Input quality and speech perception development in bilingual infants' first year of life

Individual differences in infants' native phonological development have been linked to the quantity and quality of infant-directed speech (IDS). The effects of parental and infant bilingualism on this relation in 131 five- and nine-month-old monolingual and bilingual Spanish and Basque infants (72 male; 59 female; from white middle-class background) were investigated. Bilingualism did not affect the developmental trajectory of infants' native and non-native speech perception and the quality of maternal speech. In both language groups, vowel exaggeration in IDS was significantly related to speech perception skills for 9-month-olds (r = -.30), but not for 5-month-olds. This demonstrates that bilingual and monolingual caregivers provide their infants with speech input that assists their task of learning the phonological inventory of one or two languages.

Automated summary

In this study, the influence of parental and infant bilingualism on infants' speech perception skills was investigated, and it was found that bilingualism did not affect the developmental trajectory of infants' native and non-native speech perception. However, vowel exaggeration in IDS was significantly related to speech perception skills for older infants.