Two-part vowel modifications in Child Directed Speech in Warlpiri may enhance child attention to speech and scaffold noun acquisition

• Published in: Phonetica Vol. 80; no. 1-2; p. 1
• Main Authors: Bundgaard-Nielsen, Rikke L, O'Shannessy, Carmel, Wang, Yizhou, Nelson, Alice, Bartlett, Jessie, Davis, Vanessa
• Format: Journal Article
• Language: English
• Published: Germany 23-02-2023
• Subjects: Adult; Australia; Humans; Language; Phonetics; Speech; Speech Acoustics; Speech Perception; Australia; ADS; vowels; CDS; nouns; Warlpiri
• ISSN: 1423-0321
• DOI: 10.1515/phon-2022-0039

Study 1 compared vowels in Child Directed Speech (CDS; child ages 25-46 months) to vowels in Adult Directed Speech (ADS) in natural conversation in the Australian Indigenous language Warlpiri, which has three vowels (/i/, /a/, /u). Study 2 compared the vowels of the child interlocutors from Study 1 to caregiver ADS and CDS. Study 1 indicates that Warlpiri CDS vowels are characterised by fronting, /a/-lowering,
-raising, and increased duration, but not vowel space expansion. Vowels in CDS nouns, however, show increased between-contrast differentiation and reduced within-contrast variation, similar to what has been reported for other languages. We argue that this two-part CDS modification process serves a dual purpose: Vowel space shifting induces IDS/CDS that sounds more child-like, which may enhance child attention to speech, while increased between-contrast differentiation and reduced within-contrast variation in nouns may serve didactic purposes by providing high-quality information about lexical specifications. Study 2 indicates that Warlpiri CDS vowels are more like child vowels, providing indirect evidence that aspects of CDS may serve non-linguistic purposes simultaneously with other aspects serving linguistic-didactic purposes. The studies have novel implications for the way CDS vowel modifications are considered and highlight the necessity of naturalistic data collection, novel analyses, and typological diversity.