A passive sound absorber includes a cavity opening to the outside via an input direction to form a Helmholtz resonator for a first frequency. The absorber further includes at least one moving element, or wafer, suspended or held by suspensions in a position obstructing the neck in a non-sealed manner. The relative stiffness of the suspensions and the wafer is determined so that the assembly resonates in a vibration in a piston movement at a second frequency different from the first frequency, achieving absorption for this second frequency or frequency range. A hybrid version includes a coil that is controlled to adjust the acoustic impedance of the absorber.

An acoustic wall includes a plurality of such absorbers produced by a repetitive structure opening through perforations, each receiving such a wafer, and a method of designing and manufacturing such an absorber or wall is also provided.

An object is to provide a soundproofing structure, a partition structure, a window member, and a cage which exhibit high soundproofing performance in a broad frequency band, can be miniaturized, can ensure ventilation properties, and have a light transmittance. Provided is a soundproofing structure including: a plate-like member which has a plurality of through-holes passing therethrough in a thickness direction; and a frame member which includes an opening portion, in which membrane vibration of the plate-like member is enabled by fixing the plate-like member to a peripheral edge of the opening portion of the frame member, an average opening diameter of the through-holes is in a range of 0.1 m to 250 m, and a first unique vibration frequency of the membrane vibration of the plate-like member is present in a range of 10 Hz to 100000 Hz.

Provided is a soundproofing structure including: a plate-like member which has a plurality of through-holes passing therethrough in a thickness direction, in which in a case where an average opening diameter of the through-holes is 0.1 m or greater and less than 100 m, and in a case where the average opening diameter of the through-holes is set as phi (m) and a thickness of the plate-like member is set as t (m), an average opening ratio rho of the through-holes is greater than 0 and less than 1 and falls in a range where a center is rho_center=(2+0.25t)phi.sup.1.6, a lower limit is rho_center(0.052(phi/30).sup.2), and an upper limit is rho_center+(0.795(phi/30).sup.2).

FIG. 2 shows a microperforated panel absorber 22 comprising: a microperforated facing 24; a non-perforated facing 26; and a cellular core structure 28 therebetween; the core structure 28 provides a number of primary cells 33 and a number of secondary cells 37; the secondary cells 37 each provide a reduced cell depth in comparison to the primary cells 33. FIG. 9 shows that the number of the primary cells 33 and the number of the secondary cells 37 ensures that sound absorption at frequencies up to and including the peak frequency is substantially maintained and that the sound absorption at frequencies higher than peak frequency is substantially increased relative to a comparable panel absorber in which the secondary cells are effectively replaced by primary cells.

The invention relates to a drywall construction for resonance sound absorption. The drywall construction comprises a plurality of drywall profiles and fixed thereto at least one layer of plasterboards having an opening arranged therein. The drywall construction further comprises a resonance chamber in fluid connection with the opening, the resonance chamber and the opening having a size and shape so that sound of predetermined resonance frequencies enters the resonance chamber via the opening.

There is provided a laminated soundproof structure formed by laminating a single layer soundproof structure having one or more soundproof cells which are arranged in a two-dimensional plane and each of which includes a frame, a film, and an opening portion including a hole or includes a frame and a film. The single layer soundproof structure has a shielding peak frequency, which is determined by the opening portion of each of the soundproof cells and at which a transmission loss is maximized, on a lower frequency side than a first natural vibration frequency of the film of each of the soundproof cells. The conditions of at least one of the frame, the film, or the opening portion in the laminated one and other soundproof cells are different.

There is provided a laminated soundproof structure formed by laminating a single layer soundproof structure having one or more soundproof cells which are arranged in a two-dimensional plane and each of which includes a frame, a film, and an opening portion including a hole. The single layer soundproof structure has a shielding peak frequency, which is determined by the opening portion of each of the soundproof cells and at which a transmission loss is maximized, on a lower frequency side than a first natural vibration frequency of the film of each of the soundproof cells. The soundproof cells of the single layer soundproof structures are laminated with a distance therebetween, and at least some of the laminated soundproof cells have the same conditions of the frame, the film, and the opening portion.

The invention relates to a drywall construction for resonance sound absorption. The drywall construction comprises a plurality of drywall profiles and fixed thereto at least one layer of plasterboards having an opening arranged therein. The drywall construction further comprises a resonance chamber in fluid connection with the opening, the resonance chamber and the opening having a size and shape so that sound of predetermined resonance frequencies enters the resonance chamber via the opening.

Methods, systems, and apparatuses are disclosed for reducing sound level, by providing enclosures comprising enclosure walls having integral tunable resonator cavities, and reducing sound levels within the enclosure in response to detected sound levels outside of the enclosure.

A module ensuring an acoustic attenuation of a flow of a first fluid and a heat exchange between the first fluid and a second fluid. The module comprises a perforated first wall with a cutout, a second wall, a cellular structure extending from the second wall to the first wall, a recess provided in the cellular structure between a perforated bottom and a perforated top, and a heat exchanger which is fixed inside the recess between the bottom and the top and in which the second fluid circulates. Such a module ensures an attenuation of sound waves and a heat exchange without limiting the attenuation surface.