An acoustic study of the centering diphthongs in the Rio de Janeiro variety of Brazilian Portuguese

Abstract

In this study, we offer an acoustic characterization of the occurrences of so-called centering diphthongs (CD) in the Rio de Janeiro variety of Brazilian Portuguese. We define CD as underlying monophthongs that surface as sequences of a vowel followed by a central semivowel (inglide). CD and plain monophthongs were manually segmented from a radio interview corpus, and their formant trajectories and duration were subsequently compared both visually and quantitatively, using the technique of the discrete cosine transform. Our results show that there are striking differences between these two types of vowels. The articulatory gestures involved in CD production are of greater magnitude in horizontal and vertical dimensions of the vowel space; they originate in a peripheral region and are directed towards the central region at varying heights. The duration of the CD is also longer than that of plain monophthongs, regardless of whether the environment is prosodically prominent. A distributional analysis shows that there is a preference for the occurrence of CD in prosodically prominent environments, as well as in the context of disfluencies. We suggest that this distributional bias may contribute to the emergence of a complementary distribution between plain monophthongs and CD. Finally, we suggest, based on Articulatory Phonology, that centering glides in PB can emerge as a result of imperfect synchrony between the tongue body and glottal gestures that gets enhanced in lengthening-inducing environment.

Keywords

• Português brasileiro
• Fala carioca
• Ditongo centralizante
• Fonética acústica