How Loud is Noise?
The following tables illustrate some common sounds, their intensity, and maximum allowable listening times.
But first, what is a deciBel?
A deciBel is a unit of measurement of the loudness or strength of a signal. One deciBel is considered the smallest difference in sound level that the human ear can discern. Created in the early days of telephony as a way to measure cable and equipment performance and named after Alexander Graham Bell, deciBels (dBs) are a relative measurement derived from two signal levels: a reference input level and an observed output level. A deciBel is the logarithm of the ratio of the two levels. One Bel is when the output signal is 10x that of the input, and one deciBel is 1/10th of a Bel.
A whisper is about 20 dB. A normal conversation is typically from 60 to 70 dB, and a noisy factory from 90 to 100 dB. Loud thunder is approximately 110 dB, and 120 dB borders on the threshold of pain.
Here are some examples of the loudness of common sounds:
Approximate Decibel Level |
Examples |
0 dB |
the quietest sound you can hear. |
30 dB |
whisper, quiet library. |
60 to 70 dB |
Normal conversation at 3-5 feet |
60 dB |
normal conversation, sewing machine, typewriter. |
90 dB |
lawnmower, shop tools, truck traffic; 8 hours per day is the maximum exposure (protects 90% of people). |
90 to 95 dB |
Level at which sustained exposure may result in hearing loss |
100 dB |
chainsaw, pneumatic drill, snowmobile; 2 hours per day is the maximum exposure without protection. |
115 dB |
sandblasting, loud rock concert, auto horn; 15 minutes per day is the maximum exposure without protection. |
120 to 135 dB |
Symphonic music peak, level at which sound can produce pain |
140 dB |
gun muzzle blast, jet engine; noise causes pain and even brief exposure injures unprotected ears; maximum allowed noise with hearing protector. |
150 dB |
Rock music peak |
180 dB |
Death of hearing tissue |
194 dB |
Loudest possible sound |
Daily Permissible Noise Levels (From OSAHA)
Hours Per Day |
Sound Level |
8 |
90 dB |
6 |
92 dB |
4 |
95 dB |
3 |
97 dB |
2 |
100 dB |
1.5 |
102 dB |
1 |
105 dB |
.5 |
110 dB |
.25 or less |
115 dB |