Stuttering, DevelopmentalNCT07459803
Investigating Individual Differences in Speech Motor Skills in Neurotypical Speakers and Persons With Disordered Speech
A study testing Unpredictable auditory feedback perturbation: 2 behavioral sessions, Unpredictable auditory feedback perturbation during tCS: 3 behavioral sessions and Sustained F1 auditory feedback perturbation in people with Stuttering, Developmental and Dyslexia, run by Boston University Charles River Campus at 2 sites in United States.
Trial summary
This study aims to understand how people use different types of feedback to control their speech. When an individual speaks, the brain relies on several systems at the same time, such as sensory systems that monitor an individuals own voice and the movements of their speech muscles, and a motor system that builds and… Read more about this study
- Who is it for?
- Ages 18 to 50 yearsHealthy volunteers can take part
- Conditions the study is for
- Stuttering, Developmental, Dyslexia, Healthy Participants
- What is being tested?
- Unpredictable auditory feedback perturbation: 2 behavioral sessions, Unpredictable auditory feedback perturbation during tCS: 3 behavioral sessions and Sustained F1 auditory feedback perturbation
- Type of treatment
- Lifestyle or therapy programme
- Could I receive a placebo?
- Yes, some participants may receive a placebo
- How many people
- 90 participants
- Where
- 2 sitesUnited States
- Study dates
- 12 Jun 2026to Mar 2030
- Phase
- Interventional
- Are there results?
- Not yet: the study is under way
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 to 50 years
- All sexes
- Healthy volunteers accepted
- Adult
Who may be able to join
- Native speakers of American English
- Adults age 18-50
- Age-appropriate cognitive and receptive vocabulary skills
- Age-appropriate hearing
- Adults with dyslexia will have a history of dyslexia or report of ongoing reading difficulties that will be confirmed at the first screening visit
- Adults who stutter will have a history of stuttering that will be confirmed at the first screening visit
Who cannot join
- History of neurological disorder, including a history of seizures
- Major brain injury, brain surgery, or stroke
- Orthodontia or atypical oral structure (e.g., cleft palate) that interferes with speech
- Fluency disorder (except those in the persons who stutter cohort), apraxia of speech, or dysarthria
- Language or reading disorder (except those in persons with dyslexia cohort)
- Standardized score below 80 on the Kaufman Brief Intelligence Test
Show all 11Show fewer
- Standardized score below 1 standard deviation on the NIH Toolbox Picture Vocabulary Test
- Pregnancy
- Severe claustrophobia
- Presence of magnetically or mechanically active implant, or other ferromagnetic material embedded in any part of the body
- Significant scalp lesions that would prevent transcranial direct stimulation
Trial locations and contacts
2 sites in 1 country. Contact the study team or a site near you to ask about taking part.
United States2 sites, 2 recruiting
- Recruiting
Boston University Charles River Campus
Boston, Massachusetts, 02115
Barbara G Holland, M.A., 617-353-6181, hollandb@bu.edu
- Recruiting
Boston University
Boston, Massachusetts, 02215
Frank H Guenther, Ph.D., 617-353-5765, guenther@bu.edu
Frank H Guenther, Ph.D.
About this study
Official title: Brain Mechanisms Underlying Neurotypical and Disordered Speech
This study aims to understand how people use different types of feedback to control their speech. When an individual speaks, the brain relies on several systems at the same time, such as sensory systems that monitor an individuals own voice and the movements of their speech muscles, and a motor system that builds and reads out learned motor patterns. The investigators are studying how these systems work together and how they differ across individuals.
Investigators will test 90 adults between 18 and 50 years old, including people who stutter, people with dyslexia, and people with typical speech and reading development. Participants will complete several short speech tasks in which the sounds they hear or the movements of their jaw or larynx are briefly changed. These responses will be used to measure each person's speech motor skills and to estimate the settings of a computer model called "SimpleDIVA," which simulates how the brain controls speech.
Read more
Participants will also complete an MRI scan so investigators can measure the structure and connectivity of different brain regions. These measures will help investigators understand how individual differences in the brain relate to the speech motor control skills we observe. Participants will also complete sessions with noninvasive brain stimulation (transcranial current stimulation, or tCS) to examine how stimulation of specific areas of the brain affects responses during the speech tasks.
