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

Abstract

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 formant (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's productions of /ɹ/−/w/ in comparison 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 monolingual 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 ( R 2 = .37) and narrow transcriptions ( R 2 = .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 preschool children's mastery of the /ɹ/−/w/ contrast.