Abstract: An intake sound amplifier amplifies intake sound that is transmitted from an engine mounted in an engine compartment of a vehicle to a cabin. The intake sound amplifier includes a first passage branched from an intake passage, through which intake air is introduced into an engine; a device body that includes a vibrating body vibrated by pulsation of the intake air and is connected to a downstream end of the first passage; and a second passage that is connected to a downstream end of the device body and extends to the cabin side. The device body is located outward in a vehicle width direction of a side frame that extends in a vehicle front-rear direction and separates inside of the engine compartment from outside in the vehicle width direction.

Abstract: An intake system of an engine is provided, including a first passage provided to an engine bay, for leading fresh air to the engine, a second passage branched from a branching part at an intermediate location of the first passage, and extending toward a cabin, and an intake noise increasing device provided to the second passage, and configured to increase intake pressure in response to an intake air pressure wave. The intake noise increasing device has a cylindrical bellows part configured to expand and contract in a cylindrical axis direction, and a vibrating membrane formed integrally with the bellows part to close a first opening of the bellows part. The second passage has an introducing passage section connected to a second opening of the bellows part, and extending toward the branching part, and the introducing passage section is disposed so as to be lowered while separating from the bellows part.

Abstract: A vehicle outputs a driving sound generated based on the driver's preference rather than outputting a uniform driving sound. The vehicle includes a sensor that acquires at least one of a facial image, an audio signal, and a biometric signal. A database stores a plurality of sound sources classified according to driver information. A controller calculates the driver information based on at least one of the facial image, the audio signal, and the biometric signal, selects any one of the plurality of sound sources stored in the database based on the calculated driver information, generates a driving sound based on the selected sound source, and operates a speaker to output the generated driving sound.

Abstract: Example noise attenuators for use with process control devices are described herein. An example apparatus includes a first plate and a second plate disposed in a fluid passageway of a noise attenuator. The second plate is spaced apart from the first plate. The example apparatus also includes a first support rod extending along a central axis of the fluid passageway. The first support rod is coupled to the first plate and to the second plate. The example apparatus further includes a second support rod extending along an axis parallel to and offset from the central axis. The second support rod is coupled to the first plate and the second plate.

Abstract: A suppressor element having at least some of a body portion having a body cavity defined therein; a shielding portion, wherein the shielding portion is positioned over at least a portion of the body portion, such that a venting cavity is defined between at least a portion of the body portion and at least a portion of the shielding portion; one or more support elements that extend between the body portion and the shielding portion; and a rear cap that extends from a body portion first end, wherein the rear cap includes a mounting aperture, wherein the mounting aperture allows the rear cap to be attached or coupled to a barrel or muzzle device of a firearm, and wherein at least the body portion, the shielding portion, and the one or more support elements, are formed as an integral or monolithic unit.

Abstract: A 3-D printed suppressor element having at least some of a body portion having a body cavity defined therein; a shielding portion, wherein the shielding portion is positioned over at least a portion of the body portion, such that a venting cavity is defined between at least a portion of the body portion and at least a portion of the shielding portion; one or more support elements that extend between the body portion and the shielding portion; and a rear cap that extends from a body portion first end, wherein the rear cap includes a mounting aperture, wherein the mounting aperture allows the rear cap to be attached or coupled to a barrel or muzzle device of a firearm, and wherein at least the body portion, the shielding portion, and the one or more support elements, are formed as an integral unit, via 3-D printing or additive manufacturing.

Abstract: An intake sound generator for an internal combustion engine of a vehicle, the internal combustion engine having an intake manifold for distributing a combustion mixture to a plurality of cylinders of the engine, and an engine throttle controlled by an electronic engine management system for regulating the flow of the combustion mixture into the intake manifold, the engine management system being coupled to an engine throttle lever whose position indicates the engine throttle position desired by a driver of the vehicle, and the intake sound generator comprising: a sound outlet port at an intake manifold; a first sound transmission tube connected to the sound outlet port and adapted to conduct engine-generated sound pulses from the intake manifold; sound receiving means coupled to the first sound transmission tube and operable to receive engine-generated sound pulses conducting along the first sound transmission tube; a sound throttle connected along the first sound transmission tube at a point intermediate bet

Abstract: An adjustable blocking arrangement for electronic hardware or computer racks, for preventing the undesired leakage of air through rack spaces not filled with hardware. An airflow control device is provided comprising a flexible web and a magazine adapted to receive the part of the flexible web that is not deployed. The device is adapted such that a length of the web may be deployed to sealingly block a space in the rack that is not filled with hardware modules, to prevent the flow of air through the space. The device may comprising a detection system adapted to detect the space in the rack that is not filled with hardware modules, and a processing system adapted to receive a signal from the detection system, and as a function of the signal to automatically deploy or retract the flexible web so as to sealingly block the space.

