QUOTE(nic @ Mar 28 2008, 10:36 PM)

If I were biting I imagine my teeth/jaw would feel sore? (which they don't).
Hi nic,
You could be squeezing your embouchure though and that can make the intonation sharp. I think people can subconsciously increase their embouchure pressure for the higher notes, but it shouldn't need to change at all. Also make sure that you are not over blowing. The air flow should be steady and controlled - not like you are blowing out candles.

(Seems to work with my students). Have a go at the following exercise, initially using notes you are more comfortable with - maybe middle B, A and G.
*Start a steady air flow with no embouchure pressure on the mouthpiece. This means there is no air seal and you should just get a hiss of air.
*Gradually tighten the pressure equally around the mouthpiece (think of a circle) and you start to hear a note.
*Keep tightening slowly until you hear a good clear note (with a good tone). To get to this you should hear a note increase in pitch as you tighten the embouchure.
*You may find that the embouchure pressure to achieve a good tone is less than you have been using.
*Try it with a lot of different notes including your middle D. You may find this helps with the tuning.
*Remember not to increase embouchure pressure for the higher notes.
Good luck. Lucid