Abstract
This paper investigates the production of English unstressed vowels by two groups of early (ESp) and late Spanish (LSp) bilinguals and a control group of native English (NE) monolinguals. Three acoustic measurements were obtained: duration and intensity ratios of unstressed to stressed vowels, normalized vowel formants and euclidean distances. Both groups of bilinguals showed significantly fewer differences in duration between stressed and unstressed vowels than the NE monolinguals. Intensity differences depended on whether the stress pattern of the target English words matched the stress pattern of their Spanish cognates. As for vowel quality, the early bilinguals reduced the unstressed vowels, which clustered around the midcenter area of the vowel space, in the same fashion as the NE monolinguals, suggesting that vowel reduction might be operating at the phonological level. However, the late bilinguals showed a context-dependent, phonetic-level pattern with vowels that were more peripheral in the vowel space.