Abstract: An angled connector having at least two legs (1, 2) arranged at an angle in reference to each other deviating from 0° and 180° for mounting a first part (3) to a second part (4). The connector has at least at one leg (1) and at least one intermediate layer (5) is provided made from a sound-dampening or vibration insulating material.

Abstract: An apparatus and method is provided for attenuating aerospace engine noise and unsteady pressure fluctuations associated with high velocity exhaust flows. The apparatus and method reduce acoustic fatigue damage to aerospace vehicles that may be caused by the reflection of exhaust energy from landing and/or launch platforms. The apparatus includes a passive treatment area associated with the platform operable for reducing the magnitude of the reflected sound waves and unsteady pressure fluctuations from the high velocity exhaust mass flow exiting from the engine. The passive treatment area may include a layer of sound absorptive material, at least one set of roughness elements for disrupting high velocity flow structures. A protective cover may be positioned over the passive treatment area for permitting exhaust flow to pass therethrough while still providing adequate structure to support the weight of the aerospace vehicle.

Abstract: There is provided an acoustic structure and a method of manufacturing such acoustic structure. The acoustic structure comprises at least one uncured facesheet ply defining a plurality of perforations, an adhesive that includes a corresponding plurality of perforations, and a honeycomb core portion adhered to the facesheet ply by the adhesive. The acoustic structure undergoes a single curing process, advantageously an autoclave curing process, to cure the entire acoustic structure. By adhering at least one uncured facesheet ply to the honeycomb core portion, the curing process is capable of curing both the facesheet ply and the adhesive with a single curing process. The single curing process accordingly obviates additional process steps and a sacrificial adhesive layer typically used in other acoustic structures.

Abstract: A sound attenuation panel includes a resistive layer with a reinforced structural component, comprising at least a honeycomb structure (1) flanked, on one side, with a resistive layer (2) consisting of at least a porous layer (2b) and of at least a perforated structural layer (2a), and, on the other side, with a layer forming a total reflector (3). The structural layer (2a) is perforated with non-circular holes (4) having each its largest dimension and its smallest dimension along respectively two perpendicular axes. The panel is particularly applicable to pods for aeroplane jet engines.

Abstract: A process for producing a sound absorber having skin layers constituting front and back surfaces and, interposed between the skin layers, a void layer having a number of voids, and having a plurality of formed holes each having a depth which is enough to penetrate one of the skin layers and is not enough to reach the other skin layer; comprising: providing a mold having a fixed part, a movable part, and at least one pin disposed in a manner that it can be projected into and retracted from a cavity; and having a step to cause the pin to project into the cavity during the course of charging the cavity with a resin material and molding the sound absorber and form the holes communicating with the void layer simultaneously with molding of the sound absorber.

Abstract: A steerable acoustic waveguide apparatus includes plural plates arranged in one or more linear arrays. Steering of an acoustic beam radiated from the waveguide apparatus may be achieved through differential delays of acoustic signals resulting from differences in timing, frequency, or mode or resulting from differences in physical attributes of the plates. In one aspect, where the apparatus is used with a target that is confined by a conduit such as a pipe, a longitudinal plane for the conduit intersects the linear array, an array plane for the linear array has a conduit orientation relative to the longitudinal plane, and the conduit orientation is substantially perpendicular or substantially parallel. The waveguide apparatus may serve as a thermal buffer and may simplify access to an acoustic path in a device such as an ultrasonic flowmeter.

Abstract: Panels for use in building construction (partitions, walls, ceilings, floors or doors) which exhibit improved acoustical sound proofing in multiple specific frequency ranges comprise laminated structures having as an integral part thereof one or more layers of viscoelastic material of varied shear moduli which also function as a glue and energy dissipating layer; and, in some embodiments, one or more constraining layers, such as gypsum, cement, metal, cellulose, wood, or petroleum-based products such as plastic, vinyl, plastic or rubber. In one embodiment, standard wallboard, typically gypsum, comprises the external surfaces of the laminated structure.

Abstract: The invention relates to a sound-absorbing coating for an elastic structure (1) made of at least two polymers, comprising at least one coating layer (2) closer to the elastic structure (1) and made of at least one polymer A and at least one coating layer (3) farther from the elastic structure (1) and made of at least one polymer B, the latter coating layer (3) being applied immediately on said at least one polymer A so as to form an integral composite effecting a loss factor in the range of from 0.01 to 0.6 in a temperature range of from ?20° C. to +80° C. The invention also relates to a process for preparing such a coating and the use of such a coating for making sound-absorbing coatings, for example on automotive vehicles.

