edmontondown 发表于 2013-1-2 23:56 9 i) ]* v: Q( \& O: D- b+ N$ A Nyes, may have something fell down on the other end of the hood vent
7 ~$ d4 S- V. `- M2 dAt 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.