/ti). Empirical data will be contrasted with a mathematical model of allophonic perception building up from neural oscillations and auditory temporal processing.
Children with dyslexia exhibited a general deficit in categorical precision; that is, they discriminated among phonemically contrastive pairs (around 0-ms VOT) less accurately than did chronological age controls, irrespective of the stimulus continuum. Children with dyslexia also exhibited a higher sensitivity in the discrimination of allophonic features (around ±30-ms VOT), but only for the stimulus continuum that was based on a nonlexical contrast (ba/pa).
Fitting the neural network model to the data collected for this continuum suggests that allophonic perception is due to a deficit in "subharmonic coupling" between high-frequency oscillations. Relationships with "temporal sampling framework" theory are discussed.
先前的研究证明，诵读困难者存在不同的言语感知模式，其特点是使用音位变体而非音素单位。与典型阅读者相比，诵读困难者对音素特征（如浊音）的感知不够准确，但他们对音位变体特征（即语音之间与语言无关的差异）的感知更准确。
在本研究中，我们调查了204名有或没有诵读困难的西班牙儿童对浊音对比的感知。收集了沿三个不同的语音起始时间（VOT）连续统（ba/pa、de/te和di/ti）变化的合成声音的识别和辨别数据。实证数据将与基于神经振荡和听觉时间处理建立的音位变体感知数学模型进行对比。
诵读困难儿童在类别精度方面普遍存在缺陷；也就是说，与实际年龄对照组相比，他们对音素对比对（约0毫秒VOT）的辨别不够准确，与刺激连续统无关。诵读困难儿童在辨别音位变体特征（约±30毫秒VOT）时也表现出更高的敏感性，但仅针对基于非词汇对比的刺激连续统（ba/pa）。
将神经网络模型与为此连续统收集的数据进行拟合表明，音位变体感知是由于高频振荡之间“次谐波耦合”的缺陷所致。文中还讨论了与“时间采样框架”理论的关系。
