Mini Air Cooling Fan can not exist different sound

  Problem when we use "Mini Air Cooling Fan", in addition to the cooling effect of the fan, the fan's operating noise is widespread concern, so today we are a few to discuss, fan noise is formed? When measuring the fan noise in the noise is less than 17dB required muffling chamber conducted, one meter away from the fan, and the direction of the "Mini Air Cooling Fan" fan shaft is aligned air inlet, 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 records "Mini Air Cooling Fan" noise frequency distribution, the general requirements of the fan noise to be as small as possible, but can not exist different tone.