Electronic Thesis and Dissertation Repository


Master of Science


Health and Rehabilitation Sciences


Scott G. Adams


This study investigated the effect of concurrent tasks on speech intensity in Parkinson’s disease (PD). Thirteen PD participants and twenty-two controls performed three tasks concurrent with a speech task. The speech task involved a repeated carrier phrase and a target word. The concurrent tasks involved math addition (cognitive), verb generation (linguistic), and manual visuomotor tracking (motor) at three levels of difficulty. All three concurrent tasks were associated with reduced speech intensity relative to the isolated speech task. The concurrent motor task was generally associated with the greatest reduction in speech intensity. Task performance measures were not significantly different for the concurrent and isolated tasks. PD participants demonstrated relatively worse performance on the linguistic task. The results of this study failed to support the energizing hypothesis. Instead, the results appear to support a cognitive/attention resource allocation hypothesis with regard to the effect of concurrent tasks on speech intensity regulation in PD.