Sound waves of an amplitude having a waveform (first value as a function of time and a first maximum) pass into a manifold, which subdivides flow and sound into multiple paths of differing length, yielding transit times offsetting the arrival of each instance of the waveform at an outlet or exit. This minimizes the addition of energy (sound volume, amplitude) arriving at the exit or terminus from each path. Amplitude is thereby reduced (although the waveform shape remains), repeated and offset by the transit time delays of paths discharging at the terminus. One may select the number of paths based on a desired reduction in the sound amplitude. That number is approximately inversely proportional to the ratio of the reduction. For example, six unique paths in an experiment reduced original amplitude (sound volume) to a sixth at an exit.

Method and system for filling a muffler with fibrous material. The muffler includes a muffler shell comprising a first shell member and a second shell member, at least one partition extending between the first and second shell members, and at least one slot formed in the first shell member above the partition. The first shell member is positioned and held relative to the second shell member to form an open portion, a closed portion, and a space between an upper surface of the partition and the first shell member. Fluid is introduced into the space through a fluid delivery device inserted into the muffler shell through the slot, and fibrous material is introduced into the muffler shell through a filling nozzle inserted into the muffler shell through the open portion. The fluid delivery device and nozzle are removed after filling and the shell members are closed and affixed.

Methods of and systems for filling a muffler body with a fibrous material prior to completing assembly of the muffler body are disclosed. The methods and systems prevent or otherwise reduce undesired migration of the fibrous material within the muffler body.

Sound waves of an amplitude having a waveform (first value as a function of time and a first maximum) pass into a manifold, which subdivides flow and sound into multiple paths of differing length, yielding transit times offsetting the arrival of each instance of the waveform at an outlet or exit. This minimizes the addition of energy (sound volume, amplitude) arriving at the exit or terminus from each path. Amplitude is thereby reduced (although the waveform shape remains), repeated and offset by the transit time delays of paths discharging at the terminus. One may select the number of paths based on a desired reduction in the sound amplitude. That number is approximately inversely proportional to the ratio of the reduction. For example, six unique paths in an experiment reduced original amplitude (sound volume) to a sixth at an exit.