The more vibrations there are the louder your fan will be, so the key is to try and reduce the vibrations as much as you can. My fan was really loud but then i relised a lot of the noise was because it was vibarating against the screw i used to fasen it, tightened that up and it's a lot quieter now, also not sure if this is the case for you but i have my clothes hung in where my fan is and the more clothes in the wardrobe hung up the quieter it seems to be.