The knowledge gained from this study will help researchers understand why speech motor skills vary across people and how differences in neural function may contribute to conditions such as stuttering and dyslexia.
- Conditions
- Stuttering, Developmental, Dyslexia, Healthy Participants
- Being tested
- Unpredictable auditory feedback perturbation: 2 behavioral sessions, Unpredictable auditory feedback perturbation during tCS: 3 behavioral sessions, Sustained F1 auditory feedback perturbation, Sustained F0 auditory feedback perturbation, Reflexive somatosensory perturbation
- Keywords
- Stuttering Developmental, Magnetic Resonance Imaging, Speech Motor Learning, Speech Disorders, Neurocomputational Modeling, Dyslexia
- Medical subject headings
- Stuttering, Dyslexia, Speech Disorders
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Unpredictable auditory feedback perturbation: 2 behavioral sessionsBehavioural
Participants in Arms 1 and 2 will repeat consonant/vowel/consonant (/CVC/) words containing the vowel "eh" between two consonants that they hear over headphones. As they speak, vocal output from the participant will be transduced via a microphone and then played back to the participant over headphones at an undetectable delay. On a subset of (perturbed) trials, F0 or F1 in the auditory feedback presented to the participant will be shifted relative to their vocal output. On the remaining (baseline) trials, auditory feedback will be unaltered. During each behavioral session, participants will complete 80 unperturbed trials, 40 trials that involve an F0 perturbation, and 40 trials that involve an F1 perturbation.
Unpredictable auditory feedback perturbation during tCS: 3 behavioral sessionsBehavioural
Participants in Arms 1 and 2 will repeat /CVC/ words containing the vowel "eh" between two consonants that they hear over headphones. As they speak, vocal output from the participant will be transduced via a microphone and then played back to the participant over headphones at an undetectable delay. On a subset of (perturbed) trials, F0 or F1 in the auditory feedback presented to the participant will be shifted relative to their vocal output. On the remaining (baseline) trials, auditory feedback will be unaltered. During each session, participants will complete 50 unperturbed trials, 50 trials that involve an F0 perturbation, and 50 trials that involve an F1 perturbation.
Sustained F1 auditory feedback perturbationBehavioural
Participants in Arms 1 and 2 will repeat /CVC/ words containing the vowel "eh" between two consonants that they hear over headphones. As they speak, vocal output from the participant will be transduced via a microphone and then played back to the participant over headphones at an undetectable delay. Over the course of each protocol, the first formant (F1) in the auditory feedback presented to the participant will be shifted relative to their vocal output. Trials will be organized in four phases: an initial baseline phase in which auditory feedback is unaltered, a ramp phase over which the formant of auditory feedback is gradually shifted to a maximum level, a hold phase in which the feedback shift is held at its maximum level, and then an after-effect phase in which feedback returns to normal. Four trials will be performed in each phase.
Sustained F0 auditory feedback perturbationBehavioural
Participants in Arm 1 and 2 will repeat /CVC/ words containing the vowel "eh" between two consonants that they hear over headphones. As they speak, vocal output from the participant will be transduced via a microphone and then played back to the participant over headphones at an undetectable delay. As they speak the fundamental frequency (F0) in the auditory feedback presented to the participant will be shifted relative to their vocal output. Trials will be organized in four phases: an initial baseline phase in which auditory feedback is unaltered, a ramp phase over which the formant of auditory feedback is gradually shifted to a maximum level, a hold phase in which the feedback shift is held at its maximum level, and then an after-effect phase in which feedback returns to normal.
Reflexive somatosensory perturbationBehavioural
Participants in Arms 1 and 2 will repeat /CVC/ words containing the vowel "eh" between two consonants that they hear over headphones. While they speak, speech-shaped masking noise will be presented to participants at 85 dB. On a subset of trials (word productions), movements of the jaw will be perturbed (restricted) by the rapid inflation of a balloon placed between the upper and lower teeth shortly after voice onset. On another subset of trials, the position of the larynx will be perturbed by the rapid inflation of a balloon placed against the laryngeal prominence. During the remaining (unperturbed) trials, both balloons will remain deflated.
