Pitch Variation Skills in Cantonese Speakers With Apraxia of Speech After Stroke: Preliminary Findings of Acoustic Analyses

Abstract

Purpose: Literature on apraxia of speech (AOS) in Chinese speakers is sparse compared to the English literature. This study aims to examine the pitch variation skills of Cantonese adults with AOS poststroke in terms of perceptual tone accuracy, acoustic fundamental frequency ( f o ) changes, and repetition durations on items with different syllable structures, lexical status, and tone syllables in various positions in a sequencing context. Method: Six Cantonese adults with AOS poststroke (AOS group), six adults without AOS poststroke (nAOS group), and six healthy controls (HC group) performed the tone sequencing task (TST), which was adapted from oral diadochokinetic tasks, with three different tone syllables. Tone accuracy, f o values across 10 time points, and acoustic repetition durations were compared within and between the groups. Results: The AOS group produced significantly lower tone accuracy and different f o changes on the three Cantonese tone syllables compared with the control groups and significantly longer repetition durations than the HC group. The AOS group showed more difficulty with the tone syllables with the consonant–vowel structure, while a priming effect was observed on the T2 (high-rising) syllables with lexical meanings. A unique lowering of f o in the final syllable of the trisyllabic items was observed only in the AOS group. Conclusions: The AOS group showed degraded pitch variation skills. The effects of the three linguistic elements were discussed. Future investigations are called for to adapt the TST in other tonal languages to determine if degraded pitch variation skills are present in other tonal language speakers with AOS.