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.
