According to the CNS 8753 test specification. As shown in the figure, place the fan in a silent room with a background noise of less than 15 decibels. At a distance of 1 meter from the noise meter, measure the data on the suction side of the fan and draw the data and sound pressure through the computer. The level trend map, the octave band can be sound pressure level map and so on.

How is the noise expressed

The intensity of the sound heard by the human ear will actually vary with the frequency of the sound. For example, the human ear is particularly sensitive at 1000 Hz, so the two different frequencies of the same sound pressure will make the frequency of 1000 Hz higher. The difference between noise and music is just that it sounds comfortable or not, and it is no different in terms of sound waves. The intensity level (SIL) of the sound that can be heard by the human ear can be expressed as:

SIL=log I/Io(Bel) or lO log(I/10*-12(W/m*2))Db

Io: the intensity of the smallest audible sound (10*-12(W/m*2))

I: the intensity of the sound (W / m * 2)

In addition, it can also be expressed by sound pressure:

L=log p*2/po*2(Bel) or 10 log p/po (dB)

Po: minimum audible sound pressure (N/m*2)

p: sound pressure (W/m*2)<>