edmontondown 发表于 2013-1-2 23:56 1 d& A/ ]( O M5 d# h$ F
yes, may have something fell down on the other end of the hood vent
. \. \) R1 U& v! K. i* 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.