Noise Control for grow box air duct fan

Hi
Any ideas on sound proofing my grow box? My 4 inch air duct fan is making too much noise. Ive looked into damping and vibration isolation pads that i might be placing around the fan. Thanks for any help and ideas.

Build a wooden box, line it with insulation. Or, use about 3ft of duck work hook it up to the exhaust and create a bend, that's what I did and it greatly reduced sound for me

hang your fan by bungee cords