The Effects of Acoustic-Category Definition on the Learning of Phonological Classes: Corporal Analyses, Behavioral Studies and Modeling Experiments

成年人对待语言相关和不相关的语音之间的差异不同。例如，在英语中，“pit”和“peat”的元音之间的对比是相关的（音位），因为“pit”和“peat”在含义上不同。“can 't”和“cat”的元音变化是不相关的（变音）：交换“a”的声音不影响意义，说话者根据声音上下文产生一个或另一个（例如，“can 't”中的“a”在“n”之前;“cat”中的“a”在“t”之前）。对比是否是变音必须学习，因为它们在不同的语言中是不同的。例如，在法语中，情况正好相反：“a”音之间的对比表示意义上的差异（如“bas”[低]和“banc”[长凳]），而“pit-peat”之间的对比则不表示，而是取决于元音的上下文。婴儿听到这两种类型的对比;然而，到第一年结束时，他们已经学会忽略allophonic对比。他们是如何学会注意音位而忽略音位对比的？计算模型只有在明确给出声音相似性的度量时才能区分音位和音位的对比。因此，推动当前研究的假设是，音位上产生的对比（例如，法语使用者的“a”）和字母拼写（例如，“a“s）在相似性上有所不同，这样，在对比中的同音异声彼此更相似，而幼儿对这些差异很敏感。这一假设使用两种方法进行测试。首先，语音语料库将通过记录成年人的英语和法语发言者在与婴儿和成人说话时产生两种对比（类似于“坑泥炭”和“不能猫”的差异）来创建。声学测量将确定哪些差异（如果有的话）表明声音是来自说话者的音素或音位类别。其次，行为实验将测试婴儿和成人在学习声音模式时是否使用这些可用的声学差异和分布。参与者将接触到新的语音模式，然后对遵循或违反早期模式的其他项目进行测试。新模式的学习将从遵循和违反模式的测试项目的区分中推断出来（由婴儿的听力时间差异和成人的评级差异表示）。如果声学和/或语音分布的较大差异导致参与者将声音视为音位对比的一部分，而较小的差异导致他们将声音视为音位变体，则该假设将得到支持。这项研究将深入了解用于学习语言声音系统（音位学）的可用信息和基本机制;扩展有关婴儿如何学习类别的知识;并增加我们对婴儿指导语音在语言习得中的作用的理解。发现婴儿从婴儿和成人指导的言语中学习类别的能力不同，可能会影响父母的养育技巧和早期干预策略。该项目有助于澄清早期言语感知和后期语言习得之间的关系，这最终可能使我们能够在婴儿期使用感知任务进行诊断和早期干预（例如，对母语对比的敏感性预测了以后的单词理解、单词产生和阅读技能）。最后，该奖项不仅使语音习得的研究，但是，作为学生在项目的各个阶段发挥关键作用，也教育和激励学生和未来的研究人员在语言，行为和实验方法来理解语言发展。

Adults treat linguistically relevant and not relevant contrasts between speech sounds differently. For example, in English, the contrast between the vowel sounds of "pit" and "peat" is relevant (phonemic), since "pit" and "peat" differ in meaning. Variation in the vowels of "can't" and "cat" is not relevant (allophonic): exchanging the "a" sounds does not affect meaning, and speakers produce one or the other depending on the sound context (e.g., the "a" in "can't" before "n"; and the "a" from "cat" before "t"). Whether a contrast is allophonic must be learned since they vary across languages. For example, in French the reverse is true: the contrast between the "a" sounds signals differences in meaning (as in "bas" [low] and "banc" [bench]), whereas the contrast between "pit-peat" does not and depends on the vowel context. Infants hear both types of contrasts; yet, by the end of their first year, they have learned to ignore allophonic contrasts. How do they learn to attend to phonemic and ignore allophonic contrasts? Computational models learn to differentiate phonemic from allophonic contrasts only when explicitly given measures of sound similarity. Therefore, the hypothesis driving the current research is that contrasts produced phonemically (e.g., "a"s by French speakers) and allophonically (e.g., "a"s by English speakers) differ in their similarity, such that allophonic sounds in a contrast are more similar to each other, and that young infants are sensitive to these differences. This hypothesis is tested using two approaches. First, a corpus of speech sounds will be created by recording adult speakers of English and French producing two contrasts (similar to "pit-peat" and "can't-cat" differences) when speaking to both infants and adults. Acoustic measurements will determine which differences, if any, indicate whether sounds are from phonemic or allophonic categories for the speaker. Second, behavioral experiments will test whether infants and adults use these available acoustic differences and distributions when learning sound patterns. Participants will be exposed to novel speech sound patterns then tested on additional items that either follow or violate the earlier patterns. Learning of the novel patterns will be inferred from the differentiation of test items that follow and violate the patterns (indicated by listening time differences in infants and rating differences in adults). If larger differences in acoustics and/or distribution of speech sounds induce participants to treat the sounds as part of a phonemic contrast while smaller differences induce them to treat the sounds as allophonic variants, the hypothesis will be supported. The research will provide insight into the available information and fundamental mechanisms used to learn a language's sound system (phonology); extend knowledge about how infants learn categories; and increase our understanding of the role of infant-directed speech in language acquisition. Discovering that infants differ in their ability to learn categories from infant- and adult-directed speech may influence both parenting techniques and early intervention strategies. The project contributes to the growing body of work clarifying relationships between early speech perception and later language acquisition, which may eventually enable us to use perception tasks in infancy for diagnosis and early intervention (e.g., sensitivity to native-language contrasts predicts later word comprehension, word production, and reading skill). Finally, the award not only enables research on phonological acquisition, but, as students play a key role in all phases of the project, also educates and motivates students and future researchers in linguistic, behavioral, and experimental approaches to the understanding of language development.