Abstract: A muffler for a vehicle is provided, including: a muffler housing having a first housing body and a second housing body that are divided in two parts and form an internal space with an inlet opening and an outlet opening when combined; and an internal structure inserted and forced into the internal space of the muffler housing to be detachable from the muffler housing, and allowing an exhaust gas discharged from an engine to flow into the internal space and to be discharged out of the muffler housing through a predetermined path.

Abstract: The expandable chamber acoustic silencer may be installed at the inlet or outlet of virtually any mechanism that processes air or other gas flow therethrough, to reduce the audible output of the gas flow. The silencer may be used to reduce the noise produced in an air conditioning system, in the inlet or outlet side of an air compressor, or as a muffler for an internal combustion engine, among other applications. The device includes an expansion chamber having adjustable walls driven by actuators installed within the walls to adjust the cross-sectional area of the chamber, with a portion of the walls being formed of a flexible or resilient material to enable such expansion and retraction. One or more microphones are installed at the outlet and/or inlet ends of the silencer and communicate with a controller that operates the actuators in accordance with a predetermined algorithm.

Abstract: A resonator for a vehicle is provided, including a housing having at least one chamber formed therein. The housing has at least one aperture formed in a wall thereof. The housing is in fluid communication with an air conduit of the vehicle. At least one flexible member is disposed within the chamber of the housing. The flexible member includes an outer portion and an inner extension protruding from the outer portion which vibrates to attenuate low frequency sound energy transmitted from the air conduit.

Abstract: The present invention discloses a suction muffler for a hermetic compressor which reduces noise of refrigerant. A plate film operating as a kind of flow resistance is provided on a refrigerant suction passage in various shapes and specific positions. Therefore, the suction muffler can effectively reduce pressure pulsation transferred to the outside and guarantee flow efficiency, although the refrigerant is directly sucked thereinto.

Abstract: A sound distribution apparatus provides a driver with an audible impression of the operating speed, load and performance of a vehicle engine. The sound distribution apparatus includes an assembly of one or more sound transmission ducts interconnected to conduct or transmit engine sounds from the air intake tract into the passenger compartment and to distribute the sound in a uniform fashion from behind the dashboard at the front to the passenger compartment. The sound distribution duct includes a plurality of sound diffusion apertures arranged on the outer wall, each configured to diffuse a portion of the transmitted sound into the passenger compartment. A sound permeable airflow blockage device seals the sound transmission duct interior in a gas-tight way preventing airflow.

Abstract: A system for reducing an acoustic load of a fluid flow includes a first pipe to carry the fluid flow; a standpipe connected to the first pipe at an opening in the first pipe; and a standpipe flow tripper provided in the standpipe. The flow tripper includes an edge extending through the opening into the flow on a downstream side of the opening. A method of reducing an acoustic load of a standing wave in a standpipe connected to a first pipe configured to carry a flow includes disrupting the flow in the first pipe at a downstream side of an opening in the first pipe to which the standpipe is connected.

Abstract: An intake air sound generation device 40 for an internal combustion engine 2, comprises an introduction tube 41 which is connected to an intake passage 30 of the internal combustion engine 2 to introduce an intake pulse of an intake system, a vibrating body 50 which has a vibration surface 52 that is vibrated by the intake pulse and an accordion portion 53 that promotes vibration of the vibration surface 52, and is provided to cover one end of the introduction tube 41, and a resonance tube 42 which is connected to the introduction tube 41 via the vibrating body 50 and increases a sound pressure in a predetermined frequency band of an intake air sound generated by the vibration of the vibration surface 52. Thus, the sound pressure of the intake air sound at the predetermined frequency can be increased, and the durability of the vibrating body 50 can be improved.

