Abstract: A compact muffler has a straight through inner cylindrical casing surrounded by an outer cylindrical casing defining a closed ended sound attenuating chamber therebetween. Within the outer chamber a plurality of axially extending, radially overlying, cylindrical intermediate casings form a plurality of annular sound attenuating passages. The sound passages are configured to have entrances in fluid communication either with an especially configured slot in the inner casing or between certain passages to define a plurality of discrete sound paths, with each sound path having a set length sufficient to generate a reflection wave for attenuating a sound wave having a frequency correlated to the distance of the sound path.

Abstract: A compact muffler has a straight through inner cylindrical casing surrounded by an outer cylindrical casing defining a closed ended sound attenuating chamber therebetween. Within the outer chamber a plurality of axially extending, radially overlying, cylindrical intermediate casings form a plurality of annular sound attenuating passages. The sound passages are configured to have entrances in fluid communication either with an especially configured slot in the inner casing or between certain passages to define a plurality of discrete sound paths, with each sound path having a set length sufficient to generate a reflection wave for attenuating a sound wave having a frequency correlated to the distance of the sound path.