Anodal tCS targeting pSTG and vSSCOther
Participants in Arm 1 will receive continuous anodal tCS targeting posterior superior temporal gyrus (pSTG) during a 20-minute reflexive auditory feedback task during one session and stimulation targeting ventral somatosensory cortex (vSSC) during the same task in another session. The tCS stimulation will ramp up to its maximum value (2 milliamperes) over the first 30 s of the session and will be maintained at that level throughout the remainder of the session.
Anodal tCS targeting left or right vPMCOther
Participants in Arm 2 will receive continuous anodal tCS targeting left ventral premotor cortex (vPMC) during a 20-minute reflexive auditory feedback task during one session and stimulation targeting right vPMC during the same task in another session. The tCS stimulation will ramp up to its maximum value (2 milliamperes) over the first 30 s of the session and will be maintained at that level throughout the remainder of the session.
Sham tCS targeting pSTG or vSSCOther
Participants in Arm 1 will receive Sham tCS stimulation targeting the pSTG or vSSC during a 20-minute reflexive auditory feedback task. During the minute prior to training onset, the tCS stimulator will ramp up to 2 milliamperes and then back down to 0 for the remainder of the session.
Sham tCS targeting left vPMC or right vPMCOther
Participants in Arm 1 will receive Sham tCS stimulation targeting left or right vPMC during a 20-minute reflexive auditory feedback task. During the minute prior to training onset, the tCS stimulator will ramp up to 2 milliamperes and then back down to 0 for the remainder of the session.
| Study group | Role | What they receive |
|---|---|---|
| pSTG and vSSC tCS Targeting | Experimental | Participants in Arm 1 will complete all behavioral, MRI, and tCS study procedures. During the tCS portion of the study, they will receive anodal transcranial current stimulation (tCS) targeting two brain regions: posterior superior temporal gyrus (pSTG) in one stimulation session and ventral somatosensory cortex (vSSC) in another. In a third session, they will complete the same speech task while receiving sham stimulation targeting either pSTG or vSSC. All participants in this arm will also complete speech motor control tasks involving unpredictable auditory perturbations, sustained auditory perturbations, and somatosensory perturbations, as well as one MRI session. Receives: Behavioral: Unpredictable auditory feedback perturbation: 2 behavioral sessions; Behavioral: Unpredictable auditory feedback perturbation during tCS: 3 behavioral sessions; Behavioral: Sustained F1 auditory feedback perturbation; Behavioral: Sustained F0 auditory feedback perturbation; Behavioral: Reflexive somatosensory perturbation; Other: Anodal tCS targeting pSTG and vSSC; Other: Sham tCS targeting pSTG or vSSC |
| Left and Right vPMC tCS Targeting | Experimental | Participants in Arm 2 will complete all behavioral, MRI, and tCS study procedures. During the tCS portion of the study, they will receive anodal transcranial current stimulation (tCS) targeting left ventral premotor cortex (vPMC) in one stimulation session and right vPMC in another. In a third session, they will complete the same speech task while receiving sham stimulation targeting either the left or right vPMC. All participants in this arm will also complete speech motor control tasks involving unpredictable auditory perturbations, sustained auditory perturbations, and somatosensory perturbations, as well as one MRI session. Receives: Behavioral: Unpredictable auditory feedback perturbation: 2 behavioral sessions; Behavioral: Unpredictable auditory feedback perturbation during tCS: 3 behavioral sessions; Behavioral: Sustained F1 auditory feedback perturbation; Behavioral: Sustained F0 auditory feedback perturbation; Behavioral: Reflexive somatosensory perturbation; Other: Anodal tCS targeting left or right vPMC; Other: Sham tCS targeting left vPMC or right vPMC |
What is being measured
The primary outcome is the main question the study is designed to answer.
Reflexive compensatory response
The amount of compensation to induced F0 and F1 perturbations will be calculated by finding the maximum deviation of the perturbed variable (F0 or F1) from baseline, dividing it by the perturbation size, and then averaging that across all trials of that perturbation.
