Acoustic enclosures are acoustic chambers, noise enclosures, acoustic barriers and screens, and sound isolation enclosures that minimize or attenuate noise. They are made of acoustic or acoustical materials and provide four basic functions: sound isolation, sound absorption, vibration, isolation and vibration absorption. Heavy materials such as sheet metal, timber, masonry, plasterboard, glass and loaded vinyl stop relatively large amounts of sound and can be used in acoustic enclosures of double-leaf construction. Sound absorbing materials usually have a protective face and are made of perforated sheet metal, perforated foil, or perforated vinyl. Vibration isolation requires components such as springs, rubber mounts, air cushions, pads or mats, and cork or fiberglass inserts.