edmontondown 发表于 2013-1-2 23:56 # I$ X1 J3 ?3 }yes, may have something fell down on the other end of the hood vent
) M1 W: ^+ Q% V; G) wAt the other end(outside) of the vent duct, there is usually a metal cover for the opening, it can swing up and down and if it is a windy day, it will be blown swinging, thus making a kind of banging noise.