Abstract: The present invention relates to a sound absorbing member comprising a fiber grid insert disposed between and bonded to two open cell foam panels.

Abstract: The invention relates to a noise control device which is placed between a noise source and an area which is to be protected. The device includes at least one passageway through the body portion with a plurality of chambers extending into the body portion from both sides of the passageway, the chambers and the passageway being sized to cause a 180.degree. phase lag in a sound passing through the passageway, thus causing destructive interference with sound passing over the barrier.

Abstract: A co-oscillating, volume-changing resonator in the form of a silencer, includes a lens-shaped housing formed of a material having a given flexural stiffness, the housing being arched defining an evacuated cup-shaped cavity formed therein, and a coating layer completely surrounding the housing, the coating layer being formed of a material having a flexural stiffness being at most one-third of the given flexural stiffness of the material of the housing.

Abstract: A sound absorbing block of molded structural material has a sequence of internal cavities that communicate with a region containing the sound to be suppressed through a first elongated slot located in an exterior wall of the block. The internal cavities are defined by interior walls, at least one of which also contains an elongated, sound-communicating slot. Each slot and its associated cavity define an acoustical Helmholtz resonator that dissipates sound energy incident upon the slot with an absorption peak at a natural frequency f.sub.n. The value of f.sub.n for each resonator is inversely proportional the square root of the volume of the cavity. The internal cavities are arranged to cascade in order of decreasing stiffness beginning at the first slot. In one form, two sequences of cavities in a block use a common final cavity. Also, the exterior slots can be formed in more than one wall to absorb sound produced in multiple regions.

Abstract: In sound absorbing lining, conduits (4) are provided, filled with a viscous damping fluid, and are in contact by their ends facing towards the rigid supporting wall (1) to which the lining is applied with flexible cells containing a gas and forming a readily compressible material, for example foam rubber (6). Said conduits are separated from the ambient medium (2) by a separating membrane (3) which is permeable to acoustic waves. Lining is applied to absorbing acoustic waves underwater.

Abstract: An acoustic enclosure (10) has interconnected sound reducing panels forming a substantially rectangular structure which is configured to house a computer printer. Each side (12,14) panel is a multiple strata panel having an outer polymeric stratum (26), a multiple channel intermediate thermoplastic stratum (28) and an inner open celled acoustic material stratum (30). The rear and bottom panels (16, 18) are multiple stratum panels, having multiple channel intermediate thermoplastic stratum (46) which is sandwiched between inner and outer polyurethane foam strata (44,48). An adhesive material (42) is provided for bonding the outer stratum to the intermediate stratum and the intermediate stratum to the inner stratum for each of the panels. An angle member (62) affixed to the intermediate stratum is provided for joining adjacent panels of the enclosure. A rigid thermoplastic hinged cover (22) having a uniform bend (52) is provided for closing the enclosure.

Abstract: The invention relates to a noise reduction lining of the kind for use in passenger compartments of automobiles for absorbing engine noise of five or six cylinder combustion engines, and comprises between a cover layer and a base layer an absorption layer of open-pored elastic material into which is embedded a perforsted extinction layer.

Abstract: This invention relates to vacuum-tight tubular enclosures, made of plastic material and designed for making up insulating panels. Each vacuum cell is composed of a rigid plastic tube (1), both ends of which are closed by perforated plugs (3). This tube is placed in a thin flexible sheath (6) of highly impervious plastic material, preferably polyvinylidene or a derivative of polyvinylidic alcohol. This sheath extends beyond both ends of the rigid tube and is sealed by welding after the rigid tube has been evacuated to a high vacuum, namely less than 10.sup.-3 mm Hg. The extensions of the sheath are flattened and joined together by seams in a grid pattern so as to form offset rows of alveoles (11) for effectively preventing air leaks into the evacuated tube.This invention also relates to thermal and/or acoustic insulating panels in which evacuated cells (18, FIG. 9) of the above design are inserted, preferably in overlapping layers.

Abstract: The honeycomb structure is formed by adhering corrugated sheet units of molded glass wool together.

