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

May 14, 2026 updated by: Thea Knowles, Michigan State University

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

Status

Indicates the current recruitment status or the expanded access status.
Recruiting

Conditions

Conditions

The disease, disorder, syndrome, illness, or injury that is being studied. On ClinicalTrials.gov, conditions may also include other health-related issues, such as lifespan, quality of life, and health risks.

Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.

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

Study Type

Describes the nature of a clinical study. Study types include interventional studies (also called clinical trials), observational studies (including patient registries), and expanded access.
Interventional

Enrollment (Estimated)

Enrollment

The number of participants in a clinical study. The "anticipated" enrollment is the target number of participants that the researchers need for the study.
100

Phase

Phase

The stage of a clinical trial studying a drug or biological product, based on definitions developed by the U.S. Food and Drug Administration (FDA). The phase is based on the study's objective, the number of participants, and other characteristics. There are five phases: Early Phase 1 (formerly listed as Phase 0), Phase 1, Phase 2, Phase 3, and Phase 4. Not Applicable is used to describe trials without FDA-defined phases, including trials of devices or behavioral interventions.
  • Not Applicable

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Study Contact

The name and contact information for the person who can answer enrollment questions for a clinical study. Each location where the study is being conducted may also have a specific contact, who may be better able to answer those questions.
  • 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

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Eligibility Criteria

The key requirements that people who want to participate in a clinical study must meet or the characteristics they must have. Eligibility criteria consist of both inclusion criteria (which are required for a person to participate in the study) and exclusion criteria (which prevent a person from participating). Types of eligibility criteria include whether a study accepts healthy volunteers, has age or age group requirements, or is limited by sex.

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

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

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

Arms and Interventions

Participant Group / Arm

Participant Group / Arm

A group or subgroup of participants in a clinical trial that receives a specific intervention/treatment, or no intervention, according to the trial's protocol.
Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.
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

Primary Outcome Measures

In a clinical study's protocol, the planned outcome measure that is the most important for evaluating the effect of an intervention/treatment. Most clinical studies have one primary outcome measure, but some have more than one.
Outcome Measure
Measure Description
Time Frame
Speech intensity
Time Frame: Day 1
Decibel sound pressure level (dB SPL) measured from speech audio recordings
Day 1
Voice quality
Time Frame: Day 1
Cepstral peak prominence smoothed (CPPS), measured in decibels (dB) from speech audio recordings
Day 1
Articulation
Time Frame: Day 1
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

Secondary Outcome Measures

In a clinical study's protocol, a planned outcome measure that is not as important as the primary outcome measure for evaluating the effect of an intervention but is still of interest. Most clinical studies have more than one secondary outcome measure.
Outcome Measure
Measure Description
Time Frame
Speech intelligibility
Time Frame: From end of speech study enrollment to within 1 year. Perceptual measures are elicited from naive listeners following the speech recording study.
% 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
Time Frame: From end of speech study enrollment to within 1 year. Listener effort will be elicited from naive listeners following the speech recording study.
% 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

This is where you will find people and organizations involved with this study.

Sponsor

Sponsor

The organization or person who initiates the study and who has authority and control over the study.
Michigan State University

Collaborators

Collaborators

An organization other than the sponsor that provides support for a clinical study. This support may include activities related to funding, design, implementation, data analysis, or reporting.
National Institute on Deafness and Other Communication Disorders (NIDCD)

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

Study Start

The actual date on which the first participant was enrolled in a clinical study. The "anticipated" study start date is the date that the researchers think will be the study start date.
March 1, 2024

Primary Completion (Estimated)

Primary Completion

The date on which the last participant in a clinical study was examined or received an intervention to collect final data for the primary outcome measure. Whether the clinical study ended according to the protocol or was terminated does not affect this date. For clinical studies with more than one primary outcome measure with different completion dates, this term refers to the date on which data collection is completed for all the primary outcome measures. The "anticipated" primary completion date is the date that the researchers think will be the primary completion date for the study.
December 31, 2027

Study Completion (Estimated)

Study Completion

The date on which the last participant in a clinical study was examined or received an intervention/treatment to collect final data for the primary outcome measures, secondary outcome measures, and adverse events (that is, the last participant's last visit). The "anticipated" study completion date is the date that the researchers think will be the study completion date.
May 31, 2028

Study Registration Dates

First Submitted

First Submitted

The date on which the study sponsor or investigator first submitted a study record to ClinicalTrials.gov. There is typically a delay of a few days between the first submitted date and the record's availability on ClinicalTrials.gov (the first posted date).
May 5, 2026

First Submitted That Met QC Criteria

First Submitted That Met QC Criteria

The date on which the study sponsor or investigator first submits a study record that is consistent with National Library of Medicine (NLM) quality control (QC) review criteria. The sponsor or investigator may need to revise and submit a study record one or more times before NLM's QC review criteria are met. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
May 14, 2026

First Posted (Actual)

First Posted

The date on which the study record was first available on ClinicalTrials.gov after National Library of Medicine (NLM) quality control (QC) review has concluded. There is typically a delay of a few days between the date the study sponsor or investigator submitted the study record and the first posted date.
May 20, 2026

Study Record Updates

Last Update Posted (Actual)

Last Update Posted

The most recent date on which changes to a study record were made available on ClinicalTrials.gov. There may be a delay between when the changes were submitted to ClinicalTrials.gov by the study's sponsor or investigator (the last update submitted date) and the last update posted date.
May 20, 2026

Last Update Submitted That Met QC Criteria

Last Update Submitted That Met QC Criteria

The most recent date on which the study sponsor or investigator submitted changes to a study record that are consistent with National Library of Medicine (NLM) quality control (QC) review criteria. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
May 14, 2026

Last Verified

Last Verified

The most recent date on which the study sponsor or investigator confirmed the information about a clinical study on ClinicalTrials.gov as accurate and current. If a study with a recruitment status of recruiting; not yet recruiting; or active, not recruiting has not been confirmed within the past 2 years, the study's recruitment status is shown as unknown.
May 1, 2026

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

Other Study ID Numbers

Identifiers or ID numbers other than the NCT number that are assigned to a clinical study by the study's sponsor, funders, or others. These numbers may include unique identifiers from other trial registries and National Institutes of Health grant 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

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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