Speech Amplification Devices for Parkinson Disease: Talker- and Technology-Driven Enhancements

Speech Amplification Devices for Parkinson and Related Diseases: Talker- and Technology-Driven Enhancements

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.

Study Overview

• Status: Recruiting
• Conditions: Parkinson Disease; Atypical Parkinsonism
• Intervention / Treatment: Behavioral: Behavioral speech strategies + speech amplification

Detailed Description

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.

• Study Type: Interventional
• Enrollment (Estimated): 100
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: Thea Knowles, PhD; Phone Number: 517-353-6401; Email: thea@msu.edu

Study Locations

• United States
  • Michigan
    • East Lansing, Michigan, United States, 48823
      • Recruiting
      • Michigan State University
      • Contact: Thea Knowles, PhD; Phone Number: 517-353-6401; Email: thea@msu.edu
      • Principal Investigator: Thea Knowles, PhD

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

Description

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.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: N/A
• Interventional Model: Single Group Assignment
• Masking: None (Open Label)

Number of Arms

1

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Speech Study; Single arm study: All speech conditions are administered.	Behavioral: Behavioral speech strategies + speech amplification; Behavioral speech strategies + speech amplification

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Speech intensity	Decibel sound pressure level (dB SPL) measured from speech audio recordings	Day 1
Voice quality	Cepstral peak prominence smoothed (CPPS), measured in decibels (dB) from speech audio recordings	Day 1
Articulation	Quadrilateral vowel articulation index, measured as a composite of first and second formants in Herz (Hz) across four vowels in speech audio recordings.	Day 1

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Speech intelligibility	% words correctly understood by naive listeners (0% = no words correctly transcribed; 100% = all words correctly transcribed). Listener participants transcribe speech recorded by speaker participants.	From end of speech study enrollment to within 1 year. Perceptual measures are elicited from naive listeners following the speech recording study.
Perceived Listener Effort	% along a visual analogue scale (0 = "no effort required to understand the speech"; 100 = "maximal effort required to understand the speech"). Listener participants will rate speech recorded by speaker participants.	From end of speech study enrollment to within 1 year. Listener effort will be elicited from naive listeners following the speech recording study.

Collaborators and Investigators

• Sponsor: Michigan State University
• Collaborators: National Institute on Deafness and Other Communication Disorders (NIDCD)

Study record dates

Study Major Dates

• Study Start (Actual): March 1, 2024
• Primary Completion (Estimated): December 31, 2027
• Study Completion (Estimated): May 31, 2028

Study Registration Dates

• First Submitted: May 5, 2026
• First Submitted That Met QC Criteria: May 14, 2026
• First Posted (Actual): May 20, 2026

Study Record Updates

• Last Update Posted (Actual): May 20, 2026
• Last Update Submitted That Met QC Criteria: May 14, 2026
• Last Verified: May 1, 2026

More Information

Terms related to this study

• Keywords: Parkinson's disease; speech; voice; voice disorders; dysarthria; speech acoustics; speech-language pathology; atypical parkinsonism; speech disorders; hypophonia
• Additional Relevant MeSH Terms: Synucleinopathies; Neurologic Manifestations; Brain Diseases; Central Nervous System Diseases; Nervous System Diseases; Respiratory Tract Diseases; Neurobehavioral Manifestations; Neurodegenerative Diseases; Otorhinolaryngologic Diseases; Movement Disorders; Parkinsonian Disorders; Basal Ganglia Diseases; Laryngeal Diseases; Communication Disorders; Language Disorders; Articulation Disorders; Pathological Conditions, Signs and Symptoms; Behavior; Signs and Symptoms; Communication; Verbal Behavior; Parkinson Disease; Speech Disorders; Voice Disorders; Dysarthria; Speech
• Other Study ID Numbers: 00008898; R21DC021798 (U.S. NIH Grant/Contract); CurePSP CARES Grant - Knowles (Other Grant/Funding Number: CurePSP)

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: UNDECIDED

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No