Abstract: According to one aspect of the present invention there is provided an acoustic laminate suitable for use in wall, floor and ceiling assemblies and other dividing structure assemblies, the laminate including: a viscoelastic acoustic barrier being in the form of discrete, spaced apart sections or a continuous layer; and a construction panel, the barrier affixed to one or more panel faces of the construction panel.

Abstract: An enclosure for apparatus that, during operation, generates heat and/or sound energy comprises at least one wall defining at least a portion of the enclosure hollow interior. The wall comprises in sequence outwardly from the enclosure hollow interior an inner panel, an outer panel, a support frame between the inner and outer panels to hold the inner and outer panels spaced apart, and a vibrator isolator between the support frame and the panels. Panels or panel segments of the wall primarily are made of non-metallic composites to provide a structurally strong, lightweight enclosure that includes enhanced acoustic characteristics and reduced heat transfer through enclosure walls, along with fire protection and in-plane shear loading capabilities.

Abstract: Acoustic mats include a face layer and an absorptive layer having first and second surfaces wherein the second surface of the absorptive layer may be secured to said face layer. The mat further includes a plurality of discrete segments secured to the first surface of the absorptive layer such that regions of the first surface of the absorptive layer may be exposed, thereby allowing sound to pass between adjacent discrete segments into the absorptive layer.

Abstract: A sound insulation/absorption structure, a sound insulation/absorption device, and a structure having these applied thereto and a member constituting the same, are capable of insulating or absorbing sound by stiffness control. The sound insulation/absorption structure comprises a film member, such as a polymer film or metal foil, and a frame body having at least one annular opening, the film member being fixed to the frame body, the section of the film member surrounded by the frame body being of a curved shape such as a dome, wherein the resonance frequency of the in-plane stretching of this curved shape is set at a frequency equal to or higher than the audible frequency band, so as to insulate or absorb sound by the elastic force of the film. The film member may be replaced by an acrylic, polyethylene terephthalate or other plastic plate, an aluminum or other metal plate, or a veneer or other plate member, molded into a curved shape, such as a dome, a semi-cylinder and a cone.

Abstract: An apparatus comprising a combination of a microphone and a composite acoustic panel. The composite acoustic panel comprises materials having different spectra of acoustic absorption. The materials may be integrated in a single layer or in a plurality of different layers.

Abstract: [PROBLEMS] Provided is a sound absorbing material having a light weight, a smaller thickness, and outstanding sound absorbing property and heat insulating property. [MEANS FOR SOLVING PROBLEMS] Used is a sound absorbing and heat insulating material having at least one peak of normal incident sound absorption coefficient in a range of 315 to 5000 Hz, a peak absorption coefficient not less than 80%, and a thickness of 5 to 30 mm. For example, a layer obtained by laminating a porous film layer B including a resin having a melting point not less than 120 degrees C.

Abstract: The invention relates to a protective shield for the thermal and acoustic shielding of a components of an internal combustion engine, comprising a metal net with a multiplicity of through apertures; at least on absorber layer of a sound-absorbing material; and a carrier plate; wherein the metal net is arranged on the side of the protective shield facing the component; the at least one absorber layer is arranged between the metal net and the carrier plate; and the carrier plate in its edge region is folded over about the edge of the metal net.

Abstract: The invention relates to a soundproof thermal shield (3), particularly for motor vehicles, comprising an aluminum support (4), a noise-absorbing layer (6) and an aluminum thermal covering (7). In order to make the inventive soundproof thermal shield easy to recycle while obtaining a great thermal shielding effect and noise-absorbing power, a permeable mat made of knitted aluminum is used as a noise-absorbing layer (6), said knitted aluminum being superimposed in several layers and pressed so as to form the permeable mat. The inventive thermal shield is thus made of a single material. Preferably, the support (4) is made of a microperforated aluminum sheet while the thermal covering (7) is preferably made from an aluminum film.

Abstract: A material for use in building construction (partition, wall, ceiling, floor or door) that exhibits improved acoustical sound proofing and fire resistance. The material comprises a laminated structure having as an integral part thereof one or more layers of intumescent viscoelastic material which also functions as a glue, energy dissipating layer, and a fire resistive layer; and one or more constraining layers, such as gypsum, cement, metal, cellulose, wood, or petroleum-based products such as plastic, vinyl, plastic or rubber. In one embodiment, standard wallboard, typically gypsum, comprises the external surfaces of the laminated structure.

