Stuttering, DevelopmentalNCT05437159
Investigating Speech Sequencing in Neurotypical Speakers and Persons With Disordered Speech
A study testing Learning of non-native phoneme combinations: 6 training sessions, Learning of non-native phoneme combinations: 1 training session and Learning of novel multisyllabic nonwords in people with Stuttering, Developmental and Aphasia, Primary Progressive, run by Boston University Charles River Campus at 3 sites in United States.
Trial summary
Persistent developmental stuttering affects more than three million people in the United States, and it can have profound adverse effects on quality of life. Despite its prevalence and negative impact, stuttering has resisted explanation and effective treatment, due in large part to a poor understanding of the neural… Read more about this study
- Who is it for?
- Ages 6 years and olderHealthy volunteers can take part
- Conditions the study is for
- Stuttering, Developmental, Aphasia, Primary Progressive
- What is being tested?
- Learning of non-native phoneme combinations: 6 training sessions, Learning of non-native phoneme combinations: 1 training session and Learning of novel multisyllabic nonwords
- Type of treatment
- Lifestyle or therapy programme
- Could I receive a placebo?
- Yes, some participants may receive a placebo
- How many people
- 278 participants
- Where
- 3 sitesUnited States
- Study dates
- 3 Apr 2023to 31 May 2026
- Phase
- Interventional
- Are there results?
- None posted in the registry
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 6 years and older
- All sexes
- Healthy volunteers accepted
- Child, Adult, Older adult
Who may be able to join
- Healthy individuals with no history of neurological, speech, or hearing disorders (other than stuttering in studies that involve adults who stutter).
- To maximize the uniformity of prior exposure to the speech stimuli that will be used, only native speakers of American English will be recruited, and only those with limited exposure to a second language will be enrolled.
- All adult participants will also pass a standard pure-tone hearing screening at a 25dB hearing level threshold at 500, 1k, 2k, and 4kHz frequencies.
- All participating children will pass a hearing screening at a 20 dB threshold at 500, 1k, 2k, and 4k Hz.
- Participants in experiments that require them to read orthographic stimuli must have normal or corrected-to-normal vision (MRI-safe corrective glasses are available at the Boston University Cognitive Neuroimaging Center for use during neuroimaging).
- Participating children will complete additional speech, language, hearing, and cognitive tests to ensure that they are within normal performance ranges for their age with the exception of stuttering for children in the children who stutter (CWS) group.
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- Persons who stutter will be evaluated formally by a speech-language pathologist to assess stuttering severity and to ensure the absence of other speech or language disorders. PWS will have no history of neurological disorder other than stuttering, and will demonstrate very mild to severe stuttering according to the Stuttering Severity Instrument for Children and Adults - 4th Edition (SSI-4: PRO-ED, Inc.), that is confirmed by clinical reports and expressed concern by the subject and/or guardian.
- Participants with primary progressive aphasia (PPA) will have been diagnosed through the Massachusetts General Hospital Frontotemporal Disorders Unit (MGH-FTD) by an experienced neurologist in coordination with a speech-language pathologist.
- Participants with PPA will have a score of 1.0 or lower on the Clinical Dementia Rating scale (i.e., mild cognitive impairment or mild dementia) to ensure cognitive levels are sufficient to complete the task.
- All participants with PPA must have a recent clinical assessment and T1 structural neuroimaging scan through the MGH-FTD Unit for eligibility for this study.
Who cannot join
- Participants in studies that involve tDCS or MRI scanning will have no contraindications specific to those procedures. For the tDCS study, this includes individuals who have a metallic implant in the head or electrically sensitive devices implanted in the body, a history of seizures, significant scalp lesions, or pregnancy.
- For MRI studies, this includes a history of seizures, severe claustrophobia, the presence of magnetically or mechanically active implant, ferromagnetic material embedded in any part of the body, or pregnancy).
- All participants will perform a standardized nonword repetition pre-test (the Dollaghan and Campbell Nonword Repetition Task) to assess working memory performance. Participants who perform more than 2 standard deviations below the norm for their age range will be deemed to be unable to perform the experimental task and released from further participation.
