An inline muffler for use with a positive airway pressure (PAP) apparatus. The muffler may provide an expansion chamber with baffles that capture acoustic energy using, for instance, a disruptive gas flow path to effectively reduce downstream noise associated with a flow of pressurized gas produced by the PAP apparatus. In some embodiments, the muffler is constructed of two mostly identical halves with baffle segments being integrally formed therewith.