DEVELOPMENT OF PHONETIC CATEGORIES

人们普遍认为，第二语言存在一个关键时期， (L2)言语学习然而，外国口音的实际原因 仍然不确定。这里提出的研究将评估一个模型， 试图解释与年龄相关的双语者的生产变化， 元音和辅音（“声音”）的感知在他们的L2和他们的 母语（L1）。L2中的分段产生错误很重要 因为它们会导致误解和/或减缓处理， 造成负面的个人评价。一个不太明显的，但是 然而，L1与L2语音差异的严重后果是， 部分感知错误，导致困难， 理解L2。这种错误可能是由神经系统的变化引起的 减少添加或修改感觉运动程序的能力，或 防止对未找到的声音形成知觉表征 在L1。确定分部生产的原因， 感知误差在临床上是重要的。例如，如果出现 由于成熟决定的神经可塑性的限制， 感觉运动的灵活性，那么外国口音减少的好处 治疗，或语言治疗那些谁遭受了脑外伤， 对于已经过了关键期的个人，将受到严格限制。 另一方面，如果老化仅仅导致完整的非最佳使用， 学习机制，那么新的努力必须针对确定 如何最好地构建治疗以优化成年人的能力。 根据评估的模型，外国口音的出现是因为 双语者无法有效地分离他们的声音系统。 两种语言。该模型预测了在生产过程中的三个误差来源， L2声音：（l）与邻近L1声音的属性部分合并 在L2和L1声音持续联系的情况下 （2）不正确的特征规范，在这种情况下， L2使用与L1不同的特征或特征权重;以及（3） 当一个新的类别已经 形成了九个实验将检查意大利英语的表现 或主要根据年龄而不同的日英双语者 学习（AOL）英语。根据假设，错误类型的频率#l #2将随着AOL的增加而增加，而错误类型#3将减少 随着双语者的AOL的增加，三个实验建议 将定义L1中元音之间的声学和感知关系 和L2。另一项研究将评估双语者产生L1的准确性 和L2元音，并测试元音类别的形成， 英语使用分类辨别任务。其他实验将 使用类似的技术来检查生产和感知 辅音一个有趣的问题是， 产生的英语辅音没有发现在L1库存形成 英语辅音的类别，而双语者谁产生的 英语辅音不正确地没有为他们形成类别。两 剩下的实验将评估AOL和 双语者在感知英语元音时使用非母语特征， 辅音

It is widely believed that a critical period exists for second-language (L2) speech learning. However, the actual cause(s) of foreign accent remain uncertain. The research proposed here will evaluate a model that attempts to account for age-related changes in bilinguals' production and perception of vowels and consonants ("sounds") in their L2 and in their native language (L1). Segmental production errors in the L2 are important because they result in misunderstandings and/or slowed processing, and contribute to negative personal evaluations. A less obvious, but nevertheless serious consequence of L1 vs L2 phonological differences are segmental perception errors that contribute to difficulties in comprehending the L2. Such errors might arise from neurological changes that diminish the ability to add or modify sensorimotor programs, or prevent the formation of perceptual representations for sounds not found in the L1. Deter-mining the cause(s) of segmental production and perception errors is important clinically. For example, if they arise because of maturationally determined limits on neural plasticity or sensorimotor flexibility, then the benefit of foreign accent reduction therapy, or speech therapy for those who have suffered brain trauma, may be severely limited for individuals who have passed the critical period. On the other hand, if aging merely results in a non-optimal use of intact learning mechanisms, then renewed effort must be directed at determining how therapy can best be structured to optimize adults' capabilities. According to the model under evaluation, foreign accents arise because bilinguals are unable to separate effectively the sound systems of their two languages. The model predicts three sources of error in producing an L2 sound: (l) Partial merger with the properties of a neighboring L1 sound in instances where the L2 and L1 sounds persist in being linked perceptually; (2) Incorrect featural specification, in instances where the L2 uses different features or feature weights than the L1; and (3) Deflection away from a neighboring L1 sound when a new category has been formed. Nine experiments will examine the performance of Italian-English or Japanese-English bilinguals who differ primarily according to their age of learning (AOL) English. By hypothesis, the frequency of error types #l and #2 will increase as AOL increases whereas error type #3 will decrease in frequency as the bilinguals' AOL increases. Three proposed experiments will define the acoustic and perceptual relation between the vowels in L1 and L2. Another will assess the accuracy with which bilinguals produce L1 and L2 vowels, and test for the formation of categories for vowels in English using a categorical discrimination task. Other experiments will use similar techniques to examine the production and perception of consonants. One question of interest is whether bilinguals who correctly produced English consonants not found in the L1 inventory formed categories for the English consonants whereas bilinguals who produced the English consonants incorrectly did not form categories for them. The two remaining experiments will assess the relation between AOL and the bilinguals' use of non-L1 features in perceiving English vowels and consonants.