A vehicle exhaust system includes an exhaust component comprising a wall having an outer surface and an inner surface that defines an internal exhaust component cavity. At least one hole is formed in the exhaust component to extend through the wall of the exhaust component from the outer surface to the inner surface. A membrane is configured to overlap the at least one hole, wherein the membrane is moveable relative to the wall in response to pressure fluctuations.

A muffler includes an exhaust pipe, a shell, and a cover. The exhaust pipe includes communication holes and is configured to allow an exhaust gas to flow through an interior of the exhaust pipe. The shell is disposed outside the communication holes to cover the communication holes. The cover has a tubular shape. The cover is disposed between the exhaust pipe and the shell. The cover is disposed at a distance, which is specified in advance, from the exhaust pipe.

A muffler includes an exhaust pipe, a shell, and a cover. The exhaust pipe includes communication holes and is configured to allow an exhaust gas to flow through an interior of the exhaust pipe. The shell is disposed outside the communication holes to cover the communication holes. The cover has a tubular shape. The cover is disposed between the exhaust pipe and the shell. The cover is disposed at a distance, which is specified in advance, from the exhaust pipe.

An air blower has an inlet muffler and an outlet muffler to reduce the noise of the air blower during operation. Each of the mufflers may have two sections. One section is configured to attenuate high frequency noise and the other section is configured to attenuate lower frequency noise. A tubular internal wall in each of the mufflers defines the through passage for each of the mufflers. A noise absorbent material may be fitted about the tubular wall within each muffler. A plurality of holes are formed along the tubular wall of each through passage to expose the through passage to the noise absorbent material. A heater plenum may be interposed between the blower plenum and the outlet muffler to heat the air from the blower plenum. A filter at the input muffler filters the air sucked into the air blower.

An aerial vehicle that can comprise a housing comprising an outer wall at least partially defining an interior space, a mechanical power source at least partially located in the interior space of the housing, an exhaust header in communication with the mechanical power source for communicating exhaust fluid from the mechanical power source, and an exhaust system comprising at least an exhaust chamber extending at least partially in the interior space of the housing. The exhaust chamber can be in communication with the exhaust header, and the exhaust system can comprise an exhaust outlet for communicating the exhaust fluid from the exhaust system outside the aerial vehicle.

An exhaust gas treatment device, which includes an outer layer, an inner layer that is at least in part disposed within the outer layer, and a loose-fill insulation disposed in the volume between the outer layer and the inner layer, where a piece of fiber mat is disposed between the outer layer and the inner layer and forms a barrier that at least partially prevents the loss of the loose-fill insulation from the volume between the outer layer and the inner layer and a manufacturing method that includes placing a loose-fill insulation into the volume of space between an inner layer and an outer layer and positioning a piece of fiber mat between the outer layer and the inner layer to form a barrier that at least partially prevents the loss of the loose-fill insulation from the volume of space between the outer and inner layers.

An exhaust gas treatment device, which includes an outer layer, an inner layer that is at least in part disposed within the outer layer, and a loose-fill insulation disposed in the volume between the outer layer and the inner layer, where a piece of fiber mat is disposed between the outer layer and the inner layer and forms a barrier that at least partially prevents the loss of the loose-fill insulation from the volume between the outer layer and the inner layer and a manufacturing method that includes placing a loose-fill insulation into the volume of space between an inner layer and an outer layer and positioning a piece of fiber mat between the outer layer and the inner layer to form a barrier that at least partially prevents the loss of the loose-fill insulation from the volume of space between the outer and inner layers.

A sound generator (1) includes a casing (10) with at least one exhaust gas inlet (11) and at least one exhaust gas outlet (12) that is different from the at least one exhaust gas inlet (11) and at least one electro-acoustical transducer (20). The electro-acoustical transducer (20) is configured to produce sound in dependence on an electrical control signal. The electro-acoustical transducer (20) is located within the casing or directly attached to the casing. An active noise control system (9) includes the sound generator (1). A vehicle (8) with an internal combustion engine (6) includes the active noise control system (9).

A sound generator (1) includes a casing (10) with at least one exhaust gas inlet (11) and at least one exhaust gas outlet (12) that is different from the at least one exhaust gas inlet (11) and at least one electro-acoustical transducer (20). The electro-acoustical transducer (20) is configured to produce sound in dependence on an electrical control signal. The electro-acoustical transducer (20) is located within the casing or directly attached to the casing. An active noise control system (9) includes the sound generator (1). A vehicle (8) with an internal combustion engine (6) includes the active noise control system (9).

A sound suppression apparatus for installation inside a gas transport duct is provided. The sound suppression apparatus comprises a resistive sound-absorbing element (110) and a housing providing a reactive sound-attenuating element (130) communicating with a surrounding of the apparatus via opening in an outer surface of the housing. An outer surface of the sound suppression apparatus comprises an outer surface of the resistive sound-absorbing element and the outer surface of the housing. A gas transport duct comprising the sound suppression apparatus is also provided.