The use of a dual-task paradigm for assessing speech intelligibility in clients with Parkinson disease

Differences in the clinical and ecological manifestations of reduced intelligibility for individuals with dysarthria related to Parkinson disease (PD) have been reported in the literature. The current study explored whether a dual-task paradigm could be used during intelligibility testing to collect speech samples that were representative of functional performance. Intelligibility was calculated for four speakers with PD and four agematched controls (CG) based on single-word, sentences, and monologue tasks recorded in single- and dual-task conditions and a spontaneous speech sample. In the dual-task condition, speakers produced the target speech sample and performed a simultaneous motor task, turning a nut on a bolt. No significant differences in intelligibility were found for the CG. For speakers with PD, differences between conditions were statistically significant for all speech tasks. Intelligibility scores in the dual-task condition were lower, with variability between tasks and speakers noted. There was a significant difference between scores for the monologue in the single-task condition and the spontaneous sample; however, there was no significant difference between the monologue in the dual-task condition and the spontaneous sample. Findings suggest that including a simple motor task during a clinical assessment may help elicit speech samples that are representative of a speaker's typical speech production.