Perforation acoustic muffler assembly and method of reducing noise transmission through objects

A rugged noise muffler system configured to substantially surround one or more sound-emitting openings in a working unit or structure, to absorb sound emitted from the sound-emitting openings in order that sound detected at the working unit or structure does not exceed a predetermined level, the system comprising:

• at least one barrier formed as a housing to cover a sound emitting opening of the working unit or structure to inhibit sound from emanating from the housing, except at a first barrier opening;
• wherein the housing is elongate and includes first and second opposing housing ends;
• wherein the housing is constructed to withstand compressive forces;
• wherein the first barrier opening is positioned at one of the first and second opposing housing ends to facilitate a free exchange of gases;
• wherein the housing has a predefined length from the sound emitting opening in the working unit or structure to the first barrier opening;
• wherein inner surfaces of the housing are lined with at least one layer of sound absorbing material to absorb the sound emitted from the sound emitting opening as the sound travels the length of the barrier;
• wherein the housing is configured without a bottom housing part and, for positioning on the ground or other base surface;
• wherein both the ground or other base surface and the sound attenuating material act to absorb sound emitted from the sound emitting opening of the working unit or structure before same reaches one of the first and second barrier openings;
• and
• wherein a sound transmission class (STC) of the at least one layer of sound absorbing material, a sound absorption capability of the ground or other base surface and the predefined length from the sound emitting opening in the working unit or structure to the first barrier opening determine a level of the sound emitted from the barrier opening.