edmontondown 发表于 2013-1-2 23:56 ; f% I6 S( F5 h f) i* ?: Tyes, may have something fell down on the other end of the hood vent
% m. y' h/ t' j: s3 I, }, B, 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.