Abstract: The invention relates to a thin sound absorbing multi-layer assembly, which is intended, in particular, to reduce interior or exterior noise of a motor vehicle. The assembly according to the invention comprises at least three stacked layers consisting respectively of: a first layer (4) being impervious and having an area weight of between (20) to (100 g/m2); a second layer (3) having an air flow resistance of between (250) to (2500 Ns/m3) and an area weight of between (15) to (250 g/m2); a third layer (2) being an open pored, acoustic spring type layer having a thickness of between (2) to (30 mm) and an area weight of between (50) to (1000 g/m2).

Abstract: A perforated soundproof structure is formed by oppositely arranging an external plate 1 and an internal plate 2 having a number of through-holes 2a. The board thickness, hole diameter and open area ratio of the internal plate 2 are set to satisfy design conditions to give rise to a viscous effect in the air passing through the through-holes 2a, and the design conditions are set so that the frequency bandwidth to attain an absorption coefficient of 0.3 or more is 10% or more of the resonance frequency.

Abstract: An acoustic structure that includes a honeycomb having cells in which septum caps are located. The septum caps are formed from sheets of acoustic material and include a resonator portion and a flange portion. The flange portion has an anchoring surface that provides frictional engagement of the septum caps to the honeycomb cells when the caps are inserted into the honeycomb during fabrication of the acoustic structure. An adhesive is applied to the anchoring surface of the septum caps after the caps have been inserted into the honeycomb cells to provide a permanent bond.

Abstract: A material for use in building construction (partition, wall, ceiling, floor or door) that exhibits improved acoustical sound proofing and fracture characteristics optimized for efficient installation. The material comprises a laminated structure having as an integral part thereof one or more layers of viscoelastic material which also functions both as a glue and as an energy dissipating layer; and one or more constraining layers, such as gypsum or cement-based panel products modified for easy fracture. In one embodiment, standard paper-faced wallboard, typically gypsum, comprises the external surfaces of the laminated structure with the inner surface of said wallboard being bare with no paper or other material being placed thereon.

Abstract: A noise absorbing structure of an instrument panel of a vehicle includes a first noise absorbing panel, provided in the instrument panel disposed in front of a driver seat of the vehicle, a second noise absorbing panel, provided in the instrument panel disposed in front of a front passenger seat of the vehicle, and a third noise absorbing panel, provided in the instrument panel that is disposed in front of a moisture removing ventilation port.

Abstract: A soundproofing assembly includes stacked layers in the form of a first set of layers (36) having good resistance to the passage of air, and a second set of layers (24) with mass-spring function including a layer (28) having a heavy viscoelastic mass and a spring type layer (26); the first set of layers includes a layer (36) of a foam with open cells of high porosity, high tortuosity and good resistance to the passage of air, the layer (36) having, owing to its high tortuosity, excellent sonic absorption properties at medium and high frequencies. The invention is useful for soundproofing motor car passenger compartments.

Abstract: A sound absorbing panel comprising a generally rectangular mat of sound absorbing material, a plastic non woven covering at the frontal mat surface facing towards the sound insulated space and a sheet metal plate covering at the rear. The sheet metal plate covering extends outwardly perimetrically around the mat and forms uniformly sized flange extensions bent inwardly by 180° to form lip portions and corresponding recessions between the flange extensions and associated lip portions. Four Z section edge members are employed, one for each of the four lateral sides of the mat, each Z section edge member comprising a base portion abutting the lateral side of the mat and two spaced apart flange portions projecting in opposite directions from the base portion, one of these flange portions entering within the abovementioned recessions of the sheet metal plate covering wherein it is being pressed to form a compact frame structure perimetrically around the sound absorbing panel.

Abstract: A soundproofing material for vehicle having a laminated structure comprising two sound absorbing layers and an interlayer interposed therebetween, characterized in that the interlayer is formed by bonding and laminating on the respective side of an air-impermeable film made of a thermoplastic resin film having a thickness of from 7? to 50? heat-fusible films having a thickness of from 7? to 50? made of a thermoplastic resin film having a lower melting point than that of the air-impermeable film using a multi-layer inflation method and the soundproofing material is heat pressure-molded so that the heat-fusible film is melted to cause the sound absorbing layers to be bonded to the respective side of the air-impermeable film.

