Abstract: A duct includes a duct body defining an inlet, an outlet, and a channel connecting the inlet and the outlet. The duct body also defines an upstream resonator. The upstream resonator includes an upstream annular cavity external to the channel and an annular perforated plate coplanar with the upstream annular cavity. The duct body further defines a downstream resonator. The downstream resonator includes a downstream annular cavity external to the channel and an annular neck coplanar with the downstream annular cavity.

Abstract: An object is to provide a silencing system that includes a silencer disposed in a ventilation sleeve, can suppress the generation of negative pressure in the interior, and can prevent a door or the like of an interior entrance from being difficult to open. The silencing system includes one or more silencers that are disposed in a ventilation sleeve provided to penetrate a wall separating two spaces, and “?A>10C?(0.1/P)×TL” is satisfied in a case where a gap equivalent area of the ventilation sleeve in which the silencer is installed is denoted by ?A and a normalized sound transmission loss in an octave band in which a first resonant frequency of the ventilation sleeve is present is denoted by TL. C denotes a constant determined by a measurement system in a case where there is no silencer and P denotes a transmission efficiency coefficient.

Abstract: A sound absorber includes at least one cavity and at least one mouth to communicate the at least one cavity with an outside of the sound absorber. The at least one cavity includes a top surface, a bottom surface, and a side wall. The top surface includes the mouth. The bottom surface opposes the top surface. The side wall is extended to connect the top surface with the bottom surface. At least one of the top surface and the bottom surface is inclined with respect to the side wall.

Abstract: In a stowing mechanism of a vehicular door mirror device, sound is produced when a gear plate is rotated from a state in which a clutch plate has been disengaged from the gear plate and the clutch plate engages with the gear plate under biasing force from a coil spring. Butyl tape spans between a portion of the coil spring on an upper side of a gap and a portion of the coil spring on a lower side of the gap such that vibration of the coil spring is suppressed. Accordingly, the sound is able to be damped.

Abstract: A gas turbine engine has a propulsor including a fan and a liner positioned upstream of the fan. The liner has a backing plate, a cellular structure with cells extending from the backing plate, and a perforated sheet with a depth defined as a distance between the perforated sheet and the backing sheet. The depth is selected to achieve a desired ratio of the depth relative to a gap?. A depth to gap ratio is substantially in a range of 0.035 to 0.08. A method is also disclosed.

Abstract: An auxiliary power unit inlet assembly includes an inlet duct having a first end and a second end. The auxiliary power unit inlet assembly further includes a door associated with the second end of the inlet duct. The door moves between a first position and a second position. The door closes the second end of the inlet duct when in the first position and permits air to enter the second end of the inlet duct when in the second position. The auxiliary power unit inlet assembly further includes a sound absorbing component mounted to the door and disposed proximate the inlet duct. The sound absorbing component is positioned at a location on the door such that a noise generated by the auxiliary power unit will directly impinge on the sound absorbing component.

Abstract: A panel is provided for attenuating noise. This panel includes a first skin, a second skin and a cellular core. The cellular core may be connected to and form a plurality of cavities between the first skin and the second skin. The cellular core may include a wall and a septum. The cavities may include a first cavity and a second cavity. The septum may fluidly divide the first cavity into a first sub-cavity and a second sub-cavity. One or more perforations in the first skin may be fluidly coupled with the first sub-cavity. One or more perforations in the wall may fluidly couple the first sub-cavity with at least a region of the second cavity.

Abstract: An inlet door for an auxiliary power unit includes a door body with opposed interior and exterior surfaces. The interior surface of the inlet door is curved to diffuse sound waves received by the interior surface.

Abstract: An acoustic liner has a honeycomb layer disposed between a first panel and a permeable panel and includes a plurality of serpentine walls spaced apart from one-another. Adjacent serpentine walls outline in-part a first region carried by the first panel and an opposing second region carried by the permeable panel. The first and second regions are offset such that a centerline distance extending between the regions and centered between adjacent walls is greater than a distance measured directly between the panels, enabling the design of thinner acoustic liners. The regions and adjacent walls further define a cell having a constricted portion communicating between an end portion and an entry portion such that the constricted portion creates a frequency shift.

