Changes in Temporal and Articulatory Speech Characteristics in Parkinson’s Disease Patients: A Comparison of Performance in the Early and Late Phases of Paragraphs

Objectives: To investigate the characteristics of hypokinetic dysarthria in Parkinson’s disease (PD), we compared and analyzed changes in temporal and articulatory speech characteristics occurring during the early and late phases of a paragraph reading task.Methods: Twenty PD patients at Hoehn and Yahr stage 2 and 20 age- and gender-matched healthy elderly adults (HE) performed a paragraph reading task. The entire paragraph was divided into early and late sections. Temporal indicators (reading rate, articulation rate, pause ratio, pause frequency) and articulatory indicators (consonant accuracy, speech intelligibility) were calculated. Mixed ANOVA was used to verify differences between groups and phases.Results: The PD group exhibited significantly slower reading and articulation rates compared to the HE group. The PD group exhibited a significant increase in pause frequency toward the late phase, which can be interpreted as a result of worsening under-articulation due to motor fatigue from sustained speech production. Furthermore, while the HE group showed no difference in consonant accuracy between phases, the PD group demonstrated a significant decrease in consonant accuracy in the late phase.Conclusion: PD patients exhibited a characteristic decline in reading endurance, marked by increased pausing frequency and reduced consonant accuracy toward the end of paragraphs. This suggests that the reduced communication efficiency in PD patients stems from deficits in the motor maintenance ability required to sustain speech accuracy. Therefore, clinical practice should emphasize dynamic assessment observing performance changes based on fatigue levels and intervention approaches aimed at improving speech endurance.