I agree with David. Have your hearing checked by a hearing professional; not the family doctor. And I think David might have a point about the psychological effect as well; I too don't normally notice the noise in my ear anymore.
I was playing in a loud two guitar band. When my ear started ringing, I had my hearing checked. I have significant high end loss in both ears and low end low in one ear. After they checked my hearing, they put molds in each ear and I had them order custom fitted ear plugs with interchangable filters. The type I ordered were specifically for musicians. The different filters have different levels of db cut. They were very effective with the band; those loud piercing guitars were under control. But the downside was that they significantly affected the tone I was hearing from my rig. The great tone I was getting from my Alembic and my rig was now flat and lifeless. So I told the guitar players I wasn't going to play anymore if they did not turn down. That worked much better than the ear plugs. At the lower sound level, I did not need the ear plugs, the sound was better, and the added bonus was that we could all hear each other better; thus the quality of our playing improved.
I think the straw that broke the camel's back for me was feedback. One night the guitar player was EQ'ing the PA and let loose a piercing high end feedback that was physically painful. And a lifetime of such occurances takes its toll. I think that anytime you go to a concert, or to see a band at a bar, or to play at a venue or rehearsal, and subsequently have ringing in your ears, then you've mistreated your ears. When you think about it, it would seem to make sense that a musician would value his hearing. But then I subjected my ears to such abuse for a very long time and did nothing until the damage became obvious.
So I suggest: have your hearing checked, be accepting of the current state of your hearing (the psychological factor), tell the guitar player that you will no longer be able to play with him if he insists on playing at unreasonably loud sound levels, and avoid putting yourself in situations where your ears could be further damaged.