Abstract: Embodiments of thermal-acoustic sections for an aircraft for reducing noise along an acoustic path produced from an acoustic source are provided herein. The thermal-acoustic section comprises a first porous layer having a first characteristic acoustic impedance. A second porous layer is disposed adjacent to the first porous layer and has a second characteristic acoustic impedance that is greater than the first characteristic acoustic impedance. The thermal-acoustic section is configured to be positioned along the acoustic path such that at least a portion of the noise from the acoustic source is directed through the first porous layer to the second porous layer to promote absorption of the noise.

Abstract: A wall element for the sound-insulating interior lining of a transport device, comprising at least one sandwich element, at least one insulation package and at least one absorber plane element. The sandwich element comprises at least one core layer, a first cover layer and a second cover layer, wherein the first cover layer and the second cover layer are each arranged on one side of the core layer. At least the first or the second cover layer is a microperforated layer; the sandwich element possesses a shear rigidity that is adjusted in such a way that the sandwich element comprises one or several coincidence boundary frequencies that are determined by the shear rigidity, which coincidence boundary frequencies are outside the frequency range that dominates the noise in the interior of the cabin; and the shear rigidity of the sandwich element at the same time is sufficient for said sandwich element to be used as an interior lining.

Abstract: An acoustic absorber includes a wall provided with a plurality of apertures as well as a substantially non-perforated second wall, with the first wall and the second wall being spacedly arranged to one another, and at least one honeycomb structure being provided between the walls, with the honeycomb structure having a substantially cylindrical recess in at least one area, with a funnel element opening to the first and second walls being provided in the recess, and having a height greater than the distance of the walls, with the second wall being designed pot-like in the area of the funnel element.

Abstract: Methods for vibration and acoustic abatement. The methods comprise providing a substrate with a composite layer deposited thereon, the substrate receiving a vibration energy sufficient to provide at least one bending wave therein, and converting at least a portion of the vibration energy sufficient to cause the at least one bending wave to at least one shear wave in at least a portion of the composite layer. The composite layer comprises an elastomeric polymer matrix comprising carbon nano tubes dispersed or distributed therein. Articles with the composite layer comprising carbon nano tubes disposed thereon are also disclosed and described.

Abstract: PROBLEMS The present invention provides a sound absorbing structure that enables a sound absorbing rate thereof to be raised in a low-frequency region or medium-high frequency from around 500 Hz to 10 KHz, and a thickness thereof to be reduced. SOLUTIONS The sound absorbing structure has: a non-air permeable sheet molding object having, on one surface side thereof, a plurality of cavities including recesses formed by bending; and a non-air permeable surface sheet which is layered on the sheet molding object, on a cavity open-top side surface thereof, so as to cover open-top of the plurality of cavities, wherein the surface sheet is fixed at outer peripheral sections of the sheet molding object 11 and is not fixed to the sheet molding object at portions between adjacent cavities.

Abstract: An acoustic treatment panel includes two portions with edges spaced in one direction, and from the outside to the inside, a first acoustically resistive layer, a first alveolar structure, and a reflective layer, and a block inserted between the two edges which includes, from the outside to the inside, a second acoustically resistive layer arranged at the first acoustically resistive layer and a second alveolar structure. The block includes at least one sector of alveolar structures with sloped pipes whose height is less than that of the first alveolar structure, whereby the pipes are sloped in a direction such that the ends of the pipes are close to one of the edges of the portions at the first acoustically resistive layer, and the opposite ends of the pipes are moved away from the edge and the reflective layer so as to house connecting elements between the block and the panel.

Abstract: The invention relates to a broadband sound absorber (1) which comprises a sound-absorbing filler material between two microperforated film webs (2) which are contiguous on their edges, said filler material optionally containing heavy fillers. The broadband sound absorber (1) achieving excellent acoustic insulation comprises a sound-absorbing filler material between two film webs (2) which are contiguous on their edges and have microperforations (4) all over or only in sections, said filler material optionally containing heavy fillers (mass density) and one or both microperforated film webs (2) having the same thickness across their surface or thickened portions (3, 5) of the same or a different material in some sections.

Abstract: A noise attenuation panel includes a first wall, a second wall and partition walls connected to the first and second walls and defining cells between the first and second walls. The first wall is provided with a plurality of through holes. At least two of the cells are interconnected via a communication hole. One of the through holes leads to a first of the at least two interconnected cells and a second of the interconnected cells is configured to prevent any gas flow through the second cell.

Abstract: A method for producing an acoustic treatment panel, including: assembling two plates, at least one of which is deformed so as to separate the plates locally in order to form cavities of a cellular structure between the two plates, said cavities being delimited by facets and partitions formed by at least one of the deformed plates, producing at least one opening on the facets of one of the two plates, and pressing an acoustically resistive plate against the surface of the cellular structure including the openings.

Abstract: A multilayer acoustic treatment panel including a first cellular-structure core sandwiched between a perforated skin and an intermediate skin; and a second cellular-structure core sandwiched between the intermediate skin and a continuous skin. The perforated skin includes at least one pair of high-porosity zones presenting a perforation ratio greater than a perforation ratio of a remainder of the perforated skin and including an inlet zone and an outlet zone longitudinally spaced apart from each other, the high-porosity zones of a given pair communicating through the first cellular-structure core and the intermediate skin with the two ends of a soundwave flow channel arranged in the second cellular-structure core.

Abstract: The invention describes a method for making a composite panel and the product made by the method. The composite panel is made from a soft septum treated with a composition containing silane and an organic acid. The treated soft septum is adhesively bonded between two honeycomb panels, forming a sandwich of the septum between the two honeycomb panels.

Abstract: An acoustic dampening panel comprising: (a) a first layer of expanded polypropylene; (b) a solid layer having a surface weight between 2.4 kilograms per meter squared and 25 kilograms per meter squared; and, (c) a second layer of expanded polypropylene, where the first and second layers of expanded polypropylene sandwich the solid layer therebetween. The acoustic dampening panel may further comprise a fourth layer comprising a metal skin, where the solid layer and the metal skin sandwich the second layer therebetween.

Abstract: A method for producing a double-layer or triple-layer sound-absorbing panel (10) is specified, said panel consisting of a support panel (20) and at least one cover panel or coating (30, 35) of the support panel (20), the cover panel or coating (30, 35) being fixedly connected to the support panel (20). In this case, an open-pore (121) support panel is provided as the support panel (20) and the sound-absorbing panel (10) is arranged on each side (12, 13) provided with a cover panel or coating (30, 35) with a device opposing said side emitting a laser beam, the upper face (12) of said panel (10) being subjected to the laser beam, which is designed to burn away material from the cover panel or coating (30, 35) facing said laser beam over the depth in the direction of the laser beam in a plurality of holes (31).

Abstract: An acoustic structure that includes a honeycomb having cells in which septum caps are located. The septum caps are formed from sheets of flexible material that may be perforated before or after the material is inserted into the honeycomb. The flexible material is sufficiently flexible to allow folding into the shape of a septum cap. The flexible material is also sufficiently stiff to provide frictional engagement and locking of the septum cap to the honeycomb cell when the cap is inserted into the honeycomb during fabrication of the acoustic structure. An adhesive is applied to the septum caps after the caps have been inserted into the honeycomb cells to provide a permanent bond.

Abstract: Embodiments of thermal-acoustic sections for an aircraft for reducing noise along an acoustic path produced from an acoustic source are provided herein. The thermal-acoustic section comprises a first porous layer having a first characteristic acoustic impedance. A second porous layer is disposed adjacent to the first porous layer and has a second characteristic acoustic impedance that is greater than the first characteristic acoustic impedance. The thermal-acoustic section is configured to be positioned along the acoustic path such that at least a portion of the noise from the acoustic source is directed through the first porous layer to the second porous layer to promote absorption of the noise.

Abstract: Systems and methods for noise suppression are disclosed herein. In one embodiment, an acoustic structure has a core that includes a plurality of cells. Each of the plurality of cells includes one or more engaging structures for positioning a septum relative to the cell. The acoustic structure further includes a plurality of septums positioned relative to the plurality of cells.

Abstract: A honeycomb structure that includes cells in which septums are located to provide acoustic dampening. The cells are formed by at least four walls wherein at least two of the walls are substantially parallel to each other. The septums include warp fibers and weft fibers that are substantially perpendicular to each other. The septums are oriented in the honeycomb cells such that the weft fibers and/or warp fibers are substantially perpendicular to the parallel walls.

Abstract: A sound attenuation mechanism made up of multiple substrate layers, including corrugated layers. The use of corrugation provides an inexpensive and manner of forming a plurality of highly effective acoustic attenuation channels throughout the mechanism. The multi-layered mechanism may be provided in a variety of modular forms and sizes which may be combined to form a low-cost, highly effective attenuation housing. For example, such a housing may be utilized to contain otherwise noisy large scale oilfield equipment such as coiled tubing engines. Additionally, where drainage from the housing is sought, a spiraled attenuation channel may be employed such that the effectiveness of the attenuation provided by the housing is not sacrificed.

Abstract: The invention is an acoustic liner for attenuating noise in rotating machinery. The acoustic liner may include a plurality of cells coupled together to form an annular cell matrix, the plurality of cells being made of a non-metallic material, for example, plastics, polymers, thermoplastics, or thermosets. Each cell of the acoustic liner may be hexagonally-shaped such that the annular cell matrix forms a honeycomb structure.

Abstract: A sound absorber is formed by covering the opening of a housing with a vibration member having a flat shape or a film shape so as to define an air layer therebetween. The sound absorber is attached to the wall of a room such that the vibration member is positioned opposite to the wall with a prescribed space therebetween. Sound generated in the room particularly in low frequencies enters into the space between the vibration member and the wall so as to cause vibration of the vibration member due to the pressure difference between the sound pressure applied to the space and the internal pressure of the air layer, thus consuming energy of sound waves. Thus, it is possible to efficiently absorb low-frequency sound with a reduced thickness of the air layer.

Abstract: Disclosed is a partition panel capable of improving sound insulation performance and optimizing a reverberation time. The partition panel has sound absorption and insulation functions, comprising: a front plate having a perforated section with a plurality of through-holes and an entirely-continuous peripheral edge portion located outside the perforated section; an entirely-continuous back plate disposed on a side opposite to a sound source across the front plate; an inner perforated plate disposed between the perforated section of the front plate and the back plate; a front-side honeycomb core interposed between the perforated section and the inner perforated plate; a back-side honeycomb core interposed between the back plate and the inner perforated plate; and a peripheral honeycomb core interposed between the peripheral edge portion of the front plate and a region of the back plate opposed to the peripheral edge portion.

Abstract: An aircraft cabin panel for acoustic absorption in an interior space includes a core layer, a first cover layer and a second cover layer. The first cover layer includes a space-enclosing first surface, and the second cover layer is arranged opposite the first cover layer. The first cover layer is acoustically transparent, and the core layer includes a honeycomb core with a plurality of tubular or honeycomb-like cells that are open throughout the thickness of the honeycomb core. The honeycomb core on the face pointing towards the first cover layer extends parallel to the first cover layer so as to be continuously throughout, and on the face pointing towards the second cover layer comprises recesses which extend over several cells. Absorbers are accommodated in the recesses.

Abstract: Systems and methods for noise suppression are disclosed herein. In one embodiment, an acoustic structure has a core that includes a plurality of cells. Each of the plurality of cells includes one or more engaging structures for positioning a septum relative to the cell. The acoustic structure further includes a plurality of septums positioned relative to the plurality of cells.

Abstract: The present invention relates to an acoustic absorber that is particularly suitable for aircraft engines and has a honeycomb-shaped 3-dimensional structure, which absorbs engine noise when used in an engine. The structure has a plurality of folded honeycomb structures formed by folding a flat semi-finished product.

Abstract: A wing-to-body fairing for aircraft is formed from a sandwich structure having integrated vibration damping.

