Waterproof Cooling Fan can not exist different sound

"Waterproof Cooling Fan" in addition to the cooling effect of the fan's operating noise is also widespread concern. Fan noise is the size of the generated noise of the fan work, influenced by many factors, in decibels (dB). When measuring "Waterproof Cooling Fan" noise requires less than 17dB noise silencer chamber carried away from the fan a meter and the fan shaft is aligned along the direction of the fan air intake port, the use of A-weighted manner measurement. Spectral characteristics "Waterproof Cooling Fan" noise is also very important, so we must also use a spectrum analyzer records the fan noise frequency distribution, the general requirements of the fan noise to be as small as possible, but can not exist different tone.