Dual-task costs of clear and loud speech: Implications for talkers with Parkinson disease

Abstract

Decades of research suggest that the speech production adjustments associated with adopting a clearer or louder speaking style enhance speech intelligibility, making these speech styles a common talker-oriented strategy in speech production interventions for talkers with dysarthria secondary to Parkinson disease (PD). Recent data suggest that explicit instructions to speak louder or clearer than usual may increase the processing load and effort associated with speech production. Empirical data will be presented that demonstrate these higher-effort speech styles may require greater attentional resources than habitual or conversational speech. A group of neurotypical talkers performed a sentence repetition task using Habitual, Loud, and Clear speech styles in isolation and while performing a concurrent visuomotor tracking task. Lip and jaw kinematics, speech intensity, and accuracy on the visuomotor task were collected to quantify performance on each task. Group-level data suggest that when faced with the competing task demands of the visuomotor task, neurotypical talkers prioritized the articulatory and phonatory adjustments associated with Clear and Loud speech at the cost of secondary task performance. Case examples from talkers with hypokinetic dysarthria resulting from PD will also be examined to frame and discuss clinical implications and considerations.