Quantifying articulatory impairments in neurodegenerative motor diseases: A scoping review and meta-analysis of interpretable acoustic features.
Hannah P Rowe, Sanjana Shellikeri, Yana Yunusova and 2 others
PMID 36001500WHAT IT FOUND
Vowel dispersion and stop gap duration showed the largest differences between speakers with neurodegenerative motor diseases and controls.
However, most research focused only on articulatory precision, leaving gaps in understanding coordination, consistency, speed, and repetition rate.
Key findings
01Vowel dispersion/distance and stop gap duration had mean effect sizes greater than 1.5 across all disorder groups, while second formant duration and first spectral moment coefficient had mean effect sizes smaller than 0.6.
02Articulatory precision was the most represented component in the literature (190 occurrences), while consistency was the least represented (37 occurrences).
03Different diseases showed different patterns of impairment: ALS primarily impaired precision, ataxia impaired repetition rate, Huntington's disease impaired consistency, and multiple sclerosis impaired coordination.
STILL TO COME
How it was doneWhat they foundWhat it means for SLPs
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What it does not show
The analysis did not control for speech severity, meaning differences between disease groups might reflect severity rather than the specific disease type. The review did not control for medication use, though the authors note recent work suggests Levodopa has little effect on speech performance in Parkinson's disease. Most included studies were cross-sectional, so the stability of these acoustic features over time is unknown. The focus was limited to the articulatory subsystem, excluding phonatory, respiratory, and prosodic features which may be more impaired in early disease stages. Effect sizes were combined regardless of directionality, and confidence intervals could not be calculated for every mean due to limited data points.
Declared interests
The authors report no conflicts of interest.
The easy way to misread this
Do not assume these acoustic features are ready for clinical diagnosis or differential diagnosis. The findings are preliminary because speech severity was not controlled, and the authors explicitly state they could not make specific recommendations for the most promising feature for each population due to limited data.