Comparison of Voice Quality in Persian Parkinson Patients With Healthy Counterparts Using Cepstral Peak Prominence and Cepstral Peak Prominence-Smooth and Their Relationship With Disease Severity (UPDRS-III) and Disease Duration.

Abstract

Introduction: One of the earliest impairments in Parkinson's patients is speech motor dysfunction, which adversely affects the phonation subsystem (voice). To date, acoustic frequency-dependent voice features such as cepstral peak prominence (CPP) and cepstral peak prominence-smooth (CPPS) have not been examined in Persian-speaking Parkinson's patients. This study aims to compare the voice quality of Persian Parkinson's patients with healthy counterparts using CPP and CPPS, as well as to investigate the relationship of these metrics with Unified Parkinson's Disease Rating Scale-Part III (UPDRS-III) and disease duration.

Method: This study included 35 Persian Parkinson's patients and 35 healthy individuals. Disease severity was assessed using UPDRS-III. Speech samples (sustained vowel phonation of /ɑ/ and reading of the "Grandfather Passage") were recorded by a microphone. CPP and CPPS were extracted by Praat software.

Results: The results showed that the mean CPP and CPPS in both tasks were significantly lower in the patient group compared with the healthy group (P value ≤ 0.001). Spearman correlation analysis of CPP and CPPS values in both tasks with disease severity revealed a significant negative correlation between CPP and CPPS and UPDRS-III in both tasks (P value ≤ 0.001). However, no significant correlation was observed between these indices and disease duration in any task (P value ≥ 0.001).

Conclusion: These cepstral indices effectively distinguish vocal differences between Persian Parkinson's patients and healthy individuals. Additionally, these indices show a significant association with disease severity, underscoring their potential utility in the early diagnosis and monitoring of Parkinson's disease progression through vocal screening, especially when combined with other medical and neurological evaluations. However, this study found no relationship between disease duration and these indices. The absence of such a correlation may be attributed to the medication regimens of the patients.