Vowel variability and dispersion in Brazilian Portuguese and British English: a case study¹

This paper aims at studying the effect of vowel inventory size on acoustic vowel space in languages with different size inventories: Portuguese with seven oral vowels and English with eleven. Based on Dispersion Theory, this study analyzes acoustically vowel variability and dispersion in those two languages. Contrary to the theoretical predictions, in our data, the phonetic realization of English vowels is less precise and presents greater variability than those of the smaller system (Portuguese). As for vowel dispersion and acoustic space area, contrary to predictions, our Portuguese vowels are more dispersed, occupying more extreme positions in the vowel space, covering a greater acoustic area than those of English. Our results are aligned to other research that fails to find empirical proof for the predictions proposed by Dispersion Theory. We advance another interpretation for the facts. We hypothesize that the vowel systems of English and Portuguese are somehow unstable now; however, Dispersion Theory fails to capture such facts as it is based on categorical phonemes disregarding variable allophones. Probably, a theoretical approach that takes languages as dynamic and complex systems (ELLIS; LARSEN-FREEMAN, 2009) could offer stronger evidence to understand these facts. Such approach will be undertaken in the future.

Vowel variability; Vowel dispersion; Acoustic analysis