An assembly forming an acoustic insulator having a first sheet, a pierced second sheet, and a plurality of first and second structures. Each first structure comprises a first and a second strip, wherein each is shaped to form half of the wall of a cage and wherein, for two successive halves, each strip comprises a facet of a joining wall. Each second structure is made up of a first and a second strip, wherein each is shaped to form half of the wall of a cone, wherein. For each strip, at least one of the wall halves of each cone is pierced. For two successive halves, each strip comprises one facet of the connecting wall. Each cone is located in a cell and each connecting wall is located between the two facets of a joining wall, and, between two adjacent first structures, a second structure is likewise fitted.

There is provided a soundproof structure having two or more soundproof units. Each soundproof unit has a frame having an opening portion and a sound absorbing member attached to the opening portion of the frame. Two adjacent soundproof units are disposed such that at least parts of the sound absorbing members face each other. The sound absorbing members at least parts of which face each other are spaced apart from each other. An average distance between the sound absorbing members at least parts of which face each other is less than 20 mm. Therefore, it is possible to provide a soundproof structure and a soundproof system that can soundproof low frequency side sound with a simple configuration, is small and lightweight, and can easily change its frequency characteristics.

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.

A sound insulating element includes a single body made of a mineral fibre material having acoustically insulating properties, the body including a front surface, a rear surface and a side surface connecting the front and rear surfaces. A suspended ceiling system to be suspended from a structural ceiling includes a plurality of ceiling tiles, and at least one of the ceiling tiles is a sound insulating element.

A soundproof structure includes two or more kinds of resonant type sound absorbing cells including different kinds of a first resonant type sound absorbing cell and a second resonant type sound absorbing cell that are adjacent to each other; and an opening part provided in the second resonant type sound absorbing cell, in which a resonance frequency of the first resonant type sound absorbing cell and a resonance frequency of the second resonant type sound absorbing cell match each other. As a result, the soundproof structure is capable of achieving an absorptance of more than 50%, preferably, close to 100% even in a compact, light, and thin structure which is much smaller than a wavelength, thereby obtaining a high soundproofing effect. Further, the soundproof structure is capable of obtaining air permeability and/or heat conductivity by providing a passage of air and/or heat.

There is provided a soundproof structure having two or more soundproof units. Each soundproof unit has a frame having an opening portion and a sound absorbing member attached to the opening portion of the frame. Two adjacent soundproof units are disposed such that at least parts of the sound absorbing members face each other. The sound absorbing members at least parts of which face each other are spaced apart from each other. An average distance between the sound absorbing members at least parts of which face each other is less than 20 mm. Therefore, it is possible to provide a soundproof structure and a soundproof system that can soundproof low frequency side sound with a simple configuration, is small and lightweight, and can easily change its frequency characteristics.

An acoustic panel for attenuating sound, and a system and method for making the acoustic panel. The acoustic panel employs rounded particles which are introduced into the cells of a core and fixed at a particular depth to form a septum layer providing substantially linear acoustic resistance to sound waves entering the cell. The particles may be between 100 microns and 700 microns in diameter, may be solid or hollow, may have smooth or textured surfaces, and/or may be made of syntactic foam or glass or ceramic. The system includes a positioning mechanism for positioning the particles at the particular depth, metering and gating mechanisms for introducing a metered amount of the particles into each cell, and a vibratory base for vibrating the particles to better pack them. Once the particles are in the cells, the septum layer is fixed, and the positioning mechanism is removed.

A sound absorbing structure (1) includes: a rear surface member (21) having a length in a predetermined direction; a front surface member (22) that is shorter in the predetermined direction than the rear surface member (21); and a sound absorbing material (3) that is placed in front of the rear surface member (21). The front surface member (22) is parallel to the rear surface member (21) and is separated forward from the rear surface member (21). An opening (23) is formed at a position adjoining the front surface member (22) in the predetermined direction. The sound absorbing material (3) is provided in both a first region (24) located behind the opening (23) and a second region (25) sandwiched between the front surface member (22) and the rear surface member (21).

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).

A sound absorbing cell according to an exemplary embodiment of the present invention is formed of a plurality of plates that are stacked while interposing an air layer therebetween, wherein the plurality of plates include: a reflective plate that is disposed outermost from a space where sound is generated; and a microperforated plate that is stacked on the reflective plate and having a plurality of holes perforated therein.