Abstract: A foam-barrier-foam-facing acoustical composite is disclosed having improved acoustical and flame retardant properties. The acoustical composite is a multilayered laminated fabric composed of: (a) a flame retardant polyvinyl fluoride facing layer; (b) a fire resistant acrylic adhesive layer bonded to the polyvinyl fluoride facing layer; (c) a first polyimide open cell foam layer bonded to the adhesive layer; (d) a noise barrier layer bonded to the first polyimide open cell foam layer, and (e) a second polyimide open cell foam layer bonded to the noise barrier layer.

Abstract: A sound insulating panel is provided having a support layer of honeycomb material, and a pair of covering layers, at least one of which is air-permeable. The support, honeycomb layer has a compressive strength greater than the compressive strength of each of the covering layers, in a direction transverse to the faces thereof, and has a tensile strength which is lesser, in the general direction parallel to the faces, than that each of the covering layers. The support layer is compacted over a part of its extent to a substantially closed layer of reduced thickness, this being, preferably, in the region of the border. A method of making an insulating construction element as described.

Abstract: A planar element for the absorption of air-transmitted sound, includes a flexible layer of open-cell foam material including a surface having protuberances with peaks formed thereon, and a flat closed cover layer formed of synthetic foil material fastened to the peaks of the protuberances, and a method of manufacturing the same.

Abstract: A hygienic absorbent, i.e. a substantially liquid and gas tight sound absorbent, including an under-absorbent (11), a tight foil (13) and gas-filled blisters (15) located therebetween. Preferably a supporting layer (16) is located outside the under-absorbent to support the blisters (15).

Abstract: A plate-component (1) which can be used for airborne-sound insulation has chambers (5, 6) filled with a pulverulent or granular, e.g. metallic material, whose chamber walls (2, 3, 4) at least partly are formed by a flexible material. Chambers (5, 6) are small in the vertical direction, but in the horizontal direction can form long channels. This construction not only leads to an increase in the sound insulation of a board joined to component 1 corresponding to an increase in the weight per unit area, but it is also possible to prevent coincidence breakdowns in the range 100-3000 Hz.

Abstract: A sandwich type acoustical absorbing panel for use adjacent to high speed gas flow areas in and around the engines of high speed aircraft. The panel in one embodiment comprises an imperforate facing sheet including having upright side and end walls, the inner volume of the panel and upright side and end walls are divided by means of partitions into a plurality of individual cavities or cells, each of the plurality of individual cavities or cells are filled with a bulk absorber material having many small torturous air passages, such as, open celled foam, fiberglass, felts or the like, the bulk absorber filling each cavity or cell is encapsulated in a membrane of thin limp material for preventing bulk absorber contamination and a perforated sheet overlay for attaching to the side, end walls and partitions for containing the bulk absorber within the cavities or cells.

Abstract: A noise control apparatus for reducing a sound volume of a noise propagating from a noise source such as a railroad includes a sound arresting wall placed apart from the noise source. Means for shifting in phase and refracting the acoustic wave of the noise is disposed at substantially the top of the noise arresting wall. The above means, for example, has a plurality of passageways extending substantially along the propagating direction of the acoustic wave of the noise and the length of the passageways varies. Through the above means, a part of the acoustic wave from the noise source is refracted and the phase thereof is shifted to be a refracted propagating sound, which thereafter interferes with the other part of the acoustic wave directly from the noise source to thereby reduce a sound volume to a great extent.

Abstract: A sound suppressor liner for aircraft exhaust passages is described which is based on the Helmholtz resonator principle including an inlet passage leading into a closed cavity wherein the inlet passages defined by a pair of curved walls with one wall being concave and the other wall being convex and the space between the walls gradually diminishing from the inlet of the inlet passage to the outlet within the cavity in a sense simulating an acoustic horn in reverse.

Abstract: A sound-absorbing building component for indoor paneling consisting of at least two superimposed sheets, preferably made of a synthetic resin. At least one of the sheets is provided with cup-shaped indentations lying side-by-side in the manner of a grid, the bottom surfaces of these indentations being excitable to lossy vibrations upon the incidence of sound. The upper rims of the cup-shaped indentations are all covered by a further planar sheet which is likewise capable of vibrations. This further sheet seals off the air volumes contained in the individual cup-shaped indentations in an airtight fashion. Small lumpy or irregularly-sized bodies can be provided on the bottom surfaces of the cup-shaped indentations.

