A noise reducing device for a pressurized fluid stream, i.e., a gas, includes a housing. An inlet end and an outlet end of the housing each have at least one orifice for passing a fluid therethrough. The inlet end orifice includes an inlet face and an outlet face and the inlet end orifice is configured for maintaining a backpressure upstream of the inlet end orifice. A diffusing pack material is disposed within the housing. One or more stiffeners may be disposed within the diffusing pack material to ensure that the diffusing pack material maintains contact with the outlet face of the inlet end orifice and/or to prevent the migration of the diffusing pack material within the housing, thereby maintaining a homogeneous distribution of the pack material.