Sound Power Level
Home Up Nature of Sound Waves Simple Harmonic Motion Characteristics of Sound Spectrum and Octave Band Strength of Sound Sound Pressure Level Sound Power Level Sound Intensity Level Free Field Manipulation with Decibels


7. Sound Power Level

In addition to the sound pressure level, there are other levels expressed in decibels, so one must be careful when reading technical articles about sound or regulations on environmental noise. One such level is the sound power level (PWL or Lw), which identifies the total sound power emitted by a source in all directions. Sound power, like electrical power, is measured in watts.  In the case of sound, the amount of power is very small, so the reference selected for comparison is the picowatt (10-12 watt). The sound power level (in decibels) is defined as :