An acoustic study of plosives production in Cantonese speakers with Parkinson's disease

Articulatory impairment, including consonant imprecision, has been widely studied in patients with Parkinson's disease (PD). However, acoustic investigation of articulatory impairment in Cantonese speakers with PD has been limited. The purpose of this study was to investigate the acoustic characteristics of plosives production in Cantonese speakers with PD. The participants comprised 17 Cantonese speakers with PD and 17 age- and gender-matched healthy controls (HC). Six Cantonese plosives /p, ph, t, th, k, kh/ followed by the vowel /a/ were produced at high-level tone (T1) in the context of word and sentence. All speech samples produced by PD patients were further divided into two subgroups: normal plosive production (PD-NP) and spirantized plosive production (PD-SP). Higher intensity ratio, shorter VOT and shorter closure duration during plosive production were found in both PD-NP and PD-SP subgroups when compared to the HC group. In addition, aspiration and context did affect the intensity ratio, VOT and closure duration while place of articulation only affected the VOT. Furthermore, it was found that the most commonly misarticulated plosives in Cantonese speakers with PD were bilabial stops, followed by alveolar and velar stops. This finding of spirantization of plosives is in agreement with previous studies.