Someone recently remarked that he was getting an extra pitch while he played. This can happen when your chops are not set correctly and/or you have not balanced the needs of the pitch (and your embouchure) with the amount of air support necessary. This used to happen to me in college marching band when I was really tired. Now I can reproduce it for a demonstration (but it's very uncomfortable to do so). To do this I place the mouthpiece slightly off-center on my chops, then I can force this to happen. This produces the intended pitch plus a softer note one octave lower. It's caused by the chops vibrating inconsistently across the part that is inside the rim of the mouthpiece.


If this shows up in your playing, I would start by looking at how you warm up. Be very careful with the placement of your mouthpiece on your chops. Then during your warm-up, start out in a very comfortable range and gradually work toward higher and lower notes. Start at a medium volume, then do a little work at softer volumes, then at louder volumes. As you do this, always focus on producing a full, pure tone on every note. This will help get you "set" properly. Even if you do this studiously, once you are playing in an ensemble or practicing a difficult etude, the stresses may cause the extra pitches to return now and then. But it should be less troublesome with time and careful practice.