Decoding continuous speech in infancy

认为语言习得是一个从孩子说出第一个有意义的单词开始的过程，忽视了语言发展的一个重要阶段。早在婴儿接近于给单词附加意义或说出合乎语法的话语之前，他们就必须首先学会解码语音信号。对成人语音感知的研究表明，解码语音信号是一项复杂的任务，需要对语音信号有复杂的理解。甚至识别语音中的单词边界也是一项挑战，因为没有可靠的声音线索来确定单词边界（例如，单词之间的沉默），并且没有单词以相同的方式产生两次。尽管有这些困难，婴儿很早就开始识别单词了。目前大多数的语言习得模型都把沉重的负担放在婴儿从语言输入中提取规则的能力上。已有大量的研究报告支持这种关于早期语言发展的统计学习观点，但其中许多研究都假设了理想的语音输入和成人对语音信号的关注。但这些假设并不一定是正确的。在这个项目中，我将解决这些问题，目标是更好地将当前的语言感知发展模型与正常发育的婴儿的现实生活感知和认知能力结合起来。具体的问题包括：1)婴儿是否比成人更注意韵律，2)婴儿是否比其他人更容易注意到某些上下文中的发音错误，以及3)婴儿是否能像在许多实验室研究中使用的简化语音一样容易地跟踪真实语音中的统计模式。

Thinking of language acquisition as a process that begins when children utter their first meaningful words overlooks an important stage of language development. Long before infants are even close to attaching meanings to words or producing grammatical utterances, they must first learn to decode the speech signal. Research on adult speech perception has demonstrated that decoding the speech signal is a complicated task, requiring a sophisticated understanding of the speech signal. Even identifying word boundaries in speech is challenging because there are no reliable acoustic cues to word boundaries (e.g., silences between words), and no word is produced in an identical fashion twice. Despite these difficulties, infants begin recognizing words remarkably early. Most current models of language acquisition place a heavy burden on infants' ability to extract regularities from their language input. A great number of studies have been reported which support this statistical learning view on early language development, but many of these studies assume an idealized speech input and adult-like attention to the speech signal. But these assumptions are not necessarily justified. In this project, I will address these issues with the goal of better aligning current developmental models of speech perception with the real-life perceptual and cognitive capabilities of normally developing infants. Specific issues that will be addressed include 1) whether infants are more attentive to prosody than adults, 2) whether it is easier for infants to notice mispronunciations in some contexts than others, and 3) whether infants can track statistical patterns in real speech as easily as they do so with the simplified speech used in many laboratory studies.