Abstract: An air blower is provided. The blower includes a flow modulator tube assembly positioned to modulate the flow of air into the blower and to modulate the flow of sound out of the blower. The blower also includes a sound damper. The flow modulator tube assembly directs sound to the sound damper, and the sound damper absorbs and/or reflects the sound.

Abstract: A ventilated seat system for a vehicle includes a seating assembly including a seatback operably coupled to a seat base. A blower is coupled to the seating assembly. The blower generates a sound transmission when activated. The blower includes a housing defining an inlet and an outlet. A first metamaterial silencer is coupled to an interior surface of the housing proximate to the inlet, and a second metamaterial silencer is coupled to the interior surface of the housing proximate to the outlet. Each of the first metamaterial silencer and the second metamaterial silencer reduces the sound transmission generated by the blower.

Abstract: A sound proof space, a ventilation system, and a method of ventilating a soundproof space, the ventilation system including at least one fan positioned at least one air inlet aperture or at least one air outlet aperture for sucking air therethrough and providing an air flow; at least one ventilation aperture for guiding air into the space to be ventilated; at least a first and a seconder air channel. The first and the second air channel are formed respectively into a single layer of a sandwich-type wall, roof or floor structure of the space to be ventilated; and the first and the second air channel are joined at one end thereof to form an indirect air path from the air inlet aperture to the ventilation aperture.

Abstract: A wool-like fiber member that has high permeability and low absorbability is disposed around a discharge port of a discharge pipe that is configured to discharge condensate and compressed air stored within a tank.

Abstract: An exhaust muffler includes first and second pipes which extend through a casing, and which are disposed so that a downstream end of the first pipe faces an upstream end of the second pipe, wherein the downstream end of the first pipe and the upstream end of the second pipe are disposed so as to be spaced from each other in an axial direction, one end part of a support member having a circular cross section that has a smaller diameter than those of the first and the second pipes is fixed to one of a first lid member covering an opening at the downstream end of the first pipe and a second lid member covering an opening at the upstream end of the second pipe, and the other end part of the support member is slidably fitted to the other of the first and the second lid members.

Abstract: An exhaust muffler includes a first muffler section having a tubular member made up of an inner pipe to which an exhaust pipe is connected and an outer pipe covering the inner pipe, and a connector connecting the tubular member and a second muffler section to each other, and the second muffler section having an outer shell, a first partition wall, a second partition wall, and a third partition wall. Exhaust gases delivered from the exhaust pipe are discharged from the first muffler section and the second muffler section out of the exhaust muffler. The second muffler section has a cross-sectional area larger than a cross-sectional area of the tubular member. The exhaust muffler includes a first expansion chamber, a second expansion chamber, and a third expansion chamber.

Abstract: An exhaust muffler is made up of a plurality of layers including an exhaust passage pipe and expansion chambers, and includes a front assembly and a rear assembly sub-assembled separately from the front assembly. The front assembly includes a front exhaust passage pipe, a front muffler body disposed in covering relation to the outside of the front exhaust passage pipe and cooperating with the front exhaust passage pipe in making up double-walled pipes, and an exhaust valve disposed in the front exhaust passage pipe. The rear assembly includes a rear exhaust passage pipe and a rear muffler body disposed in covering relation to the outside of the rear exhaust passage pipe and cooperating with the rear exhaust passage pipe in making up double-walled pipes. There is thus provided an exhaust device for an internal combustion engine in which the accuracy of a position where the exhaust valve is installed is high.

Abstract: Sound absorption units for fluid ducts include two acoustically coupled pairs of Helmholtz resonators. The two resonators within each pair have identical resonance frequency, however the upstream resonator within each pair is partly filled with an acoustically lossy porous material, so that the upstream resonator within each pair has greater acoustic loss than its coupled downstream resonator. The upstream pair of resonators has a relatively low resonance frequency, while the downstream pair of resonators has a relatively high resonance frequency. The combination of frequency mismatch between the resonator pairs, and loss mismatch within each resonator pair, produces consistently high sound absorption across a broad frequency spectrum.

Abstract: A method of passively suppressing noise within a heat exchanger comprises the steps of preselecting a plurality of sound wave travel distances formed between a plurality of surfaces within the heat exchanger to cause destructive interference of a preselected set of sound waves as the sound waves travel the preselected sound wave travel distances and assembling the heat exchanger to have the preselected plurality of sound wave travel distances formed between the plurality of surfaces formed within the heat exchanger.

