Things have been slowly improving for me.
Yesterday and the day before, I made it a point to check to see if my lips were buzzing as I was playing–especially during my warm up. It seems when they are actively buzzing around G on the staff (or around there), I have a bad sound, bad sensations, etc.
It seems that checking every so often and opening up the aperture when needed, helped me have a better sound and better sensations and seems like it’s helped me move forward–back towards where I was in December.
I still don’t think I’m back to where I was but in some ways things seem even better–I’m able to do lip slurs higher than before. And a resonant sound is coming back; I still don’t have quite the sensation of ease that I recall from before, but it’s improving.
It’s not clear to me if we’re not supposed to be actively buzzing throughout most registers, or just to a certain point. It seems like I can’t play middle C on the staff without buzzing in the mouthpiece.
Also, it seems that playing just the mouthpiece by blowing relaxed through it with the ahh-oohh sensation (kind of a pucker), then bringing in the corners to ascend then relexing the corners to descend, allowing the middle of the lips to buzz without pinching the middle together, gives me really good focus/sensations when putting the mouthpiece back in the horn–it seems like playing higher with a better sound is easier.
Was thinking some long tones might do me some good–including going up as high as I can.