Creating invariant representations from an everchanging speech signal is a major challenge for the human brain. Such an ability is particularly crucial for preverbal infants who must discover the phonological, lexical, and syntactic regularities of an extremely inconsistent signal in order to acquire language. Within the visual domain, an efficient neural solution to overcome variability consists in factorizing the input into a reduced set of orthogonal components. Here, we asked whether a similar decomposition strategy is used in early speech perception. Using a 256-channel electroencephalographic system, we recorded the neural responses of 3-mo-old infants to 120 natural consonant–vowel syllables with varying acoustic and phonetic profiles. Using multivariate pattern analyses, we show that syllables are factorized into distinct and orthogonal neural codes for consonants and vowels. Concerning consonants, we further demonstrate the existence of two stages of processing. A first phase is characterized by orthogonal and context-invariant neural codes for the dimensions of manner and place of articulation. Within the second stage, manner and place codes are integrated to recover the identity of the phoneme. We conclude that, despite the paucity of articulatory motor plans and speech production skills, pre-babbling infants are already equipped with a structured combinatorial code for speech analysis, which might account for the rapid pace of language acquisition during the first year.

从不断变化的语音信号中创建不变的表示是人类大脑面临的一项重大挑战。这种能力对于前语言婴儿尤其重要，他们必须发现极其不一致的信号的语音、词汇和句法规律才能获得语言。在视觉域内，克服可变性的有效神经解决方案包括将输入分解为一组减少的正交分量。在这里，我们询问是否在早期语音感知中使用了类似的分解策略。使用 256 通道脑电图系统，我们记录了 3 个月大的婴儿对 120 个具有不同声学和语音特征的自然辅音-元音音节的神经反应。使用多元模式分析，我们展示了音节被分解为辅音和元音的不同且正交的神经代码。关于辅音，我们进一步证明了两个处理阶段的存在。第一阶段的特征在于用于方式维度和发音位置的正交和上下文不变的神经代码。在第二阶段，整合方式和地点代码以恢复音素的身份。我们得出的结论是，尽管缺乏发音运动计划和言语生产技能，但学龄前婴儿已经配备了用于言语分析的结构化组合代码，这可能是第一年语言习得速度快的原因。第一阶段的特征在于用于方式维度和发音位置的正交和上下文不变的神经代码。在第二阶段，整合方式和地点代码以恢复音素的身份。我们得出的结论是，尽管缺乏发音运动计划和言语生产技能，但学龄前婴儿已经配备了用于言语分析的结构化组合代码，这可能是第一年语言习得速度快的原因。第一阶段的特征在于用于方式维度和发音位置的正交和上下文不变的神经代码。在第二阶段，整合方式和地点代码以恢复音素的身份。我们得出的结论是，尽管缺乏发音运动计划和言语生产技能，但学龄前婴儿已经配备了用于言语分析的结构化组合代码，这可能是第一年语言习得速度快的原因。