Always use hearing protection (earplugs) when at a concert or a club playing loud music, when cutting grass, when using a blower or electric power tools, and for sure when shooting a gun. Any situation where a continuous 100db sound is present.
Also, don't listen to music over 100dbs for long periods of time. OSHA recommends no more than 1 hour @ 105dbs. I would NEVER go more than 20 minutes straight at 105dbs, if that. Also, be careful with ibuprofen and prescription drugs.