Abstract: A process for producing through-holes in a sheet member to form a perforated article, such as an arcuate (non-planar) acoustic skin suitable for use in an acoustic panel of an aircraft engine nacelle. The process includes deforming a sheet member to have an arcuate shape with an arcuate surface, mounting and rotating the arcuate-shaped sheet member on a mandrel and then, while rotating the sheet member, directing an electron beam at the arcuate surface of the sheet member and deflecting the electron beam toward multiple locations on the arcuate surface to produce the through-holes through the sheet member in a defined hole pattern and thereby yield a perforated arcuate-shaped sheet member with holes having axes substantially normal to the arcuate surface. The holes are not subjected to elongation in a nonuniform manner after they are produced, and have the same transverse cross-sectional shape.

Abstract: A method for splicing honeycomb core together to form a core structure, such as an acoustic panel for an aircraft. The core structure may comprise a first honeycomb core, a second honeycomb core, and an intermediate bonding part disposed between the first and second honeycomb cores. The intermediate bonding part may comprise a syntactic core wrapped with or sandwiched between a non-foaming film adhesive. The syntactic core sandwiched between a first and second layer of film adhesive and a first and second honeycomb core is then compressed by vacuum and cured to bond the honeycomb cores together, forming the core structure.

Abstract: An acoustical panel construction useful as a suspended ceiling tile having a rectangular shape bounded by edges and establishing a face area comprising at least one corrugated layer or layers of a total thickness, the layer or layers having a multitude of parallel flutes extending across an expanse of the rectangular shape substantially from one edge of the panel to an opposite edge, the flutes being formed by walls of the layer or layers and being of known volume, a series of apertures each of known area through the wall or walls of the flutes communicating with the atmosphere at the face, the aperture area, flute cavity volume associated with an aperture, and the total thickness of the corrugated layers associated with an aperture being arranged to produce a maximum absorption frequency between 200 and 2,000 Hz.

Abstract: The invention relates to a cellular-core structure (10) that can be used in an acoustic panel for a turbojet nacelle, comprising at least one cellular unit (12; 14), each cellular unit (12; 14) comprising two end sheets (18; 20), the end sheets (18; 20) being joined together by joining elements (24) that are placed so as to form cellular cells (32). The subject of the invention is also a method of producing such a structure, an acoustic panel comprising such a structure, and a nacelle comprising such an acoustic panel.

Abstract: Systems and methods for noise suppression are disclosed herein. In one embodiment, an acoustic structure has a core that includes a plurality of cells. Each of the plurality of cells includes one or more engaging structures for positioning a septum relative to the cell. The acoustic structure further includes a plurality of septums positioned relative to the plurality of cells.

Abstract: An acoustic panel includes a main body portion having a substantially planar front surface for orientation toward a sound source and an opposite, substantially convoluted rear surface. An airflow-resistive layer of material is secured to the planar front surface in face-to-face contacting relationship. The airflow-resistive layer of material may have a specific airflow resistance of between about 50-20,000 mks rayls, and may be configured to attenuate sound at one or more predetermined frequencies. A depth of convolution of the rear surface is between about forty percent to about seventy-five percent (40%-75%) of a thickness of the main body portion.

Abstract: The different advantageous embodiments provide an inner barrel structure comprising an outer skin, an inner skin, a number of septa, and a truss core.

Abstract: A noise attenuation panel includes a first wall, a second wall and partition walls connected to the first and second walls and defining cells between the first and second walls. The first wall is provided with a plurality of through holes. At least two of the cells are interconnected via a communication hole. One of the through holes leads to a first of the at least two interconnected cells and a second of the interconnected cells is configured to prevent any gas flow through the second cell.

Abstract: A method of installing an acoustical system that provides a desired sound attenuation includes attaching an acoustical panel having a first density, a first porosity and a first void volume to the substrate. A first finishing layer is prepared with first particles, a first binder, a first rheological modifier and water which are combined, applied to the substrate and dried. The first finishing layer has a first density. When the first sound attenuation changes to a second sound attenuation a second finishing layer is prepared to include second particles, a second binder, a second rheological modifier and water. The dried second finishing layer has a second density. If the second density is less than the first density, the second sound attenuation is greater than the first sound attenuation. If the second density is greater than the first density, the second sound attenuation is less than the first sound attenuation.