- Participating children will have no history of neurological disorder other than stuttering, and will demonstrate very mild to severe stuttering according to the Stuttering Severity Instrument for Children and Adults, 4th Edition, that is confirmed by clinical reports and expressed concern by the subject and/or guardian.
- Children under the age of 6 and over the age of 8 will not enrolled in this study.
- Participants with PPA will not be eligible for this study if they are taking any medications that would be expected to affect speech or language.
Trial locations and contacts
3 sites in 1 country.
United States3 sites
University of Michigan
Ann Arbor, Michigan, 48109
Massachusetts General Hospital
Boston, Massachusetts, 02129
Boston University
Boston, Massachusetts, 02215
About this study
Official title: Sequencing and Initiation in Speech Production: Investigating Speech Sequencing in Neurotypical Speakers, Persons Who Stutter, and Persons With Primary Progressive Aphasia
Persistent developmental stuttering affects more than three million people in the United States, and it can have profound adverse effects on quality of life. Despite its prevalence and negative impact, stuttering has resisted explanation and effective treatment, due in large part to a poor understanding of the neural processing impairments underlying the disorder. The overall goal of this study is to improve understanding of the brain mechanisms involved in speech motor planning and how these are disrupted in neurogenic speech disorders, like stuttering. The investigators will do this through an integrated combination of experiments that involve speech production, functional MRI, and non-invasive brain stimulation. The study is designed to test hypotheses regarding the brain processes involved in learning and initiating new speech sound sequences and how those processes compare in persons with persistent developmental stuttering and those with typical speech development. These processes will be studied in both adults and children. Additionally, these processes will be investigated in patients with neurodegenerative speech disorders (primary progressive aphasia) to further inform the investigators understanding of the neural mechanisms that support speech motor sequence learning. Together these experiments will result in an improved account of the brain mechanisms underlying speech production in fluent speakers and individuals who stutter, thereby paving the way for the development of new therapies and technologies for addressing this disorder.
- Being tested
- Learning of non-native phoneme combinations: 6 training sessions, Learning of non-native phoneme combinations: 1 training session, Learning of novel multisyllabic nonwords, Anodal tDCS, Sham tDCS
- Keywords
- Stuttering, Developmental, Magnetic Resonance Imaging, Transcranial Direct Current Stimulation, Speech Motor Learning, Speech Disorders, Neurocomputational Modeling
- Medical subject headings
- Stuttering, Aphasia, Primary Progressive, Speech Disorders
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Learning of non-native phoneme combinations: 6 training sessionsBehavioural
Each trial of the training sessions will follow a simple reaction time protocol in which a nonsense syllable containing novel consonant clusters (e.g., GDADK) is produced as quickly and accurately as possible after an auditory prompt presented via earphones. During each training session, the participant will practice producing a set of 8 stimuli (the Fully Learned stimuli). Each of the 8 Fully Learned stimuli will be produced 60 times over the 6 training sessions.
Learning of non-native phoneme combinations: 1 training sessionBehavioural
Each trial of the training sessions will follow a simple reaction time protocol in which a nonsense syllable containing novel consonant clusters (e.g., GDADK) is produced as quickly and accurately as possible after an auditory prompt presented via earphones. During the training session, the participant will practice producing a set of 3 stimuli (the Fully Learned stimuli). Each of the 3 Fully Learned stimuli will be produced 60 times.
Learning of novel multisyllabic nonwordsBehavioural
Each trial of the training sessions (total of 6 training sessions over 2 days) will follow a simple reaction time protocol in which a nonword stimulus formed by 2 or 3 syllables that are legal in American English is presented auditorily to the participant, who then produces the stimulus as quickly and accurately as possible. During training, each participant will repeatedly produce 6 nonwords, with each nonword produced a total of 60 times over the 6 training sessions.
Anodal tDCSOther
Continuous anodal tDCS is delivered to a speech processing area of the brain during a 19-minute speech training session. The tDCS stimulation will ramp up to its maximum value (2 milliamperes) in the minute prior to the training session and maintained at that level throughout the session.
