People with dysarthria due to Parkinson's disease (PD) frequently present with reduced intelligibility, which can have significant consequences, including reduced participation in situations involving communicating with others and resulting in social isolation.1-5 Few effective treatments exist to ease the intelligibility burden of dysarthria in PD, and most require significant cognitive and physical effort on the part of the speaker to achieve and maintain gains.6,7 Once people with PD have progressed beyond the early stages of the disease, and their cognitive and physical impairments limit their ability to use traditional speech therapy techniques, they are not realistic treatment candidates for current interventions; and no other interventions are available to support their communication. This is a serious and consequential gap in clinical care for people with PD. The current proposal addresses this critical gap by shifting the weight of behavioral change from the speaker to the listener, specifically key communication partners such as family. Indeed, for older adults, most of their time spent with others is spent with family members.8 Further, key partners of patients with PD wish to have a more significant and active role in communication rehabilitation.9,10 A listener-targeted remediation approach for intelligibility impairments in people with dysarthria and PD is firmly grounded in theoretical models of perceptual learning11-13 and rigorously supported by our decade-long research program targeting perceptual learning of dysarthric speech.14-30 To date, this line of investigation has chiefly targeted the theory of listener adaptation to the degraded signal; however, robust intelligibility improvements of up to 20 percent across studies have been observed.15 With a rigorous account of how and what listeners adapt to, we are ideally positioned to move this work from bench to bedside, establishing listener (i.e., perceptual) training as a clinical intervention to improve intelligibility in people with PD. Here, we establish the efficacy of listener training for patients with PD and their primary communication partners using a repeated-measures, randomized controlled trial (SA1). Immediate acquisition and retention of intelligibility improvements will be examined as a function of speaker severity. We then evaluate three theoretically and empirically-motivated communication benefits of listener training that extend beyond intelligibility, including listening effort, comprehension, and communicative participation (SA2). Finally, we engage stakeholder input to inform clinical implementation of listener training using qualitative semi-structured interviews (SA3) with patients with PD and their partners. This will provide insights into the effectiveness and feasibility of the intervention approach, ensuring that their needs and preferences are considered and that they feel empowered and motivated for a listener training approach. Thus, in three independent aims, this proposal will address a current void in our clinical toolbox, establishing a new realm of clinical practice in which communication challenges in PD are managed by training partners to better understand the degraded speech.
