Get a 12" windtunnel if you want to control the speed with no noise. 4-8" windtunnel fans has a fixed-frequency capacitor wired in that can cause an audible frequency whine that can also cause interferences when used with any variable speed controller. I've done this already. Why not hang it with bungee and keep it running full speed? The only sound you hear from them is wind output which can't be helped.