I used to lag duct work in building to kill the noise (not as loud as an airgun shooting through it mind you)
we used glass wool that had a ali foil on the outside .
like this http://www.rock-wool-insulation.com/...s-blanket.html
I used to lag duct work in building to kill the noise (not as loud as an airgun shooting through it mind you)
we used glass wool that had a ali foil on the outside .
like this http://www.rock-wool-insulation.com/...s-blanket.html