I posted this originally about 3 years ago, but wanted to re-post for the benefit of those who are new to the thread. Don't screw around with your ears, folks... wear earplugs, even in relatively 'quiet' settings. Maintain your ears the way you (should) maintain all your other equipment.
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I've shared my story before, but this thread brought it out of the coffers of my mind again. When I first started playing music over 15 years ago, I did my first jam session in a drummer friend's basement. The guitarist brought a small combo in and proceeded to crank it... this one of the first formal jam session experiences I'd ever been a part of so I had no idea what to expect. My ears hurt from the first few notes we played, and I spent half the session tapping my notes on the fingerboard so I could keep one hand over one ear, and my other ear buried in my shoulder. No one would turn down, no one had any earplugs. Each cymbal crash and guitar line felt like a knife going into my eardrum. I stuffed some toilet paper in my ears to help calm things down, but it did little to help. The session ended soon after. BUT, I learned my lesson.
After that ONE session I vowed never to practice or gig in any situation without ear protection, or without having it readily available. A drummer I work with regularly wears custom plugs and our rule of thumb is that if the volume gets uncomfortable for us wearing 'hi-fi' filters, it's *past* time to turn down. That rarely happens, though. Also, never forget to bring your earplugs to concerts that you are attending either... I can't go hear 99% of live gigs without needing my plugs. What's 'comfortable' or 'normal' for other folks is painful and damaging to those who regularly use hearing protection.
So, fast-forward to 15 years later and after using hearing protection on tons of gigs in various genres (even 'quiet' jazz gigs), my hearing is nearly as good now as it was then. I used foam earplugs for the longest time but finally got some proper 'musician's earplugs', the Hearos Hi-Fi plugs. I always suggest these to my musician friends. If you can't afford custom plugs, I say go with these. They are usually around $12-15 for a set and last a good while. I've gone through 4 pairs in 4 years... not bad for the money. Plus, you can disassemble and clean them.
In short, if you are a musician, you need earplugs. Wear them even when you don't think you need them... and especially wear them during sound check when mics are moving and levels are getting tweaked. You never know when that blast of banshee feedback will happen.
All the ego-centric guys out there who think plugs are 'un cool' or think they take away from the music are missing one very important point... if you can't HEAR, you can't make music!