Hornguy, there are many functioning combinations. With Dizzy, he in fact has a huge oral cavity, but the blown out cheeks may be a stiffer outside wall, which could compensate OR his chops were strong enough that the added inefficiency was not of consequence. WE have to be careful assuming that the valid technical explanation suggests a universal solution - it doesn't. My only point is that when we are playing, that there is no such thing as fast air (considering the physics of a trumpet, it can't even exist at pressures our body can generate). What does exist is air pressure in front of and behind the lips. When that is in sync, we have better high chops!