Speaking rate effects on stops produced by Spanish and English monolinguals and Spanish/English bilinguals

Four groups of 10 subjects each (English and Spanish monolinguals, and two groups of Spanish/English bilinguals) produced Spanish or English sentences at speaking rates designated 'normal', 'slow', and 'fast'. Voice onset time (VOT) was measured in word-initial tokens of /p/ and /t/ found in sentence-initial, -medial, and -final words. The four groups produced comparable changes in sentence duration across the three rates. The speaking rate changes exerted less effect on the VOT in stops spoken by the Spanish than the English monolinguals. Moreover, whereas English monolinguals produced /p,t/ (with shorter VOT at a fast than at a normal rate, many Spanish monolinguals showed a trend in the opposite direction. As expected, all 10 early bilinguals produced English stops with VOT values that were similar to the English monolinguals'. They also showed speaking rate effects on VOT that were similar to those observed for the English monolinguals. The late bilinguals, who had begun learning English as adults, showed smaller effects of speaking rate on VOT than did the English monolinguals. Their mean VOT values for English stops spanned a wide range of values. Just 3 of the late bilinguals produced English stops with VOT values that fell within the range of values observed for the English monolinguals.