Rates of Typical Disfluency in the Conversational Speech of 30-Month-Old Spanish-English Simultaneous Bilinguals.

Purpose: The aim of this study was to investigate the typical disfluency rates at 30 months old in a large group of simultaneous bilingual children and also investigate the relationships between disfluency rates and linguistic complexity (mean length of utterance in words [MLU-W]), vocabulary diversity (VocD), and speaking rate (utterances per unit time). Method: Fifty-three typically developing children who had been exposed to Spanish and English from birth participated in this descriptive study. The average percent input at home was 46% in English and 54% in Spanish. Outside the home, the children averaged 9 hr of exposure per week in each language. Spontaneous speech samples in both languages were obtained during play sessions between the children and a parent. Results: Nonparametric tests revealed a significant difference in typical disfluency rates across languages, with more children being disfluent in English and with a larger range of disfluency rates in English. The effect size for this difference was small. The children had significantly higher MLU-W in English; there were no differences in VocD or speaking rate between the 2 languages. Typical disfluency rate in Spanish was not significantly correlated with MLU-W, VocD, or speaking rate. Typical disfluency rates in English were correlated with MLU-W and VocD, but not with speaking rate. Conclusion: This article described the typical disfluency rates of a large group of simultaneous Spanish-English bilingual children at 30 months of age. The typical disfluency rates reported here are lower than those reported in the literature for monolingual children of similar ages. Clinical implications of these findings are addressed.