A first ventilation duct line has a first portion having a first sectional area, a second portion having a second sectional area larger than the first sectional area, and a third portion having an inclined inner face connecting the first portion and the second portion to each other. Further, there is a second ventilation duct line having an opening portion positioned on an inner side of the first portion of the first ventilation duct line.

Resonating patch for acoustic treatment comprising a resonant plate, a transducer and an electrical circuit electrically connected to the transducer, the resonant plate comprising a peripheral strip extending along the perimeter of the resonant plate.

The patch comprises cutouts together defining deformable lamellae having at least one end connected to the peripheral strip.

A silencer module for an air handling unit includes a first baffle and a second baffle spaced apart from the first baffle to form an air channel between the first baffle and the second baffle. The air channel is configured to receive a fluid flow and direct the fluid flow through the silencer module. The silencer module also includes a reactive acoustic feature formed in the first baffle. The reactive acoustic feature includes an attenuation profile configured to reduce propagation of tonal acoustic waves through the air channel.

An acoustic damper includes a low porosity layer section and a housing. The low porosity layer section is formed in a liner of a gas turbine combustor and has an arrangement of elongated generally S-shaped slots formed therein. The housing has a plurality of feed apertures. The housing is coupled to the low porosity layer section thereby defining a cavity such that air outside the housing is configured to flow through the apertures and through the elongated generally S-shaped slots in the low porosity layer section, thereby transforming acoustic energy into thermal energy and aiding in providing an acoustic dampening effect for the gas turbine combustor during operation thereof.

Provided is a silencing tubular structure body that has high strength and can be disposed in a narrow space. A tubular member including a tubular portion having a tubular shape, and a frame portion having at least a part formed integrally with an inner peripheral surface side of the tubular portion; and a lid member that is exchangeably disposed on an opening surface of the frame portion of the tubular member are included, in which the frame portion and the lid member form a resonant silencing structure.

Embodiments of the present disclosure provide a diffusion muffling device, a diffusion resonance muffling device, a full-frequency diffusion muffling device, a muffling system for a ventilation channel, and a muffling method using the same, which include a plurality of diffusion muffling units disposed in the ventilation extension direction of the ventilation channel, wherein the plurality of diffusion muffling units are arranged in parallel in a direction with a predetermined angle between the direction and the ventilation extension direction of the ventilation channel, and a muffling passage is formed between each two adjacent diffusion muffling units, wherein each of the diffusion muffling units includes at least one diffuser, and each diffuser includes a plurality of convex portions so that sound waves entering the muffling passage are reflected multiple times in the muffling passage by the plurality of convex portions and then sound is attenuated. In the present disclosure, the diffusers are disposed to diffuse and reflect sound waves, so that the sound is attenuated in a long and narrow passage by multiple times of reflections of the sound waves, thereby improving the low-frequency sound muffling performance in the ventilation channel so as to effectively achieve an effect of sound muffling and noise reduction in ventilation.

A muffler for an exhaust system of an internal combustion engine includes a muffler housing having a peripheral wall elongated along a longitudinal housing axis. The muffler has an end wall on each axial end region of the peripheral wall and a muffler insert, surrounded by the peripheral wall and supported on the peripheral wall. A retaining wall extends substantially in the direction of the longitudinal housing axis and a first exhaust-gas routing pipe is positioned with a first end region engaging in an opening in the peripheral wall and is secured to the peripheral wall and retained with a second end region on the retaining wall. The first exhaust-gas routing pipe is retained in its second end region on the retaining wall by force closure or interlocking.

A muffler for an exhaust system of an internal combustion engine includes a muffler housing having a peripheral wall elongated along a longitudinal axis of the muffler housing. The peripheral wall has first and second end walls. A muffler insert is surrounded by the peripheral wall and is supported thereon. The muffler insert has a retaining wall extending in a direction of the longitudinal axis. The peripheral wall has a peripheral wall opening and a first exhaust-gas routing pipe has a first end region and is positioned with the first end region thereof engaging in the peripheral wall opening. The first exhaust-gas routing pipe has a second end region and is secured by the second end region thereof to the retaining wall. The first exhaust-gas routing pipe is of multi-part configuration and has a first pipe part and a second pipe part.

An acoustic core may include an array of resonant cells configured as a plurality of resonant cell groups. The resonant cell groups may include a plurality of resonant cells configured as a partitioned resonant cell that include a converging resonant cell and a diverging resonant cell. The converging resonant cell and the diverging resonant cell may be defined by a plurality of cell walls integrally formed with one another and a partition integrally formed with the plurality of cell walls. The partition may at least partially delimit the converging resonant cell from the diverging resonant cell. The converging resonant cell may define an upper resonant space delimited by the partition and a top face of the array of resonant cells. The diverging resonant cell may define a lower resonant space delimited by the partition and a bottom face of the array of resonant cells.

A sound attenuator has an inner pipe (12) with expansion sections (121) of enlarged diameter corresponding to the constriction sections (141) of an outer pipe (14). The expansion sections (121) in pairs axially delimit an intermediate inner pipe section (122) containing a wall opening (18) and having a reduced diameter relative to the expansion sections (121). The inner surface of the outer pipe (14) in each of its constriction sections (141) is connected to the outer surface of the inner pipe (12) in its respective corresponding expansion section (121). A method of manufacturing such a sound attenuator (10) also is provided and uses internal high-pressure forming.