Acoustic and aerodynamic characteristics of nasal diphthongs in Brazilian Portuguese

Abstract

Previous studies describe acoustic and aerodynamic aspects of nasalized vowels in Brazilian Portuguese. However, there are few studies characterizing nasal diphthongs in this language. The aim of this work is to analyze acoustic and aerodynamic characteristics of nasal diphthongs of Brazilian Portuguese spoken in the city of São Paulo. We compared oral and nasal diphthongs to identify the main features of these sounds and to understand the timing of velum movements. Our data was recorded with the Portable EVA 2 workstation. The corpus of this experiment was made of ten oral and ten nasal diphthongs, with back and front glides at the end: /aw/ and /ej/; /ãw̃/ and /ẽj̃/. Words were inserted in the following sentence [i.gʊ___kadɐ iɐ] and [i.gʊ___todʊ iɐ]. The first phrase was repeated three times with six subjects and the second with three subjects. The corpus was analyzed with the Signal Explorer and Phonédit Softwares. The aerodynamic parameters analyzed were duration, peak and volume of nasal airflow. The acoustic parameters analyzed were formants patterns and FFT spectrum. Aerodynamic and acoustic data show that in nasalized diphthongs, the nasalized vowel is followed by a nasal glide and a short nasal appendix. The peak of nasal airflow at the end of the nasal diphthong is due to the fact that the oral closure, which is made for the following voiceless stop, is produced with an open velum.