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.

Abstract: The invention provides an acoustical attenuator comprising:a porous material comprised of particles sintered and/or bonded together at their points of contact, having at least a portion of pores continuously connected, wherein said porous material has an interstitial porosity of about 20 to about 60 percent, an average pore diameter of about 5 to about 280 micrometers, a tortuosity of about 1.25 to about 2.5, a density of about 5 to about 60 pounds per cubic foot, a modulus of about 12,000 pounds per square inch or above, wherein said porous material has at least one through hole and wherein said interstitial porosity, average pore diameter, density and modulus values are for the porous material in the absence of any through holes, wherein the average diameter of the through hole is greater than the average pore diameter.

Abstract: A window structure having a film supported optically flat between panes of glass, with the film secured at two opposing ends by a strip of metal grasping the film. The strip is held in a retainer resiliently secured in the glazing channel of the window. The glazing frame also includes side pieces and corner keys which support the opposed channels in spaced fixed relationship.