Abstract: Viscoelastically damped reinforced skin structures wherein a sandwich skin having a relatively thick core is supported by structural elements, such as stringers and frames, are disclosed. In one form (FIG. 1), a main skin (15) is supported by stringers (13) that are in turn supported by frames (11). The skin, stringers and frames are securely attached to one another by any suitable means, such as a bonding adhesive, rivets, bolts, etc. Located between the stringers are core layers (17) formed of honeycomb or foam materials. A first plate (21) overlies each core layer and extends to the flanges of the adjacent stringer. A second plate (25) overlies each adjacent pair of first plates. The core layer is viscoelastically attached (19 and 23a) to the skin and the first plate; and, the first plate is viscoelastically attached (23b, c and 27a, b) to the stringer flanges and to the second plate. Alternatively, a single plate (49, FIG. 3) can overlie the core layers (47) and the stringers (43).

Abstract: An underwater acoustic array comprises an acoustic skirt baffle positioned djacent to a hull surface for reducing the transmission of shipboard noise; an acoustic conditioning module positioned over the acoustic skirt baffle; and an outer layer secured to the acoustic conditioning module and containing a plurality of hydrophone units.The acoustic conditioning module comprises inner and outer spaced coverplates; a plurality of spacer elements extending between the coverplates to form a plurality of closed chambers therebetween; and "tuned" viscoelastic damping elements secured to the outer coverplate.

Abstract: The invention relates to a sound damping material in the shape of foils or strips comprising open-pored foam material impregnated with different quantities of a viscoelastic compound, which is intended for application to attenuated structures, particularly automobile body panels.

Abstract: A method for preparing a resistive screen for underwater sound absorption consisting of a metallic honeycomb structure, adding a thermosetting plastic material to the cells within said structure, heating said structure under pressure and forming small apertures within said thermosetting plastic material.

Abstract: Disclosed herein is a flexible acoustical laminate construction which can be applied to noisy enclosures in order to attenuate noise therein. The construction of the invention finds particular use as a cabliner for the cabs or crew compartments of heavy construction, industrial, mining and transportation equipment of various types.

Abstract: A plurality of parallel and laterally spaced impermeable walls define an array of side-by-side elongate fluid filled cavities. Adjacent open ends of the cavities provide a sound-receiving or admittance end for the sound waves into the cavities. An acoustically reflective, preferably impermeable, barrier is disposed adjacent the ends of the cavities remote from their sound-receiving end and terminates the cavities. The cavities are uniquely configured to provide an effective geometrical sound absorbing structure while minimizing the structural elements required and, thus, the cost of manufacture.

Abstract: A noise reducing resonator, herein referred to as a silator due to its no silencing quality, is made up of primary struts forming a main frame and secondary struts forming at least one subframe enclosed by a vacuum tight cover to enclose a vaulting evacuated volume. Each frame has a given span width and a vaulting height corresponding to 0.005 to 0.05 times the respective span width. The frames are arranged in a hierarchic order which means that a larger main frame holds a smaller subframe which in turn holds a still smaller subframe and so on. The resonance frequency increases with the number of subframes held in a main frame. Interconnected silators may cover entire surface areas for noise reduction or absorption.

Abstract: A noise control device which relies upon retroreflection for sound attenuation. The device comprises an array of corner reflectors recessed into a surface and forming a sound retroreflecting panel. This cavitated surface provides the desired retroreflection of impinging sound waves so as to preclude undesirable onward propagation. The invention is particularly suitable for noise control applications in the presence of severe environmental conditions, and may also be used in combination with sound absorbing materials.

Abstract: A non-porous, sound-absorbing panel which can be readily cleaned and which is intended for use in high humidity, sanitary environments. The panel comprises two non-porous membranes or panels bonded to opposite sides of a honeycomb structure. At least one membrane is formed of sound-absorbing material with the membrane natural frequency, the membrane/honeycomb cavity natural frequency and the standing wave natural frequency of the honeycomb cavities being closely matched. In a preferred embodiment of the invention, the membrane comprises a polyurethane panel; while the honeycomb structure is formed from phenolic impregnated paper.