Abstract: Provided in the present invention are a muffler (2) for use in a refrigerating device and a refrigerating device. The muffler comprises an outer casing (23), an inner wall (24), and a sound absorbing material (26) provided between the inner wall and the outer casing, the inner wall defining a fluid inlet (21), a fluid outlet (22), and a fluid passage deflected between the fluid inlet and the fluid outlet, wherein at least a partial region of the inner wall is provided with perforations (241, 242, 243, 244), and the inner wall has a higher perforation rate at the inner side of the fluid passage than that at the outer side of the fluid passage. The muffler according to the embodiment of the present invention significantly reduces the sound and vibration of the refrigerating device.

Abstract: A turbomachine vane includes an electroacoustic source including two membranes fixed on a support arranged such that the membranes and the support delimit a first cavity. The membranes are arranged on two opposite sides of the first cavity between the two aerodynamic surfaces of the vane. A first of the aerodynamic surfaces includes a first region arranged facing a first of the membranes for the passage of acoustic waves. The membranes and membrane vibration device are configured such that the membranes vibrate in phase opposition and along a same emission direction by applying forces to the support such that the resultant force is approximately zero. The mechanical energy lost in the form of vane deformations due to membrane vibrations can thus be minimized.

Abstract: An expansion chamber for a rotary vane vacuum pump is provided. The expansion chamber is in fluid communication with the discharge side of the rotary vane vacuum pump, such that the expansion chamber attenuates sound as a Helmholtz resonator. The expansion chamber includes an internal volume of between 80 cubic centimeters and 100 cubic centimeters, inclusive, and includes a curved sidewall that extends partially around, and generally conforms to, the exterior of the rotary vane vacuum pump. The expansion chamber also includes a downward extending port, open to the atmosphere, for attachment to a hose in applications in which the expansion chamber is below a water line.

Abstract: A firearms suppressor incorporates one or more thermal energy absorbing elements, or “thermal energy sponges”, fabricated from porous metal. These elements efficiently absorb heat from the propellant gas generated when the firearm is discharged, thus reducing its pressure and the blast noise it creates. The thermal energy absorbing elements are manufactured from porous metal, a material which, due to its high efficiency in absorbing thermal energy, provides a unique solution to designing smaller, lighter, modular, more efficient and less expensive to manufacture firearm suppressors. In addition, as a result of the relationship described in the Darcy-Forchheimer equation, these porous metal elements provide the suppressor with an intrinsic, self-regulating capability, thus allowing the suppressor's use with a variety of different cartridges and different calibers with little to no change to a baseline design.

Abstract: A two-stage venturi cooler comprises a first tubular conduit having a longitudinal axis, the first elongate tubular conduit having an exhaust gas inlet at one end, a mixed gas outlet at an opposing end, and a cooling gas inlet, wherein structures inside the first stage define a venturi that forms a column of mixed gas, wherein the column of mixed gas comprises a ring of exhaust gas surrounding a core of cooling gas; and a second tubular conduit that is coaxial with the first tubular conduit, wherein the second tubular conduit has a mixed gas inlet at one end and a mixed gas outlet at an opposing end, and wherein the mixed gas inlet is to receive the column of mixed gas and to surround the column of mixed gas with an entrained column of ambient air.

Abstract: A muffler including an inlet member, an outlet member, an exhaust-gas cleaning device including an exhaust-gas cleaning material, the exhaust-gas cleaning device including a first inlet side coupling section and a first outlet side coupling section detachably coupled to the inlet member and the outlet member by couplers, and an intermediate member including a second inlet side coupling section and a second outlet side coupling section detachably coupled to the inlet member and the outlet member by couplers same as the couplers, instead of the exhaust-gas cleaning device. The intermediate member is a cylinder body allowing exhaust gas in the inlet member to flow directly to the outlet member without passing through the exhaust gas cleaning material, and includes a resistance generation section providing the intermediate member with exhaust resistance substantially equal to that of the exhaust-gas cleaning device.

Abstract: An exhaust system for an internal combustion engine for a vehicle includes a turbine positioned in an exhaust stream from the internal combustion engine, a first diesel oxidation catalyst positioned upstream of the turbine within the exhaust stream, and a bypass for selectively bypassing the exhaust stream around the diesel oxidation catalyst to the turbine.

