| dc.description.abstract | Talkers with Parkinson’s disease (PD) exhibit a wide variety of perceptual speech patterns. Although heterogeneity of dysarthria manifestation across talkers with PD has long been acknowledged, they are still poorly understood. The current dissertation aims to better understand the heterogeneity of dysarthria in PD by 1) identifying and characterizing dysarthria subgroups within a large cohort of talkers with PD using an auditory free classification task paradigm and 2) investigating variable effects of loud, clear, and slow speech cues on perceptual outcome measures in talkers with PD. The results of the first study showed that listeners distinguished six identified subgroups based on perceived differences in dysarthria severity and various perceptual speech features that contributed to perceived dysarthria severity (i.e., imprecise consonants, increased rate in segments, harsh and hoarse voice qualities), as well as three specific perceptual speech characteristics (i.e., irregular articulatory breakdowns, fast rate, strained-strangled voice). The second study’s findings revealed multiple distinct response patterns based on changes in speech intelligibility and perceived dysarthria severity and demonstrated that regardless of the outcome measure, more talkers with PD responded positively to clear and loud than slow speech cues. In addition, the presence or absence of specific speech characteristics (i.e., monopitch/reduced stress, hyponasality/loudness decay, and strained-strangled voice) at baseline during the habitual speech condition differentiated responders from non-responders. Study outcomes can facilitate improved research designs of future investigations (e.g., recruitment of more homogeneous samples) and set the stage for personalized dysarthria management of talkers with PD. | |