Abstract: Method of making attenuation sandwich panels having a cellular core positioned between and bonded to an imperforate facing sheet on one surface thereof and a perforate sheet with an outer layer of porous fabric material adhered to the other surface. The combined perforate facing sheet and porous fibrous material have a predetermined open surface area prior to its adherence to the cellular core. A coating of adhesive is applied to either the facing sheets or to the faying surface of the cellular core. The sheets are then properly positioned with respect to the cellular core. The porous fabric surface of the combined perforate sheet and porous fibrous material is positioned against a perforated plate. The opposite surface of the perforated plate is positioned against a bonding tool that has a plurality of longitudinal grooves on its perforated plate adjacent surface.

Abstract: A laminate structure for acoustical applications which comprises a porous, flexible, non-woven, needle punched mat of inherently non-burning, fine glass or other material fibers affixed as a facing to a sound absorbing, flame retardant, flexible backing such as a layer of open cell foam or a mat of glass or mineral fibers. The invention also contemplates the method of manufacture of such a laminate structure. Depending upon the materials used therefor, the facing and the backing may be joined together by needle punching and subsequent chemical bonding, chemical bonding, flame bonding and, in the case of an open cell foam backing, the backing may be foamed in place on the facing forming an intimate bond therewith.

Abstract: An adjustable light and air-admitting thermal and acoustic barrier has a plurality of sound-attenuating blades pivotally mounted in a frame in a mutually spaced, parallel relationship. When the barrier is mounted at an open window, the blades may be adjusted to various open positions to allow desired amounts of outside light and air into a room, but cooperate in such open positions to form an effective sound trap for annoying outside sounds. Each of the blades functions as both a sound absorber and a sound transmission barrier, and comprises an elongated, relatively thin core of solid, sound-reflective material having longitudinally extending edge and intermediate flanges which define cavities on opposite sides of the core. Secured within the cavities by the flanges are strips of sound-absorbing insulating material, the core and insulating material being laterally enfolded by a cover secured to the flanges.

Abstract: An article especially suited for use as a vibration isolating or shock absorbing structure comprising a multitude of short, resiliently compressible, elastic, tubular, rubbery bodies held together in closely-packed relationship by restraining means. The rubbery bodies comprise a cured thermosetting millable extrudable composition having in the cured state an elasticity in excess of 200% and an elongation at break in excess of 300%. The tubular bodies are characterized by having a length to diameter ratio from about 2:1 to about 8:1 and a wall thickness of at least 0.025 inch.

Abstract: An acoustical-reflective ceiling panel for directing incident light from a remotely positioned light source toward a selected area and for attenuating ambient noise. The panel includes a plurality of pyramidal reflector units arranged in an array of rows and columns and a plurality of acoustical holes which trap the ambient noise to thereby reduce the noise level in the vicinity of the panel. The pyramidal reflector units each have reflective surfaces facing in different directions and are located in staggered rows in which the pyramidal reflector units in alternate rows form the columns. Light emitted from a light source positioned laterally with respect to the pyramidal reflector units is reflected off those reflective surfaces that face the light source onto the selected surface area.

Abstract: A sound absorbing and attenuating panel is located at one end of an engine compartment for silencing the noise generated by an engine cooling fan located in the compartment. The panel includes a first set of laterally spaced, vertically extending silencing units comprising sound absorbing material encased in perforated containers and a second set of silencing units located one each between each of the first set of units and each comprising a container defining a combination of a pair of resonator chambers separated by a cavity filled with sound absorbing material.

Abstract: A noise reducing liner panel, such as a headliner and interior panel, and the like for motor vehicles, formed of a lamination of a substantially rigid, plastic sheet, a thin, flexible, foam plastic layer, and an outer fabric covering, all bonded together while flat. Numerous, small, closely spaced perforations are formed in pre-determined areas in the rigid sheet before laminating. The initially flat, rigid sheet is permanently bent and distorted, after the bonding, into pre-determined cross-sectional contours and shapes, including forming relatively deep depressions in the uncovered surface of the rigid sheet, at pre-selected areas, which depressions include areas of perforations. The depressions may be filled with sound absorbing materials, such as pieces of foam plastic, for thereby forming selected panel areas with greater sound absorbing capacity.

