Category formation and the role of spectral quality in the perception and production of English front vowels

This study aimed at comparing the perception and production of English front vowels by 17 proficient Brazilian speakers of English as a second language (L2) and 6 native speakers of American English. Towards this end, three experiments were carried out: (i) a production test measuring the first two formants of the participants' English front vowels, (ii) an oddity discrimination test investigating the formation of vowel categories, and (iii) a discrimination test with synthetic stimuli which assessed the participants' reliance on spectral quality when perceiving English vowels. The results of these experiments suggest a strong relationship between L2 vowel perception and production, since the vowel pairs which were produced with similar formant values by the Brazilian participants were also poorly discriminated in the two perception tests. In addition, the findings suggest that vowel perception might precede vowel production, as high rates on the discrimination of vowel pairs on both perception tests were a prerequisite for differentiating the same two vowels on the production test. Lastly, some Brazilian participants obtained native-like scores on the category formation test without manifesting native-like reliance on spectral quality, indicating that other acoustic cues, such as vowel duration, might be playing a role in their perception of English vowels.