Effects of speaking rate, loudness, and clarity modifications on kinematic endpoint variability.
Antje S Mefferd
PMID 30668156WHAT IT FOUND
In 17 typical talkers, jaw endpoint variability was larger during loud speech than typical speech, while slow speech showed a similar trend but was not clearly different.
Tongue endpoint variability did not change across rate, loudness, or clarity.
Key findings
01Jaw endpoint area was significantly larger during loud speech than typical speech, and slow speech tended to produce a larger area than typical speech.
02Tongue endpoint area showed no significant task effect across typical, slow, clear, and loud speech, although slow speech tended to be larger than the other conditions.
03Jaw endpoint spread was significantly smaller during typical speech than during loud and slow speech, while tongue endpoint spread showed no significant task effect.
STILL TO COME
How it was doneWhat they foundWhat it means for SLPs
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What it does not show
Only 17 of the 31 completed participants were analysed, because 14 were excluded for sensor malfunction, reduced kinematic accuracy, or head movement correction failure. The participants were young typical talkers with mean age 22.8 years, so the findings do not show how older adults or people with motor speech disorders respond. The outcome was kinematic endpoint variability, not speech intelligibility, listener perception, or clinical improvement. Only a single sentence and two movement endpoints were studied, and tongue movements crossed a word boundary. The speech modifications were cued without a practice period, and precision demands were not explicitly defined for slow speech. The study measured endpoint variability in only two dimensions of the sagittal plane.
Declared interests
No author conflict-of-interest declaration appears in the supplied text. The publication types list research support from NIH extramural funding and non-U.S. government funding.
The easy way to misread this
Do not conclude that speaking slower, louder, or clearer improves articulatory control in patients. This study tested typical adults and measured movement scatter, not speech intelligibility; jaw endpoint variability was greater during loud and slow speech, and tongue endpoint variability did not change significantly.