Abstract: A sound-absorbing structure comprising a plurality of linear and parallel grooves in the surface of the structure and ribs between the grooves. The structure is employed to damp, in a semi-space which is delimited by a substantially plane surface, e.g. a ground surface, a sound field propagating essentially in parallel with said surface. The sound field originates in for instance traffic on a motorway or an airport. The grooves of the structure are arranged in such manner, that a sound attenuation is obtained, in terms of the direction of propagation of the sound field, behind the structure by means of an acoustic coupling between adjoining grooves at the sound frequencies to be damped. The surface of the sound-absorbing structure is situated substantially in the surface delimiting the above mentioned semi-space. The cross-section of the structure has an outline similar to a square wave or a sine curve.

Abstract: A plurality of parallel and laterally spaced impermeable walls define an array of side-by-side elongate fluid filled cavities. Adjacent open ends of the cavities provide a sound-receiving or admittance end for the sound waves into the cavities. An acoustically reflective, preferably impermeable, barrier is disposed adjacent the ends of the cavities remote from their sound-receiving end and terminates the cavities. The cavities are uniquely configured to provide an effective geometrical sound-absorbing structure while minimizing the structural elements required and, thus, the cost of manufacture.

Abstract: A laminated noise attenuation panel for both sound absorption and sound transmission loss having as its principal layers an expanded thermoplastic core with alternately inverted cavities, half opening to each side of said core and a sheet of cured resinous material having hollow microspheres with substantially reduced atmospheric pressure randomly dispersed in said resinous material, said cured resinous sheet facing away from the noise source. The cavities of said core panel facing away from said noise source may be filled with cellulose. The side of said core panel toward the noise source may include a laminated layer of a perforated material and a decorative layer. The side of said panel away from the noise source may also include a layer of other materials and a decorative layer. Data for the noise attenuation properties of various combinations of laminations are presented.

Abstract: A noise barrier pad and a method for the production of same comprises the steps of forming a tread layer by reacting a mixture for polyurethane foam in a hollow mold having separable upper and lower parts and which is shaped so as to form the tread layer, curing the foam, removing the upper part of the mold, placing a blank of noise barrier material on the surface of the foam which corresponds to the bottom side of the tread layer, and forming a bottom foam layer on the tread layer and barrier material by placing another upper mold constructed in accordance with the bottom layer of the noise barrier pad and defining a cavity over the tread layer and barrier material and filling the cavity with the reaction mixture for the polyurethane foam.

Abstract: A lightweight wall covering and method of making same are provided wherein such wall covering has a substantially smooth inside surface and a textured outer layer comprised of a substrate having an exposed surface defining the inside surface, a fluid impervious film bonded against the substrate, and an embossed expanded vinyl plastisol bonded against the film and defining the textured outer layer with the textured outer layer being defined by alternating recesses and dense projections substantially free of air spaces and with the textured outer layer having a substantially fluid imprevious skin.

Abstract: The noise emanating from a noise-generating source, such as a machine tool or a stock tube, is reduced by covering the surface from or through which the noise emanates with a cladding comprising a first layer, an intermediate layer, and an outer layer. The first layer, 1 to 5 mm thick, of a resilient vibration-isolating material, being plastic foam, rubber foam, rubber, or fibrous material, has the function of decoupling the intermediate layer from the surface. The intermediate layer, 0.25 to 2.5 mm thick, of lead or metal-loaded plastic material in contact with and supported by the first layer, has the function of a sound-insulating barrier. The outer layer, resistant to impact, wear, and abrasion, has the function of surface protection. The total thickness of the three layers need be no more than 6 mm.

Abstract: This invention relates to acoustic liners having a plurality of cavities defining Helmholtz resonators in which the adjacent cavities are asymmetrical causing a pressure imbalance across the coupling means (tube, slot or aperture) between these cavities in the frequency range of interest. Such liners are particularly useful in turbofan engine noise reduction applications where low frequencies are encountered.

