edmontondown 发表于 2013-1-2 23:56 - w X7 \; J8 i* q3 m, T
yes, may have something fell down on the other end of the hood vent
* h" Y: ?4 I9 NAt 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.