Objective: To examine how dysarthria resulting from Parkinson’s Disease (PD) affects lexical tone production in Cantonese-speaking patients and to evaluate the effects of medication

Background: Currently it is unclear how speech breakdown in PD dysarthria may interact with the properties of the language spoken by the patient (Pinto et al. 2017). Cantonese offers a unique chance to test this perspective, consider it being a tonal language with six contrastive tones that signal meaning differences. Given that monopitch is a hallmark feature of dysarthria in PD, how would lexical tone production be affected in PD patients speaking Cantonese? And how would medication affect this tone production?

Methods: The study used a group (patients vs. normal; 12 per group) x medication (on-med. vs. off-med.) design. Each participant read aloud 30 monosyllabic words that are tone minimal pairs contrasting in all the 6 tones, allowing us to study how lexical tone is realized and distorted at word level. Fundamental frequency (F0) was measured at 20 equidistant time points of the target syllables, to compare shapes of the pitch contours. Off and on medication data were taken. Functional data analyses were used to examine specific locations of significant differences in pairs of F0 curves (Chen et al. 2017).

Results: When PD patients produced various tones (Tones 1,3,4,5,6), their F0 plots were significantly different from the healthy controls, especially when they were “off-med”. Moreover, medication seemed to affect specifically the lower-pitch tones (Tones 4,5,6): F0 plots “on-med” were not significantly different from the controls, unlike the “off-med” condition. Further analyses will compare tonal space and incorporate perceptual evaluations.

Conclusions: There is significant differentiation between PD patients and healthy controls regarding F0 in Cantonese lexical tone production. Subject to further confirmation, dopaminergic medication may improve the production of certain lexical tones in PD patients.

References: Chen, Si, Caicai Zhang, Adam G. McCollum, and Ratree Wayland. (2017). Statistical Modelling of Phonetic and Phonologised Perturbation Effects in Tonal and Non-Tonal Languages. Speech Communication 88 (April): 17-38. doi: 10.1016/j.specom.2017.01.006. Pinto, S., Chan, A., Guimarães, I., Rothe-Neves, R. & Sadat, J. (2017). A cross-linguistic perspective to the study of dysarthria in Parkinson’s disease. Journal of Phonetics. Vol. 64, pp. 156-167. https://doi.org/10.1016/j.wocn.2017.01.009.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/effect-of-medication-on-lexical-tone-production-in-cantonese-patients-with-parkinsons-disease/