Measured: Day 1 and Day 2
Adaptive compensatory response
The adaptive compensatory response to persistent F0 and F1 perturbations will be calculated by subtracting the mean F0/F1 from the baseline phase from the mean during the after-effect phase, then dividing by the perturbation size to obtain percent adaptation.
Measured: Day 1 and Day 2
Secondary outcomes (10)
Stuttering Severity
The composite score of the Stuttering Severity Instrument, 4th Edition, and the frequency of stuttering-like dysfluencies will be used to identify correlations between stuttering severity and other outcome measures in persons who stutter.
Measured: Baseline
Dyslexia Severity
A mean composite score from subtests of the Test of Word Reading Efficiency and the Woodcock Reading Mastery Test will be used to identify correlations between dyslexia severity and other outcome measures in persons with dyslexia.
Measured: Baseline
Verbal and Nonverbal Intelligence
The composite score from the Kaufman Brief Intelligence Test for each participant will be used to identify correlations between intelligence and other outcome measures.
Measured: Baseline
Receptive Vocabulary
The score from the Picture Vocabulary Test (PVT) from the NIH Toolbox for each participant will be used to identify correlations between receptive vocabulary and other outcome measures.
Measured: Baseline
Brain region volume
Volume (mm^3) will be extracted for subcortical regions of interest (ROIs). ROIs will be delineated and volume measures extracted using FreeSurfer's standard structural MRI processing pipeline.
Measured: Day 2
Brain region area
Area (mm^2) will be extracted for cortical regions of interest (ROIs). ROIs will be delineated and area measures extracted using FreeSurfer's standard structural MRI processing pipeline.
Measured: Day 2
Brain region cortical thickness
Cortical thickness (mm) will be extracted for cortical regions of interest (ROIs). ROIs will be delineated and cortical thickness extracted using FreeSurfer's standard structural MRI processing pipeline.
Measured: Day 2
Brain region cortical gyrification
Local gyrification index (a unitless measure of the ratio of pial surface and external surface in an area) will be extracted for cortical regions of interest (ROIs). ROIs will be delineated and cortical thickness extracted using FreeSurfer's standard structural MRI processing pipeline.
Measured: Day 2
Brain region functional connectivity
Functional connectivity between pairs of brain ROIs will be estimated from resting state functional MRI using the CONN functional connectivity toolbox.
Measured: Day 2
Brain region structural connectivity
Structural connectivity between pairs of brain ROIs will be estimated from diffusion-weighted MRI using components of the FSL Diffusion Toolbox and the MRtrix software package.
Measured: Day 2
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted10 Mar 2026
- Study start12 Jun 2026
- Primary completionMar 2030 (estimated)
- Study completionMar 2030 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Stuttering, DevelopmentalStudies of the same condition, open and under way.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase N/A
- Primary purpose
- Basic science
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- Single blind
- Who is masked
- Participant
- Enrolment
- 90 participants (estimated)
Sponsor and investigators
- Lead sponsor
- Boston University Charles River Campus
- Sponsor type
- University, hospital or other
- Collaborators
- National Institute on Deafness and Other Communication Disorders (NIDCD)
- Responsible party
- Sponsor
- Investigators
- Frank H Guenther, Ph.D., Principal investigator, Boston University
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07459803
- Sponsor's protocol ID
- Guenther_8013
- Other IDs
- R01DC022014-01
- Status last verified
- Jul 2026
- First submitted
- 12 Dec 2025
- Last updated
- 21 Jul 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- Yes
Study at a glance
From the registry record, last updated by the sponsor on 21 Jul 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Brain Mechanisms Underlying Neurotypical and Disordered Speech
- ClinicalTrials.gov ID
- NCT07459803
- Acronym / sponsor ID
- Guenther_8013
- Conditions
- Stuttering, Developmental, Dyslexia, Healthy Participants
- Keywords
- Stuttering Developmental, Magnetic Resonance Imaging, Speech Motor Learning, Speech Disorders, Neurocomputational Modeling, Dyslexia
- Study type
- Interventional
- Recruitment status
- Recruiting
- Enrolment
- 90 participants (estimated)
- Lead sponsor
- Boston University Charles River CampusUniversity, hospital or other
- Collaborators
- National Institute on Deafness and Other Communication Disorders (NIDCD)
- Study start
- 12 Jun 2026 (actual)
- Primary completion
- Mar 2030 (estimated)
- Study completion
- Mar 2030 (estimated)
- First posted
- 10 Mar 2026 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
This study aims to understand how people use different types of feedback to control their speech. When an individual speaks, the brain relies on several systems at the same time, such as sensory systems that monitor an individuals own voice and the movements of their speech muscles, and a motor system that builds and reads out learned motor patterns. The investigators are studying how these systems work together and how they differ across individuals.
