Tone sequencing performance in children with childhood apraxia of speech: Acoustic analyses

Pitch (fundamental frequency f0) has recently been proposed as a measure to differentially diagnose childhood apraxia of speech (CAS) in Cantonese-speaking children (Wong et al., 2021). This study addresses the limitations of previous studies and aims to examine f0 changes within tone-syllables and also the effects of syllable structure, lexical status, and syllable position on pitch variation in Cantonese-speaking preschool children with and without CAS. Ninety-seven Cantonese-speaking children participated in this study and were assigned to four groups based on assessment results, including CAS, non-CAS speech sound disorder only (SSD), non-CAS speech and language disorder (S&LD), and typical speech-language development (TD) groups. All of the participants performed the Tone Sequencing Task (TST), which required five repetitions of monosyllabic and trisyllabic items. Growth curve analysis (Mirman, 2014) was employed to model f0 within syllables with three Cantonese tones (high-level, high-rising, and low-falling). Within- and between-group comparisons were conducted to examine the effects of syllable structure (V versus CV), lexical status (word versus non-word), and syllable position (initial, medial, and final) on f0. Within each group, the effects of syllable structure and position on f0 were found with different patterns. Between-group comparisons showed that the CAS group had reduced tone contrast. The CAS group could be differentiated from the control groups based on interactions of tone with syllable structure and position, but not lexical status. The dissimilarity detected between the CAS and SSD/TD groups was more prominent than that observed between the CAS and S&LD group. Cantonese-speaking children with CAS had reduced tone contrasts, suggesting a possible method for differential diagnosis. A distinct approach to analyzing pitch production in children with and without CAS was suggested. Future development of an objective measure for CAS identification is recommended.