Sometimes, when I`m playing my clarinet, some of the air comes out of my nose, instead of my mouth. I can still play, for a while, but eventually I can`t get enough air to go into the horn because it`s all coming out of my nose. I can`t make it stop, and after a while it really gets to be annoying. Has anyone else had this problem? Any advice?

Okay, wow. I have never heard of this before. All I have to say is that is crazy! lol

Its something that your body does naturally and involves your epiglottis.

I suggest that you either:

a. Find a speech and language therapist to give you some exercises to help you control this problem
b. Talk to your doctor for exercises (though they probably will refer you to the above)
c. Stop when you find this happening - take a rest, swallow, drink something etc.

Chances are the reason why you`re finding its occurring is that you may have weak muscles in your throat, and with the forced back-pressure of the clarinet, the glottis just gives way.

Ok spoke to a few medical staff yesterday regarding this (its good having a physio as yer gf!).

Seems that the process for directing air either through the mouth or nose is directly linked to tongue position.

It probably sounds that you need more practice developing embouchure, or just giving it a rest when it occurs, slowly developing muscle tone.