edmontondown 发表于 2013-1-2 23:56 7 y5 n. J% w. r7 E$ cyes, may have something fell down on the other end of the hood vent
4 ]1 o9 \* o+ |7 c$ ~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.