Produced by the compression of the atmosphere by wind blades. When the fan on the roof of Nanning Xingye Plaza operates at high speed, the fan blades will compress the atmosphere. At this time, the pressure of the compressed atmosphere by the fan blades will be high and a certain amount of noise will be generated, and a certain amount of low noise will also be generated when absorbing the low-pressure atmosphere, especially The noise will be louder with a hood.