I've noticed at my trumpet lessons alot of times if I'm playing an Arban excercise that is page length, maybe about 1/2 way down the page my tone starts getting a little airy. This is what happened with my solo at solo+ensemble. I'm not sure if it is just my lips being tired from playing things before these pieces or if it is endurance, but are there any thoughts as to how to best go about being able to keep my good tone I have throughout the piece? My instructor just stops me some in the middle of these excercises for a little bit and continues on, but I don't feel like this is helping improve my abilities at all. Edit- I feel fine most of the time getting through these passages, just the tone gets lost a bit sometimes. It could very well be endurance issues too, because sometimes when this happens it grows untill the end when my lips just feel like crap and can't realy play anything well. However, a fair number of times I don't have any problems getting to the end, just somewhere I loose some of my tone for the 2nd part of the passage.