Abstract: The present invention relates to a muffler facia assembly including a muffler with at least one thermoplastic shell formed into a facia assembly on a motor vehicle. The facia may be any suitable body part of a motor vehicle, such as a bumper, a rocker panel, an air dam, a spoiler, a sideboard or a body module. An assembly in accordance with the present invention includes structural members to provide crash management features to increase the strength and impact resistance. In accordance with the present invention, the long fiber thermoplastic material and moldings may also be combined with over-molding of preforms of unidirectional or woven inlays, which provide local structural performance. The use of such preforms is particularly suited to use in the manufacture of high temperature, structural articles such as bumper muffler combinations.

Abstract: A sound generator for a vehicle is provided, including a hollow drum having a sound radiation panel structurally and acoustically coupled thereto. The drum has an aperture formed in an outer wall thereof. The drum is adapted to be in fluid communication with an air conduit of the vehicle. The sound radiation panel covers at least a portion of the aperture and is adapted to radiate sound energy to at least one of an engine compartment and an interior of the vehicle. A vehicle system including the sound generator and a method for manufacturing the sound generator are also provided.

Abstract: A muffling chamber (5) is located between a first main body wall (42A) and a second main body wall (42B) with respect to a height direction (AE). An outflow pipe (8) has: a first opening (8A) that connects an outflow passage (8R) with a muffling chamber (5) in the vicinity of a first main body wall (42A); and a second opening (8C) that connects the outflow passage (8R) with the muffling chamber (5) in the vicinity of a second main body wall (42B). The liquid staying on the first main body wall (42A) of a first muffler (4A) flows into the outflow passage (8R) through the first opening (8A). The liquid staying on a second main body wall (42B) of a second muffler (4B) flows into the outflow passage (8R) through a second opening (8C). Therefore, the symmetry of the first muffler (4A) and the second muffler (4B) is compatible with anti-corrosion.

Abstract: A device for amplifying the suction noise of a vehicle is disclosed. The device comprises an intake duct, a connecting pipe and a composite membrane. The intake duct is for feeding air to an engine intake port. A connecting pipe is connected to an interior of the intake duct. The composite membrane is positioned within the connecting pipe. The composite member blocks an interior passage formed in the connecting pipe. The composite member further includes at least two elastic membranes with one of masses and rigidities that different from each other. A method is also disclosed.

Abstract: A connection between a plate and a pipe wherein the pipe passes through an opening in the plate, and wherein the plate has a spring-elastic tongue at the opening which is fixedly connected to the pipe.

Abstract: A sound-baffling arrangement for use in conjunction with an air-handling unit. One or more sound baffle columns are mounted for rolling or sliding movement within the interior of the air handling unit housing. Each baffle column may be selectively moved between a use position proximate to the fan assemblies, and a non-use position more distal from the fan assemblies. The movable sound baffles permit the air-handling unit to be fabricated to fit within a smaller housing, and thus to have a smaller, more economical footprint.

Abstract: The invention uses tubes for the reduction of radiated duct noise. The tubes may be used to attenuate narrow band noise by diverting a portion of the acoustic energy through the tubes back into the duct. Upon reintroducing the diverted flow out of phase with the primary flow, acoustic cancellation is achieved. The frequency at which this occurs is dependent on the difference in the path lengths through the tubes and the separation distance—the distance separating the inlet and outlet of the tube. This invention can be used over varying frequency ranges by using an arrangement of flexible, constant length tubes. The effective frequency range is tailored by varying the separation distance and also allows the varying the angular arrangement of the tubes for more effective attenuation of spinning modes having varying propagation angle.

Abstract: The invention uses tubes for the reduction of radiated duct noise. The tubes may be used to attenuate narrow band noise by diverting a portion of the acoustic energy through the tubes back into the duct. Upon reintroducing the diverted flow out of phase with the primary flow, acoustic cancellation is achieved. The frequency at which this occurs is dependent on the difference in the path lengths through the tubes and the separation distance—the distance separating the inlet and outlet of the tube. This invention can be used over varying frequency ranges by using an arrangement of flexible, constant length tubes. The effective frequency range is tailored by varying the separation distance and also allows the varying the angular arrangement of the tubes for more effective attenuation of spinning modes having varying propagation angle.