Abstract: A compressor recirculation valve having a noise-suppressing muffler. The muffler has a double-walled construction, including a perforated outer wall and a non-perforated inner wall. The muffler is arranged surrounding the RCV such that when the RCV valve member is in an open position, compressed recirculation air is constrained to flow along the non-perforated inner wall and past an upper end thereof before reaching and flowing radially outwardly through the perforated outer wall to a transverse flow passage for delivery back into an inlet of the compressor.

Abstract: A noise attenuation panel for a bleed flow is presented that causes a total pressure loss of the bleed flow before it is exhausted. The total pressure loss results from at least two regions in which the flow area contracts and then rapidly expands, with the rapid expansion causing mixing and turbulence rather than full total pressure recovery. This reduced pressure means that when the flow is exhausted into a flow (which may be the bypass flow of a gas turbine engine), its energy, and thus its noise, are reduced.

Abstract: An exhaust muffler in which the anti-scattering property of a sound deadening element is high and for which shaping is not required and a sound deadening element for use with the exhaust muffler. An exhaust muffler includes an expansion chamber into which exhaust gas of an engine is introduced, and a sound deadening element in which the expansion chamber is inserted. The sound deadening element is configured from a knitted article formed by knitting continuous fibers of glass fiber. The exhaust muffler further includes an inner pipe inserted in a spaced relationship from an inner circumferential wall of the expansion chamber in the expansion chamber and configured to introduce the exhaust gas therethrough. The sound deadening element is disposed between an outer circumferential wall of the inner pipe and the inner circumferential wall of the expansion chamber.

Abstract: The present invention is for a firearm sound suppressor which is attached to the barrel of a firearm to reduce the noise and flash generated by the firearm. The firearm sound suppressor improves the dissipation of heat and provides a breach head on the end thereof for use as a ramming and breaching instrument.

Abstract: The present invention in one or more embodiments provides a muffler, where the muffler includes a housing extending along a longitudinal direction, and a resonator device supported on the housing and including a body, the body including a first portion and a second portion spaced apart from and to be in fluid communication with the first portion, the fluid communication being positioned in a direction transverse to the longitudinal direction, at least one of the first portion and second portion being of a closed-loop in cross-section. The muffler of the present invention may effectively enhance reduction of low frequency noise without having to necessarily increase package volume.

Abstract: A wheel assembly includes a wheel including a spoke portion radially supporting a rim portion about a central axis, wherein the rim portion presents a radial outer surface relative to the central axis. A tire is mounted to the wheel and cooperates with the wheel to define a tire cavity between the radial outer surface of the rim portion and the tire. A foamed aluminum portion is supported by the wheel, and includes a plurality of pores arranged to define an open-cell foam. The plurality of pores of the foamed aluminum portion is disposed in fluid communication with the tire cavity to absorb noise from within the tire cavity. The foamed aluminum portion may be integrally cast with the wheel, or otherwise affixed to the wheel.

Abstract: Examples provide data center canopies, data center housings, and data centers including turning vanes to facilitate air flow. In some examples, a data center canopy may include turning vanes to direct portions of an exhaust flow from an exhaust inlet toward floor sections to be output via exhaust outlets opposite the floor sections. Other examples are described and claimed.

Abstract: An exhaust system component (1), for an exhaust system of an internal combustion engine, includes a metallic first part (3), which is inserted into a metallic second part (2), such that an inner jacket section (7) of the first part (3) is arranged coaxially in an outer jacket section (5) of the second part (2), as well as at least one weld joint (10), which permanently connects the outer jacket section (5) to the inner jacket section (7). To simplify the assembly of the parts (2, 3) with one another, a plurality of centering contours (11, 12) are formed integrally on the outer jacket section (5), projecting inwardly, and/or are formed integrally on the outer jacket section (7), projecting outwardly, and are located at spaced locations from one another in the circumferential direction (6). The centering contours center the inner jacket section (7) in the outer jacket section (5).

Abstract: Noise attenuating members for use in noise attenuating units for engine systems are disclosed that include a core, having an interior surface defining a hollow inner cavity and a plurality of radial openings, and a porous material disposed about an exterior surface of the core. The porous material may be a strip which is engaged with the exterior of the core and wrapped around the core to form a plurality of layers of porous material. A noise attenuating unit is disclosed to include a housing, having an internal cavity, first port, and second port, and an attenuating member disposed within the internal cavity. A method of making a noise attenuating member is disclosed that includes providing a core having an hollow cavity and radial openings, providing a strip of porous material, and wrapping the strip of porous material about the core to form one or more layers.

