TubeNet

Have your MD check your ears. You may have a blockage in the inner ear or eustacheon tubes that causes swelling, thus aching ears,when practicing. Your inter-oral pressure may be out of whack (choking off your air causing air to be routed into the nearerst open space) but that is a long shot. You may also be suffering from sinus problems. Playing may be swelling the sinus cavities enough to put pressure on your ears. Oddly enough, before I had my sinuses routed out, my teeth would hurt after playing too much. Good luck, consult a Doctor before you do some damage.

Chuck

I thought that I had an ear infection/sinus problem and it turned out to be my jaw being out of wack. Go see the doctor...it could be a number of things, and he/she will be able to figure it out quite quickly or send you to someone who can. Good luck!

Cassi

Paul M wrote: Now I've tried ear plugs, but that kills any ability to hear my sound and also leads to a lot of pressure in my sinuses which doesn't feel too good. Any advice?

You may want to try "Musician's Earplugs" which give a much clearer sound, just lower dB. My favorite is:
http://www.etymotic.com/ephp/er20.aspx
You can also try just putting an earplug in the ear on the bell side of the tuba. That should help sompe with the pressure problems.