What is a decibel, and how is it measured?

What is a decibel, and how is it measured?

 

 The decibel (abbreviated dB) is the unit used to measure the intensity of a sound. The decibel scale is a little odd because the human ear is incredibly sensitive. Your ears can hear everything from your fingertip brushing lightly over your skin to a loud jet engine. In terms of power, the sound of the jet engine is about 1,000,000,000,000 times more powerful than the smallest audible sound. That's a big difference!

 

Humans can hear sounds between 0 and 140 decibels.  0 decibel does not mean that there is no sound, merely that we cannot hear it. 0 decibel is the so-called hearing threshold for the human ear. While we can hear more than 140 decibels, it is too painful for our ears and if you expose yourself to such a loud noise you are at extremely high risk of permanent damage to your hearing. The table blow shows how loud sound is.

 

Decibels meter

 

According to United Kingdom legislation you are obliged to wear hearing protection if you work in an environment with 80 decibels of sound or higher on a daily basis. For fun, check out the following decibel meter. 

 

Example of decibels

DECIBEL

SOUND

EXAMPLE

10

Almost inaudible

A leaf falling

20

Audible

Rustles of autumnal leaves

30

Very quiet

Whispering

40

Quiet

Living room, quiet classroom

50

Limited sound

Refrigerator working, car driving past

55

Limited sound

Percolating coffee-maker

60

Audible

Sound of human voice, machinery

70

Irritating

Television set on loud, vacuum cleaner, several people on the telephone

75

Constant sound

Busy restaurant around lunchtime

80

Unpleasant

Alarm clock, freight traffic, doorbell

85

Loud

Sawing, mixer

90

Extremely unpleasant

Truck close by, screaming, yelling, shouting

95

Noisy

Drill, violin

100

Extremely unpleasant

Machine in a factory, compressor, fighter jet at 300 m

105

Even louder

Helicopter close by, large drum

110

Extremely loud

Rock concert, chainsaw

120

Extremely loud

Human voice at its loudest, police siren

130

Extremely loud

Thunder

140

Pain threshold

First Monday of the month siren from close by

150

Permanent damage to hearing

Fireworks

160

Permanent damage to hearing

Shooting with pistol or rifle

170

Permanent damage to hearing

Avalanche firework

180

Permanent damage to hearing

Rocket launch platform

194

Permanent damage to hearing

Saturn rocket

 

 

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