Phonetic realization of vowel reduction in Brazilian Portuguese

This study explored the phonetic realization of vowel reduction in Brazilian Portuguese, which reportedly exhibits raising of non-high vowels in unstressed syllables. Specifically, we tested the influence of speech rate on the realization of /a/ in five prosodic positions: word-initial pretonic, medial pretonic, tonic, medial posttonic, and final posttonic. The results showed that, while both speech rate and prosodic position had a clear effect on the phonetic duration of vowels, F1 values were far better predicted by the vowel’s prosodic position (non-posttonic vs. posttonic), although some effects of speech on F1 were observed in vowels at word edges. Correlations between phonetic duration and F1 were statistically significant but generally weak in all positions. We argue these findings suggest that vowel reduction in Brazilian Portuguese primarily reflects phonological patterning rather than phonetic undershoot, although phonetic reduction is also apparent. We discuss the results in the context of cross-linguistic studies of vowel reduction, and the relation between phonetics and phonology.