A sound attenuation apparatus includes a body and a stacked cavity structure. The structure includes a structure inlet formed in the top surface of the body; a passage extending from the structure inlet into the interior of the body to a base surface within the body; a first cavity with a first cavity inlet fluidly coupled to the passage and being formed by a first arm, a first side wall within the interior of the body, and the base surface; and a second cavity with a second cavity inlet fluidly coupled to the passage and being formed by a second arm, the first side wall, and the first arm. Each of the first and second arms extends from the first side wall and includes at least two arm segments oriented at different angles relative to the first side wall longitudinal axis.

Exemplary air amplifiers described herein can utilize a high-pressure stream of gas to accelerate a low-velocity stream of gas to provide a high-velocity, high-volume stream of gas. This high-velocity, high-volume stream of gas can generate unwanted noise as the high-velocity, high-volume stream of gas propagates through the air amplifier. The exemplary air amplifiers described herein can passively and/or actively suppress, for example, diminish, re-tune, or even completely cancel, the unwanted noise as the high-velocity, high-volume stream of gas propagates through these exemplary air amplifiers. The exemplary air amplifiers described herein can include one or more absorption materials to passively suppress the unwanted noise generated by the high-velocity, high-volume stream of gas. The exemplary air amplifiers described herein can generate multiple noise suppression waves to actively suppress the unwanted noise generated by the high-velocity, high-volume stream of gas. The multiple noise suppression waves can destructively combine with the unwanted noise generated by the high-velocity, high-volume stream of gas to suppress the unwanted noise.

A silencing device, an air purifier, and a method for producing the same are provided. The method includes that: a sound wave spectrum when an air purifier to be silenced performs operations is acquired; a frequency value, which exceeds a sound wave frequency limit for the air purifier, of the sound wave spectrum is calculated; and a silencing device adapted to the air purifier to be silenced is produced according to the frequency value. At least one structural parameter of the silencing device is configured according to the frequency value. The silencing device is configured to reduce a sound with the frequency value exceeding the sound wave frequency limit.

Described herein are noise attenuating ducts and vehicles using these ducts for environmental control systems. A duct comprises an exoskeleton structure and a sound-absorbing structure, disposed within and conforming to the exoskeleton structure. The exoskeleton structure provides external mechanical support to the sound-absorbing structure thereby helping to maintain the tubular shape of the sound-absorbing structure. This external support does not interfere with the airflow inside the sound-absorbing structure. Furthermore, the external positioning of the exoskeleton structure allows the integration of various support mounting features for the installation of the duct in a vehicle. In some examples, the exoskeleton structure comprises a plurality of enclosed openings to reduce the weight of the exoskeleton structure and provide additional flexibility. Furthermore, additive manufacturing of the exoskeleton structure allows achieving a monolithic structure with various features and characteristics described above.

Exemplary air amplifiers described herein can utilize a high-pressure stream of gas to accelerate a low-velocity stream of gas to provide a high-velocity, high-volume stream of gas. This high-velocity, high-volume stream of gas can generate unwanted noise as the high-velocity, high-volume stream of gas propagates through the air amplifier. The exemplary air amplifiers described herein can passively and/or actively suppress, for example, diminish, re-tune, or even completely cancel, the unwanted noise as the high-velocity, high-volume stream of gas propagates through these exemplary air amplifiers. The exemplary air amplifiers described herein can include one or more absorption materials to passively suppress the unwanted noise generated by the high-velocity, high-volume stream of gas. The exemplary air amplifiers described herein can generate multiple noise suppression waves to actively suppress the unwanted noise generated by the high-velocity, high-volume stream of gas. The multiple noise suppression waves can destructively combine with the unwanted noise generated by the high-velocity, high-volume stream of gas to suppress the unwanted noise.

A vapour barrier lamina, particularly for acoustic insulation of a pipe or duct, including a fiberglass moisture-proof foil layer, an acoustic insulation layer adjacent a first side of the moisture-proof layer, and a protection layer adjacent a second side of the moisture-proof layer. The vapour barrier lamina may also include a structural layer located between the moisture-proof foil layer and the acoustic insulation layer, for additional protection, and the structural layer may be a fiberglass screen.

The present disclosure provides a laminated structure with a through hollow structure having heat insulation, a light weight, durability, and sound absorption performance to reduce wind noise, transmitted noise, and the like. The laminated structure of the present disclosure has a foamed resin layer having continuous pores containing fused resin foam particles, and an air-impermeable outer layer provided on one side of the foamed resin layer, where a part of the foamed resin layer of the laminated structure cut out with a diameter of 41.5 mm? has an amount of air permeability of 2.5 cm.sup.3/(cm.sup.2.Math.s) to 40 cm.sup.3/(cm.sup.2.Math.s) measured by the Frazier method in which the foamed resin layer is set as an air introduction side.

A pipe clip includes a metal annular clip body having at least two opposing radial flanges defining an opening adapted to arrange the pipe clip around a pipe. The clip body has at one of the radial flanges a female fastening. The pipe clip includes a tightening screw having a head and a shank. The shank is provided with a male thread adapted to cooperate with the female fastening. The head engages the other of the flanges so as to tighten the flanges towards each other and tighten the pipe clip around the pipe. The pipe clip has a vibration insulating lining provided on the inner side of the clip body. A torque limiting cap is arranged on the screw head of the tightening screw. The torque limiting cap includes at least one torque transferring feature that couples the cap to the screw head in a rotational direction.

A cellular glass system for an outer surface of a pipe. An insulation layer surrounds the outer surface of the pipe. The insulation layer has an outer surface and an inner surface and comprises cellular glass. A foam fills an annular space between the outer surface of the pipe and the inner surface of the insulation layer and is configured to limit water intrusion into the annular space and attenuate sound. The system may also include another insulation layer and another foam layer between the two insulation layers.

A pipe lagging system for acoustically insulating a drain piping system includes at least one drain pipe and drain pipe connector coupled to the drain pipe. The pipe lagging system includes at least one preformed acoustic lagging sleeve adapted to be put over the drain pipe of the piping system for acoustical insulation, at least one preformed acoustic clamshell jacket adapted to fit over the drain pipe connector of the piping system for acoustically insulating the pipe connector. The clamshell jacket is adapted to receive an end portion of the tubular sleeve put over the drain pipe. At least one mechanical fastener is adapted to mechanically secure the clamshell jacket and the received tubular sleeve to the underlying drain pipe. At least one of the at least one tubular sleeve and clamshell jacket includes a sound-insulating foam material.