edmontondown 发表于 2013-1-2 23:56 5 Y( P( D8 G9 x: A/ iyes, may have something fell down on the other end of the hood vent
; Y7 P& u8 Z/ Z) LAt 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.