Abstract: Enclosure 1 constructed of panels 20 which can be joined by tongue and groove or press fit spline 46 and groove 26 technique. Acoustic shielding is achieved by properly selected materials of construction, e.g. syntactic, cellular composites.The doorway 10 of the enclosure is closed by a door 210 penetrated only by a guide 175. The latch mechanism 170 and 340 seals the door against the door jamb 185 by means of cam rollers 316 which engage indentations 189 (which may have specialized cam surfaces or inclined surfaces) along the door frame. The latch mechanism can be actuated from either side of the door by mechanical means engaging the guide.

Abstract: Enclosure 1 constructed of panels 20 which can be joined by tongue and groove or press fit spline 46 and groove 26 technique. Acoustic shielding is achieved by properly selected materials of construction, e.g. syntactic, cellular composites. The doorway 10 of the enclosure is closed by a door 210 penetrated only by a guide 175. The latch mechanism 170 and 340 seals the door against the door jamb 185 by means of cam rollers 316 which engage indentations 189 (which may have specialized cam surfaces or inclined surfaces) along the door frame. The latch mechanism can be actuated from either side of the door by mechanical means engaging the guide.

Abstract: A method of using a material as an acoustical barrier in an ambient medium. The material comprises microbubbles having average outer diameters of 5 to 150 microns, bound together at their contact points. The material is characterized by either a porosity of 20 to 60 percent, or by voids between the microbubbles which have characteristic diameter within an order of magnitude of the viscous skin depth of the ambient medium, as calculated at 1 kHz; an air flow resistivity of 0.5.times.10.sup.4 to 4.times.10.sup.7 mks rayls/meter, and an attenuation of sound comparable to mass law performance. The microbubbles can be sintered into direct contact with each other, or one of many types of binder material can be used to support the microbubbles within a composite material.