Sound intensities are typically measured in decibels (dB). A decibel is defined as 10 times the logarithm of the power ratio (power ratio is the ratio of the intensity of the sound to the intensity of an arbitrary standard point.) Normally a change of 1 dB is the smallest volume change detectable by the human ear.
Sound intensity is also defined in terms of energy (ergs) transmitted per
second over a 1 square centimeter surface. This energy is proportional to the
velocity of propagation of the sound.
|
Decibels |
Degree |
Sound Source |
|
225 |
Deafening |
12" Cannon @ 12' in front and below |
|
195 |
Deafening |
Saturn rocket |
|
180 |
Deafening |
Aircraft at take-off |
|
160 |
Deafening |
Ram jet |
|
150 |
Deafening |
Turbo jet |
|
140 |
Deafening |
Artillery fire |
|
130 |
Deafening |
Threshold of pain, decibels at or above 130 cause immediate ear damage. Hydraulic press, pneumatic rock drill |
|
120 |
Deafening |
Riveter, chipper, thunder, diesel engine room, fireworks display |
|
110 |
Deafening |
Punch press, close to a train, ball mill |
|
100 |
Very Loud |
Passing truck, home lawn mower, car horn @ 5 meters, wood saw, boiler factory |
|
90 |
Very Loud |
Decibels at or above 90 regularly cause ear damage. Noisy factory, truck without muffler |
|
80 |
Loud |
Noisy office, electric shaver, alarm clock, police whistle |
|
70 |
Loud |
Average radio, normal street noise |
|
60 |
Moderate |
Conversational speech |
|
50 |
Moderate |
Normal office noise, quiet stream |
|
45 |
Moderate |
To awaken a sleeping person |
|
40 |
Faint |
Average residence, normal private office |
|
30 |
Faint |
Recording studio, quiet conversation |
|
20 |
Very Faint |
Whisper, empty theater, ticking of watch |
|
10 |
Very Faint |
Threshold of good hearing |
|
0 |
|
Threshold of excellent youthful hearing |