Abstract: A method of decreasing engine noise in machines, such as internal combustion engines, by replacing metallic engine components that serve as noise transmission pathways such as oil pans, valve covers, gear covers with similar components made of syntactic foam with a density of at least 0.5 g/cm3 and a hardness at least about equal to that of an equivalent metallic engine part which it is replacing. The syntactic foam is comprised of fluid-filled microballoons in a foam matrix. The microballoons have an outer shell harder than that of the surrounding foam matrix, and a majority of the microballoons are out of contact with one another.

Abstract: The invention relates to the layered sound absorptive non-woven fabric containing the resonance membrane and at least one another layer (1, 3) of the fibrous material at which the resonance membrane is created by a layer (2) of nanofibres having diameter to 600 nanometers and of surface weight 0.1 to 5 g/m2, at the same time the resonance membrane together with at least one layer (1, 3) of fibrous material is formed by cross laying to the required thickness and surface weight.

Abstract: An acoustic liner 20 includes a remote panel 26, a perforated proximate panel 22 transversely spaced from the remote panel and one or more partitions 32 spanning across the space between the panels. At least one baffle 44 cooperates with the partitions to define a resonator chamber 34b and an associated neck 56 for establishing communication between the resonator chamber and a fluid stream G flowing past the proximate panel.

Abstract: The present invention provides an acoustical firewall attenuating assembly. The assembly includes a first frame assembly having a first plate, a second plate and a first plurality of elongate members spaced from one another and extending between the first plate and the second plate. A structure is spaced from the first frame assembly and has an outer surface. A cement wall is positioned between the first frame and the structure and is attached to at least the first frame assembly by a first vibration dampener.

Abstract: A sound absorbing material (1a) comprising a film (11) composed of a silicone rubber and a porous layer (12) (i.e., a first porous layer) laminated on the back surface of the film (11). The film (11) is made of a material which has flame retardancy and generates no noxious fume during combustion, such as a silicone rubber comprising only polysiloxane. The film (11) used is preferably one which has an oxygen index of 25 or higher, which exhibits a heat release value of combustion per unit volume of 8 MJ/m or less and which exhibits a heat release rate of combustion of [200 kW/m2]·10 sec or less. The first porous layer (12) is formed from a material having flame retardancy, such as glass wool, rock wool or a mixture thereof. A structure (3a) can be formed by providing the sound absorbing material (1a) having the construction described above on a rigid wall (2) in parallel, with the first porous layer (12) facing to the rigid wall (2).

Abstract: An acoustical panel comprising a continuous phase of an interlocking set gypsum matrix and a method of preparing an acoustical panel are disclosed.

Abstract: A composite panel has one or more recesses, or smoothly-contoured recesses formed in one or both opposing sides of a core. Reinforcement conforming to each recess is coupled to the core at the recess. First and second facing sheets are respectively coupled to the first and second opposing sides of the core.

Abstract: According to one aspect of the present invention there is provided an acoustic laminate including: a first layer of viscoelastic acoustic barrier material; a sound absorbing/decoupling batt affixed to the first layer of viscoelastic acoustic barrier material, the batt at rest defining a batt plane; the batt including a plurality of batt fibres; the batt further including retaining fibres, wherein the batt fibres and/or retaining fibres are disposed perpendicular to the batt plane and having end portions thereof disposed at a batt surface, the end portions affixed to the viscoelastic barrier material so that either the first layer of viscoelastic acoustic barrier material or the sound absorbing/decoupling batt itself may be retained in spaced relation from a mounting surface when the laminate is so mounted, the retention being achieved in any orientation by bearing a mass load of the batt or first layer of viscoelastic material along the axis of the affixed batt fibres and/or retaining fibres.

Abstract: A sound absorbing body 40 has a molded body 44 including two unexpanded layers 41, 42 and an expanded layer 43 having a number of voids and held between these unexpanded layers 41, 42, a plurality of holes 41A of a depth that passes through the unexpanded layer 41 and does not reach the other unexpanded layer 42 are formed at any positions on the molded body 44, a cross-sectional area of the hole 41A is in the range from 0.785 to 314 mm2, and the pitch is 1 mm or larger. Laminating a plurality of materials is not required, and both the sound absorbing capability and sound insulating capability can be secured by integral molding, and further, only unpleasant sounds can selectively be absorbed.

Abstract: A cooled acoustic liner useful in a fluid handling duct includes a resonator chamber 52 with a neck 56, a face sheet 86, and a coolant plenum 80 residing between the face sheet and the chamber. Coolant bypasses the resonator chamber, rather than flowing through it, resulting in better acoustic admittance than in liners in which coolant flows through the resonator chamber and neck. In one embodiment, the liner also includes a graze shield 88. Openings 40, 38 penetrate both the face sheet and the shield to establish a relatively low face sheet porosity and a relatively high shield porosity. The shielded embodiment of the invention helps prevent a loss of acoustic admittance due to fluid grazing past the liner. Another embodiment that is not necessarily cooled, includes the resonator chamber, low porosity face sheet and high porosity shield, but no coolant plenum for bypassing coolant around the resonator chamber.

