Characterization of Primary Muscle Tension Dysphonia Using Acoustic and Aerodynamic Voice Metrics.
Adrianna C Shembel, Jeon Lee, Joshua R Sacher and 1 others
PMID 34281751WHAT IT FOUND
Standard acoustic and aerodynamic voice tests could not distinguish patients with primary muscle tension dysphonia from those with other voice disorders.
There was substantial overlap in results between the groups, meaning these metrics alone are not reliable for diagnosis or for selecting research participants.
Key findings
01Acoustic and aerodynamic metrics showed substantial overlap between patients with pMTD and those with other voice disorders, regardless of the statistical method used.
02Even the most important parameters identified by modeling accounted for only 65% of the variance in the data.
03Cluster analysis placed the majority of pMTD patients in a group that also contained patients with organic, neurological, and structural voice disorders, showing these metrics cannot separate diagnoses.
STILL TO COME
How it was doneWhat they foundWhat it means for SLPs
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What it does not show
The study was retrospective, relying on data collected during busy clinical days, which introduces potential for input errors and variability in how tasks were elicited by different speech-language pathologists. Sound pressure level (SPL) was not directly calibrated prior to each voice evaluation, although equipment and distance were kept consistent. The vocal tasks used (sustained vowels, simple sentences) may not have been challenging enough to reveal the specific deficits in pMTD, which often appear under higher vocal demand. The analysis excluded patients who did not have complete data for all 15 metrics, which reduced the sample size from 92 pMTD patients to 65.
Declared interests
None of the authors have a conflict of interest to declare.
The easy way to misread this
Do not interpret the lack of distinct clusters as evidence that pMTD patients have 'normal' voices. The study suggests that standard clinical tasks may not be sensitive enough to capture the physiologic effort or fatigue characteristic of pMTD, rather than proving the voice output is indistinguishable from healthy controls in all contexts.