Investigators will test 90 adults between 18 and 50 years old, including people who stutter, people with dyslexia, and people with typical speech and reading development. Participants will complete several short speech tasks in which the sounds they hear or the movements of their jaw or larynx are briefly changed. These responses will be used to measure each person's speech motor skills and to estimate the settings of a computer model called "SimpleDIVA," which simulates how the brain controls speech.
Participants will also complete an MRI scan so investigators can measure the structure and connectivity of different brain regions. These measures will help investigators understand how individual differences in the brain relate to the speech motor control skills we observe. Participants will also complete sessions with noninvasive brain stimulation (transcranial current stimulation, or tCS) to examine how stimulation of specific areas of the brain affects responses during the speech tasks.
The knowledge gained from this study will help researchers understand why speech motor skills vary across people and how differences in neural function may contribute to conditions such as stuttering and dyslexia.
Study design
- Primary purpose
- Basic science
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- Single blind (participant)
- Number of arms
- 2
| Arm | Type | Receives |
|---|---|---|
| pSTG and vSSC tCS Targeting | Experimental | Behavioral: Unpredictable auditory feedback perturbation: 2 behavioral sessions, Behavioral: Unpredictable auditory feedback perturbation during tCS: 3 behavioral sessions, Behavioral: Sustained F1 auditory feedback perturbation, Behavioral: Sustained F0 auditory feedback perturbation, Behavioral: Reflexive somatosensory perturbation, Other: Anodal tCS targeting pSTG and vSSC, Other: Sham tCS targeting pSTG or vSSCParticipants in Arm 1 will complete all behavioral, MRI, and tCS study procedures. During the tCS portion of the study, they will receive anodal transcranial current stimulation (tCS) targeting two brain regions: posterior superior temporal gyrus (pSTG) in one stimulation session and ventral somatosensory cortex (vSSC) in another. In a third session, they will complete the same speech task while receiving sham stimulation targeting either pSTG or vSSC. All participants in this arm will also complete speech motor control tasks involving unpredictable auditory perturbations, sustained auditory perturbations, and somatosensory perturbations, as well as one MRI session. |
| Left and Right vPMC tCS Targeting | Experimental | Behavioral: Unpredictable auditory feedback perturbation: 2 behavioral sessions, Behavioral: Unpredictable auditory feedback perturbation during tCS: 3 behavioral sessions, Behavioral: Sustained F1 auditory feedback perturbation, Behavioral: Sustained F0 auditory feedback perturbation, Behavioral: Reflexive somatosensory perturbation, Other: Anodal tCS targeting left or right vPMC, Other: Sham tCS targeting left vPMC or right vPMCParticipants in Arm 2 will complete all behavioral, MRI, and tCS study procedures. During the tCS portion of the study, they will receive anodal transcranial current stimulation (tCS) targeting left ventral premotor cortex (vPMC) in one stimulation session and right vPMC in another. In a third session, they will complete the same speech task while receiving sham stimulation targeting either the left or right vPMC. All participants in this arm will also complete speech motor control tasks involving unpredictable auditory perturbations, sustained auditory perturbations, and somatosensory perturbations, as well as one MRI session. |
Who may qualify
- Ages
- 18 to 50 years
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Adult
Key inclusion criteria (6 listed)
- Native speakers of American English
- Adults age 18-50
- Age-appropriate cognitive and receptive vocabulary skills
- Age-appropriate hearing
- Adults with dyslexia will have a history of dyslexia or report of ongoing reading difficulties that will be confirmed at the first screening visit
Key exclusion criteria (11 listed)
- History of neurological disorder, including a history of seizures
- Major brain injury, brain surgery, or stroke
- Orthodontia or atypical oral structure (e.g., cleft palate) that interferes with speech
- Fluency disorder (except those in the persons who stutter cohort), apraxia of speech, or dysarthria
- Language or reading disorder (except those in persons with dyslexia cohort)