Sham tDCSOther
Sham tDCS stimulation is delivered to a speech processing area of the brain during a 19-minute speech training session. During the minute prior to training onset, the tDCS stimulator is ramped up to 2 milliamperes and then back down to 0.
Learning of non-native phoneme combinations: 8 training sessionsBehavioural
Each trial of the training sessions will follow a simple reaction time protocol in which a nonsense syllable containing novel consonant clusters (e.g., GDADK) is produced as quickly and accurately as possible after an auditory prompt presented via earphones. During each training session, the participant will practice producing a set of 3 stimuli (the Fully Learned stimuli). Each of the 3 Fully Learned stimuli will be produced 120 times over the 8 training sessions.
| Study group | Role | What they receive |
|---|---|---|
| Sub-syllabic learning and fMRI | Experimental | 60 adults with neurotypical speech development will participate in this arm. Subjects will learn novel 1-syllable nonsense words formed by non-native phoneme combinations during 6 training sessions over 2 days. Following training, subjects will participate in a functional magnetic resonance imaging (fMRI) session on a third day to measure brain activity associated with producing the words learned during training and with a set of unfamiliar words also formed by non-native phoneme combinations. Receives: Behavioral: Learning of non-native phoneme combinations: 6 training sessions |
| Sub-syllabic learning and anodal tDCS of inferior frontal sulcus | Experimental | 35 adults with neurotypical speech development will participate in this arm. Subjects will learn novel 1-syllable nonsense words formed by non-native phoneme combinations. During the training, anodal transcranial direct current stimulation (tDCS) will be applied to the the subject's left inferior frontal sulcus. Receives: Behavioral: Learning of non-native phoneme combinations: 1 training session; Other: Anodal tDCS |
| Sub-syllabic learning and anodal tDCS of cerebellum | Experimental | 35 adults with neurotypical speech development will participate in this arm. Subjects will learn novel 1-syllable words formed by non-native phoneme combinations. During the training, continuous anodal transcranial direct current stimulation (tDCS) will be applied to the the subject's right cerebellum. Receives: Behavioral: Learning of non-native phoneme combinations: 1 training session; Other: Anodal tDCS |
| Sub-syllabic learning and sham tDCS | Sham comparator | 35 adults with neurotypical speech development will participate in this arm. Subjects will learn novel 1-syllable words formed by non-native phoneme combinations. During training, Sham transcranial direct current stimulation stimulation (tDCS) will be delivered to the subject's brain. Receives: Behavioral: Learning of non-native phoneme combinations: 1 training session; Other: Sham tDCS |
| Multisyllabic learning and fMRI in adults | Experimental | 30 adults persistent developmental stuttering (AWS) and 30 adults with neurotypical speech development (ANS) will participate in this arm. Subjects will learn nonsense words formed by novel combinations of 3 syllables that are legal in American English during 6 training sessions over 2 days. Following training, subjects will participate in a functional magnetic resonance imaging (fMRI) session on a third day to measure brain activity associated with producing the words formed by pairing 2 learned 3-syllable strings learned during training and those formed by pairing 2 unfamiliar 3-syllable strings. Behavioral measures extracted from the data will be used to compare performance before and after training and across the AWS and ANS participants. Receives: Behavioral: Learning of novel multisyllabic nonwords |
| Multisyllabic learning in children | Experimental | 45 children with persistent developmental stuttering (CWS) and 45 children with neurotypical speech development (CNS) will participate in this arm. Subjects will learn nonsense words formed by novel combinations of 2 syllables that are legal in American English during 6 training sessions over 2 days. Behavioral measures extracted from the data will be used to compare performance before and after training and across the CWS and CNS participants. Receives: Behavioral: Learning of novel multisyllabic nonwords |
| Sub-syllabic learning in PPA | Experimental | 30 adults with primary progressive aphasia (PPA) will participate in this arm. Subjects will learn novel 1-syllable nonsense words formed by non-native phoneme combinations during 8 training sessions over 2 days. Following training, subjects will complete a behavioral test to compare their performance on the words learned during training with a set of unfamiliar words also formed by non-native phoneme combinations. Receives: Behavioral: Learning of non-native phoneme combinations: 8 training sessions |
What is being measured
The primary outcome is the main question the study is designed to answer.