Abstract: A novel extendible flexible flood barrier manufactured from textile and membrane materials has been developed which comprises a textile/membrane wall and support posts configured to be movable between a stowed position and a deployed position and wherein, in the deployed position, forms a leak-free barrier against flood water or other fluids. The flexible wall is stored in a container on one side of the opening to be protected and extended to the receiver on the opposite of the opening to deploy the barrier. Structural members, such as posts or a building itself will react to the load from the flood water impinging on the wall. Intermediate posts or bollards can be added to lengthen the wall so larger spans can be closed-off with the flexible wall. The flexible wall can be configured for use in many applications including entire buildings, building entrances, transit system passages, such as ventilation shafts or elevator shafts, stairwells, and other openings that can be threatened by flooding.

Abstract: The invention relates to a method for joining a composite sheet to a metallic substrate, wherein the composite sheet has at least one metallic top layer and at least one non-metallic layer which consists of a plastic material, wherein an opening is introduced into the composite sheet, and wherein at least one joining element is provided which is inserted into the opening of the composite sheet. A method for joining a composite sheet to a metallic substrate with process reliability and of specifying a corresponding structure is achieved by forming the joining element as a metallic sleeve, wherein the metallic sleeve is deformed, so that it joins together with the composite sheet in a form-fit and force-fit manner, and wherein the metallic sleeve is firmly bonded to the substrate with the end pointing towards the substrate using a filler material, wherein the filler material is arranged inside the sleeve.

Abstract: An air inlet assembly comprising an entrance region configured to receive an airflow, an exit region configured to output the airflow, and an attenuation region disposed between the entrance region and the exit region. The attenuation region has a cross section aspect ratio of at least about 5-to-1, and comprises acoustic absorbing material.

Abstract: A flap of the type that is movably connected to an aircraft wing to provide control of an aircraft in flight includes opposite ends, wherein at least a first opposite end includes a plurality of substantially rigid, laterally extending protrusions that are spaced apart to form a plurality of fluidly interconnected passageways. The passageways have openings adjacent to upper and lower sides of the flap, and the passageways include a plurality of bends such that high pressure fluid flows from a high pressure region to a low pressure region to provide a boundary condition that inhibits noise resulting from airflow around the end of the flap.

Abstract: A sound absorbing body includes parts of different densities including a plurality of non-dense parts of lower density and a plurality of dense parts of higher density. The non-dense parts and the dense parts are alternately laminated obliquely.

Abstract: A system for reducing noise emissions in underwater environments is presented. The system can be extended to applications in any two-fluid environments where one fluid (gas) is contained in an enclosed resonator volume connected to the outside environment at an open end of the resonator body. The resonators act as gas-containing (e.g., air) Helmholtz resonators constructed into solid panels that are submerged in the fluid medium (e.g., sea water) in the vicinity of a noise generating source. The oscillations of the trapped air volume in the resonators causes reduction of certain noise energy and a general reduction in the transmitted noise in the environment of the system.

Abstract: The bandwidth or acoustical range of an acoustic structure is increased by locating a sound wave guide within the acoustic cell. The wave guide divides the cell into two acoustical chambers. The two chambers provide an effective increase in resonator length of the cell.

Abstract: A multi-sectional acoustic septum that includes sections which have different acoustic resistance properties. The multi-sectional acoustic septums extend vertically with the acoustic cell and are capable of increasing the effective acoustical length of the acoustic cell. The multiple acoustic properties provided by the multiple acoustic sections also make it possible to target specific frequency ranges within the overall frequency range of the acoustic cell.

