Monotongação de ditongos decrescentes orais no português brasileiro: uma revisão sistemática da literatura/Monophthongization of Oral Falling Diphthongs in Brazilian Portuguese: a Systematic Literature Review

: Diphthongs are usually defined as a sequence of one vowel (a, e, i, o, u) and one semivowel (i, u) in the same syllable. However, diphthongs classified as falling, in which the semivowel follows the vowel, have variable realizations in Brazilian Portuguese. Words like peixe (fish) are realized as pexe [‘pe.ʃɪ], caixa (box) as caxa [‘ka.ʃə], cenoura (carrot), as cenora [se.’no.ɾə], results of monophthongization in which a diphthong is reduced into a monophthong. This phenomenon has already been extensively investigated in different dialectal regions from Brazil. Nevertheless, the fragmented nature of the studies turned out not to be considerably resourceful in order to build a comprehensive overview that may contribute to pedagogical applications, for example. In this text, we present an attempt to systematize the diphthongs that can be converted to monophthongs in Brazilian Portuguese and the constraints that constraints condition the application of the variable rule of monophthongization from an integrative systematic review. The target diphthongs of the phenomenon are, in a descending order of percentage of monophthongization: [oʊ̯], [eɪ̯], [aɪ̯], and [oɪ̯]. The monophthongization of [oʊ̯] is seen as a consolidated change in Brazilian Portuguese. The monophthongization of [eɪ̯] has internal constraints in relation to the following phonological context composed of palatal and tap consonants. The diphthong [aɪ̯] undergoes monophthongization in open syllable when followed by a palatal consonant; and in closed syllable when the final fricative is palatalized. The diphthong [oɪ̯] is monophtongized in closed syllables in specific lexical items, and also when the final fricative is palatalized. The results point to the fact that monophthongs have acoustic intermediate features between the preserved diphthong and the simple vowel.