Accounting for variability in North American English /ɹ/: Evidence from children's articulation

This acoustic and articulatory pilot study examines the North American English /ɹ/ productions of English-speaking children during acquisition, and compares their early- and later-stage productions with /ɹ/ allophony patterns reported in previous studies with adults. Ultrasound imaging is used to investigate the articulatory behavior of four children, aged 3-6 years, during production of familiar lexical items containing prevocalic, post-vocalic, and syllabic /ɹ/. Shape analysis of the tongue is conducted using a technique that is highly robust against rotational and translational differences from token to token. Participants exhibited behaviors that are consistent with adults' in previous studies, showing both intra- and inter-speaker variability, and similar patterns of allophony based on syllable position, consonant place of articulation, and vowel quality. For three participants, variable behavior occurred prevocalically, in contexts where adults tend to exhibit the greatest amount of allophonic variation. Variable behavior during acquisition of an articulatorily complex speech sound provides a plausible explanation for the variability that has been previously reported with adults. If a child's dominant strategy for reaching adult-like targets proves ineffective in certain contexts, that may motivate exploratory behavior that could lead to a stable alternative strategy in those contexts over time. Participants' later-stage productions mirror allophony patterns observed with adults in previous studies. The current research adds to the literature on children's articulatory behavior during acquisition, and to the body of accumulated knowledge on North American English /ɹ/.