Change from baseline in production error rate
Investigators will compare mean error rates when producing newly learned speech sequences versus novel speech sequences of the same length in each arm. This measure will be used to test hypotheses regarding speech motor learning and brain activity and how these compare in persons with persistent developmental stuttering and persons with neurotypical speech.
Measured: Evaluated at Baseline and immediately following intervention
Change from baseline in utterance duration
Investigators will measure changes in utterance duration before and after speech sequence training to test hypotheses concerning differences in the neural mechanisms responsible for speed/duration improvements compared to improvements in accuracy (i.e., reductions in error rate).
Measured: Evaluated at Baseline and immediately following intervention
Change from baseline in reaction time
Investigators will measure the time interval between the prompt to begin speech and the subject's speech onset. Mean reaction time will be compared for learned and novel nonwords in persons with persistent developmental stuttering and persons with neurotypical speech.
Measured: Evaluated at Baseline and immediately following intervention
Percentage of words stuttered
Investigators will compare the percentage of words stuttered under different experimental conditions. This measure will be used to test hypotheses regarding the effect of speech motor learning on stuttering rate and the relationship between stuttering rate and brain activity.
Measured: Evaluated at Baseline and immediately following intervention
Brain activity measured with functional magnetic resonance imaging
Investigators will measure blood oxygen level dependent (BOLD) brain activity when producing speech utterances in different experimental conditions in adults with persistent developmental stuttering and those with neurotypical speech.
Measured: Evaluated at Baseline and immediately following intervention
Secondary outcomes (5)
Cortical white matter connectivity
Diffusion-weighted MRI will be collected and used to identify relationships between white matter connectivity and behavioral measures.
Measured: Evaluated during the MRI scanning procedure
Cortical morphometry
Structural MRI will be collected and used to identify relationships between cortical morphometry and behavioral measures.
Measured: Evaluated during the MRI scanning procedure
Working memory test scores
The Comprehensive Test of Phonological Processing (CTOPP) Second Edition working memory subtest scores for each participant will be used to identify correlations between working memory capacity, task performance, and brain measures in all studies.
Measured: Evaluated at Baseline
Forward digit span
Scores from the Forward Digit Span task from the Uniform Data Set neuropsychological test battery will be used for each participant with PPA to identify correlations between phonological working memory and task performance.
Measured: Evaluated at Baseline
Stuttering Severity
The Stuttering Severity Instrument, 4th Edition, will be administered to persons show stutter to identify correlations between stuttering severity and task performance and functional and structural brain measures.
Measured: Evaluated at Baseline
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted29 Jun 2022
- Study start3 Apr 2023
- Primary completion31 May 2026
- Study completion31 May 2026
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
- None (open label)
- Enrolment
- 278 participants (actual)
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), University of Michigan, Massachusetts General Hospital
- Responsible party
- Sponsor
- Investigators
- Frank H Guenther, PhD, Principal investigator, Boston UniversitySoo-Eun Chang, PhD, Principal investigator, University of Michigan
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT05437159
- Sponsor's protocol ID
- R01DC007683
- Other IDs
- 2R01DC007683-16A1, 1F31DC020352-01A1
- Status last verified
- Jul 2026
- First submitted
- 1 Jun 2022
- Last updated
- 24 Jul 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- No
Study at a glance
From the registry record, last updated by the sponsor on 24 Jul 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Sequencing and Initiation in Speech Production: Investigating Speech Sequencing in Neurotypical Speakers, Persons Who Stutter, and Persons With Primary Progressive Aphasia
- ClinicalTrials.gov ID
- NCT05437159
- Acronym / sponsor ID
- R01DC007683
- Keywords
- Stuttering, Developmental, Magnetic Resonance Imaging, Transcranial Direct Current Stimulation, Speech Motor Learning, Speech Disorders, Neurocomputational Modeling
- Study type
- Interventional
- Recruitment status
- Completed
- Enrolment
- 278 participants (actual)
- Lead sponsor
- Boston University Charles River CampusUniversity, hospital or other
- Collaborators
- National Institute on Deafness and Other Communication Disorders (NIDCD), University of Michigan, Massachusetts General Hospital
- Study start
- 3 Apr 2023 (actual)
- Primary completion
- 31 May 2026 (actual)
- Study completion
- 31 May 2026 (actual)
- First posted
- 29 Jun 2022 (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.
