Sound intensity level

Sound intensity level or acoustic intensity level is a logarithmic measure of the sound intensity in comparison to the reference level of 0 dB (decibels).

The measure of a ratio of two sound intensities is

<math>

L_J=10\, \log_{10}\left(\frac{J_1}{J_0}\right)dB <math>

where J₁ and J₀ are the intensities.

The sound intensity level is given the letter "L_J" and is measured in "dBW". dB is dimensionless.

If J₀ is the standard reference sound intensity, where

<math>J_0 = 10^{-12} \frac{W}{m^2}<math>

(W = watt), then instead of "dB" we use "dB SWL". (SWL = sound intensity level).