Generally, if you want to know how much noise the user will feel when using the product, you are more inclined to measure the sound pressure level. Taking the driving position of a car as an example, the approximate position of the driver when driving a car is fixed. Therefore, if you want to understand the noise value of the driver when driving a car, it is recommended to measure the sound pressure level directly at the driver position. However, if you want to compare the noise characteristics of the product, you should measure the sound power level of the product, because the sound power level has a characteristic irrelevant to the measured position (that is, a fixed value), which is generally not affected by the difference in the measured position. In recent years, more and more international certification organizations are using sound power level as the standard of defining the product noise value, such as the German steel (Blue Angel), northern Europe, Nordic Swan (Nordic Swan), the United States Energy Star (Energy Star), the European Union, the EU Eco - flower, the TCO, GS Mark, and even Taiwan Green logo (Green Mark) have been used as the judgement standard of sound power level.

Sound power level measurement in accordance with the following ISO, GB standards and related ISO, GB and enterprise standards:

1、ISO 3745 Acoustics — Determination of sound power levels of noise sources using sound pressure — Precision methods for anechoic and hemi-anechoic rooms

2、ISO 3744: Acoustics-Determination of sound power levels of noise sources using sound pressure- Engineering method in an essentially free field over a reflecting plane

3、GB/T 6882 Acoustics--Determination of sound power levels of noise sources using pressure--Precision methods for anechoic and hemi-anechoic rooms

4、GB/T 6881 acoustics--determination of sound power levels of noise sources--precision methods and engineering methods for reverberation rooms

When measuring, the product under test is wrapped in a semi-spherical or parallel hexahedron structure arranged by a microphone matrix (select the appropriate measurement envelope according to the characteristics and dimensions of the product under test) for measurement.As shown below: