I am trying to increase my range on the trombone. I noticed that when I play notes that push my range, my bottom lip moves toward my throat and creates a larger opening for air. Is that normal, or should I avoid that?

that seems like a drasic adjustment. you definatly want to limit shifts in your embeshure as much as posible. all i can advize is to think of saying "ooo" as you go higher. this will cause you to put more lip into the mouthpiece in a round shape and will hopfully discuarge adding presure. also, focus on faster, more direct air. if you do this it will hopfully keep you from going into strange adjustments

The only difference between high notes and low notes is the speed of the air passing the lips. High speed = fast vibration. Low speed = slow vibration.

When we work on pp playing, the aperture is small.
The opposite applies for ff playing.

When we work on high playing, the aperture is small.
The opposite applies for low playing.

If your lips are opening wider for high notes, you are probably creating tension somewhere else to get the speed of the air fast enough to play the notes.

The best way to control and train in your situation (without seeing and hearing you play), is to practise Clarke studies in a whisper.

Good luck!

BrassMusician.com - The online magazine for brass players