An alternating clockwise and counterclockwise helicoid cell structure for use in acoustic panels. The cell structure geometry may be easily replicated and tiled using additive manufacturing. The cell structure has at least an outer cavity and an inner cavity. The cavities are coaxial, share the same height, same entrance side, and same cell structure floor. The inner cavity includes a number of equal-volume inner chambers rotated uniformly in a first direction around the shared central axis; and the outer cavity includes a second number of equal-volume outer chambers rotated uniformly in an opposite direction to the first direction around the shared central axis. In various embodiments, one or more perforated baffles may extend, internally, across a chamber, perpendicular to direction of sound waves at the location of the perforated baffle. In various embodiments, one or more port openings from the outer cavity to the inner cavity may be present.

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 μm to 250 μm, 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.

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.

An alternating clockwise and counterclockwise helicoid cell structure for use in acoustic panels. The cell structure geometry may be easily replicated and tiled using additive manufacturing. The cell structure has at least an outer cavity and an inner cavity. The cavities are coaxial, share the same height, same entrance side, and same cell structure floor. The inner cavity includes a number of equal-volume inner chambers rotated uniformly in a first direction around the shared central axis; and the outer cavity includes a second number of equal-volume outer chambers rotated uniformly in an opposite direction to the first direction around the shared central axis. In various embodiments, one or more perforated baffles may extend, internally, across a chamber, perpendicular to direction of sound waves at the location of the perforated baffle. In various embodiments, one or more port openings from the outer cavity to the inner cavity may be present.

An object is to provide a silencing system that includes a silencer disposed in a ventilation sleeve, can suppress the generation of negative pressure in the interior, and can prevent a door or the like of an interior entrance from being difficult to open. The silencing system includes one or more silencers that are disposed in a ventilation sleeve provided to penetrate a wall separating two spaces, and “αA>10.sup.C−(0.1/P)×TL” is satisfied in a case where a gap equivalent area of the ventilation sleeve in which the silencer is installed is denoted by αA and a normalized sound transmission loss in an octave band in which a first resonant frequency of the ventilation sleeve is present is denoted by TL.

C denotes a constant determined by a measurement system in a case where there is no silencer and P denotes a transmission efficiency coefficient.

A soundproof fume discharge conduit adapted to be arranged between a ventilation system and an outlet chimney, the conduit defining a fume path therein, wherein at least one side surface of the conduit is provided with at least two protrusions, each protrusion internally defining a respective step-shaped recess, whereby the path is provided with at least two step-shaped recesses adapted to reflect sound waves propagating along the path, and wherein the step shape of each recess is defined by two first walls, which are incident at a first end thereof, and at least one wall of the two first walls is coated with a first sound absorbing material.

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.

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.

An acoustic panel is disclosed. In various embodiments, the acoustic panel includes a first layer; a cell having a first cell end connected to the first layer and a second cell end spaced a cell length from the first cell end, the cell having a first wall extending between the first cell end and the second cell end; and a septum having a central portion positioned within the cell and a first tab extending from the central portion, the first tab defining a first surface positioned against the first wall and a first distal end positioned adjacent the first layer.

A soundproofing device according to the present disclosure includes a Helmholtz resonator including: a wall that forms a Helmholtz resonance chamber; and a first opening formed in the wall so as to cause the Helmholtz resonance chamber to communicate with an outside of the Helmholtz resonance chamber. At least a part of the wall is configured by a sound source member that radiates sound. The Helmholtz resonator includes: one or more partition walls formed so as to divide the Helmholtz resonance chamber into a plurality of regions, and a second opening formed in the one or more partition walls so as to cause the plurality of regions to communicate with each other.