Abstract: The invention relates to a bag (1) for insertion into a cavity of a silencer, which cavity is intended for sound damping or absorption, having a cover (2) which is closed on all sides and having a sound-damping or sound-absorbing filling (3). It is provided according to the invention that the cover consists of glass fibers and the filling is blown into the interior of the bag through the cover of the bag.

Abstract: A muffler for a motor vehicle has a muffler housing with a packing void into which an envelope containing a loose fill material is installed during assembly. The envelope contains elongated strands of continuous strand fiberglass, woven as a fiberglass mesh fabric, and having a thin organic polymer coating to reduce sliding and/or being formed with a Leno or gauze weave structure. The envelope is joined at one or more stitched seams, preferably with cotton thread, to enclose a volume. The volume is packed with uncoated continuous strand fiberglass roving, filling the volume to complement the packing void. The cotton thread and the thin polymer coating are consumable by hot gas in the exhaust path, but produce minimal smoke and odor due to their compositions and the small proportion of the packing volume and surface area that the consumable portions occupy.

Abstract: A muffler for an exhaust system of an internal combustion engine having a housing wall, having a muffler housing with at least one inlet pipe guided through the housing wall and at least one outlet pipe guided through the housing wall, wherein the inlet pipe has at least one outflow opening via which the exhaust gas can flow from the inlet pipe into the outlet pipe, whereby, within the muffler housing, at least one coupling chamber with a chamber wall is provided with a center axis, which forms a flow channel between the inlet pipe and the outlet, whereby the chamber wall encloses the inlet pipe or the outlet pipe in the receiving direction E1 with respect to the center axis and is connected only indirectly via the inlet pipe and the outlet pipe or a muffler housing intermediate wall in a form- or material-fitting manner to the housing wall, whereby the chamber wall of the coupling chamber has a diameter D and whereby the exhaust pipe has an outer diameter d, whereby for the ratio of D/d, 20/10>?D/d>=11

Abstract: Examples provide data center canopies, data center housings, and data centers including turning vanes to facilitate air flow. In some examples, a data center canopy may include turning vanes to direct portions of an exhaust flow from an exhaust inlet toward floor sections to be output via exhaust outlets opposite the floor sections. Other examples are described and claimed.

Abstract: A muffler for a motor vehicle has a muffler housing with a packing void into which an envelope containing a loose fill material is installed during assembly. The envelope contains elongated strands of continuous strand fiberglass, woven as a fiberglass mesh fabric, and having a thin organic polymer coating to reduce sliding and/or being formed with a Leno or gauze weave structure. The envelope is joined at one or more stitched seams, preferably with cotton thread, to enclose a volume. The volume is packed with uncoated continuous strand fiberglass roving, filling the volume to complement the packing void. The cotton thread and the thin polymer coating are consumable by hot gas in the exhaust path, but produce minimal smoke and odor due to their compositions and the small proportion of the packing volume and surface area that the consumable portions occupy.

Abstract: Exhaust apparatus for four cycle (including Wankel) internal combustion engines is disclosed. The apparatus is configured to manage pressure waves created by expanding gas emitted from the engine combustion chambers, the net result being to enhance engine performance and attenuate noise over a wide range of engine RPMs.

Abstract: An adsorption unit for combustion gas of an internal combustion engine has an adsorption housing having a chamber section with an inner wall. An adsorption element disposed in the adsorption housing is made of a gas-permeable adsorption medium that is formed to a hollow body and encloses an interior of the adsorption element. The hollow body has opposed open ends. A main flow passage extends through the hollow body and the combustion gas flows in main flow direction through the hollow body. The adsorption element has an exterior circumferential side facing away from the interior and delimiting together with the inner wall of the chamber section a bypass chamber surrounding the absorption element outwardly. In the main flow direction, the bypass chamber has a downstream end that is closed off and an upstream end that has at least one bypass opening that communicates with the main flow passage.

Abstract: Provided is an exhaust apparatus for a utility vehicle which discharges exhaust gas from exhaust pipes connected to exhaust ports of an engine including cylinders, the apparatus including an exhaust gathering portion gathering the exhaust pipes, a catalyst portion located on a downstream side of the exhaust gathering portion and purifying the exhaust gas, and a sensor attaching pipe provided between the exhaust gathering portion and the catalyst portion and to which an exhaust gas sensor is detachably attached, wherein the sensor attaching pipe, in a state where the exhaust gas sensor is attached, has a height in which a sensing portion of the exhaust gas sensor is located in the sensor attaching pipe, and the sensor attaching pipe is provided such that a top end to which the exhaust gas sensor is detachably attached is located above a base end and away from a surrounding heat source.

