"DC Fan" in addition to the cooling effect of the fan noise at work is also widespread concern. Fan noise is the size of the noise generated when the fan works, influenced by many factors, in decibels (dB). When measuring the noise of the fan needs to be less than 17dB noise silencer chamber is performed, one meter away from the fan, and the fan is aligned along the axis of rotation of the fan air intake port, using the A-weighted measurements manner. The spectral characteristics of the fan noise is also very important, so we must also use a spectrum analyzer record fan noise frequency distribution of the general requirements of the fan noise to be small, and can not exist different tone. Fan noise and friction, the relevant air flow. Fan speed, the greater the amount of wind noise caused will be greater, additional fan vibration itself also can not be ignored.