Articulatory kinematics during atypical stop productions in Parkinson’s disease

Background: People with Parkinson’s disease (PD) often produce more atypical stop consonant productions (with either absent or multiple bursts) compared to their healthy control counterparts. However, the physiological underpinnings of these productions are not well understood. Therefore, the primary aim of this study was to examine the articulatory correlates of atypical stop consonant production in speakers with PD. Methods: A total of 30 speakers with PD read a passage in their typical speaking voice while electromagnetic articulography sensors tracked lip and tongue movement. The number of bursts and classification of stop types (prototypical, absent, and multiple bursts) were determined by trained research assistants based on the speech acoustics. The number of articulatory releases and the magnitude of release were determined from the tracings of the lip and alveolar apertures. Generalized mixed-effects models were used to determine whether the number of articulatory releases significantly differed between prototypical and atypical stop productions. Linear mixed-effects models were used to determine whether the magnitude of release was significantly different between prototypical and atypical stop productions. Results: There were no significant differences in the number or magnitudes of articulatory releases between prototypical stop productions and atypical productions (e.g., absent and multiple burst productions). Conclusions: These results do not support that articulatory kinematics are the driving force behind these atypical stop productions in PD. Future research should investigate the influence of other speech subsystems on these productions.