edmontondown 发表于 2013-1-2 23:56 - x c3 n& o& J, c7 X+ r$ {5 zyes, may have something fell down on the other end of the hood vent
: f' m `# P. X, H# @3 zAt 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.