Sound power

Regulations often specify a method for measurement[3] that integrates sound pressure over a surface enclosing the source.

The A-weighting scale is used in the calculation as the metric is concerned with the loudness as perceived by the human ear.

The required environment is on hard ground in a large open space or hemi-anechoic chamber (free-field over a reflecting plane.)

This is the parameter one would be interested in when converting noise back into usable energy, along with any losses in the capturing device.

Sound power level, denoted LW and measured in dB,[9] is defined by:[10] where The commonly used reference sound power in air is[11] The proper notations for sound power level using this reference are LW/(1 pW) or LW (re 1 pW), but the suffix notations dB SWL, dB(SWL), dBSWL, or dBSWL are very common, even if they are not accepted by the SI.