I work as salesman of instruments for measuring everything related to health and safety. Some weeks ago I took a measure of noise with a soundmeter in the rehearsal room. The instruments played were drums, 2 amp heads and 4x12 cabs for each, bass amp. No vocals that day. This is what got registered in 1 hour. Laeq: 107,5 db (this is the average) LCPeak: 135,2 db (this is the peak) Lepd: 98,1 db (this is the diary level, hard to explain in a thread, in some countries is called TWA) Dose: 6.530,2 % (limit of the dose is 100%, this dose was reached within only 1 hour of measure) Projected Dose: 55.621,4% (this is the theorical dose for 8 hours at this level) 87 db is the highest limit in spanish legislation and most European countries (some are 85db) for jobs and workspaces. So, this is unacceptable and it is highly recommended to use earplugs to prevent hearing loss. I use 3M reusable protectors that can attenuate up to 25db, even with this it is harmful to rehearse everyday for some hours. Every year I do audiometries to check my hearing and fortunately I am ok but some musician friends have 30% of hearing loss for not taking care of their ears. I know many people in this forum spends thounsand of hours rehearsing, playing live, in studio so that is why I considered a good idea to post this thread. If you want to simulate a hearing loss, listen to the audio clip in this site. Amazing. http://www.hse.gov.uk/noise/demonstration.htm Another important thing to know is that hearing never recovers or improve. So, watch out, beware of the noise, beware of Manowar shows in first row, use plugs, be happy, fuck as much as you can and never trust a nun.