Effects of Age and Parkinson's Disease on the Relationship between Vocal Fold Abductory Kinematics and Relative Fundamental Frequency.
Jennifer M Vojtech, Cara E Stepp
PMID 35393167WHAT IT FOUND
Speakers with Parkinson’s disease had lower RFF and longer vocal fold opening, but the RFF difference was not explained by group differences in vocal fold opening.
Age did not track RFF, so RFF is not just an abduction measure.
Key findings
01In adults with typical voices, older age was associated with smaller glottic angles at voicing offset, but not with RFF or abduction duration.
02Speakers with Parkinson’s disease had more negative RFF at voicing offset cycle 10 (−2.04 ST) and longer abduction duration (67.4 ms) than age- and sex-matched controls (−1.27 ST; 53.9 ms), while glottic angle was similar.
03In the model that included age, sex, glottic angle and abduction duration, glottic angle and abduction duration were significant predictors of RFF, but Parkinson’s disease group was not.
STILL TO COME
How it was doneWhat they foundWhat it means for SLPs
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What it does not show
The study is observational, so it cannot show that vocal fold abduction causes changes in RFF. The samples were small and limited to adults with typical voices or idiopathic Parkinson’s disease, so the findings may not apply to other voice disorders. A large portion of productions was rejected during processing, and in Experiment 1 female speakers had more missing or unusable productions than male speakers. The Parkinson’s group was on usual carbidopa/levodopa medication, and deep brain stimulation devices were turned off during recording, so the results do not show untreated Parkinson’s disease. Laryngeal muscle tension was not directly measured, so the authors could not confirm whether tension explains RFF differences. The analysis focused on RFF at voicing offset cycle 10 during /ifi/, so it may not generalize to other utterances or other points in the offset.
The easy way to misread this
Do not conclude that a lower RFF in Parkinson’s disease is caused by vocal fold abduction. The Parkinson’s group had lower RFF and longer abduction duration, but the model showed the group difference in RFF was not explained by group differences in abduction, and tension was not directly measured.