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回答，那就是第二语言(L2)音系到底有多本土化--就像所谓的母语样的成人音系学一样。本论文对语音渗透率假说(PPH)进行了检验，该假说认为，如果成年期以同样的方式习得母语和看似成功的非母语语音系统，那么第三种语言的加入将同样影响这些语音系统。或者，如果它们在头脑中的配置不同，那么随着对L3熟练程度的提高，加法系统将受到来自第三语言(L3)的更快、更普遍的跨语言语音干扰。为了确定青春期前和青春期后的语音系统之间可能的差异(或缺乏差异)，与具有相同语言配对的同时双语者的母语系统进行比较，研究L3语音系统对连续的L2系统的跨语言影响被认为是至关重要的，因为这与他们的心理结构有关。这项研究将绘制在两种类型的英语/西班牙语双语者之间完全浸入的第一年中，从最初的状态开始，巴西葡萄牙语在语音上的习得情况：连续的双语者，即年轻时达到接近母语西班牙语水平的英语母语者，以及同时使用英语和西班牙语的双语者。对音系不同层次的现象的分析将通过螺旋化(一种音段现象)和元音中和(一种受重音制约的音段现象，一种超音段现象)来进行。来自先导研究的证据支持PPH，因此提供了初步的音系学证据来支持表征缺陷假说，至少在音系学领域，该假说声称成人语言习得并不涉及儿童习得中使用的(全部)生物天赋的语言机制。这一研究结果将有助于当代成人第二语言习得和心理理论的争论。

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.