Vocalization with semi-occluded airways is favorable for optimizing sound production
Fig 5
Expansion of the minor diameters of the elliptical glottal sections with 2.5 kPa lung pressure and 3.0, 4.0, 5.0, and 6.0 mm tube diameters at the mouth.
The vertical to horizontal aspect ratio is 6.67 (5 sections have 8 mm length).