this is my new pet hypochondriac obsession (last year i thought my teeth might be about to crumble, but i think tinnitus is more probable).
i don't tend to be aware of ringing during the day, but once in bed, when everything else has gone quiet, i'm very aware of ringing and lower frequency noise in my ears. i'm not sure what to attribute it too though. i know i have some music-related ear damage, especially in one ear, but i've also read that body noise (blood flow, etc.) and neural noise (the actual sound of your neurons firing, especially during periods of high stress) become audible in quiet surroundings (unbearably so in an anechoic chamber).