Abstract: A duct and a method for damping pressure waves caused b thermoacoustic instability, the duct comprising: a locking Helmholtz resonator positioned on the circumference of the duct, the locking Helmholtz resonator tuned to a first frequency, and one or more damping Helmholtz resonators positioned on the circumference of the duct at or adjacent to 90 and/or 270 degrees from the locking Helmholtz resonator, wherein the damping Helmholtz resonators are tuned to a second frequency which is different from the first frequency of the locking Helmholtz resonator.

Abstract: The invention relates to a method for joining a composite sheet to a metallic substrate, wherein the composite sheet has at least one metallic top layer and at least one non-metallic layer which consists of a plastic material, wherein an opening is introduced into the composite sheet, and wherein at least one joining element is provided which is inserted into the opening of the composite sheet. A method for joining a composite sheet to a metallic substrate with process reliability and of specifying a corresponding structure is achieved by forming the joining element as a metallic sleeve, wherein the metallic sleeve is deformed, so that it joins together with the composite sheet in a form-fit and force-fit manner, and wherein the metallic sleeve is firmly bonded to the substrate with the end pointing towards the substrate using a filler material, wherein the filler material is arranged inside the sleeve.

Abstract: A tunable acoustic panel that functions as an acoustic diffuser and absorber is disclosed. The acoustic properties of the tunable acoustic panel can be quickly and conveniently modified by moving a handle. The tunable acoustic panel is wall-mountable for use as an acoustical room treatment to selectively vary the acoustical response of a room or performance space.

Abstract: Sound diffusers are important components in enhancing the quality of room acoustics. The present disclosure relates to a sound diffuser obtained by using properties of the cymatics phenomena. Cymatics is the study of sound and vibration made visible, typically on the surface of a plate, diaphragm or membrane. Two examples of diffusers are designed by the cymatic shapes and modeled by using a quadratic quadratic residue sequence. It is found that this type of acoustic diffusers can be used to maintain the acoustic energy in a room and at the same time can treat unwanted echoes and reflections by scattering sound waves in many directions. The design allows for creating different interior space designs by changing the arrangement of the diffuser panels, and this leads to different applications for the diffusers.

Abstract: An acoustic insulator for a motor vehicle is provided comprising a mass providing an acoustic barrier and a spring providing an acoustic absorber overlying the mass. The mass comprises a first acoustic mass layer underlying a second acoustic mass layer. The first acoustic mass layer is provided by a thermoplastic sheet having a thickness in a range of 0.5 mm to 1 mm. The second acoustic mass layer is provided at one or more localized areas formed in place on a backside surface of the first acoustic mass layer to increase an overall thickness of the mass at the one or more localized areas. The spring layer is formed in place on a backside of the second acoustic mass layer and the backside of the first acoustic mass layer.

Abstract: A phononic device is provided suitable for attenuating mechanical vibration, as well as acoustic vibration that propagate through a medium. Through the periodic inclusion of domains of a material in a matrix that vary in the ratio of the longitudinal speed of sound (CL) and the transverse speed of sound (CT) between the domains and the matrix of equal to or greater than 2.0 and 40, respectively; improved significant attenuation of vibration is achieved.

Abstract: A firearm muzzle silencer includes an elongated cylindrical body having a cylindrical bore, a firearm mounting end, and a projectile discharge end. At least one helical insert is positioned in the cylindrical bore and proximate to the firearm mounting end. The helical insert has an insert axial bore that extends through the helical insert and a spiral groove formed on an exterior of the helical insert to define a spiral path between the helical insert and the cylindrical bore. A chamber is defined in the elongated cylindrical body adjacent to the helical insert, wherein the helical insert is positioned between adjacent to the helical insert and the helical insert is positioned between the chamber and the firearm mounting end. A plurality of ports is formed in the elongated cylindrical body adjacent to the spiral path, wherein the plurality of ports is in communication with the chamber via the spiral path.

Abstract: A method for producing acoustical panels with a three-dimensional surface bonds stacks of design pieces to a flat panel. A layer of adhesive is applied over the assembly, and then a fabric layer is applied over the assembly to bond the fabric over the panel and design pieces.