Abstract: A heat and sound insulating panel assembly for wall, ceiling or floor construction consists of a plurality of interlocking vacuum-chambered panel elements fabricated from a relatively hard, low thermally-conductive, fire-resistant or fireproof material with heat-reflective, moisture-restraining coatings on its inner and outer surfaces. Abutting surfaces may be provided with sound-cushioning pads, and vacuum-chambered spacer column elements may be employed, interlocked between panel elements, for uniform increased panel wall thickness.

Abstract: The present noise absorbing or damping devices are shaped as funnels or horns of various configurations which may be coiled, spiraled, rolled and/or bent or twisted. The open funnel mouth of each funnel faces toward the source of the noise. The volume confined by the funnel walls may be filled with noise absorbing material such as an open cell foam. Preferably at least the funnel neck is filled with such material. A plurality of funnels may be arranged on the walls of a room and the funnel mouths facing into the room may be covered with blankets or mats of noise absorbing material.

Abstract: A device for controlling a propagation direction of noise, which is preferably associated with a sound insulating wall to significantly improve its sound reducing effect of alleviating noise emitted from a noise source such as a railroad, highway and the like on which an electric car and automobiles run. The device comprises a hollow structural body composed of a plurality of elongated vertical hollow passages arranged at right angles to a substrate and spaced apart from each other by means of partition walls. The upper noise inlet side surface of the hollow passages face a propagation direction of noise emitted from the noise source and serve to refract and lag in phase the noise passed therethrough, thereby producing a sound reducing region located intermediate between a direct sound propagation and the refracted sound propagation. In one embodiment, a pair of hollow structural bodies are arranged in opposition to each other to form an arch type device.

Abstract: A noise control device which produces behind it an enlarged sound reducing region is disclosed. The device comprises a hollow structural body composed of a plurality of elongate hollow passages which are different in length and constructed such that the passage length is made the longest at a substantially center part in a vertical direction and is made gradually shorter from the center part toward upper and lower edges of the hollow structural body. The upper and lower edges allow direct propagation sound emitted from a noise source to pass thereover and therethrough.

Abstract: The disclosed foam laminate preferably includes a corrugated paper sheet, a layer of thermosetting resin foam wherein the corrugations extend into and are bonded to the foam layer and a relatively flexible finish sheet bonded to the foam layer. The corrugated sheet preferably includes a corrugated paper sheet bonded to a relatively flat sheet. In the disclosed automotive headliner, the corrugations preferably extend perpendicular to the headliner side edges, providing support for the concave midportion of the headliner and preventing delamination of the paper and foam laminae.

Abstract: A plurality of parallel and laterally spaced impermeable walls define an array of side-by-side elongate fluid filled cavities. Adjacent open ends of the cavities provide a sound-receiving or admittance end for the sound waves into the cavities. An acoustically reflective, preferably impermeable, barrier is disposed adjacent the ends of the cavities remote from their sound-receiving end and terminates the cavities. The cavities are uniquely configured to provide an effective geometrical sound absorbing structure while minimizing the structural elements required and, thus, the cost of manufacture.

Abstract: This invention relates to acoustic liners having a plurality of cavities defining Helmholtz resonators in which the adjacent cavities are asymmetrical causing a pressure imbalance across the coupling means (tube, slot or aperture) between these cavities in the frequency range of interest. Such liners are particularly useful in turbofan engine noise reduction applications where low frequencies are encountered.

Abstract: A sound absorbing body which can effectively be utilized as an exterior sound absorbing wall or an interior wall of a house is disclosed. The sound absorbing body comprises a number of sound absorbing cavities inclined at an angle .alpha. which is smaller than 80.degree. with respect to a transverse horizontal sectional plane of the body, the sound absorbing cavities being opened at the sound incident surface.

Abstract: An embossed film-to-foam laminate is provided having perforations through the film selectively distributed essentially along the sidewalls and valleys of the embossed pattern. The integrity of the laminated film material is retained on the crowns of the embossed patterned surface, since the perforations in the film material are mainly distributed on the sidewalls and valleys of the embossed pattern. The laminated product has a water-resistant and abrasion-resistant upper surface imparted by the film material on the crowns while the perforations in the sidewalls and valleys permit sound to pass through the film and be exposed to the acoustical matrix of the open cell foam component of the laminate. The film and/or the foam material are heated to supply adhesive material by melting or softening which serves to bond the film material to the foam.