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.