The decibel (unit symbol dB) is a derived quasi-unit for loudness. It is not a true unit, but rather an indication that the value given is the decadic logarithm of a ratio. Generally speaking, a 10 dB increase in sound pressure is perceived by a person as approximately twice as loud.
Generally speaking, the pain threshold of a sound is about 134 dB. In the case of long-term exposure, however, damage to hearing is assumed to occur from as low as 85 dB.
A few exemplary volumes
|Leaf noise, quiet breathing||10 dB|
|Normal conversation||40-60 dB|
|Car at 10 m distance||60-80 dB|
|Main road at 10 m distance||80-90 dB|
|Compressed air hammer||100 dB|
|Fighter aircraft||110-140 dB|
|Rifle shot||140 dB|