Persistent developmental stuttering affects more than three million people in the United States, and it can have profound adverse effects on quality of life. Despite its prevalence and negative impact, stuttering has resisted explanation and effective treatment, due in large part to a poor understanding of the neural processing impairments underlying the disorder. The overall goal of this study is to improve understanding of the brain mechanisms involved in speech motor planning and how these are disrupted in neurogenic speech disorders, like stuttering. The investigators will do this through an integrated combination of experiments that involve speech production, functional MRI, and non-invasive brain stimulation. The study is designed to test hypotheses regarding the brain processes involved in learning and initiating new speech sound sequences and how those processes compare in persons with persistent developmental stuttering and those with typical speech development. These processes will be studied in both adults and children. Additionally, these processes will be investigated in patients with neurodegenerative speech disorders (primary progressive aphasia) to further inform the investigators understanding of the neural mechanisms that support speech motor sequence learning. Together these experiments will result in an improved account of the brain mechanisms underlying speech production in fluent speakers and individuals who stutter, thereby paving the way for the development of new therapies and technologies for addressing this disorder.
Study design
- Primary purpose
- Basic science
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- None (open label)
- Number of arms
- 7
| Arm | Type | Receives |
|---|---|---|
| Sub-syllabic learning and fMRI | Experimental | Behavioral: Learning of non-native phoneme combinations: 6 training sessions60 adults with neurotypical speech development will participate in this arm. Subjects will learn novel 1-syllable nonsense words formed by non-native phoneme combinations during 6 training sessions over 2 days. Following training, subjects will participate in a functional magnetic resonance imaging (fMRI) session on a third day to measure brain activity associated with producing the words learned during training and with a set of unfamiliar words also formed by non-native phoneme combinations. |
| Sub-syllabic learning and anodal tDCS of inferior frontal sulcus | Experimental | Behavioral: Learning of non-native phoneme combinations: 1 training session, Other: Anodal tDCS35 adults with neurotypical speech development will participate in this arm. Subjects will learn novel 1-syllable nonsense words formed by non-native phoneme combinations. During the training, anodal transcranial direct current stimulation (tDCS) will be applied to the the subject's left inferior frontal sulcus. |
| Sub-syllabic learning and anodal tDCS of cerebellum | Experimental | Behavioral: Learning of non-native phoneme combinations: 1 training session, Other: Anodal tDCS35 adults with neurotypical speech development will participate in this arm. Subjects will learn novel 1-syllable words formed by non-native phoneme combinations. During the training, continuous anodal transcranial direct current stimulation (tDCS) will be applied to the the subject's right cerebellum. |
| Sub-syllabic learning and sham tDCS | Sham comparator | Behavioral: Learning of non-native phoneme combinations: 1 training session, Other: Sham tDCS35 adults with neurotypical speech development will participate in this arm. Subjects will learn novel 1-syllable words formed by non-native phoneme combinations. During training, Sham transcranial direct current stimulation stimulation (tDCS) will be delivered to the subject's brain. |
| Multisyllabic learning and fMRI in adults | Experimental | Behavioral: Learning of novel multisyllabic nonwords30 adults persistent developmental stuttering (AWS) and 30 adults with neurotypical speech development (ANS) will participate in this arm. Subjects will learn nonsense words formed by novel combinations of 3 syllables that are legal in American English during 6 training sessions over 2 days. Following training, subjects will participate in a functional magnetic resonance imaging (fMRI) session on a third day to measure brain activity associated with producing the words formed by pairing 2 learned 3-syllable strings learned during training and those formed by pairing 2 unfamiliar 3-syllable strings. Behavioral measures extracted from the data will be used to compare performance before and after training and across the AWS and ANS participants. |
| Multisyllabic learning in children | Experimental | Behavioral: Learning of novel multisyllabic nonwords45 children with persistent developmental stuttering (CWS) and 45 children with neurotypical speech development (CNS) will participate in this arm. Subjects will learn nonsense words formed by novel combinations of 2 syllables that are legal in American English during 6 training sessions over 2 days. Behavioral measures extracted from the data will be used to compare performance before and after training and across the CWS and CNS participants. |
| Sub-syllabic learning in PPA | Experimental | Behavioral: Learning of non-native phoneme combinations: 8 training sessions30 adults with primary progressive aphasia (PPA) will participate in this arm. Subjects will learn novel 1-syllable nonsense words formed by non-native phoneme combinations during 8 training sessions over 2 days. Following training, subjects will complete a behavioral test to compare their performance on the words learned during training with a set of unfamiliar words also formed by non-native phoneme combinations. |
Who may qualify
- Ages
- 6 years and older
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Child, Adult, Older adult
Key inclusion criteria (10 listed)
- Healthy individuals with no history of neurological, speech, or hearing disorders (other than stuttering in studies that involve adults who stutter).
