Speech Movement Variability in People Who Stutter: A Vocal Tract Magnetic Resonance Imaging Study.

The study included only adults with developmental stuttering who had at least mild severity, so it does not tell us what happens in children or in people with other speech or neurological conditions. The analysis used repeated pseudowords inside an MRI scanner, not connected speech or everyday conversation, so it may not show how these movements behave during real communication. The MRI method sampled movement at 33.3 frames per second and did not use a carrier phrase, which the authors say made timing of very short words less precise and may explain the unexpected high variability for the one-syllable word. The pseudowords were mostly bilabial sounds, so the soft palate had limited movement to make, and the task may not represent a full range of speech sounds. Nearly all participants had prior speech therapy, but the type and duration varied, and the researchers could not separate the possible effect of earlier therapy from the movement measurements. Many people who stutter had variability scores within the range of fluent controls, so this pattern is not a clean diagnostic marker.

The work was supported by UK research councils and the Wellcome Centre for Integrative Neuroimaging. Charlotte Wiltshire was supported by an Economic and Social Research Council UK DPhil scholarship and an Engineering and Physical Science Research Council UK scholarship, Mark Chiew by the Royal Academy of Engineering, the study by the Medical Research Council UK, and the Wellcome Centre by Wellcome Trust core funding. The supplied text does not report other conflicts of interest.

Do not treat greater movement variability as a diagnostic sign of stuttering or as a measure of severity. Many participants who stutter had variability within the fluent control range, and no relationship was found between variability and SSI-4 score.