Abstract: An apparatus for sonic coupling between an intake tract or engine compartment and a vehicle interior of a motor vehicle has a housing into which sound enters from the intake tract via a first line, and out of which sound exits into the vehicle interior via a second line. A transmission body is arranged in the housing, the transmission body having a gas-tight separating wall between a sound inlet into the housing and a sound outlet out of the housing. The position of the separating wall is held essentially constant by a positioning device. A transmission wall between the separating wall and the housing provides an acoutis transfer function that is adjustable. The separating wall runs generally perpendicular to the longitudinal axis of sound propagation and the transmission wall runs at an angle ? to the longitudinal axis of sound propagation.

Abstract: The present invention relates to a muffler for a line conveying gas and airborne sound, in particular for an exhaust system of an internal combustion engine, preferably in a motor vehicle. The muffler has a housing in which there are at least two inside pipes for carrying gas in the interior of the housing and which contains at least one inside plate for reinforcing the housing. The two inside pipes are inserted one inside the other in a sliding seat area and are axially movable in relation to one another.

Abstract: An assembly useful in reducing aircraft engine noise such as turbofan engine noise (730) comprises: (1) at least one tube “H-Q” having an inlet end (738), an outlet end (740) and a central tube portion therebetween; an (ii) at least one actuator operatively interconnected to at least one tube, wherein the actuator is capable of causing dynamic response by the tube. The assembly of this invention may be used in a method for reducing noise, the method comprising: (a) providing means for generating non-uniform noise energy about an inner surface and within a disclosure having at least an inlet; (b) providing an assembly for reducing noise comprising; (i) at least one tube having an inlet end, an outlet end and a central tube portion therebetween, and (ii) at least one actuator operatively interconnected to at least one tube, wherein the actuator is capable of causing dynamic response by the tube; and (c) directing at least a portion of the non-uniform noise into the assembly.

Abstract: An apparatus for sonic coupling between an intake tract or engine compartment and a vehicle interior of a motor vehicle has a housing into which sound enters from the intake tract via a first line, and out of which sound exits into the vehicle interior via a second line. A transmission body is arranged in the housing, the transmission body having a gas-tight separating wall between a sound inlet into the housing and a sound outlet out of the housing. The position of the separating wall is held essentially constant by a positioning device. A transmission wall between the separating wall and the housing provides an acoustic transfer function that is adjustable. The separating wall runs generally perpendicular to the longitudinal axis of sound propagation and the transmission wall runs at an angle ? to the longitudinal axis of sound propagation.

Abstract: A control system (10) controls a variable acoustical damping device (20) disposed in a sound producing channel (5) of a vehicle engine (1). The control system includes a controller (12) and a selection device (14). The controller is coupled to the variable acoustical damping device and stores a plurality of control patterns (A. B) for different levels of acoustical damping of the acoustical damping device. The selection device outputs a selection signal to the controller so that the controller controls the variable acoustical damping device based on one of the control patterns corresponding to the selection signal.

Abstract: The present invention provides a resonator for attenuating acoustic vibration from an air intake passage. The resonator includes a neck, a resonator chamber, a piston-type member, and an actuator. The neck is attached between the air passage and the resonator chamber. The neck has two overlapping portions allowing the neck to extend within the resonator chamber. The piston-type member is located within the resonator chamber and is translated by the actuator to change the volume of the resonator and the neck length. By changing the volume and neck length of the resonator, the frequency attenuated by the resonator can be adjusted.

Abstract: A device for active noise reduction has a chamber, which is arranged laterally in relation to a gas flow, and a chamber opening constructed in one wall of the chamber. In the area of the chamber opening, a deflection device is adjustably arranged. The deflection device, in a first position, at least partially directs the gas flow running by the chamber opening into the chamber, in order to compress air there, and, in a second position, directs the gas from the chamber to the gas flow, in order to release the gas inside the chamber. The resulting alternating pressure inside the chamber is radiated through the chamber opening as sound and overlays the disturbing sound.

Abstract: A silencer or sound attenuator for gas flows that makes use of noise baffles is provided with a lateral movement mechanism which allows the baffles to be moved perpendicular to the direction of the gas flow within the silencer. A silencer provided with the lateral movement mechanism allows personnel to have access to the interior of the silencer so that the baffles can be cleaned without having to remove the baffles from the silencer. The lateral movement mechanism may include a roller assembly installed at the top of each baffle which operates within a corresponding track that is provided to the inner upper surface of the housing. The lateral movement mechanism may also include a caster assembly, which is provided to the bottom of each baffle to aid in lateral movement.

