Phonetic and phonological vowel reduction in Brazilian Portuguese

The present study examines the phonetic and phonological status of vowel reduction in Brazilian Portuguese. In order to compare the effects of duration and metrical structure, we tested the influence of duration on the realization of /a/ in five prosodic positions: word-initial pretonic, word-medial pretonic, tonic, word-medial posttonic, and word-final posttonic. The results revealed that, while both phonetic duration and prosodic position had effects on F1 values for /a/, the categorical effect of prosodic position was much stronger and more reliable. In particular, F1 values for /a/ were best predicted by a two-way distinction between posttonic and non-posttonic syllable positions. Correlations between a vowel's duration and its F1 frequency were statistically significant but generally weak in all positions. We argue that these findings suggest that vowel reduction in Brazilian Portuguese primarily reflects phonological patterning rather than phonetic undershoot, although there was also evidence for some amount of undershoot. Brazilian Portuguese can therefore be said to have a mixed system of phonological and phonetic reduction. The present study discusses the results in the context of Brazilian Portuguese metrical organization, sound change, and the relation between phonetics and phonology.