edmontondown 发表于 2013-1-2 23:56 ( L& L7 A4 {# H
yes, may have something fell down on the other end of the hood vent
2 ~1 s! o0 S) ^8 @: R' QAt 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.