A silencer with a casing and at least one inlet passage for leading gas into said casing, and at least one outlet opening for leading gas out of said casing, said silencer containing at least one acoustic chamber contained in the casing, at least one porous body inside said chamber, the porous body comprising a through-flow filter occupying at least part of the chamber, where said at least one porous body is designed to retain particles contained in the gas, at least one connecting passage for leading gas from each one of the at least one acoustic chamber to another of the at least one acoustic chamber or to an exterior environment or an exterior chamber, wherein at least part of at least one of said connecting passages extends along an outer surface of the porous body, so as to lead gas along a helical flow path.