Abstract: In a device for establishing noise in a motor vehicle, including a housing having an inlet space, which is in communication via an inlet line with a gas-carrying part of an internal combustion engine arranged in the motor vehicle, and an outlet space, which is acoustically coupled by means of an outlet line to an interior space of the vehicle or the space surrounding the vehicle, the inlet space is separated from the outlet space at least by an acoustically substantially inactive wall. Arranged inside the housing is a sound transmission device, which has vibratable elements, one arranged in the inlet space and onother arranged in the outlet space and connected to each other by a curved connecting element, which is mounted on the acoustically inactive wall, for the transmission of sounds introduced through the inlet line into the inlet space to the outlet space.

Abstract: A mobile work zone protection device includes a front carrier, a barrier beam assembly, and a rear carrier. In one embodiment, the barrier beam assembly includes two sets of telescoping beam structures. Each of these structures can rotate from one side of the device to the other, and thus can be deployed to create a safe work zone for roadway workers on either side of the device. The structure can also be left in the transit position to provide an enclosed safe work zone.

Abstract: An assembly useful in reducing aircraft engine noise such as turbofan engine noise (730) comprises: (i) at least one tube “H-Q” having an inlet end (738), an outlet end (740) and a central tube portion therebetween; and (ii) at least one actuator operatively interconnected to at least one tube, wherein the actuator is capable of causing dynamic response by the tube. The assembly of this invention may be used in a method for reducing noise, the method comprising: (a) providing means for generating non-uniform noise energy about an inner surface and within a disclosure having at least an inlet; (b) providing an assembly for reducing noise comprising; (i) at least one having an inlet end, an outlet end and a central tube portion therebetween, and (ii) at least one actuator operatively interconnected to at least one tube, wherein the actuator is capable of causing dynamic response by the tube; and (c) directing at least a portion of the non-uniform noise into the assembly.

Abstract: A device for noise structuring in a motor vehicle has a plurality of gas-carrying lines connected to an internal combustion engine. At least two of the gas-carrying lines are acoustically linked together by at least one connection.

Abstract: An exhaust processor comprises a Helmholtz resonance chamber with a variable tuning throat. The tuning frequency of the exhaust processor changes as the outlet opening from the variable tuning throat into the Helmholtz resonance chamber changes.

Abstract: A muffler for equipment powered by compressed air, the muffler comprising a flexible muffler body formed from a sufficiently resilient material to resiliently deform under the influence of an exhaust air stream from an air motor, the body having an inlet and an outlet; a plurality of flexible baffles located within said body to muffle the sound of the air powered equipment; and an oil mist remover extending at least partially through said body, said oil mist remover being sized and shaped to prevent trapped oil from being re-misted by said exhaust air stream.

Abstract: An exhaust processor comprises a Helmholtz resonance chamber with a variable tuning throat. The tuning frequency of the exhaust processor changes as the outlet opening from the variable tuning throat into the Helmholtz resonance chamber changes.

Abstract: An exhaust processor comprises a Helmholtz resonance chamber with a variable tuning throat. The tuning frequency of the exhaust processor changes as the outlet opening from the variable tuning throat into the Helmholtz resonance chamber changes.

Abstract: A flattened acoustic muffler for use on stock cars. The muffler mounts to the standard exhaust system pipes and to the lower chassis of the car, routing exhaust gasses to one or both sides of the car while providing improved ground clearance between the exhaust pipe and the surface of the race track. The muffler contains a plurality of spiral acoustic traps, which attenuate exhaust noise while producing little additional backpressure.

Abstract: An acoustic absorber (10) comprises a housing or wall (11), defining an interior absorber chamber (12) connected by openings (13) to a duct (20) to reduce the sound in the duct (20). The natural frequency and impedance of the absorber (12) are variable, so that the absorber (12) can be adapted to a sound field in the duct (20) in a manner corresponding to the respective operating conditions. Such adaptation is achieved mechanically, for example, by an elastic membrane (15) for varying the volume of chamber (12), or thermally, for example, by a heating wire (14) or a wire braid (17).

Abstract: A device for noise structuring in a motor vehicle has a plurality of gas-carrying lines connected to an internal combustion engine. At least two of the gas-carrying lines are acoustically linked together by at least one connection.

