The proposed research aims to investigate the use of speech amplification devices as a potential treatment option for people with Parkinson's disease and related disorders who exhibit hypophonia, a voice disorder that affects over half of those with Parkinson's disease. By characterizing the acoustic and perceptual effects of speech amplification and identifying ways to optimize outcomes through talker- and device-specific enhancements, this project seeks to develop personalized, evidence-based treatment options for hypophonia. The current proposal will move this effort forward by systematically eliciting and modifying speech amplification device output that leverage both behavioral and technological approaches.

Though intensive behavioral speech intervention is considered the "gold standard" for treating hypophonia in Parkinson's disease (PD), many individuals struggle to transfer or maintain these behavioral strategies into their daily communication. This is because PD, affecting over six million people worldwide, is a progressive, neurodegenerative disorder that also impairs cognition, sensorimotor integration, and fatigue. Speech amplification devices are a type of augmentative technology that have been shown to improve communication related outcomes in PD. Amplification devices increase the volume of a person's natural speech and can be used on their own or to augment behavioral speech outcomes. The specific acoustic mechanisms underlying these benefits are unknown, though previous evidence suggests that increased signal intensity alone is not responsible for improved auditory-perceptual outcomes. The overall goal of this proposal is to identify the relationship between acoustic and perceptual consequences of amplification devices with and without the use of behavioral speech strategies. Aim 1 of this proposal will quantify the acoustic and auditory-perceptual effects of speech amplification devices for talkers with PD. In addition to using an amplification device, participants will speak with both their habitual speech style and a hyperarticulated, clear speech style. Aim 2 will identify the contribution of resultant acoustic features as well as targeted acoustic enhancements that optimize intelligibility in amplified speech. Acoustic modifications that impact the relative contributions of low to high frequency spectral energy will be made to a subset of the speech recordings from Aim 1. These acoustic enhancements will serve to simulate potential technological improvements to amplification devices. Naïve listeners will hear the speech recordings made in Aims 1 and 2 and will provide measures of listener accuracy and effort. Improvements in speech intelligibility of amplified speech are hypothesized to be associated with acoustic measures that reflect relative greater high to low frequency components of the speech signal. The most positive change is hypothesized to occur when talkers combine behavioral speech strategies with amplification compared to behavioral changes or amplified speech alone. Furthermore, auditory-perceptual outcomes are hypothesized to improve following implementation signal enhancements that could be directly integrated into future amplification device development. Collectively, this study will identify ways to maximize speech treatment outcomes of speech amplification devices through behavioral changes made by the talker or acoustic enhancements to the device output itself. Results will guide behavioral treatment strategies and future device modifications that will improve the efficacy of speech amplifiers in this population. This work is innovative for establishing ways to leverage behavioral speech strategies with advances in augmentative technology for PD. It is theoretically significant for defining the role of spectral acoustics in auditory-perceptual outcomes in disordered speech. It is clinically significant for advancing patient-centered augmentative speech treatment technology for PD.

Inclusion Criteria:

• Dominant speakers of North American English
• Have received a neurologist's diagnosis of Parkinson disease or parkinsonism (e.g., PSP/MSA/PSP)
• Present with changes in their speech/voice

Exclusion Criteria:

• History of any other speech, language, or neurological concern other than Parkinson/parkinsonism.
• Uncorrected hearing loss that exceeds a threshold of 40 dB HL in more than one ear (as per baseline screening audiometry) and/or use of a cochlear implant.