Intra-participant variability in Parkinson's disease: An electropalatographic examination of articulation

Abstract

The articulation of individuals with dysarthria has traditionally been described as consistent. However, conflicting findings have resulted from research examining intra-participant variation in the articulation of individuals with Parkinson's disease (PD) and hypokinetic dysarthria. The current study used electropalatography (EPG) to examine the degree of intra-participant variation in both tongue-palate contact patterns and duration of contact in a group of speakers with PD and hypokinetic dysarthria including consonant imprecision (n = 8). The study also aimed to determine if ageing contributed to any articulatory instability observed. Therefore, two control groups were employed consisting of aged adult (n = 7) and young adult (n = 8) speakers respectively. Participants were asked to read aloud the phrase “I saw a CVC today” were C = /t/, /s/, and /l/ and V = /a/. Intra-participant variation in tongue-palate contact was measured using the absolute and relative variability indexes. Coefficients of variation of duration of tongue contact were employed to examine intra-participant variation in consonant duration. In contrast to the study hypotheses, similar levels of intra-participant variation were observed across the three groups. However, a trend towards increased intra-participant variation in consonant duration was noted in the group with PD. The results of the study suggest that, at least spatially, the articulatory errors of individuals with PD are consistent across repetitions. Research including increased participant numbers and individuals exhibiting greater severity of dysarthria is required to provide further understanding of intra-participant variation in consonant duration in PD.

Keywords:

• Variability
• hypokinetic dysarthria
• Parkinson's disease
• articulation
• electropalatography

Notes

1. Tarp: Short form of tarpaulin; Sarge: Short form of sergeant; Lark: A singing bird or a merry adventure/prank (colloquial).