Silencer

The sound attenuator has an inner part (1) and an outer part (2) enclosing the inner part, whereby the inner part has an inner wall (4) with openings (3) and the outer part forms an outer wall (5) extending along the inner wall. The outer wall is in the form of a folding bellows (6) that defines individual cavities (7) with the inner wall, whereby the openings in the inner wall open into the cavities.