When "Waterproof Cooling Fan" work, since the blades periodically subjected to export uneven airflow pulse dynamic action, noise; on the other hand, due to uneven pressure on the blade itself and the blade distribution, rotation and parts of surrounding gas also constitutes a rotation noise disturbance; Furthermore, since "Waterproof Cooling Fan" turbulence generated when the gas flows through the blade attachment level, vortex and vortex detachment, causing pulsating pressure distribution on the blade and vortex noise. This is due to three reasons "Waterproof Cooling Fan" comprehensive noise can be called a "cut wind noise", generally a big fan air flow pressure, which cut wind noise as well.