L2 and L3 Acquisition of the Portuguese Stressed Vowel Inventory by Native Speakers of English

摘要

This dissertation explores the potential differences in the acquisition of the sound system of a second language (L2) versus a third language (L3), building on recent research on adult L2 speech learning and testing the hypothesis that new category acquisition is available across the lifespan. On the one hand, recent influential theories of L2 speech learning predict that new sound categories will be difficult to acquire due to complex interactions among the phonetic categories residing in one same perceptual space. On the other, there exists the common assumption that the more sound categories one’s native language contains, the less difficult it will be to acquire new ones in a native-like fashion. My work provides additional evidence to this discussion, while providing speech data from the following five different speaker groups: (1) native speakers of American English; (2) native speakers of Mexican Spanish; (3) native speakers of Brazilian Portuguese; (4) native speakers of English learning Portuguese as their L2, and (5) native speakers of English learning Portuguese as their L3, who speak Spanish as their L2.The dissertation consists of three content chapters. The first of the content chapters describes the vowel systems of Mexican Spanish, American English and Brazilian Portuguese as informed by production data of the three native speaker groups above (1, 2 and 3). The second and third chapters describe and contrast the vowel system(s) of the two learner groups (4 and 5) as informed by their production and perception of Portuguese vowels respectively. The results from the analysis of the data from the various production and perception experiments performed as part of this dissertation provide evidence for (a) phonetic category assimilation and dissimilation processes in post-L1 speech learning and phonetic category interactions in general; (b) the relevance of quality and quantity of input in language learning; (c) the discussion on the relation between perception and production in post-L1 speech learning; and (d) the need for an extension of current models of L2 speech learning and cross-linguistic speech perception in order for these to address post-L2 speech learning processes, among other topics.