Fan Muffler Silencer 40mm

thingiverse

This is my attempt of a fan silencer/muffler. It's basically a Helmholtz Cavity type of silencer with an extra center cavity. The idea is to trap more noise with the extra cavity, but not sure if it's all that necessary since I havn't try the actually Helmholtz type silencers. But regardless, I was able to reduce around 6dB of noise. It was measured around 5cm away from the fan from all directions; the app then gives an average. In hope for a better result, I stuffed some sponge into the cavity which doesn't make much difference in the noise level, but reduced some weird resonance from the center piece. Then I thought, I am already stuffing sponge down the cavity (which defeats the whole purpose of the "noise trap"), why not make a duct silencer/muffler type of design. So that's my next plan. Note: printing it upside down with supports will probably give better finish. I know the design is not optimised for printing, but this is just a proof of concept so I didn't bother. ------ Update 18/01/2022: V2 - revert back to the Helmholtz Cavity style but with array of holes in the inner wall. The design itself performs similar to the V1 only with higher pitch. But when stuffed the cavity with cotton, it was able to reduce the noise level by another 3dB (9dB in total), making it barely sub-60dB (OEM fan). Printed upright with no support. ------