Optimizing Diameter, Length, and Water Immersion in Flow Resistant Tube Vocalization.
Ingo R Titze, Lynn Maxfield, Karin Titze Cox
PMID 36357237WHAT IT FOUND
Narrowing the tube diameter raises oral pressure far more effectively than lengthening it.
Submerging the tube in water adds pressure directly equal to the immersion depth in centimeters. A 2.5 mm tube at 20 cm length with 10 cm water immersion can reach 40 cm H2O.
Key findings
01Reducing tube diameter is much more effective than increasing length for raising oral pressure and resistance.
02Submerging the distal end of the tube in water adds hydrostatic pressure directly to the oral pressure, equal to the depth in centimeters.
03High-resistance training using a narrow, long tube with 10 cm water immersion can raise oral pressure to 40–50 cm H2O.
STILL TO COME
How it was doneWhat they foundWhat it means for SLPs
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What it does not show
Airflows were not measured during human subject phonation, only estimated. The study included only eight subjects, limiting generalizability. There was no attempt to obtain exact point-by-point pressure comparisons between different tube dimensions due to unmeasured airflows.
The easy way to misread this
Do not assume that all patients will respond identically to water immersion. The study found that females did not gain any additional pressure from water immersion during loud phonation, whereas males did, suggesting individual variation in how the intervention affects oral pressure.