# The Lawnmowers (Harmonization of Noise Emission Standards) Regulations 1992, Paragraph 3.4: Sound power level LWA is obtained by applying the weighting A to the sound power level LW.


The sound power level LW expressed in dB, of a sound source is defined by:
LW=10log10WW0 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 LWA of the A-weighted sound power level, expressed in dB, is obtained by applying the weighting A to the measuring system.

---
Source: https://www.legislation.gov.uk/uksi/1992/168/schedule/3/paragraph/3.4 (the official version)
Page: https://openlegislation.uk/lawnmowers-harmonization-of-noise-emission-standards-regulations-1992/schedule-3/paragraph-3.4
Contains public sector information licensed under the Open Government Licence v3.0. Source: legislation.gov.uk, The National Archives.