Here’s a video that bass trombonist Denson Paul Pollard posted to YouTube about high and low range. He talks a bit about air stream direction, breathing, and relaxation. Take a look and see if you can guess his embouchure type. My guess after the break.
Pollard isn’t clear about how he knows his air stream is directed downward as he plays, but based on his mouthpiece placement (which determines the air stream direction) I would say it’s very likely he’s a downstream player. He plays with a lot more upper lip inside the mouthpiece.
His embouchure motion is a little inconsistent, but this is something you sometimes see, particularly in the extreme ends of a player’s range. For the most part, Pollard pushes his mouthpiece and lips together up to ascend and pulls down to descend. However, when he gets to around Eb above high Bb he reverses the direction of his embouchure motion and starts pulling back down to ascend. This is somewhat common for “very high placement” embouchure type players in the extreme upper range, perhaps because the player is going too far with the ascending embouchure motion in the first place and needs to reverse the direction to put the mouthpiece and lips together in their proper position along the teeth at a particular point in their upper register. Personally, I prefer to try to keep the direction of the embouchure motion consistent throughout the entire range by fine tuning the amount of push/pull so that this reversal doesn’t happen.
As an aside, I have a similar issue that I have to Pollard, except this tends to happen to me in the low register. I have a habit of pushing up too far to descend to low Bb and when I do I have to pull back down to ascend to pedal Bb. I have a different embouchure type and a different direction of embouchure motion, but you can catch me doing this in the video here.
My best guess is Pollard has a “very high placement” embouchure type, in spite of the reversal of embouchure motion direction at his upper register. What did you think?