Voice source differences in Brazilian Portuguese vowels for application in singing studies

Abstract

Research Question/Problem
The motivation for the study is the lack of research that accounts for the interplay between vowel quality and stress in the acoustic parameters of the modal voice. Several questions related to voice quality (Laver, 1980) will be addressed here, but the two main questions are: Are the f0 values of Brazilian Portuguese correlated with vowel quality? Do the BP stressed vowels have different voice quality values from their unstressed counterparts? Some previous studies shed some light to answer these questions (Leung et al., 2016, Hanson et al., 2001).
Objectives
This study aims to obtain results of spectral differences on spoken vowels in order to provide a future basis of qualitative and quantitative analysis of voice qualities produced by singers in the songs “Como nossos pais” (Belchior) and “Man in the box” (Alice in Chains).
Method
This study compares the spectral parameters of 10 spoken vowels in Brazilian Portuguese in terms of vowel quality and stress. Four Brazilian Portuguese subjects read with modal voice the Brazilian Portuguese version of “The NorthWind and the Sun”, a standard text used to illustrate phonetic differences among languages. Thirteen voice quality parameters were automatically extracted using the VoiceSauce software (Shue, 2010). All statistical analyses were run in R Studio (1.0.153).
Results
Our results have shown that: a) low vowels had smaller f0 values than high vowels; b) stressed vowels had higher values of CPP, Energy, and HNR than unstressed vowels; c) stressed vowels had higher values of F1 and F2; and d) the F1 bandwidth of unstressed vowels was higher than stressed vowels. In contrast, the parameters H1*, H1*H2*, H1*A3* did not show a clear distinction pattern between stressed and unstressed vowels, suggesting that we should control f0 and intensity in future studies, in order to observe the effects of these parameters in vowel quality.
Conclusions and Implications
Our findings indicate that different vowel qualities and stress may influence spectral parameters of modal voice. Among the benefits of this research we emphasize that knowing with accuracy the different voice qualities has an important role on the fundamentals for singers, singing teachers and voice coaches. We argue that the awareness of phonation mode by voice professionals will lead them to a better vocal performance.
Keywords (3 to 5 descriptors)
voice quality, vowels, speech register, phonation mode
References
Hanson, H. M., Stevens, K. N., Kuo, H.-K. J., Chen, M. Y. and Slifka, J. (2001). “Towards models of phonation,” Journal of Phonetics, vol. 29, pp. 451–480.
Laver, J. (1980). The phonetic description of voice quality. Cambridge: Cambridge University Press.
Leung, K. K. W, Jongman, A., Wang, Y. and Sereno, J. A. (2016). “Acoustic characteristics of clearly spoken English tense and lax vowels,” JASA, vol. 140(45), pp. 45–58.
Y.-L. Shue, (2010). The Voice Source in Speech Production: Data, Analysis and Models. PhD Thesis. Los Angeles: UCLA.