Evaluation of Acoustic Voice Quality Index in Persian-Speaking Parkinson's Patients Compared to Healthy Controls and Its Association With Disease Severity Based on UPDRS-III and Dysarthria Severity.

Introduction: Parkinson's patients with dysarthria often suffer from multiple impairments in speech subsystems, including phonation. The Acoustic Voice Quality Index (AVQI) may be considered as a predictor of the onset and severity of Parkinson's disease.

Objective: Investigating the AVQI in Persian-speaking Parkinson's patients compared to healthy controls and its association with disease severity based on Unified Parkinson's Disease Rating Scale-Part III (UPDRS-III) and dysarthria severity.

Method: This is an epidemiological descriptive-analytical study with a sample size of 30 Parkinson's patients with hypokinetic dysarthria and 30 healthy controls. Disease severity was first assessed using the UPDRS-III, followed by speech sample recording (sustained vowel/a/phonation and reading of the text "grandfather") using a specialized microphone and dysarthria severity assessment. Finally, AVQI scores were extracted using the Praat software.

Results: An independent t test was used to compare mean AVQI between the healthy and patient groups. The mean voice quality index was higher in the patient group than in the healthy controls, and the difference between the two groups was significant (P value ≤ 0.001). Correlation analysis of AVQI with disease severity and dysarthria severity using Spearman's test showed that voice quality index was significantly positively correlated with disease severity (UPDRS-III) and dysarthria severity (P value ≤ 0.001).

Conclusion: The AVQI can differentiate between the presence of voice disorders in Persian-speaking Parkinson's patients with hypokinetic dysarthria and healthy controls. This index showed a positive correlation with Parkinson's disease severity and dysarthria severity in Persian. It is recommended that this correlation be investigated in other languages as well.