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| Unpredictable auditory feedback perturbation: 2 behavioral sessionsParticipants in Arms 1 and 2 will repeat consonant/vowel/consonant (/CVC/) words containing the vowel "eh" between two consonants that they hear over headphones. As they speak, vocal output from the participant will be transduced via a microphone and then played back to the participant over headphones at an undetectable delay. On a subset of (perturbed) trials, F0 or F1 in the auditory feedback presented to the participant will be shifted relative to their vocal output. On the remaining (baseline) trials, auditory feedback will be unaltered. During each behavioral session, participants will complete 80 unperturbed trials, 40 trials that involve an F0 perturbation, and 40 trials that involve an F1 perturbation. | Behavioural | Left and Right vPMC tCS Targeting, pSTG and vSSC tCS Targeting |
| Unpredictable auditory feedback perturbation during tCS: 3 behavioral sessionsParticipants in Arms 1 and 2 will repeat /CVC/ words containing the vowel "eh" between two consonants that they hear over headphones. As they speak, vocal output from the participant will be transduced via a microphone and then played back to the participant over headphones at an undetectable delay. On a subset of (perturbed) trials, F0 or F1 in the auditory feedback presented to the participant will be shifted relative to their vocal output. On the remaining (baseline) trials, auditory feedback will be unaltered. During each session, participants will complete 50 unperturbed trials, 50 trials that involve an F0 perturbation, and 50 trials that involve an F1 perturbation. | Behavioural | Left and Right vPMC tCS Targeting, pSTG and vSSC tCS Targeting |
| Sustained F1 auditory feedback perturbationParticipants in Arms 1 and 2 will repeat /CVC/ words containing the vowel "eh" between two consonants that they hear over headphones. As they speak, vocal output from the participant will be transduced via a microphone and then played back to the participant over headphones at an undetectable delay. Over the course of each protocol, the first formant (F1) in the auditory feedback presented to the participant will be shifted relative to their vocal output. Trials will be organized in four phases: an initial baseline phase in which auditory feedback is unaltered, a ramp phase over which the formant of auditory feedback is gradually shifted to a maximum level, a hold phase in which the feedback shift is held at its maximum level, and then an after-effect phase in which feedback returns to normal. Four trials will be performed in each phase. | Behavioural | Left and Right vPMC tCS Targeting, pSTG and vSSC tCS Targeting |
| Sustained F0 auditory feedback perturbationParticipants in Arm 1 and 2 will repeat /CVC/ words containing the vowel "eh" between two consonants that they hear over headphones. As they speak, vocal output from the participant will be transduced via a microphone and then played back to the participant over headphones at an undetectable delay. As they speak the fundamental frequency (F0) in the auditory feedback presented to the participant will be shifted relative to their vocal output. Trials will be organized in four phases: an initial baseline phase in which auditory feedback is unaltered, a ramp phase over which the formant of auditory feedback is gradually shifted to a maximum level, a hold phase in which the feedback shift is held at its maximum level, and then an after-effect phase in which feedback returns to normal. | Behavioural | Left and Right vPMC tCS Targeting, pSTG and vSSC tCS Targeting |
| Reflexive somatosensory perturbationParticipants in Arms 1 and 2 will repeat /CVC/ words containing the vowel "eh" between two consonants that they hear over headphones. While they speak, speech-shaped masking noise will be presented to participants at 85 dB. On a subset of trials (word productions), movements of the jaw will be perturbed (restricted) by the rapid inflation of a balloon placed between the upper and lower teeth shortly after voice onset. On another subset of trials, the position of the larynx will be perturbed by the rapid inflation of a balloon placed against the laryngeal prominence. During the remaining (unperturbed) trials, both balloons will remain deflated. | Behavioural | Left and Right vPMC tCS Targeting, pSTG and vSSC tCS Targeting |
