A method, system, and apparatus for fabricating an acoustic metamaterial is provided. In an embodiment, a method for fabricating an acoustic metamaterial includes determining at least one tuned physical property for each of a plurality of micro-resonators according to a desired acoustic property of the acoustic metamaterial. For a particular physical property, a value of the tuned physical property for at least one of the plurality of micro-resonators is different from a value of the tuned physical property for at least one other of the plurality of micro-resonators. The method also includes additively forming the acoustic metamaterial such that the acoustic metamaterial comprises a first structure and the plurality of micro-resonators embedded within the first structure. Forming the acoustic metamaterial is performed such that an actual physical property of each of the plurality of micro-resonators is equal to a corresponding tuned physical property for each of the plurality of micro-resonators.

A method, system, and apparatus for fabricating an acoustic metamaterial is provided. In an embodiment, a method for fabricating an acoustic metamaterial includes determining at least one tuned physical property for each of a plurality of micro-resonators according to a desired acoustic property of the acoustic metamaterial. For a particular physical property, a value of the tuned physical property for at least one of the plurality of micro-resonators is different from a value of the tuned physical property for at least one other of the plurality of micro-resonators. The method also includes additively forming the acoustic metamaterial such that the acoustic metamaterial comprises a first structure and the plurality of micro-resonators embedded within the first structure. Forming the acoustic metamaterial is performed such that an actual physical property of each of the plurality of micro-resonators is equal to a corresponding tuned physical property for each of the plurality of micro-resonators.

A dynamic acoustic jacket device and a dynamic acoustic jacket system, that includes a single piece of material folded into acoustic jacket for covering a lighting fixture, using locking devices or the cut away portion of the device, to quickly and easily install the acoustic jacket over suspension cables so that the acoustic jacket can be lowered and raised over the lighting fixture without the need to be attached thereto.

A dynamic acoustic jacket device and a dynamic acoustic jacket system, that includes a single piece of material folded into acoustic jacket for covering a lighting fixture, using locking devices or the cut away portion of the device, to quickly and easily install the acoustic jacket over suspension cables so that the acoustic jacket can be lowered and raised over the lighting fixture without the need to be attached thereto.

An object is to provide a silencing system that can achieve both high ventilation performance and high soundproof performance, can silence a plurality of pieces of resonant sound, and has high general-purpose properties since the silencing system does not need to be designed according to a tubular member. In a silencing system where silencers are disposed on a tubular member, the silencers silence sound having a frequency of first resonance of the tubular member, each silencer includes a cavity portion and an opening portion, the opening portions are connected to a sound field space of the first resonance of the tubular member, a conversion mechanism for converting sound energy into thermal energy is disposed in each cavity portion or at a position where the conversion mechanism covers the opening portion, a ratio S.sub.1/S.sub.d of the area S.sub.1 to the area S.sub.d satisfies “0<S.sub.1/S.sub.d<40%” in a case where the area of the opening portion of the silencer is denoted by S.sub.1 and the surface area of an inner wall of the cavity portion is denoted by S.sub.d, and the depth L.sub.d of the cavity portion in the traveling direction of an acoustic wave in the silencer satisfies “0.011×λ<L.sub.d<0.25×λ,” in a case where the wavelength of an acoustic wave at the resonant frequency of the first resonance is denoted by λ.

An object is to provide a silencing system that can achieve both high ventilation performance and high soundproof performance, can silence a plurality of pieces of resonant sound, and has high general-purpose properties since the silencing system does not need to be designed according to a tubular member. In a silencing system where silencers are disposed on a tubular member, the silencers silence sound having a frequency of first resonance of the tubular member, each silencer includes a cavity portion and an opening portion, the opening portions are connected to a sound field space of the first resonance of the tubular member, a conversion mechanism for converting sound energy into thermal energy is disposed in each cavity portion or at a position where the conversion mechanism covers the opening portion, a ratio S.sub.1/S.sub.d of the area S.sub.1 to the area S.sub.d satisfies “0<S.sub.1/S.sub.d<40%” in a case where the area of the opening portion of the silencer is denoted by S.sub.1 and the surface area of an inner wall of the cavity portion is denoted by S.sub.d, and the depth L.sub.d of the cavity portion in the traveling direction of an acoustic wave in the silencer satisfies “0.011×λ<L.sub.d<0.25×λ,” in a case where the wavelength of an acoustic wave at the resonant frequency of the first resonance is denoted by λ.

An acoustic absorption structure comprising a plurality of resonators. Each resonator comprises a first chamber which has a first mouthpiece delimited by an edge pressed against an inner surface of a porous zone of a skin so that the first chamber and the skin delimit a first cavity, a second chamber, in which is positioned the first chamber, which delimits, with the first chamber, a second cavity, at least one acoustic orifice passing through the first chamber, at least one drainage orifice passing through the first chamber and at least one drainage hole passing the second chamber, each drainage orifice and each drainage hole being configured to limit an accumulation of fluid in the resonator. Also, an aircraft propulsive assembly or an aircraft comprising the acoustic absorption structure are provided.

An acoustic absorption structure comprising a plurality of resonators. Each resonator comprises a first chamber which has a first mouthpiece delimited by an edge pressed against an inner surface of a porous zone of a skin so that the first chamber and the skin delimit a first cavity, a second chamber, in which is positioned the first chamber, which delimits, with the first chamber, a second cavity, at least one acoustic orifice passing through the first chamber, at least one drainage orifice passing through the first chamber and at least one drainage hole passing the second chamber, each drainage orifice and each drainage hole being configured to limit an accumulation of fluid in the resonator. Also, an aircraft propulsive assembly or an aircraft comprising the acoustic absorption structure are provided.

A Helmholtz resonator and a low-frequency broadband sound-absorbing and noise-reducing structure based on the same is provided. The Helmholtz resonator includes a Helmholtz resonator body, at least one embedded tube is disposed in the Helmholtz resonator body, and an inner surface of an opening of the Helmholtz resonator body wraps around an outer side of one of the embedded tubes; and all the embedded tubes are not in contact with each other. The low-frequency broadband sound-absorbing and noise-reducing structure includes a rigid framework, and at least two Helmholtz resonators are disposed in parallel in the framework. The Helmholtz resonator not only achieves a better low-frequency broadband sound absorption and noise reduction effect, but also reduces a thickness of the Helmholtz resonator more effectively. The low-frequency broadband sound-absorbing and noise-reducing structure enhances a sound absorption effect of each weak sound-absorbing Helmholtz resonator, and further achieves more efficient sound absorption.

A Helmholtz resonator and a low-frequency broadband sound-absorbing and noise-reducing structure based on the same is provided. The Helmholtz resonator includes a Helmholtz resonator body, at least one embedded tube is disposed in the Helmholtz resonator body, and an inner surface of an opening of the Helmholtz resonator body wraps around an outer side of one of the embedded tubes; and all the embedded tubes are not in contact with each other. The low-frequency broadband sound-absorbing and noise-reducing structure includes a rigid framework, and at least two Helmholtz resonators are disposed in parallel in the framework. The Helmholtz resonator not only achieves a better low-frequency broadband sound absorption and noise reduction effect, but also reduces a thickness of the Helmholtz resonator more effectively. The low-frequency broadband sound-absorbing and noise-reducing structure enhances a sound absorption effect of each weak sound-absorbing Helmholtz resonator, and further achieves more efficient sound absorption.