Abstract: The image forming apparatus in this disclosure includes a main body, a plate-shaped frame member, a perforated portion, a sound generating source, an external cover member, and a space forming portion. The plate-shaped frame member configures a part or the whole of the side surface of the main body. The perforated portion has a plurality of holes and is formed in the frame member. The sound generating source is an inner portion of the main body and is disposed at a position corresponding to the perforated portion. The external cover member is disposed at and separated by a predetermined distance from the frame member on an outer side of the frame member. The space forming portion forms a space between the perforated portion and the external cover member that is tightly enclosed except for the perforated portion.

Abstract: The invention relates to an acoustic absorber comprising an absorption layer (1a, 1b) composed of an open-pored porous material. According to the invention, the open-pored porous material is flexurally stiff in such a way that the absorption layer (1a, 1b) is stimulated to flexurally oscillate when sound waves impinge on the absorption layer and the absorber can absorb sound waves of a first frequency range because of the inflow of air into the open-pored porous material of the absorption layer and can absorb sound waves of a second frequency range that comprises lower frequencies than the first frequency range because of the stimulation of flexural oscillations of the absorption layer. The invention further relates to an acoustic transducer and to a method for producing an acoustic absorber or an acoustic transducer.

Abstract: A linear acoustic liner for an aircraft includes a cellular core having a first surface and an opposed second surface. A substantially imperforate back skin covers the first surface, and a perforate face skin covers the second surface of the core. The perforate face skin includes an outer face skin layer having a first plurality of spaced openings, an inner face skin layer having a second plurality of spaced openings, and a porous layer disposed between the outer face skin layer and the inner face skin layer. Each of the first plurality of spaced openings are substantially aligned with one of the second plurality of spaced openings.

Abstract: Disclosed are a sound absorbing panels and a sound absorbing system using such panels, particularly for use in reducing highway and railway noise. The panel includes an enclosure including a first panel face with a number of apertures or holes to allow sound passage, where the ratio of the area of the apertures to the total area of the first panel face is set at a predetermined percentage. The enclosure is configured such that an inner surface of the first panel face is proximate to a fibrous sound absorbing material with an area approximately equal to the total area of the first panel face. The panel enclosure may have various shapes and configurations for optimal sound absorption, and may be configured in a sound absorbing system such that one or more of the panels are mountable to existing structures, such as sound barrier walls in a retrofit manner.

Abstract: A laminated panel is provided including a first layer of material having external and internal surfaces; a second layer of material having external and internal surfaces; a layer of viscoelastic glue in contact with the internal surface of said first layer of material and with the internal surface of said second layer of material; said glue including an acrylic polymer in a concentration between 10% and 60% by weight, or a tackifier in a concentration between 1% and 70%; or a plasticizing compound in a concentration between 0% and 15%; or a material with Tg greater than 0° C. in a concentration between 0% and 30%. A soundproof assembly is also provided including a first and second panel; at least one spacer between the panels, and a gap between the panels, wherein at least one of the panels comprises a laminated panel as provided above.

Abstract: A sound barrier comprises a substantially periodic array of structures disposed in a first medium having a first density, the structures being made of a second medium having a second density different from the first density, wherein one of the first and second media is a porous medium other than a porous metal, the porous medium having a porosity of at least about 0.02, and wherein the other of the first and second media is a viscoelastic or elastic medium.

Abstract: An acoustic treatment panel that is connected to an air intake of an aircraft nacelle, includes at least one acoustically resistive structure (30) and a reflective layer (32), between which are located—in a direction that is essentially perpendicular to the longitudinal direction of the nacelle—bands (34) of alveolar cells spaced in such a way as to allow the passage of hot air provided for a frost treatment, characterized in that it includes pipes (36) for hot air that are each delimited by at least one partition that extends from the acoustically resistive layer (30) up to the reflective layer (32) in such a way as to insulate the bands (34) of cells in the longitudinal direction.

Abstract: A method and apparatus are present for reducing noise. The apparatus comprises a core and a face sheet. The core is configured to reduce a speed of shear waves traveling through the core. The face sheet is located over a first surface of the core and is configured to reduce a speed of bending waves traveling through the face sheet. A second surface of the core is configured for attachment to a surface of a structure.