Abstract: A wall or ceiling panel secures a grid insert, preferably of an architectural metal mesh, within a frame using a series of spring clips. The spring clips engage the metal mesh and are retained in a securing slot provided at an interior edge of the panel frame. Each spring clip includes at least one engagement member that passes through and engages the grid insert. The spring also includes a securing base that is received and retained within the securing slot of the frame. The panel can also include a securing arrangement for supporting the grid member at a position spaced from the frame to avoid downward bowing of the metal mesh.

Abstract: A sound insulating component includes a decoupling layer disposed under a cap layer comprising a thermoplastic cellular foam. Advantageously, the cap layer has sufficient rigidity to maintain a predetermined shape and has an airflow resistance that allows a predetermined amount of airflow through the sound insulating component. In another embodiment, a hybrid sound insulating component includes a cap layer and a decoupling layer with an airflow control layer interposed thereof. A method of making the sound control components is also provided.

Abstract: A multi-layered fiber reinforced thermoplastic sound absorbing panel includes a porous fiber reinforced thermoplastic core layer having a first surface and a second surface, and includes a thermoplastic material and from about 20 weight percent to about 80 weight percent fibers, a tie layer covering the second surface of the core layer and including a thermoplastic material, and a barrier layer covering the tie layer. The barrier layer includes a thermoplastic material having a melting temperature higher than the melting temperature of the core layer thermoplastic material. The tie layer bonds the barrier layer to the core layer. The panel also includes a non-woven layer including a fabric bonded to the barrier layer. The non-woven layer forms an outer surface of the panel.

Abstract: An integrated noise suppression acoustic panel includes a back plate, a face plate, and a bulk foam absorber disposed between the back plate and the face plate. The bulk foam absorber is formed of a thermoset material, such as bismaleimide or phenolic, and is manufactured using a low pressure process. In particular, a foamable material is melted, and a blowing agent is mixed with the foamable material to obtain a mixture. The foam is formed and the mixture is cured by heating it to a temperature, and maintaining the mixture at the temperature for a time sufficient to cure the mixture.

Abstract: Sound insulation constructions, multilayer constructions for acoustically insulating a source of sound from a receiver that include one or more sound insulation constructions, structures comprising one or more sound insulation constructions and/or multilayer constructions, and a method for acoustically insulating a source of sound from a receiver. In some embodiments, the sound insulation construction includes a first layer and a second layer. The first layer can include a bonded fiber nonwoven web exhibiting a work of compression of at least about 0.7 kJ/m3 and an airflow resistance of no greater than 10,000 Rayls/m. The second layer can exhibit an airflow resistance of greater than 10,000 Rayls/m. In some embodiments, the method includes coupling the first layer to a surface of a vehicle to attenuate sound in at least a portion of the vehicle.

Abstract: A device including a membrane having first and second faces; a first substrate disposed on the first face of the membrane and having (i) a plurality of first absorptive regions and (ii) a plurality of first reflective regions formed as wells in a face of the first substrate, the first absorptive regions and the first reflective regions arranged in a pre-defined grid pattern; a second substrate disposed on the second face of the membrane and having (i) a plurality of second absorptive regions and (ii) a plurality of second reflective regions formed as second wells in a face of the second substrate, the second absorptive regions and the second reflective regions arranged in the pre-defined grid pattern.

Abstract: An acoustic liner 20 includes a remote panel 26, a proximate panel 28 transversely spaced from the remote panel and a resonator chamber 34b residing between the panels. Perforations 38 penetrate the proximate panel in registration with the resonator chamber 34b. A neck 56 with an inlet 58 recessed from the proximate panel establishes communication between the chamber and a fluid stream G flowing past the proximate panel. A bypass coolant passage 66 guides coolant through the perforations without guiding it through the resonator chamber.

Abstract: An enclosure having at least one wall, the wall includes an inner panel comprising, in sequence outwardly from the enclosure hollow interior, an inner sheet comprising a plurality of perforations extending therethrough, a plurality of panel stiffening members coupled to the inner sheet, and at least one inner panel sound absorption member comprising non-metallic sound absorption material positioned between adjacent of the plurality of panel stiffening members, and an outer panel comprising in sequence inwardly from outside of the enclosure, an outer panel sandwich member comprising non-metallic composite material including spaced-apart first and second walls and a plurality of spaced-apart transverse walls extending between the first and second walls defining hollow chambers therebetween, the outer panel coupled to the inner panel such that an outer surface of the inner panel is substantially flush against an outer surface of the outer panel.

