A venturi muffler is made of a plurality of metallic tubular stepped members which are stacked together and define at least one sound-reflective chamber which opens through an annular venturi passage into an axial flow passage of the venturi muffler thereby creating a partial vacuum in the annular chamber. The annular chambers include aligned openings through which exhaust gasses flow but are also reflected by walls of the sound-reflective chambers. Therefore, the exhaust sound or noise is dampened by the cancellation of sound waves 180 degrees out of phase with each other, the creation of a partial vacuum through which sound cannot propagate or propagates minimally, and by the heat removed by all of the metallic heat-conductive venturi-forming segments of the venturi muffler.