Foreign language accent perception of Brazilian Portuguese and second language acquisition of oral and nasal vowels

Abstract

Although contextual nasalization is a common phenomenon in the world’s languages, contrastive nasal vowels are less common. The pronunciation of contrastive nasal vowels in Portuguese is a challenge for adult language learners. This study examines Brazilian Portuguese (BP) oral and nasal vowels through acoustic analysis of native speakers (NSs) and nonnative speakers (NNSs) and accent perception by BP NSs. In a production experiment, 11 NSs, 13 inexperienced NNSs, and nine experienced NNSs of BP were recorded in an elicited imitation task with tokens containing [a i u ɐ̃ ĩ ũ] in syllables bearing primary stress. These disyllabic tokens, recorded in carrier phrases, contain target vowels in syllables bearing stress in ultimate or penultimate position. Segment duration, intensity, F1, F2, and F3 of each target vowel were measured using Praat. Statistical analyses determined which acoustic characteristics were most significantly different among the three groups of participants. These most significantly different acoustic cues were vowel height of [a] and [ɐ̃], vowel advancement of [u], and duration of word-final [i] and [u]. In an accent perception experiment, 20 BP NSs assigned accent ratings to the previously recorded tokens in carrier phrases. Statistical analyses of the accent ratings showed that level of experience with BP as a foreign language correlated with higher accent ratings (i.e., more nativelike). In a comparison of accent ratings and acoustic characteristics of vowel segments, shorter segments correlated with higher accent ratings for four of the six vowels. Furthermore, acoustic cues suggesting a lower articulation for [a], a higher articulation for [ɐ̃], and a more anterior (less fronted) articulation for [u] correlated with higher accent ratings. The comparisons among the two levels of NNS groups and the NS group suggest that more time spent learning BP tends to improve vowel segment pronunciation and accentedness. These findings add to existing research on second language acquisition and BP phonetics and phonology. Also, some practical pedagogical implications for the teaching of pronunciation of Portuguese as a foreign language emerge from the results.