The Acquisition of Articulatory Timing for Liquids: Evidence From Child and Adult Speech

Formant dynamics in second language speech: Japanese speakers' production of English liquids

This article reports an acoustic study analysing the time-varying spectral properties of word-initial English liquids produced by 31 first-language (L1) Japanese and 14 L1 English speakers. While it is widely accepted that L1 Japanese speakers have difficulty in producing English /l/ and /ɹ/, the temporal characteristics of L2 English liquids are not well-understood, even in light of previous findings that English liquids show dynamic properties. In this study, the distance between the first and second formants (F2-F1) and the third formant (F3) are analysed dynamically over liquid-vowel intervals in three vowel contexts using generalised additive mixed models (GAMMs). The results demonstrate that L1 Japanese speakers produce word-initial English liquids with stronger vocalic coarticulation than L1 English speakers. L1 Japanese speakers may have difficulty in dissociating F2-F1 between the liquid and the vowel to a varying degree, depending on the vowel context, which could be related to perceptual factors. This article shows that dynamic information uncovers specific challenges that L1 Japanese speakers have in producing L2 English liquids accurately.

A Cross-Sectional Age Group Study of Coarticulatory Resistance: The Case of Late-Acquired Voiceless Fricatives in English

PURPOSE

As a class, fricatives are more "resistant" to consonant-vowel coarticulation than other English sounds. This study investigates the relative coarticulatory resistance of /θ, s, ʃ/ in child and adult speech to better understand the acquisition of individuated speech sounds.

METHOD

Ten 5-year-old children, seven 8-year-old children, and nine college-age adults produced [əFV] sequences in carrier phrases, where F was /θ/, /s/, or /ʃ/ and V was /æ/, /i/, or /u/. In Experiment 1, coarticulation was perceptually indexed: 65 adults predicted the target stressed vowel based on forward-gated audiovisual speech samples for a subset of four speakers from each age group. In Experiment 2, dynamic spectral measures of the /əFV/ sequences were analyzed using smoothing spline analysis of variance to again test for vowel effects on fricative articulation across age groups.

RESULTS

The perceptual results indicated that fricatives blocked vowel-vowel coarticulation across speaker age groups. Contrary to expectation, vowels were most accurately predicted when F was /s/ and not when it was /ʃ/ or /θ/ across age groups. Acoustic results indicated the expected biomechanically motivated /ʃ/ > /s/ > /θ/ coarticulatory resistance hierarchy in adults' speech. By contrast, /ʃ/ > /s/ were similarly influenced by context in 8-year-olds' speech, and the results from 5-year-olds' speech suggested an influence of order of acquisition in that /θ/ was surprisingly resistant to coarticulation.

CONCLUSION

The study results are taken to suggest that a temporal constraint on fricative articulation interacts with biomechanical constraints during development to influence patterns of coarticulation in school-age children's speech.