I made a post a while back entitled “Getting up there”, and I’m happy to say that my high range has improved since then!! At least when I’m fresh (so daily routine time window), I can consistently get “up there” and I’ve been even getting double Bb’s! However, I’ve noticed that, especially as the day goes on, my ability to access my high range decreases and gets a very scratchy or airy tone quality. I’ve also noticed this problem when practicing 3 octave scales and whatnot for periods of 15+ minutes. Any suggestions would be appreciated, thank yall!

Your problem is called "fatigue" and the solution is to slowly build up your strength. Lots of us use long tones for this purpose. Also, when you are tired STOP PRACTICING. If you are in the middle of a gig, try to get through as best you can.

It's all about the air and the support. When that starts to go the chops and endurance starts to go. And Bruce is absolutely correct: when you get tired, stop practicing...it's pointless to practice the errors! On a gig try to get the horn off your face as much as you can get away with and take DEEP RELAXING BREATHS. Then do you best!

this video is supposed to be about embouchure, but will explain breathing, too

<YOUTUBE id="LMmJi6ssErc">https://youtu.be/LMmJi6ssErc</YOUTUBE>

I've returned to the horn in recent months after a 15 year hiatus. As I've started to increase my practice time I've noticed after about 2-3 hrs of playing my air support starts to get lazy. If I'm not mindful, I will fall out of proper form and start crutching through music with poor technique. Body posture will become lazier as well. Hips will slump forward, chest/shoulder will collapse - these are very subtle, not as if I'm losing 2" of height.

To the same effect, regardless of practice time that day, after about 8pm I start to notice similar issues. Fatigue sets in, mental and physical. I try to do more listening along with sheet music, marking music, singing/humming/buzzing .. positive things that don't require the entire body or instrument. I try to slow my whole process down to make sure I'm not falling into bad habits, or I just call it a day on the instrument, hydrate, and rest.

My high range ceiling isn't near what yours is, but it's definitely noticeable when my body becomes tired. I won't necessarily feel sore anywhere on the body, but I can tell I'm not passively engaging my air support. I will lose the musical peak of my high range, sometimes struggle to finish the whole note at the end of the etude, notice I need to take unusually timed breaths in familiar music, etc.