Acoustic Analyses of Tone Productions in Sequencing Contexts Among Cantonese-Speaking Preschool Children With and Without Childhood Apraxia of Speech

PURPOSE: Pitch variations (tone productions) have been reported as a measure to differentiate Cantonese-speaking children with and without childhood apraxia of speech (CAS). This study aims to examine fundamental frequency (F0) changes within syllables and the effects of syllable structure, lexical status, and syllable positions on F0 in Cantonese-speaking preschool children with and without CAS. METHOD: Six children with CAS, six children with non-CAS speech sound disorder plus language disorder (S&LD), 22 children with speech sound disorder only (SSD), and 63 children with typical speech-language development (TD) performed the tone sequencing task (TST). Growth curve analysis was employed to analyze and compare the F0 values within syllables with three Cantonese tones (high level, high rising, and low falling). The analysis considered the effects of syllable structure (vowel and consonant-vowel), lexical status (word and nonword), and syllable position (initial, medial, and final) on F0, as well as comparisons within and between groups. RESULTS: Within each group, the effects of syllable structure and position on F0 values were found with different patterns. Between-group comparisons showed that the CAS group had reduced F0 contrasts. The CAS group could be differentiated from the control groups based on interactions of F0 with syllable structure and position, but not lexical status. The dissimilarity of F0 values detected between the CAS and SSD/TD groups was more prominent than that observed between the CAS and S&LD groups. CONCLUSIONS: This study demonstrated that Cantonese-speaking children with CAS had difficulty in varying F0 within syllables as compared to those without CAS, suggesting pitch variation difficulty and language-specific impairment profiles in CAS. Future investigations of objective measures for identifying Cantonese speakers with CAS and cross-linguistic investigations using growth curve analysis and the TST are suggested.