Abstract: Prepare an acoustical polymeric foam by providing at least two initial polymeric foams, perforating all the way through the initial polymeric foams and then laminating the perforated initial foams together such that a perforated surface of one foam adheres to a perforated surface of an adjoining perforated initial foam.

Abstract: Systems and methods for noise suppression are disclosed herein. In one embodiment, an acoustic structure has a core that includes a plurality of cells. Each of the plurality of cells includes one or more engaging structures for positioning a septum relative to the cell. The acoustic structure further includes a plurality of septums positioned relative to the plurality of cells.

Abstract: An acoustic structure that includes a honeycomb having cells in which septum caps are located. The septum caps are formed from sheets of flexible material that may be perforated before or after the material is inserted into the honeycomb. The flexible material is sufficiently flexible to allow folding into the shape of a septum cap. The flexible material is also sufficiently stiff to provide frictional engagement and locking of the septum cap to the honeycomb cell when the cap is inserted into the honeycomb during fabrication of the acoustic structure. An adhesive is applied to the septum caps after the caps have been inserted into the honeycomb cells to provide a permanent bond.

Abstract: An acoustical building panel and method of manufacturing it are disclosed. Embodiments of the panel include a porous nonwoven scrim, a coating deposited on the scrim, a base mat, and an adhesive deposited on either the base mat or the scrim in a discrete form such as in droplets. Embodiments of the method of manufacture include steps of perforating the base mat, applying the adhesive to the base mat in the discrete form, laminating the scrim onto the base mat, and applying the coating to the scrim surface.

Abstract: A method for manufacturing a sandwich panel includes, but is not limited to the steps of providing at least one air-permeable core layer and at least one porous cover layer, applying an adhesive onto a first area of the core layer, pressing the cover layer onto the first area of the core layer to connect the cover layer to the core layer, and applying an airstream that from the outside is directed onto the cover layer and that moves through the cover layer and the core layer. By means of such an airstream it is possible to prevent excessive accumulation of adhesive on the cover layer, which otherwise would result in partial blocking of the cover layer. By varying the intensity of the airstream the flow resistance of the arrangement including, but not limited to, the cover layer and the core layer may be determined and set during the bonding process. In this way a sandwich panel with precise sound-absorption behavior can be manufactured.

Abstract: A speaker enclosure having a substantially seamless rigid outer skin, a middle sound absorbing layer, and a substantially seamless inner skin results in a lightweight speaker having sound absorbing characteristics. The speaker enclosure is comprised of two basic parts, a box section and a baffle section where each of these sections include a rigid outer skin, the middle sound absorbing layer and a seamless inner skin and are made according to the same method. The outer skin is formed from a layer of sheet molding compound, the middle sound absorbing layer includes pieces of honeycomb material, and the inner skin is formed from a layer of sheet molding compound. The layers of material are placed into a mold and then cured through vacuum bagging and heating thereby producing a strong, lightweight speaker enclosure made of materials which attenuate the transmission and retransmission of errant sound waves in the enclosure thereby reducing distortion of the sound signal produced by the speaker.

Abstract: A trim panel for an aircraft interior includes a first sound attenuating layer, a structural layer and a second sound attenuating layer. The structural layer is coupled to the exterior sound attenuating layer, and has an exterior side and an opposite interior side. The structural layer defines a plurality of passages that open to both the exterior side and the interior side so as to minimize radiation of noise due to a hydrodynamic shortcut created by each of the passages across the structural layer. The second sound attenuating layer is coupled to the structural layer and has a high sound absorption characteristic. The second sound attenuating layer is configured to be disposed adjacent to the aircraft interior.

Abstract: In order to provide sound absorbing structure capable of reducing the noise of electronic equipment while maintaining the cooling capability of the electronic equipment, there is provided sound absorbing structure in which a plurality of penetrating openings are provided by arranging a plurality of acoustic materials having a predetermined shape at predetermined intervals in a flow channel of cooling fluid from a blower, and the plurality of acoustic materials are arranged so that the sound vertically incident on a penetrating plane of the penetrating openings from the blower does not directly go out of the electronic equipment.