Abstract: A plenum with features to disperse acoustic energy in an airflow while maintaining a relatively small pressure drop in the airflow is disclosed. A general structure of the plenum may include a perforated airflow passage surrounded by a substantially large space enclosed between the airflow passage and a plenum. The perforated airflow passage has a perforated wall that may allow the acoustic energy to be dispersed into the substantially large space when flowing through the airflow passage. Acoustic energy dispersing materials may also be disposed in the substantially large space and/or on the perforated wall to help disperse acoustic energy by, for example, absorbing the acoustic energy. The plenum can help disperse the acoustic energy while helping minimize the pressure drop in the airflow.

Abstract: A device is provided for damping hydrosound in liquid emitted from a sound-emitting body in the liquid. The device includes a plurality of envelope bodies distributed in the liquid in an area of the hydrosound-emitting body and at a distance from each other. A material, diameter and pressure of each envelope body is configured such that a natural frequency of the envelope body corresponds to an emitted frequency range of the hydrosound so as to dampen the hydrosound. The device also includes at least one mass body disposed in the liquid. The envelope bodies are connected to the mass bodies so as to prevent the envelope bodies from rising up in the liquid.

Abstract: An acoustical phase plug for use in loudspeakers produces a planar rectangular wavefront, or a wavefront with a desired amount of curvature, from the output aperture of the phase plug device when presented with a planar circular wavefront at the input aperture. The phase plug utilizes a waveguide that equalizes the travel paths from the input aperture to the output aperture. The waveguide essentially eliminates surface discontinuities thereby resulting in the reduction of diffraction of the wavefront travelling through the phase plug device.

Abstract: A combination acoustic and flash suppression system and method for use with a weapon that fires a bullet. A noise suppressor module or section of the system is adapted to be connected to a distal end of a barrel of the weapon, and a flash suppressor module or section of the system is adapted to be connected to the outlet end of the noise suppressor module, so that the downstream position of the flash suppressor module relative to the noise suppressor module helps to disrupt a Mach disk from forming at a downstream location from the discharge port when a bullet fired from the barrel exits from the discharge port so as to suppress both flash and noise.

Abstract: A blower for an HVAC system of a motor vehicle. A fan is supplied with airflow by a duct having a bend adjacent to the fan that causes a low-pressure region at a face of the fan. A baffle is located immediately adjacent to the fan face and collocated with at least a portion of the low-pressure region to impede airflow through the face of the fan at that location. The baffle acts to reduce unwanted low frequency noise and improves the mechanical efficiency of the fan. The baffle covers a circular segment of the fan face and may have sound-suppressing features, such as ridges formed on at least one surfaces.

Abstract: A home appliance, such as a clothes washing machine, has a source of noise and an acoustic insulator. The source of noise moves between a first position and a second position during operation of the appliance. The acoustic insulator has a movable portion that moves with the source of noise between the first position and the second position during operation of the appliance and an interface that remains substantially stationary as the source of noise moves between the first and second positions.

Abstract: An acoustical reflector is provided. The reflector includes a top end, a bottom end, a first side, a second side, a front surface, and a rear surface. The reflector may further include a plurality of reflector rows, such as vertical reflector rows. Each reflector row may be formed from the top end to the bottom end and is substantially parallel relative to one another. The plurality of reflector rows may from a concave shape on the front surface of the reflector from the first side to the second side.

Abstract: A pulsation damper (1) for damping pressure pulsations of a fluid is insertable into the fluid line as intermediate piece by forming an axial flow channel (3), and the pulsation damper (1) featuring a housing (2). The pulsation damper (1) is characterized by the fact that the housing (2) has at least one hollow space (23) communicating with the flow channel (3) and in which at least one attenuator (4) is disposed movably in axial direction.

Abstract: A speaker enclosure and method of building same is provided for redirecting standing waves outside the enclosure. The enclosure includes an exterior and an interior comprised of a body having six interior surfaces defining the interior. One of the surfaces has a speaker opening and another of the surfaces has a tuned port opening and defines four corners opposite the speaker opening. An element having an acoustically reflective surface faces the interior and is positioned in a plane that intersects and is inclined with respect to each of the interior surfaces that form the corner. A handle system that includes an attachment means is mounted to the exterior of the enclosure. A rotatable and detachable handle is mounted to the attachment means.

