Relationship Tiny Cooling Fan speed and noise

"Tiny Cooling Fan" Speed is the number of revolutions per minute of the fan blades, the unit is rpm. Fan speed is determined by the motor inside the coil turns, voltage, number of fan blades, angle, height, diameter and bearing systems. Fan speed and quality are not necessarily linked. Fan speed can be measured by the internal speed signal, it can also be measured by the external. In addition to the cooling effect, "Tiny Cooling Fan" operating noise is also widespread concern. Fan noise is the size of the noise generated when the fan works, influenced by many factors, in decibels (dB). Fan noise measurement requires less than 17dB noise muffler chamber is performed, one meter away from the fan, and the fan shaft is aligned along the direction of the fan air intake, way of using the A-weighted measurements. The spectral characteristics of "Tiny Cooling Fan" Noise is also very important, so we must also use a spectrum analyzer record fan noise frequency distribution, the general requirements of the fan noise to be as small as possible, but can not exist different tone.