Abstract ISO 17624:2004 deals with the effectiveness of acoustical screens. It specifies the acoustical and operational requirements to be agreed upon between the supplier or manufacturer and the user of acoustical screens. ISO 17624:2004 is applicable to the following types of acoustical screens: free-standing acoustical screens for offices, service areas, exhibition areas, and similar rooms; acoustical screens integrated in the furniture of such rooms; portable and removable acoustical screens for workshops; fixed room partitions with more than 10 % of the connecting area open and acoustically untreated. Walls of partial acoustic enclosures and cabins which, together with the room boundary surfaces, also partition a room and provide more than 10 % open and acoustically untreated area, are also treated as acoustical screens. ISO 17624:2004 is not applicable to cabinet walls and similar multi-layer walls whose thickness exceeds 0,2 m, nor to banners and other types of suspended baffles.