Abstract: A muffler for a vehicle exhaust system includes a plastic outer shell that defines an internal cavity. A metal pipe extends through the internal cavity from an inlet to an outlet. A Helmholtz chamber is formed within the plastic outer shell to attenuate a desired frequency.

Abstract: A component of an exhaust system for a combustion engine, particularly of a motor vehicle, which at least in part regions includes a self-supporting jacket. The jacket includes a porous, open-pore or closed-pore cellularly constructed foam. The foam is of a self-supporting design. By using such a foam the insulation of the component can be improved.

Abstract: An exhaust device of an engine includes an exhaust pipe connected to the engine, a silencer connected to the exhaust pipe and structured of an outer cylinder and an inner cylinder in which plural holes are formed, and a sound absorbing material disposed in a space formed between the inner cylinder and the outer cylinder. The exhaust device further includes a partition wall partitioning the space and supporting the sound absorbing material so that the sound absorbing material does not move in an axial direction of the silencer, and the partition wall includes a continuous hole allowing exhaust gas to flow through an upstream side to a downstream side of the partition wall in the space.

Abstract: An engine-driven power generator apparatus, which includes, within a case, an engine and a power generator drivable with the engine, and in which an operation panel is provided on a front cover and an air intake louver for introducing air into the case is provided within the case, includes: a waterproof cover covering the operation panel and the air intake louver; an air guide passage of a labyrinth shape provided within the waterproof cover and communicating the outside of the waterproof cover with the air intake louver; and a brush-shaped water separation unit provided in the air guide passage and having a plurality of pins projecting in a direction intersecting flows of air in the air guide passage.

Abstract: An exhaust system for an engine includes an exhaust pipe connected to an exhaust port of an engine and a muffler attached to the exhaust pipe and configured to reduce exhaust noise. The muffler includes an inner cylinder part connected to the downstream end of the exhaust pipe, an outer cylinder part configured to cover an outside of the inner cylinder part and noise absorbing materials disposed between the inner cylinder part and the outer cylinder part. A plurality of first communication holes providing communication between an inside and an outside of the inner cylinder part is formed in an upstream portion of the inner cylinder part. A plurality of second communication holes providing communication between the inside and the outside of the inner cylinder part is formed in a downstream portion of the inner cylinder part. Guide walls extend toward the inside of the inner cylinder part.

Abstract: In a motorcycle in which an internal combustion engine including a crankcase, a cylinder, and a cylinder head is attached to a vehicle body frame, an exhaust system includes an exhaust pipe connected to the cylinder head, and a resonator having a communication hole in communication with an inside of the exhaust pipe. The exhaust pipe is curved after being extended forward from the cylinder head and is then extended rearward in such a manner as to pass by a lateral side of the cylinder above the crankcase, while the resonator is arranged in a space between the exhaust pipe and the cylinder, and is joined to a side surface of the exhaust pipe facing inwardly of the motorcycle.

Abstract: A muffler comprising an inner pipe having one end connected to an upstream side of an exhaust pipe of an engine exhaust system, and another end connected to a downstream side of the exhaust pipe, an outer pipe covering at least part of the inner pipe, a hole being formed in a pipe wall of the inner pipe, a resonance chamber formed in a space between the inner pipe and the outer pipe, and a connection passage formed on an outer peripheral surface of the inner pipe along an axial direction of the inner pipe. The connection passage comprising a plurality of sections connected in series to form the connection passage as a single continuous passage.

Abstract: A double-walled exhaust system component having glass bubbles disposed between inner and outer pipes and method of making the same. The glass bubbles have a size distribution wherein, on a bulk volume basis, at least 90 percent of the glass bubbles have a size of less than 150 micrometers.

Abstract: The present invention relates to an air intake duct for an internal combustion engine that is capable of reducing the noise associated with the induction of air. The air intake duct includes an inlet and an outlet as well as an opening in a side wall located between the inlet and outlet. Mounted within this opening is a woven acoustic membrane. The acoustic membrane reduces inlet snorkel noise by dissipating pressure waves in the duct. The woven acoustic membrane is formed from a material that allows sufficient air flow into the air intake duct and also resists water penetration into the air intake duct.

