Perceptual Characterization of Voice Quality in Non-Advanced Stages of Parkinson’s Disease

Introduction: Parkinson’s disease is a neurodegenerative disorder that impacts motor and nonmotor systems, and consequently influences voice. In later stages of the disease, people with Parkinson’s disease develop salient hypokinetic dysarthria. However, it is unclear how extensive the voice impairment is in the non-advanced stages of Parkinson’s disease. Therefore, the aim of the current research was to investigate the auditory-perceptual characteristics of voice in people with Parkinson’s disease (PWPD) in non-advanced stages.

Methods: 29 PWPD and 32 healthy older controls were recruited. For each participant, a recording of the sentence “We were away a year ago” was acquired. These recordings were evaluated by two licensed and experienced speech-language pathologists, who provided perceptual ratings of overall dysphonia severity, breathiness, roughness, and perceived age.

Results: MANCOVA analysis showed that, when controlling for age and intensity, there was a significant effect of group (p=0.001) on perceptual voice quality. PWPD were perceived to be significantly older, more breathy and more severely dysphonic than the older healthy controls. No differences were found for the perceived roughness.

Conclusions: The results suggest that features of hypokinetic dysarthria in voice, specifically breathiness, are present in non-advanced stages of PWPD and may contribute to listener perceptions of speaker age. Moreover, the perceptual voice profiles in PWPD showed great variability, possibly reflecting the heterogeneity of disease impact on individuals. The results of this study may inform how research targets rehabilitation and maintenance of voice and laryngeal function in PWPD, specifically those at non-advanced stages.