Abstract: A composite structure, and method of manufacturing it, having a specified width, length, and height defining a top and bottom the composite structure. The composite structure includes a three dimensional structural core constructed of a polymer with a first series of a geometric pattern repeated along its length. The structural core also has a second series of the geometric pattern repeated along the width thereof. The geometric patter may be a sinusoidal curve or a substantially pyramidal shape. The composite structure also includes a first reinforcement layer made of a polymer positioned above the structural core and bonded thereto. It also includes a second reinforcement layer made of a polymer that is positioned below the structural core and bonded thereto. The composite structure may also include a decorative layer above the first reinforcement layer, an acoustical batting layer positioned between the first reinforcement layer and the structural core, and may include fire retardant chemicals.

Abstract: A floor covering characterized as having a strong noise-reducing properties for the interior trim of means of transport. The floor covering has, on the passenger side, a textile or non-textile surface, acoustically coupled through at least one microperforated sheet to a fibrous non-woven and/or foamed plastic. A microperforated sheet having a hole diameter from 0.2 to 0.5 mm and an interhole distance from 3 to 7 mm.

Abstract: In order to provide a sound-absorbing panel and a production method of the same which has excellent freedom of design and have small differences in the maximum sound-absorbing coefficients among products, a sound-absorbing panel is adopted which is characterized by a panel main body (4) which is constituted by arranging both a porous veneer (2) of 0.02-0.5 mm thickness with multiple pierced apertures of 0.1 mm or smaller aperture diameters or 0.2 mm or smaller aperture diameters and a porous sound-absorbing base material (3) set at a backside (2a) of the porous veneer (2) so as to be overlapped, and is characterized by having a value of airflow resistance in a range of 0.1-1.0 Pa.

Abstract: The present invention provides means of enhancing the acoustic attenuation and vibration damping of a material by (1) embedding a plurality of small particles of either a high characteristic acoustic impedance or a low characteristic acoustic impedance or combinations of high and low characteristic acoustic impedance materials to form a matrix material to act as a acoustic attenuator or vibration damper; and (2) combing this matrix material with a second layer of a decoupling material that serves to effectively isolate the matrix material and reduce its tendency to vibrate sympathetically to the impinging acoustic energy. The mass of the resultant material may be very low while retaining excellent acoustic attenuation, vibration damping, and structural characteristics.

Abstract: Acoustic attenuation materials are described that comprise outer layers of a stiff material sandwiching a relatively soft elastic material therebetween, with means such as spheres, discs or wire mesh being provided within the elastic material for generating local mechanical resonances that function to absorb sound energy at tunable wavelengths.

Abstract: To obtain a wide passenger compartment space, the thickness of a heat insulating acoustical layer is reduced, and for this purpose, a comfortable in-car environment is obtained by using a vacuum insulating panel which combines high heat insulating performance and sound insulating performance. A heat insulating acoustical layer 20 is formed on one surface of a lightweight alloy structure 10 of double skin construction by using a vacuum insulating panel 21 as a middle member and sandwiching two surfaces of the panel with elastic sound absorbing materials 22, 23 made of a nonwoven fabric or a foamed body, and the heat insulating acoustical layer is covered with an interior material 24. Owing to this construction, the transmission loss of a noise which transmits from the double skin structure side is improved by the mutual actions of the elasticity of the sound absorbing material and the rigidity of the vacuum heat insulating panel.

Abstract: A radio frequency (“RF”) shielded and acoustically isolated enclosure that efficiently employs multiple layers of sound insulation and absorbs airborne noise and the noise provided by magnetic resonance imaging (“MRI”) equipment through the supports of such equipment. The RF enclosure uses multiple layers and types of insulating materials positioned to maximize the noise absorption of the RF enclosure. This reduces the cost and space required by the enclosure. In one embodiment the enclosure includes a ceiling, a floor and a plurality of walls. The ceiling and walls include one or more multiple layers of different insulating materials that either abut each other or form air gaps. In one embodiment the floor includes a heavy metal plate on which the MRI equipment sits. The plate elastically couples to a conductive shield. The elastic coupling attenuates certain frequencies above the natural frequency of the metal sheet.