| Anodal tCS targeting pSTG and vSSCParticipants in Arm 1 will receive continuous anodal tCS targeting posterior superior temporal gyrus (pSTG) during a 20-minute reflexive auditory feedback task during one session and stimulation targeting ventral somatosensory cortex (vSSC) during the same task in another session. The tCS stimulation will ramp up to its maximum value (2 milliamperes) over the first 30 s of the session and will be maintained at that level throughout the remainder of the session. | Other | pSTG and vSSC tCS Targeting |
| Anodal tCS targeting left or right vPMCParticipants in Arm 2 will receive continuous anodal tCS targeting left ventral premotor cortex (vPMC) during a 20-minute reflexive auditory feedback task during one session and stimulation targeting right vPMC during the same task in another session. The tCS stimulation will ramp up to its maximum value (2 milliamperes) over the first 30 s of the session and will be maintained at that level throughout the remainder of the session. | Other | Left and Right vPMC tCS Targeting |
| Sham tCS targeting pSTG or vSSCParticipants in Arm 1 will receive Sham tCS stimulation targeting the pSTG or vSSC during a 20-minute reflexive auditory feedback task. During the minute prior to training onset, the tCS stimulator will ramp up to 2 milliamperes and then back down to 0 for the remainder of the session. | Other | pSTG and vSSC tCS Targeting |
| Sham tCS targeting left vPMC or right vPMCParticipants in Arm 1 will receive Sham tCS stimulation targeting left or right vPMC during a 20-minute reflexive auditory feedback task. During the minute prior to training onset, the tCS stimulator will ramp up to 2 milliamperes and then back down to 0 for the remainder of the session. | Other | Left and Right vPMC tCS Targeting |
Primary outcome
Reflexive compensatory response
Time frame: Day 1 and Day 2
The amount of compensation to induced F0 and F1 perturbations will be calculated by finding the maximum deviation of the perturbed variable (F0 or F1) from baseline, dividing it by the perturbation size, and then averaging that across all trials of that perturbation.
Adaptive compensatory response
Time frame: Day 1 and Day 2
The adaptive compensatory response to persistent F0 and F1 perturbations will be calculated by subtracting the mean F0/F1 from the baseline phase from the mean during the after-effect phase, then dividing by the perturbation size to obtain percent adaptation.
10 secondary outcomes
Stuttering Severity
Time frame: Baseline
Dyslexia Severity
Time frame: Baseline
Verbal and Nonverbal Intelligence
Time frame: Baseline
Receptive Vocabulary
Time frame: Baseline
Brain region volume
Time frame: Day 2
Brain region area
Time frame: Day 2
Brain region cortical thickness
Time frame: Day 2
Brain region cortical gyrification
Time frame: Day 2
Brain region functional connectivity
Time frame: Day 2
Brain region structural connectivity
Time frame: Day 2
Results and safety
This study is still under way. Results are not available in the source record yet.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 21 Jul 2026.
- Individual participant dataSharing planned: Yes
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part.
Frank H Guenther, Ph.D. principal investigator
Boston University
2 sites in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing Unpredictable auditory feedback perturbation: 2 behavioral sessions, Unpredictable auditory feedback perturbation during tCS: 3 behavioral sessions and Sustained F1 auditory feedback perturbation in people with Stuttering, Developmental and Dyslexia, run by Boston University Charles River Campus at 2 sites in United States.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 6 inclusion and 11 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: looking for participants now, as of the sponsor's last update on 21 Jul 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 2 sites in United States. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
This study is still under way. Results are not available in the source record yet.
How can a doctor refer a patient or contact the research team?
Contact Frank H Guenther, Ph.D. (617-353-5765, guenther@bu.edu), or a site near the patient. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Reflexive compensatory response (time frame: Day 1 and Day 2). The study lists 2 primary outcomes in all. It is what the study was designed to measure, not a finding.
Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 21 Jul 2026.