The strength of the human ear "Mini Air Cooling Fan" to listen to the sound, with the frequency of the sound actually vary, for example, are particularly sensitive to the human ear at the time of 1000Hz, so the two different frequencies of the same sound pressure will avoid frequency of 1000Hz its volume is large. The so-called "Mini Air Cooling Fan" the difference between noise and music just sounds comfortable or not, and no two in sonic terms. Should be stored in a dry environment, avoiding motor damp. "Mini Air Cooling Fan" at the open storage, proper defensive measures. In the storage and handling process should prevent the fan bump avoid fan damage