Abstract: The present invention relates to an active sound absorber (3) for an exhaust system (1) of an internal combustion engine, preferably of a motor vehicle, comprising a housing (7), a connecting pipe (8) for the acoustic and fluidic connecting of the housing (7) with the exhaust system (1), an active membrane (10) which in the housing (7) separates a front volume (12), fluidically connected with the connecting pipe (8), from a back volume (13), and an actuator (11) for vibration stimulation of the active membrane (10). A risk of damage by condensate in the back volume (13) can be reduced by at least one condensation line (14), which fluidically connects the back volume (13) with the front volume (12), in which vapour contained in the exhaust gas condenses, and which directs the condensate which occurs to the front volume (12).

Abstract: The present invention provides an acoustic attenuation based on sound ray deflection theory and a muffler. The method of the present invention provides a temperature gradient between the interior and the exterior of the chamber of the muffler through the low temperature refrigeration system, in which the temperature inside the pipe wall is higher than that outside the pipe wall. The said temperature gradient may deflect the acoustic ray towards the low temperature direction, so as to capture and reduce the noise.

Abstract: A muffler having an inlet and an outlet, through which exhaust gas flows; a tubular main body; a heat exchanger inside the main body; a noise-deadening first conduit, which extends at least partly inside the main body, from a fork region located directly downstream from the inlet, to a converging region directly upstream from the outlet; a second conduit, which extends through the heat exchanger and at least partly inside the main body, from the fork region to the converging region and parallel to the first conduit; and a regulating valve located outside the main body, to selectively direct exhaust gas flow along the first conduit or the second conduit.

Abstract: A fiberglass-binder insert is made by fabricating a shape-constant, cured fiberglass-binder mixture, into a shape-constant insert core, and shrink-wrapping the core while leaving exposed any bore which extends into the core. The core is fabricated by mixing fiberglass and uncured binder in a mixer, dropping the mixture into a conforming guide such as a funnel, and moving the mixture through the conforming guide and into a mold. A tamper can tamp the mixture to move the mixture from the conforming guide into the mold, and to distribute portions of the mixture vertically in the mold. Rotation of the mold effects circumferential distribution of the mixture in the mold. The mixture in the mold is heated to cure the binder, thus to establish a fixed shape of the resultant core product. A shrink film is shrunk about the core, providing apertures in the shrunk film at bore openings in the core.

Abstract: The present invention relates to an exhaust gas treatment unit for an exhaust system of a combustion engine, in particular of a motor vehicle, includes a housing, a plurality of exhaust gas treatment elements, which are arranged in the housing and through which a parallel flow is possible. The unit further includes an outlet nozzle, which penetrates a side face of the housing, and an outlet space disposed in the housing, whereby the outlet of at least one of the exhaust gas treatment elements opens into the outlet space. The rigidity and/or effectiveness of the exhaust gas treatment unit can be improved by means of a funnel body disposed in the outlet space, and comprising a funnel surface which is permeable to exhaust gas. The funnel body connects an outlet end of one of the exhaust gas treatment elements with the outlet nozzle.

Abstract: A compressor has first and second enmeshed rotors rotating about first and second axes to pump refrigerant to a discharge plenum. The compressor includes a muffler system comprising a sound absorbing first element and a sound absorbing second element. The second element at least partially surrounds the first element and defines a generally annular flow path portion between the first element and the second element At least one of the first and second elements comprises an expanded bead material.

Abstract: The soundproofed exhaust duct for a turbine engine comprises a perforated inner shell defining a flow passage, and a solid outer shell, the inner and outer shells defining between them a space that is closed at the upstream and downstream ends of said space. A core extends between the inner and outer shells at a distance therefrom, and contains at least one sound energy dissipating layer made up of hollow beads that are held against one another. A frame with upstream and downstream portions connected together by longitudinal members supports the core and partitions it into a plurality of boxes that are filled with hollow beads that are held between perforated textures, the frame being secured to the outer shell and/or to the inner shell via at least one of its upstream and downstream portions.

Abstract: A sound muffler combines a resonator chamber with a dissipative layer surrounding a through pipe. The muffler provides sound attenuation over a wide range of sound frequencies while maintaining unimpeded flow of gases through the pipe. This attenuation is achieved by combining dissipation with a frusto-conical resonant chamber. The dissipation is achieved by encircling the through passage with a layer of low density material such as metallic or ceramic foam or loosely packed fibers of a heat resistant material. The low density material attenuates the high frequency waves while permitting the passage of low frequency sound waves into the frusto-conical resonant chamber.