edmontondown 发表于 2013-1-2 23:56 4 M) {& _) n. m; e9 wyes, may have something fell down on the other end of the hood vent
7 x/ U* V' z# D* A% s! `
At 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.