Data are occasionally presented in sound pressure level format when sound power level format is desired, or vice versa. Two methods of determining corrections factors between LWA and LPA are provided.
Sound power level refers to the global noise emission of a noise source and is analogous to the BTU or Watt rating of a heater. When A-weighted, the sound power level is notated LWA.
Sound pressure level refers to the local sound pressure caused by all the noise sources in the space. Analogous to temperature, it is dependent on the sound power level of the various noise sources plus distance, direction, properties of the host space and the ambient sound level. When A-weighted, the sound pressure level is notated LPA.
Approximate Sound Pressure/Power Conversion Worksheet
A simplified conversion method for sound pressure/power conversion is described in Sound Power-Pressure Conversion. Use this worksheet to get a quick and easy estimate of the conversion between sound power level and sound pressure level.
Room Correction for Surface Properties Worksheet
A more detailed approach for sound pressure/power conversion based on room acoustics considerations is given in the Calculation of Room Correction for Surface Properties spreadsheet.
This spreadsheet calculator is based on a commonly accepted room acoustics method that computes the relationship between the source sound power level and the reverberant field sound pressure level. The spreadsheet assumes a greater degree of sophistication on the users’ part, and requires that measured data be available in octave bands.