Doctoral Dissertation Research: The Phonological Permeability Hypothesis: The (In)stability of L2 Phonology as Evidenced By the Acquisition of a Third Language (L3)

在第二语言（L2）音系学中，有一个问题仍然没有得到解答，那就是所谓的母语成人的L2音系系统到底有多像母语。本论文项目测试了语音渗透假说（PPH），该假说预测，如果母语和看似成功的非母语语音系统在成年期以相同的方式习得，那么第三语言的加入将对这些系统产生同等的影响。或者，如果它们在大脑中的配置不同，那么随着第三语言熟练程度的提高，第三语言（L3）对第二语言的跨语言语音干扰将会更加迅速和普遍。研究L3语音系统对连续L2系统的跨语言影响，并与具有相同语言配对的同时双语者的母语系统进行比较，对于确定青春期前和青春期后语音系统之间可能存在的差异（或缺乏差异）至关重要，因为这与他们的心理构成有关。本研究将在两种类型的英语/西班牙语双语者之间绘制L3巴西葡萄牙语的语音习得图表，从最初的状态到完全沉浸的第一年：连续双语者，即母语为英语的人在年轻时达到接近母语的西班牙语水平，以及英语和西班牙语同时双语者。通过测试螺旋化（一种音段现象）和元音中和（一种由重音决定的音段现象，一种超音段现象）来分析语音层次的各个层次的现象。一项初步研究的证据支持PPH，因此提供了支持表征缺陷假说的初步音系证据，至少在音系领域，该假说声称成人语言习得并不涉及（全部）与儿童习得相同的生物学赋予的语言机制。本研究的结果将有助于当代关于成人二语习得和心智理论的争论。

One question that remains unanswered within Second Language (L2) phonology concerns just how native-like a so-called native-like adult L2 phonological system truly is. This dissertation project tests the Phonological Permeability Hypothesis (PPH), which predicts that if native and seemingly successful non-native phonological systems are acquired in the same manner in adulthood, then an addition of a third language will affect these systems equally. Alternatively, if they are configured differently in the mind, then the additive system will undergo much more rapid and pervasive cross-linguistic phonological interference from the Third Language (L3) on the L2 as proficiency in the L3 increases. Examining cross-linguistic effects of L3 phonological systems on a successive L2 system as compared to a native system of simultaneous bilinguals with the same language pairings is deemed crucial to determine possible differences (or lack thereof) between pre- and post-pubescent phonological systems as it relates to their mental constitutions. This study will chart the phonological acquisition of L3 Brazilian Portuguese from the initial state throughout the first year of complete immersion between two types of English/Spanish bilinguals: successive bilinguals, i.e., native speakers of English who attained near-native Spanish proficiency as young adults, and simultaneous bilingual speakers of English and Spanish. Analyses of phenomena at various levels of the phonological hierarchy will be made via the testing of spirantization (a segmental phenomena) and vowel neutralization (a segmental phenomena conditioned by stress, a suprasegmental phenomenon). Evidence from a pilot study supports the PPH, therefore providing initial phonological evidence in support of representational deficit hypotheses, at least in the domain of phonology, which claim that adult linguistic acquisition does not implicate (all of) the same biologically endowed linguistic mechanisms used in childhood acquisition. This results of this study will contribute to contemporary debates in adult second language acquisition and theory of mind.