Product noise evaluation may be a legal requirement, to drive quality or other design criteria. For example, certain types of outdoor machinery are regulated to control the noise they produce in order to reduce its environmental impact.
Usually the Sound Power of the device is required and in it's simplest terms this can be derived from a series of Sound Pressure measurements at known distances. The testing environment however plays a critical role.
The Sound Intensity technique is another way to establish the Sound Power value but this requires more sophisticated instrumentation.
Acoustics — Determination of sound power levels and sound energy levels of noise sources using sound pressure — Engineering methods for an essentially free field over a reflecting plane
Acoustics — Determination of sound power levels of noise sources using sound intensity — Part 3: Precision method for measurement by scanning
Acoustics — Determination of sound power levels and sound energy levels of noise sources using sound pressure — Survey method using an enveloping measurement surface over a reflecting plane