Field measurements to determine potential conversion factor for terminal units’ combined path sound pressure data to sound power spectra

Accurately predicting mechanical noise levels requires reliable sound power spectra of mechanical equipment. However, some manufacturers of electric fan-powered units publish only sound pressure level data, commonly citing the JIS B8616 standard without strictly adhering to its procedural requirements. This practice combines radiated, inlet, and discharge noise into a single dataset. It becomes necessary to determine the sound power level for each path (i.e., discharge, inlet, and radiated) from this single sound dataset. Converting sound pressure spectra to sound power by applying basic acoustic principles can yield inconsistent results lacking precision. This study uses field-measured HVAC data to establish relationships between back-calculated sound power levels and manufacturer-provided “combined” sound pressure data.