Validation and Evaluation of the Effects of Semi-Occluded Face Mask Straw Phonation Therapy Methods on Aerodynamic Parameters in Comparison to Traditional Methods.
Randal Mills, Cameron Hays, Jehad Al-Ramahi and 1 others
PMID 27210476WHAT IT FOUND
Adding a face mask to a tube and airflow system did not change the pressure and flow needed to start vocal fold vibration in excised dog larynges.
It may allow continuous speech, but that was not tested in people.
Key findings
01In excised canine larynges, adding the face mask did not significantly change phonation threshold pressure or phonation threshold flow compared with the tube alone across all constriction and extension conditions.
02Varying constriction levels significantly changed phonation threshold pressure and phonation threshold flow, while varying extension levels at least trended toward significance.
03Oppositional airflow did not raise supraglottal pressure except at the 6.5 mm constriction, where it was 0.35 cmH2O with the mask and 0.41 cmH2O without it.
STILL TO COME
How it was doneWhat they foundWhat it means for SLPs
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What it does not show
The study used 30 excised canine larynges, not human patients, so it cannot show what happens in a living person's voice. It measured only phonation threshold pressure, phonation threshold flow, and supraglottal pressure, not voice quality, comfort, effort, or connected speech in people. The mask's proposed benefit, allowing continuous speech, was not tested in humans. The pressure transducer was accurate only to ±0.1 cmH2O and could not measure pressure directly at the top of the vocal folds, which may explain why supraglottal pressure changes were hard to detect.
The easy way to misread this
Do not conclude that face-mask straw phonation improves voice or reduces vocal effort in patients. The study tested only excised dog larynges with a tube and continuous airflow, and measured the pressure and flow needed to start vibration, not human speech, comfort, effort, or voice outcomes.