Mute the cooling fan and the volume level

In the cooling fan on the market, many vendors will launch mute the cooling fan, the so-called silent, silent cooling fan, generally is the enterprise standard, customised by the manufacturer. But our country 'household and similar electrical noise limit' national standard, the noise limit is mandatory to home appliance, such as, washing machine washing and dewatering noise of highest limit 62 db and 72 db respectively; The refrigeration power according to size, air conditioning indoor machine noise limit in the 40 - 63 decibels. From the analysis on human feeling, generally less than 40 db, can be called a mute, less than 20 db, could be called super mute. With no national standard stipulated by the industry, we usually as a standard. For 8 db - in background noise A ring in the room, we x20x10mm 20 and 25 x25x7mm radiator cooling fan can reach 18 db - minimum noise A, less than 20 db, can call it silent cooling fan, and according to the classification standard of human feeling, our small and medium size cooling fan can be to mute the cooling fan. For many, the volume of the db is a very abstract concept, we introduce by analogy to over 70 decibels below: the volume of 190 decibels killed 140 db (a) the European Union defined cause hearing damage the highest point of 139 db (a) of the 130 World Cup fans db rocket voice 120 db (a) to 125 decibels jet aircraft take off in this environment to stay more than a minute will produce temporary deafness 110 decibels propeller plane sound, the sound of a rock concert 105 decibels permanent hearing damage 100 decibels pneumatic drill noise, compress the hammer beat the sound of heavy things 90 db noise bar environment sound, the sound of the electric saw saw wood below 85 db and does not destroy the cochlea hair cells within the office 80 db noise, the voice of the highway 75 decibels sound environmental comfort level cap of 70 db (a) street human ears