Manny- I have a student I'm switching over to horn. He's experiencing some jaw pain where the lower jaw hinges on the upper jaw. He also mentions that he gets pain there after about 2 hours or so on trumpet (after festival rehearsals). I have my suspicions, but want to check what you say to see if I'm right. As a side, he has always had some articulation problems...sounds almost like he uses an L instead of "tooh"...it's been imporving over time with a steady diet of Arban.