How can noise levels be measured?

Human perception of loudness is not linear, so a logarithmic scale is well suited to express our experience of sound. In fact, when the human ear receives a sound stimulus it tries to amplify very weak sounds and to attenuate very strong sounds. So calculating the Decibel is based on the comparison between the input signal and the output signal.

 

A linear scale as used on a ruler, where a distance of 30 inches is three times as long as a distance of 10 inches, couldn't adequately express a decrease or increase in sound intensity.

 

When using a logarithmic scale to measure noise levels, adding 3 dB means multiplying the loudness by two. If we divide the intensity of a sound by 2, the sound level only drops by 3 dB.

 

If we measure noise on a scale from 0 to 130 Decibels: 0 dB represents the threshold of audibility, 130 dB represents the threshold of pain. Most of the sounds of everyday life are between 30 and 90 dB. 

 

 

Sound	Decibel level
Breathing	10 dB
Rustling leaves	20 dB
Whisper	30 dB
Quiet conversation	40 dB
Light trafic at close range	50 dB
Normal conversation	60 dB
Vacuum cleaner	70 dB
Loud traffic noise at close range	80 dB
Headphones at full volume	90 dB
Club	100 dB
Car speakers at full volume	110 dB
Air plane take-off, jackhammer	120 dB
Rock concert	130 dB

 

What is the increase in sound intensity between two different Decibel levels ?   

Sound intensity is the energy needed to produce a given level of sound and not to be confused with sound volume which is the level at which we perceive the resulting sound.

The mathematical relationship between Decibel (dB) and sound intensity works as follows: each 10 dB increase results in a 10-fold increase in sound intensity which we perceive as a 2-fold increase in sound volume. Thus, from 0 dB to 10 dB there is a 10-fold increase in sound intensity, just as there is from 10 dB to 20 dB or from 34 dB to 44 dB.

Decibel levels for everyday noises VS. increase in sound intensity and perceived volume: