Hi !
well, it was my understanding that at certain point, in the upper register actually, it is not necessary that the air stream has to be straight in the mouthpiece. I think it’s more about the concept of airspeed and how the energy is transferred to the mouthpiece.
In a recent video of John Snell at Bob Reeves Mouthpiece, he also shows that blowing in a mouthpiece with a hole that makes the air not travel into the leadpipe does make a trumpet sound. Well, a bad one. But a sound anyway. As in the upper register there is little air involved, I’d say that it’s not the direction of airstream that makes you fight the instrument.
I guess it’s more the aperture and aperture corner and the energy you put into the mouthpiece that makes you feel bigger resistance, and maybe too much.
I’d love to hear what Greg has to say about it. In a recent video, he’s also pointing out a woman that her airstream is not straight when doing the exercise of blowing a piece of tissue.
But that is at a big aperture. I think airstream direction does play a bigger role at the lower and medium range, but the higher you get, maybe the less important it is.
But I can be totally wrong 😀