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.

中文翻译：

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双语婴儿出生后第一年的输入质量和语音感知发展

婴儿原生语音发育的个体差异与婴儿定向语音 (IDS) 的数量和质量有关。调查了 131 名 5 个月和 9 个月大的单语和双语西班牙语和巴斯克婴儿（72 名男性；59 名女性；来自白人中产阶级背景）的父母和婴儿双语对这种关系的影响。双语不影响婴儿母语和非母语语音感知的发展轨迹和母语的质量。在两个语言组中，IDS 中的元音夸张与 9 个月大的语言感知技能显着相关（r = −.30)，但不适用于 5 个月大的婴儿。这表明双语和单语照顾者为他们的婴儿提供语音输入，帮助他们学习一种或两种语言的语音清单。