I've had this same problem for years and never mentioned it to anyone because I thought it made me a "crappy musician" since, during practice, I couldn't always differentiate from Low E till about F#. I just joined a band last week (first time in 5 or so years) and I just mentioned it to the guitarists and they said "No problem. We'll just tell you what note(s) when we're playing down that low. Teamwork is wonderful I also have a bad case of tinnitus, had it since my first concert (Ozzy) when I was 16 (28 years ago). However, when I had my hearing checked a few years back, the doc said all was well as far as my hearing spectrum. Go figure. Another odd thing I've encountered from time to time is if I sit too close to my practice amp (a 15watt) which isn't on too loud but I'm playing very low notes and there is a lot of sympathetic vibration going on, an the sound waves are reverberating around me, I get a mild case of dizziness. Weird. Anyone else have this???