Relating Acoustic Measures to Listener Ratings of Children’s Productions of Word-Initial /ɹ/ and /w/

Purpose: The /ɹ/ productions of young children acquiring American English are highly variable and often inaccurate, with [w] as the most common substitution error. One acoustic indicator of the goodness of children’s/ɹ/ productions is the difference between the frequency of the second formant (F2) and the third for-mant (F3), with a smaller F3–F2 difference being associated with a perceptually more adultlike /ɹ/. This study analyzed the effectiveness of automatically extracted F3–F2 differences in characterizing young children’sproductions of /ɹ/−/w/ in com-parison with manually coded measurements. Method: Automated F3–F2 differences were extracted from productions of a variety of different /ɹ/-and /w/-initial words spoken by 3-to 4-year-old monolin-gual preschoolers (N = 117; 2,278 tokens in total). These automated measures were compared to ratings of the phoneme goodness of children’s productions as rated by untrained adult listeners (n = 132) on a visual analog scale, as well as to narrow transcriptions of the production into four categories: [ɹ], [w], and two intermediate categories. Results: Data visualizations show a weak relationship between automated F3– F2 differences with listener ratings and narrow transcriptions. Mixed-effects models suggest the automated F3–F2 difference only modestly predicts listener ratings (R2 =.37) and narrow transcriptions (R2 =.32). Conclusion: The weak relationship between automated F3–F2 difference and both listener ratings and narrow transcriptions suggests that these automated acoustic measures are of questionable reliability and utility in assessing pre-school children’s mastery of the /ɹ/−/w/ contrast.