"24V DC Cooling Fan" in addition to the cooling effect of the fan noise at work is widespread concern. Fan noise is noise generated when the size of the fan works, influenced by many factors, in decibels (dB). When measuring "24V DC Cooling Fan" in need of noise is less than 17dB noise silencer chamber conducted one meter from the fan, and the fan shaft is aligned along the direction of the fan air intake port, the use of A-weighted measurements manner. Spectral characteristics "24V DC 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.