A silencer or sound attenuator for gas flows that makes use of noise baffles is provided with a lateral movement mechanism which allows the baffles to be moved perpendicular to the direction of the gas flow within the silencer. A silencer provided with the lateral movement mechanism allows personnel to have access to the interior of the silencer so that the baffles can be cleaned without having to remove the baffles from the silencer. The lateral movement mechanism may include a roller assembly installed at the top of each baffle which operates within a corresponding track that is provided to the inner upper surface of the housing. The lateral movement mechanism may also include a caster assembly, which is provided to the bottom of each baffle to aid in lateral movement.