A good “rule of thumb” for determining if your work area or activity requires hearing protection is as follows. If you have difficulty hearing or understanding a “normal” tone of voice at a distance of about three feet (90 centimeter), noise levels are probably exceeding safe levels and you should be using hearing protection. Many activities and tools require the use of hearing protection. This includes, but is not limited to, lawn mowers, tractors, leaf blowers, weed trimmers, chain saws, concrete saws, concrete/hammer drills, snow blowers, power saws, working near running chillers, etc. Firearm uses ALWAYS requires hearing protection.
EventAverage dBMax. exposure time Gun shot, gun shot124 – 1610! Treshold of pain Concerts / festivals115< 30 seconds Sporting event114< 45 seconds iPod, MP3 players112< 1 minute Jackhammer, chainsaw1092 minutes Motor Cycle9822 minutes Aerobic class94< 1 hour Subway93< 1,5 hour Heavy traffic858 hours Vacuum cleaner, busy street, alarm clock80> 8 hours