Abstract: A lightweight acoustic enclosure (1.1), for the reduction of noise transmission from monopole, quadrapole and higher order noise sources via airborne paths at frequencies lower than the approximate ring frequency of the enclosure (1.1), comprising an approximately spherical shaped enclosure (1.1), which is made from stiff materials to reduce the amount of stretching of the enclosure wall and substantially encases the noise source, all structural paths between the enclosure and the noise source comprising vibration isolation (2.4). The thickness of the enclosure wall can be relatively thin. The enclosure (1.1) can comprise multiple concentric layers of stiff material, ideally with adjacent layers having at least one compliant layer, such as foam rubber, sandwiched between them. The enclosure (1.1) can comprise several component parts such as spherical shell elements (1.2), with radii less than that of the approximate radius of the enclosure (1.1). Additional webbings or flanges (1.