Abstract
Background: Phonatory onset is important for speech and voice and may be substantially impaired in people with Parkinson's Disease (PD). However, the physiologic contributions of laryngeal and respiratory control to phonatory onset in PD are not well understood. Acoustic measurement of phonatory onset in neurological disease has been limited due to the confounding effects of dysarthria and the limited yield of physiologic detail. Objective: The purpose of this study was to test whether air flow measures would be useful to characterize respiratory and laryngeal contributions to phonatory onset, whether acoustic and air flow measures of phonatory onset were aberrant in PD, and whether deficits were significantly associated with voice severity. Methods: Twenty-one PD participants were tested and compared with 25 healthy controls. Testing included acoustic and air flow measures of phonatory onset during syllable production ([pa]) and measures of voice severity. Results: Air flow assessment was possible for all participants; acoustic assessment was only possible for 86% of PD participants. Air flow and acoustic measures revealed shorter phonatory onset times for PD participants than controls. Air flow measures also revealed that PD participants expelled less lung air volume per syllable. Aberrant timing of phonatory onset and reduced lung air volume were associated with increased voice severity. Conclusions: These findings suggest that air flow measures may be useful to assess the laryngeal and respiratory contributions to phonatory onset. These results also suggest that both respiratory and laryngeal control deficits may contribute to phonatory errors in PD, and that phonatory onset deficits are associated with voice severity.