The Ultimate Sound power level - American History Information Guide and Reference

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

The measure of a ratio of two sound powers is

$L_W=10\, \log_{10}\left(\frac{W_1}{W_0}\right)dB$

where W₁ and W₀ are the powers.

The sound power level is given the letter "L_w" or SWL and is measured in "dBW". dB is dimensionless.

If W₀ is the standard reference sound power, where

W 0 = 10 - 12 W

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

Your American History Reference Guide! - Sound power level