This whole conversation is at once interesting, tough to absorb, and confusing. Please indulge me in a few questions, that if answered will help me - if no one else. 1. Lip "tension" if you will, there are a few ways to accomplish this - opposing force top to lower lips (think tight corners, perhaps even tight near the aperture), curling lips over the teeth, supposedly a slight pucker in the lip, but that seems a contradiction, and "stretching the lips" by making a kind of smile. The lips are the guitar string if you will, that are vibrated, and ultimately define the pitch. 2. Pressure - ostensibly to make a seal, but also, I think sometime used to help increase the tension of the lips. 3. Air velocity - the subject of this thread - it seems is a function of (and it's been a while since physics), pressure - internal and external, the volume of the source, and the shape/volume of the various cavities. As the volume of the cavity y goes down, or there is a restriction of volume at an aperture, there is a pressure differential from one side to the next so the fluid (air) speeds up even while the volume goes down. 4. In order for the tongue to affect the volume of air, would not you need to have a seal between the tongue and the lower portion of the mouth? If there is no seal, it's possible that more air gets directed into one portion of the oral cavity then the other, and those opposing forces come together at the edges of the tongue, or right behind the aperture. It seems like the tongue "shapes" the air column more than changes the volume/speed. As previously mentioned, it is possible to raise/lower the tongue without changing pitch or pressure (as applied by chest/back muscles/no more "push). 4A (edit) When we say oh - eh - oh, there are a lot of things changing besides the tongue as far as the muscular structure of our face is concerened - could we be changing the tension of the lips (see item 1) the shape of our lips (ever so slightly), changing the elasticity of our lips (I am leaning toward this one), or something else??? So then, the question is, what percentage do you think each of these play in this, or where are the faults in my analysis?