- To maximize the uniformity of prior exposure to the speech stimuli that will be used, only native speakers of American English will be recruited, and only those with limited exposure to a second language will be enrolled.
- All adult participants will also pass a standard pure-tone hearing screening at a 25dB hearing level threshold at 500, 1k, 2k, and 4kHz frequencies.
- All participating children will pass a hearing screening at a 20 dB threshold at 500, 1k, 2k, and 4k Hz.
- Participants in experiments that require them to read orthographic stimuli must have normal or corrected-to-normal vision (MRI-safe corrective glasses are available at the Boston University Cognitive Neuroimaging Center for use during neuroimaging).
Key exclusion criteria (6 listed)
- Participants in studies that involve tDCS or MRI scanning will have no contraindications specific to those procedures. For the tDCS study, this includes individuals who have a metallic implant in the head or electrically sensitive devices implanted in the body, a history of seizures, significant scalp lesions, or pregnancy.
- For MRI studies, this includes a history of seizures, severe claustrophobia, the presence of magnetically or mechanically active implant, ferromagnetic material embedded in any part of the body, or pregnancy).
- All participants will perform a standardized nonword repetition pre-test (the Dollaghan and Campbell Nonword Repetition Task) to assess working memory performance. Participants who perform more than 2 standard deviations below the norm for their age range will be deemed to be unable to perform the experimental task and released from further participation.
- Participating children will have no history of neurological disorder other than stuttering, and will demonstrate very mild to severe stuttering according to the Stuttering Severity Instrument for Children and Adults, 4th Edition, that is confirmed by clinical reports and expressed concern by the subject and/or guardian.
- Children under the age of 6 and over the age of 8 will not enrolled in this study.
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 |
|---|---|---|
| Learning of non-native phoneme combinations: 6 training sessionsEach trial of the training sessions will follow a simple reaction time protocol in which a nonsense syllable containing novel consonant clusters (e.g., GDADK) is produced as quickly and accurately as possible after an auditory prompt presented via earphones. During each training session, the participant will practice producing a set of 8 stimuli (the Fully Learned stimuli). Each of the 8 Fully Learned stimuli will be produced 60 times over the 6 training sessions. | Behavioural | Sub-syllabic learning and fMRI |
| Learning of non-native phoneme combinations: 1 training sessionEach trial of the training sessions will follow a simple reaction time protocol in which a nonsense syllable containing novel consonant clusters (e.g., GDADK) is produced as quickly and accurately as possible after an auditory prompt presented via earphones. During the training session, the participant will practice producing a set of 3 stimuli (the Fully Learned stimuli). Each of the 3 Fully Learned stimuli will be produced 60 times. | Behavioural | Sub-syllabic learning and anodal tDCS of cerebellum, Sub-syllabic learning and anodal tDCS of inferior frontal sulcus, Sub-syllabic learning and sham tDCS |
| Learning of novel multisyllabic nonwordsEach trial of the training sessions (total of 6 training sessions over 2 days) will follow a simple reaction time protocol in which a nonword stimulus formed by 2 or 3 syllables that are legal in American English is presented auditorily to the participant, who then produces the stimulus as quickly and accurately as possible. During training, each participant will repeatedly produce 6 nonwords, with each nonword produced a total of 60 times over the 6 training sessions. | Behavioural | Multisyllabic learning and fMRI in adults, Multisyllabic learning in children |
| Anodal tDCSContinuous anodal tDCS is delivered to a speech processing area of the brain during a 19-minute speech training session. The tDCS stimulation will ramp up to its maximum value (2 milliamperes) in the minute prior to the training session and maintained at that level throughout the session. | Other | Sub-syllabic learning and anodal tDCS of cerebellum, Sub-syllabic learning and anodal tDCS of inferior frontal sulcus |
| Sham tDCSSham tDCS stimulation is delivered to a speech processing area of the brain during a 19-minute speech training session. During the minute prior to training onset, the tDCS stimulator is ramped up to 2 milliamperes and then back down to 0. | Other | Sub-syllabic learning and sham tDCS |
