A compressor unit having a housing consisting of steel inner and outer shells, the shells being spaced apart from each other to provide an attenuation cell substantially occupying all of the space between the shells, a suction gas inlet and a discharge gas outlet extending through both of the shells and the cell and being isolated from the outer shell by sound absorbing means, and spacer material having sound absorbing properties positioned between the shells and maintaining the spacing therebetween, the spacing being, preferably, at least about 0.06 in. in width over at least a major portion of the cell.