Abstract: A performance-enhancing crossover muffler for internal combustion engines includes an enclosed case having an inside, and two inlet pipes located inside the case having respective inlet ends extending through a frontside of the case for connection with two outside engine exhaust manifolds, and respective interior ends which merge together to define a merge entry. The muffler also includes one or more outlet pipes located inside the case with outlet end extending through a backside of the case for connection with an outside tailpipe, an interior end defining a merge exit, and one or more apertures in the outlet pipe communicating with the inside of the case. The muffler further includes a piping merge zone between the merge entry and the merge exit for commingling exhaust flows from the two engine exhaust manifolds. The two inlet pipes and the piping merge zone are without communication with the inside of the case.

Abstract: Air bubbles may be used to reduce radiated underwater noise. Two modalities of sound attenuation by air bubbles were shown to provide a reduction in radiated sound: bubble acoustic resonance damping and acoustic impedance mismatching. The bubbles used for acoustic resonance damping were manifested using gas-filled containers coupled to a support, and the acoustic impedance mismatching bubbles were created using a cloud of freely-rising bubbles, which were both used to surround an underwater sound source.

Abstract: A modal attenuator may include an attenuator body having a lead-in segment and a lead-out segment joined by a connection segment, a perforated screen disposed within the attenuator body and spaced apart from the attenuator body to form an annular space, and a plurality of rings disposed between the perforated screen and the attenuator body. When fluid flows through the modal attenuator, sound waves pass through the perforated screen and are reflected back by the plurality of rings to disrupt other sound waves, thereby reducing fluid noise in the modal attenuator.

Abstract: An acoustic-attenuating wall panel for a nacelle of a turbine engine may include a radiused portion. The radiused portion may include an airflow surface having a concave configuration and which may be exposed to an airflow passing through the nacelle. The radiused portion may include an acoustic attenuating section.

Abstract: Apparatus and methods for attenuating noise, vibration, and/or acoustic energy in a turbomachine. The apparatus includes a first base plate having first base plate perforations defined therethrough. The apparatus also includes first and second spacers each extending from the first base plate, being spaced apart from each other, and defining a first channel therebetween. The apparatus further includes a first insert disposed in the first channel and having insert perforations defined therethrough, the first base plate, the first and second spacers, and the first insert at least partially defining a first acoustic chamber therebetween, wherein the base plate perforations and the insert perforations are in communication with the first acoustic chamber.

Abstract: Vibro-acoustic attenuation or reduced energy transmission. The present invention relates to devices that display frequency zones of strong vibro-acoustic attenuation or reduced energy transmission. This can be used in particular, although not necessarily solely, in applications that require lightweight materials with good mechanical properties and good vibro-acoustic response or in applications that require materials with high sound reflection, absorption or sound isolation in a certain frequency band.

Abstract: The present invention relates to a sound-proof material containing a first sound-absorbing material disposed facing a sound source, a first soft sound-insulating layer laminated on a face of the first sound-absorbing material opposite to the sound source and having an air permeability measured in accordance with JIS L1018 of 10 cc/cm2·sec or lower, a second sound-absorbing material laminated on the first soft sound-insulating layer, and a second soft sound-insulating layer laminated on the second sound-absorbing material and having an air permeability measured in accordance with JIS L1018 of 10 cc/cm2·sec or lower and a Young's modulus measured in accordance with JIS K7127 greater than or equal to five times that of the first soft sound-insulating layer, in which at least the second soft sound-insulating layer is partially or entirely bonded to the second sound-absorbing material.

