Patterns of vowel modification in mother–child speech

ABSTRACT Patterns of vowel articulation in conversational speech to an adult and to child listeners were analysed in the speech of nine mothers. Formant frequency analysis of vowels embedded in 2,406 words found in varying syntactic environments and uttered by women to pre-verbal, holophrastic and more advanced child listeners (MLUs 2·5–4·0) revealed an emerging pattern of content word clarification, as measured by wider dispersion and decreased overlap between vowel phoneme categories in formant characteristics. Additionally, function word clarification was noted in speech to the oldest children. Vowel production appears to be modulated by child–addressee language ability. Earlier studies suggesting a lack of phonetic clarification in mother–child speech may have investigated speech to children too mature to elicit maternal clarification behaviours.