Paragraph 3.4 Sound power level LWA is obtained by applying the weighting A to the sound power level LW.

The sound power level L_W expressed in dB, of a sound source is defined by:

L W = 10 \log 10 \frac{W}{W 0}

where:

W is the total sound power generated by the sound source, expressed in watts;
W₀ is the reference sound power, equal to 10⁻¹² W.
The value L_WA of the A-weighted sound power level, expressed in dB, is obtained by applying the weighting A to the measuring system.