Abstract: An improved exhaust pressure pulsation control apparatus for a marine propulsion system has a front ring, a reflector disk located downstream of the front ring, and a plurality of connecting members connecting the front ring to the reflector disk. Each connecting member has a concave outer edge to facilitate mounting the apparatus within an exhaust tube. A clamp outside of the exhaust tube clamps the exhaust tube against the concave outer edges of the connecting members to secure the apparatus longitudinally within the exhaust tube. The apparatus is preferably made of a fiberglass reinforced thermoplastic material, such as 33% fiberglass reinforced polythalamide or nylon 4,6, through an injection molding process.

Abstract: A device for reducing certain sound ranges of tire/road surface noise of a motor vehicle includes sound absorbers in the form of resonators positioned at the inner wall of a wheel well of the vehicle in the area of sound projection of the tire/road surface noise. The device has an electronic control device for receiving a signal preferably derived from an ABS system in the form of the wheel rpm. The control device adjusts the resonators according to the number of tread blocks of the tire, the sound emission characteristics, and the wheel rpm. In another embodiment the electronic control device is supplied with signals received from a sound receiver that records the course over time of the sound pressure. The control device adjusts the resonators such that the measured sound pressure signal is minimized. In another alternative the device has a data processing unit including an electronic control device.

Abstract: An attenuator for pressure and sound energy pulsations, such as are commonly produced in refrigerant gas discharged from a piston-type refrigerant compressor, is provided. The attenuator includes an annular elastomeric body supported by a rigid tubular housing. The body forms a cavity filled with a damping fluid and annular dividers define multiple chambers that are concentrically disposed about a central refrigerant gas flow passage. Damping tracks are provided in the dividers to allow fluid flow between the chambers. As refrigerant gas flows through the passage, the pressure/sound pulsations are flattened and smoothed. The resilient walls of the body are designed to bulge inwardly for a maximum 50% restriction. Gas flow orifices of the dividers have substantially the same cross-sectional area as the refrigerant line.

Abstract: A number of embodiments of internal combustion engine exhaust systems each of which is effective to provide good silencing for exhaust gases through the use of an elastic diaphragm that dampens pulsations. In some embodiments, this elastic diaphragm forms a portion of a Helmholz resonator and in some the diaphragm is cooled by submerging in a cooling jacket of the engine or its exhaust system or by means of cooling air fins. Also, various arrangements are incorporated for adjusting or tuning the rigidity of the diaphragm. Furthermore, in some embodiment the diaphragm is suspended in such a way as to act as a vibration damping member between mechanical components of the exhaust system.

Abstract: An extruded buckling-resistant longitudinally insertable drain or venting hose of PVC or a similar thermoplastic material which can be mounted in inaccessible hollows of a conveyance, especially a motor vehicle body, has longitudinally-extending radial ribs coextruded with the PVC body and composed preferably of chlorinated polyethylene. As a result, the hose has improved sound-damping properties and can be more readily inserted into place.

Abstract: A fluid friction controller that includes an outer member having a first friction control surface and an inner member having a second friction control surface. The control surfaces coact to define an elongated orifice that diverges from its entrance toward its exit. The length of the orifice is related to the angle of divergence so that the flow of a fluid passing therethrough remains attached to the control surfaces and the dynamic pressure in the flow does not exceed the static pressure at any point along the length of the orifice.

Abstract: A sound suppression system having a sound suppression chamber formed from a longitudinally extending tubular housing. One end of the tubular housing is closed by an end plug which has a bore through which passes one end of a tubular member. The tubular member comprises a gun barrel having a cylindrical sleeve surrounding a predetermined length of the gun barrel. The tubular member has a plurality of tubular passages each of which have their one end in communication with the bore of the gun barrel and their other end longitudinally displaced therefrom adjacent the end of the gun barrel to place them in communication with the interior of the sound suppression chamber. A baffle having a cylindrical body approximating the interior diameter of the tubular housing is positioned within the tubular housing. Both the interior of the tubular housing and the outer cylindrical housing of the baffle are threaded so that the baffle may be adjustably positioned through the length of the tubular housing.

Abstract: A device for amplifying the suction noise of a vehicle is disclosed. The device comprises an intake duct, a connecting pipe and a composite membrane. The intake duct is for feeding air to an engine intake port. A connecting pipe is connected to an interior of the intake duct. The composite membrane is positioned within the connecting pipe. The composite member blocks an interior passage formed in the connecting pipe. The composite member further includes at least two elastic membranes with one of masses and rigidities that different from each other. A method is also disclosed.