An acoustic structure presenting a front surface and a back surface is provided. The acoustic structure includes a support layer comprising the back surface, a honeycomb core comprising a thickness defined between a back and a front, and a plurality of walls that define a plurality of honeycomb cells, wherein the plurality of honeycomb cells extend through the thickness of the honeycomb core opening out toward at least the front, and wherein the back of the honeycomb core is affixed to the support layer, a mesh layer affixed to the front of the honeycomb core, and a knit fabric layer affixed to the mesh layer and conforming to the front surface of the acoustic structure.

A soundproof system includes a tube structure having one or more opening ends and a soundproof structure having an opening portion or a radiation surface. The following Expression (1) is satisfied in a case in which a phase difference between sound incident on the soundproof structure and sound re-radiated from the soundproof structure is defined a phase difference as θ1; for one or more maximum values of the pressure of sound formed in the tube structure, a distance between the opening portion or the radiation surface and a position where the sound pressure has a maximum value in the tube structure is L; a wavelength of the incident sound is λ; and a phase difference θ2 is defined as 2π×2L/λ:
|θ1−θ2|≤π/2  (1). The soundproof system with a small size can obtain high transmission loss in a wide band.

A soundproof system includes a tube structure having one or more opening ends and a soundproof structure having an opening portion or a radiation surface. The following Expression (1) is satisfied in a case in which a phase difference between sound incident on the soundproof structure and sound re-radiated from the soundproof structure is defined a phase difference as θ1; for one or more maximum values of the pressure of sound formed in the tube structure, a distance between the opening portion or the radiation surface and a position where the sound pressure has a maximum value in the tube structure is L; a wavelength of the incident sound is λ; and a phase difference θ2 is defined as 2π×2L/λ:
|θ1−θ2|≤π/2  (1). The soundproof system with a small size can obtain high transmission loss in a wide band.

A soundproof member is provided. The soundproof member includes a structural element, and a first composite film which is disposed on the bottom surface of the structural element. The structural member includes at least one through hole and the through hole passes through the structural element. The first composite film includes a polymer material and an inorganic nanoscale material, wherein the inorganic nanoscale material is a one-dimensional inorganic nanoscale material or a two-dimensional inorganic nanoscale material.

Disclosed a molded body including: a plurality of cavity portions formed inside a molding material; and a plurality of neck portions provided in each of the plurality of cavity portions and configured to communicate with the cavity portions, wherein some of the plurality of neck portions communicate with a surface and/or the cavity portion exposed on the surface, wherein at least some of the plurality of neck portions cause the plurality of cavity portions to communicate with each other, and wherein an inner surface of the neck portion is formed by the molding material itself.

A ventilation component includes a circumferential wall. At least a part of the circumferential wall is formed by the wall portion, which includes the inner layer and the outer layer. The inner layer contains fibers and has permeability, and the outer layer is provided on the radially outer side of the inner layer and has elasticity. The wall portion forms a vibration system including the inner layer as a mass portion and the outer layer as a spring portion. The vibration system has a partially varying natural frequency.

A ventilation component includes a circumferential wall. At least a part of the circumferential wall is formed by the wall portion, which includes the inner layer and the outer layer. The inner layer contains fibers and has permeability, and the outer layer is provided on the radially outer side of the inner layer and has elasticity. The wall portion forms a vibration system including the inner layer as a mass portion and the outer layer as a spring portion. The vibration system has a partially varying natural frequency.

A system for fabricating an acoustic metamaterial is provided. In an embodiment, a system 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 system also includes an additively manufacturing device configured to form 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 system for fabricating an acoustic metamaterial is provided. In an embodiment, a system 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 system also includes an additively manufacturing device configured to form 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 vehicle wheel includes: a rim including a well portion with an outer circumferential surface, the well portion having a recessed portion formed on the outer circumferential surface; a sub-air chamber member serving as a Helmholtz resonator; and a joining member including a joining portion disposed in the recessed portion. The sub-air chamber member is attached to the outer circumferential surface of the well portion via the joining member.