A customary logarithmic measure most commonly used (in various ways) for measuring sound.Sound is measured on a logarithmic scale. Informally, if one sound is \(1\,bel\) (10 decibels) "louder" than another, this means the louder sound is 10 times louder than the fainter one. A difference of 20 decibels corresponds to an increase of 10 x 10 or 100 times in intensity.
The beginning of the scale, 0 decibels, can be set in different ways, depending on exactly the aspect of sound being measured. For sound intensity (the power of the sound waves per unit of area) \(0\,decibel\) is equal to \(1\,picoWatts\,per\,Metre\,Squared\). This corresponds approximately to the faintest sound that can be detected by a person who has good hearing. For sound pressure (the pressure exerted by the sound waves) 0 decibels equals \(20\,micropascals\,RMS\), and for sound power \(0\,decibels\) sometimes equals \(1\,picoWatt\). In all cases, one decibel equals \(\approx\,0.115129\,neper\).