Abstract: A family of acoustical ceiling panels for schools, offices, hospitals and other public buildings provides for one consistent look throughout the building while yet provide a range of desired acoustical performances. The family includes a group of substrate mats of a bonded mixture of mineral fiber, glass fiber, and bi-component fibers. Each mat is chosen from a group including a thickness of ¾?, ?? and 1? depending upon acoustical performance. The group of substrate mats all have an exposed surface chosen from a group including fine texture, heavy texture, medium texture and light texture. The group of mats all have an edge chosen from a group including square, tegular and narrow tegular.

Abstract: The invention relates to a method for the reduction of the natural vibration (resonance) of a component (2). According to the invention a vibration behavior of component (2) is determined, wherein to each of the positions having vibration amplitudes, which exceed a preset threshold value, an attenuation element (1) is locally mounted, which is formed as a multilayered adhesive element including a support layer (1.1) and a self-adhesive damping mass. Moreover the invention relates to an attenuation element (1) for the reduction of the natural vibrations of a component (2). According to the invention the attenuation element (1) is formed as a multilayered adhesive element of a support layer (1.1) and a self-adhesive damping mass (1.2), wherein the support layer (1.1) is formed of a bend-resistant material and the damping mass (1.2) preferably is formed of butyl rubber.

Abstract: A tensegrity apparatus having multiple tensegrity units for the transmission of solitary waves with adjustable profiles into a material or structure, and the detection of such waves from a material or structure.

Abstract: A moldable acoustic facing comprises cellulosic fibers and synthetic fibers entangled together. The acoustic facing has a basis weight of from about 1.5 to about 5.0 ounces per square yard (osy), a thickness of less than about 0.050?, a mean pore size of between about 8 microns and about 40 microns, and an elongation at break of at least twenty percent. The acoustic facing includes less than about five percent synthetic microfiber and has an acoustic resistance of at least about 250 Rayls.

Abstract: The invention relates to a two-stroke engine for an engine-driven tool, including a muffler, especially for a manually operated engine-driven tool such as a maintenance device for gardens or green spaces, for a hand-held tool such as a chain saw, a hand-held circular saw or an angle grinder or for a small motorcycle, a boat engine and the like, wherein the flow channel between the muffler inlet and the first chamber is formed so as to promote flow such that the exhaust gas entering the muffler inlet mainly enters the first chamber due to its inertia and once the first chamber is full flows back again. The counterpressure of the exhaust gas is produced at a point in time in which the piston releases the outlet and the fuel-air mixture at least for its most part has entered the combustion chamber through the at least one transfer passage.

Abstract: An aircraft propulsion system has a propulsive rotor assembly rotatable about an axis of rotation and comprising a plurality of blades and a rotationally fixed vane assembly located adjacent to the propulsive rotor assembly and arranged circumferentially around the axis of rotation. As airflow enters the propulsive rotor assembly, a portion of the airflow passes over the vane assembly which is configured to direct the airflow away from the rotor blades so as to reduce the relative velocity of the redirected airflow over the rotor blades. This results in a reduced tendency of the airflow through the propulsive rotor assembly to become choked.

Abstract: An acoustic attenuator assembly for an acoustic tool for performing acoustic investigation of a subterranean formation is disclosed. The acoustic attenuator assembly includes a first end portion (205) and a second end portion (215) having a bore therethrough to enable passage of an electrical line. The acoustic attenuator assembly further includes a fiber portion (230) disposed between the first and second end portion so that the fiber portion attenuates at least a portion of acoustic energy when the acoustic energy is received by one or both of the first (205) and second (215) end portions.

Abstract: A device for reducing booming noise in a motor vehicle has a wind deflector (3) having openings. The device furthermore has an air source (1), which is arranged in the motor vehicle and connected to the wind deflector. The air provided by the air source can be channeled to the wind deflector and released through the openings (4) thereof.

Abstract: The invention is comprised a sound deadening or sound buffering material including but not limited to, foam, plastic, or fabric that covers at least part of the child, thereby reducing both the decibel level coming from the child and the decibel level coming to the child. This creates a quieter environment for the child while serving a dual purpose to reduce any noise coming from the child.