Measurement of Loudness
Loudness is measured on a logarithmic scale. This means that an increase of 10 decibels (dB) represents a 10-fold increase in sound intensity and a doubling of the perceived loudness. Thus, 20 dB is 100 times the intensity of 0 dB and seems 4 times as loud; 30 dB is 1,000 times the intensity of 0 dB and seems 8 times as loud. | |
Decibels | Example |
0 | Faintest sound heard by human ear |
30 | Whisper, quiet library |
60 | Normal conversation, sewing machine, or typewriter |
90 | Lawnmower, shop tools, or truck traffic (90 dB for 8 hours per day is the maximum exposure without protection*) |
100 | Chainsaw, pneumatic drill, or snowmobile (2 hours per day is the maximum exposure without protection) |
115 | Sandblasting, loud music concert, or automobile horn (15 minutes per day is the maximum exposure without protection) |
140 | Gun muzzle blast or jet engine (noise causes pain, and even brief exposure injures unprotected ears, and injury may occur even with hearing protectors) |
180 | Rocket launching pad |
* This level is the mandatory federal standard, but protection is recommended for anything more than very brief exposure to sound levels above 85 dB. | |