Apparatus (10, 200) for the provision of TNP therapy to a wound is described, the apparatus (10, 200) including: a waste canister (22, 204) into which fluid is aspirated from a wound by aspiration pump means (44, 248) and a fluid flow path (420, 422) for at least a part of said aspirated fluid on an outlet side of said aspiration pump means (44) wherein said fluid flow path (420, 422) on the outlet side comprises a silencing system (400) having a plurality of silencing elements (402, 404, 406) therein.