Patent ID: 6983820

Claim:
A noise suppressor comprising modular portions, each having an internal duct length, said modular portions being engaged in series to define a plurality of suppression chambers and an internal duct including said duct lengths, each suppression chamber communicating with the internal duct via one or more apertures, each aperture having an area and each suppression chamber thereby having an associated total aperture area, wherein one combination of one of said chambers with its associated total aperture area has different noise suppression characteristics compared to a combination of another of said chambers with its associated total aperture area, and each suppression chamber is bounded by parts of two of said modular portions, so that each chamber is separated from an adjacent chamber by a respective internal wall of the modular portions, and wherein, for each two of said modular portions, there is only one chamber, and each said chamber is undivided, wherein the suppressor has at least one insert part removably mountable in the inlet of at least one chamber partially to obstruct said inlet, the insert part being arranged to affect the noise suppression characteristics of said at least one chamber.