| Learning of non-native phoneme combinations: 8 training sessionsEach trial of the training sessions will follow a simple reaction time protocol in which a nonsense syllable containing novel consonant clusters (e.g., GDADK) is produced as quickly and accurately as possible after an auditory prompt presented via earphones. During each training session, the participant will practice producing a set of 3 stimuli (the Fully Learned stimuli). Each of the 3 Fully Learned stimuli will be produced 120 times over the 8 training sessions. | Behavioural | Sub-syllabic learning in PPA |
Primary outcome
Change from baseline in production error rate
Time frame: Evaluated at Baseline and immediately following intervention
Investigators will compare mean error rates when producing newly learned speech sequences versus novel speech sequences of the same length in each arm. This measure will be used to test hypotheses regarding speech motor learning and brain activity and how these compare in persons with persistent developmental stuttering and persons with neurotypical speech.
Change from baseline in utterance duration
Time frame: Evaluated at Baseline and immediately following intervention
Investigators will measure changes in utterance duration before and after speech sequence training to test hypotheses concerning differences in the neural mechanisms responsible for speed/duration improvements compared to improvements in accuracy (i.e., reductions in error rate).
Change from baseline in reaction time
Time frame: Evaluated at Baseline and immediately following intervention
Investigators will measure the time interval between the prompt to begin speech and the subject's speech onset. Mean reaction time will be compared for learned and novel nonwords in persons with persistent developmental stuttering and persons with neurotypical speech.
Percentage of words stuttered
Time frame: Evaluated at Baseline and immediately following intervention
Investigators will compare the percentage of words stuttered under different experimental conditions. This measure will be used to test hypotheses regarding the effect of speech motor learning on stuttering rate and the relationship between stuttering rate and brain activity.
Brain activity measured with functional magnetic resonance imaging
Time frame: Evaluated at Baseline and immediately following intervention
Investigators will measure blood oxygen level dependent (BOLD) brain activity when producing speech utterances in different experimental conditions in adults with persistent developmental stuttering and those with neurotypical speech.
5 secondary outcomes
Cortical white matter connectivity
Time frame: Evaluated during the MRI scanning procedure
Cortical morphometry
Time frame: Evaluated during the MRI scanning procedure
Working memory test scores
Time frame: Evaluated at Baseline
Forward digit span
Time frame: Evaluated at Baseline
Stuttering Severity
Time frame: Evaluated at Baseline
Results and safety
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 24 Jul 2026.
- Individual participant dataSharing planned: No
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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. This study is not recruiting at the moment.
Frank H Guenther, PhD principal investigator
Boston University
Soo-Eun Chang, PhD principal investigator
University of Michigan
3 sites in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing Learning of non-native phoneme combinations: 6 training sessions, Learning of non-native phoneme combinations: 1 training session and Learning of novel multisyllabic nonwords in people with Stuttering, Developmental and Aphasia, Primary Progressive, run by Boston University Charles River Campus at 3 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 10 inclusion and 6 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: finished, as of the sponsor's last update on 24 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 3 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. Some participants in this study may receive a placebo. 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?
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
How can a doctor refer a patient or contact the research team?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Change from baseline in production error rate (time frame: Evaluated at Baseline and immediately following intervention). The study lists 5 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 24 Jul 2026.