Effects of Increasing Vocal Tract Insertion Depth in Semi-Occluded Vocal Tract Exercises on an Excised Canine Model.
Jakob R Holm, Sylvia Green, Tomas K Gilvydis and 4 others
PMID 39848849WHAT IT FOUND
Inserting a straw into the mouth reduces the pressure needed to start phonation.
However, pushing the straw deeper into the vocal tract does not provide any additional benefit compared to a standard shallow insertion.
Key findings
01Using a semi-occluded vocal tract straw significantly lowered phonation threshold pressure compared to no straw.
02There was no significant difference in phonation threshold pressure between a shallow (20 mm) and deep (60 mm) straw insertion.
03Phonation threshold flow did not change significantly with any straw insertion depth.
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 excised canine larynges, which cannot replicate the neuromuscular control, tissue health, or anatomical variations of living human patients. The sample size was very small, consisting of only five larynges. Vocal fold tension was not directly measured or controlled, which is a key variable in human voice production. The study only tested two specific depths (20 mm and 60 mm) and may have missed optimal depths between these points.
Declared interests
The authors declared no conflicts of interest.
The easy way to misread this
Do not apply these findings directly to human patients. The mechanical properties of excised canine tissue differ significantly from living human vocal folds, and the lack of benefit from deeper insertion in this model does not prove it is ineffective in clinical practice.