Abstract: An acoustical diffuser is disclosed for diffusing sound. A preferred diffuser includes a first fibrous material, a first separator layer, a diffuser material a second separator layer, a second fibrous material and an acoustically transparent material. The subject invention also includes a preferred method of molding such diffuser. The subject invention further includes a panel that has an acoustically reflective side and an acoustically transparent side over a frequency range that can be attached to the walls of a room to enhance the acoustical characteristics of the room. A preferred method of installing such panels includes installing fabric retainer members to the walls between the panels and attaching an acoustically transparent material to the fabric retainer members such that the panels and fabric retainers are covered by the acoustically transparent material.

Abstract: A wave absorber is provided which has a wave absorption characteristic of 20 dB in a frequency band of 1 GHz to 20 GHz, is nonflammable, compact and lightweight, and has excellent durability. A porous ferrite is produced as the base material for which is an Ni--Zn type ferrite which has an excellent wave absorption characteristic in the high frequency range, and this serves as a wave absorber formed in the shape of a pyramid or triangular prism.

Abstract: A reverberation room comprising walls, ceiling and floor having specific dimensions and spatial relationships used in an automotive testing laboratory to analyze sound for the purposes of measuring transmission loss and sound absorption. The room possesses two transmission loss test windows. One window is placed in the ceiling and one is placed in a side wall. Samples for testing can be mounted horizontally in the ceiling window. A rotating microphone boom is used in combination with the room to sample the sound field in the reverbration room and in reception chambers attached thereto. Three loudspeakers are also positioned in the room to generate the sound field in the reverberation room and indirectly in the reception chambers.

Abstract: Soundproofing of a machine, such as a rotary printing pres, is provided by a plurality of soundproofing doors. Each of these doors is provided with a hinge at each of its four corners. The doors can each be selectively pivoted open or closed about either of two separate pivot axes or can be locked in place.

Abstract: To provide a sound absorbing structure having a superior sound absorbing characteristic and an external appearance of the sound absorbing structure which does not cause flicker or the like, by disposal, for example, in the front of an air chamber, a plurality of ribs (2a) are disposed on one surface of the sound absorbing board body (2), and a plurality of through-holes (3) are provided in basal portions (2b) between the ribs (2a) to form a porous structure. Concealing materials (5) are provided between the ribs (2a) of the sound absorbing board body to conceal the through-holes (3), respectively.

Abstract: Airborne resonance buildup (in directions parallel with and/or at acute angles to the first and second major skins or panels of enclosed cavities) is damped by locating anisotropic porous damping materials within the cavity between the first and second major skins or panels of the cavities. In one preferred embodiment, one or more anisotropic fibrous blankets are located between the skins of a cavity with the fibers of the blanket(s) lying in planes generally perpendicular to the first and second skins and parallel to one pair of the sidewalls of the cavity.

Abstract: A two-dimensional binary amplitude diffusor (BAD) offering both absorption and modest diffusion is disclosed. The invention consists of a flat-faced panel with a series of alternating reflective and absorptive regions or patches defined by a binary sequence consisting of zeros and ones with a flat power spectrum, such as the Maximum Length Sequence (MLS) based upon shift register theory. Combining regions of absorption and reflection in the manner described herein results in an effective combination of absorption and diffusion.

Abstract: An acoustic absorption device preferably includes a platform having a rectangularly-shaped top surface and four side surfaces, each of the surfaces comprising a perforated material. A plurality of spires upstand from the top surface, the spires extending from a first to an opposite second of the sides. A first of the spires is provided with a wall surface comprising a continuation of a third of the platform side surfaces to form a device first planar end, and a second of the spires is provided with a wall surface comprising a continuation of a fourth of the platform side surfaces to form a device second planar end. The spires are spaced one from another to form a channel therebetween. The spires are at least in part covered with the perforated material. The platform and the spires each house a body of sound absorbing material.

Abstract: A foil sound absorber consists of at least two smooth, flat and air-tight foils separated from each other and from a reverberant rear wall R by different distances D.

Abstract: A chair includes a main body with a seat, openings formed in the greater part of the lower surface of the seat, a sound absorbing structure contained in the seat while facing the openings, and a louver having a series of openings defined with a number of slats that may be turned for opening and closing. The louver is located in front of the series of openings. When the seat is unoccupied, the slats of the louver are turned for opening. When the seat is occupied, the slats are turned for closing. The chair is adequate for concert halls or theaters.

Abstract: By means of this acoustic protection it is possible to protect the payloads of expandable launch vehicles effectively against noise emissions from the rocket propulsion system which result in damage of the payloads. For this purpose acoustic absorbers (8) tuned to a defined frequency range are provided and are arranged in foamed plastic mats (7) disposed on the insides (6) of the payload fairing (1). The acoustic absorbers (8) are composed of a cup-shaped lower part (12) and an upper part (13) having a horn (18). The horn (8) tapers in a curved-conical manner from a larger diameter (D.sub.m) to a smaller diameter (D.sub.t) and projects into the lower part (12) by a defined distance (a) from a bottom (14) thereof. Slits (21) for the dissipation of the directed flow energy occurring in the horn (18) are disposed in the wall of the horn in the area of the smaller diameter (D.sub.t).

Abstract: Numerous embodiments of a nestable sound absorbing foam each including a reduced area of attachment to an adjacent wall surface and a variable depth air cavity to enhance absorption. The embodiments include various configurations of "one-dimensional" sine waves, saw tooth cross-sections, triangular and crown shaped cross-sections as well as square wave cross-sections and part cylindrical cross-sections. In addition, two-dimensional nested topologies with a variable depth air cavity are also described. In each embodiment, the major portion of the rear surface of the material which is to be attached to a wall surface is spaced as far as possible from the wall surface creating a variable depth air cavity to enhance sound absorption. When the rear air cavity is sealed, additional low frequency absorption is achieved by increased air flows through the foam material caused by the pressure gradient in the low frequency pressure zone.

Abstract: A molded article for the absorption of airborne sound, to be used principally in the engine compartment of motor vehicles and particularly as a sound absorber inside partial and complete motor encapsulations, is formed by a porous absorber (1) of which the core (6), being sealed on both sides (7,8) over its complete surface by a respective PU film of a thickness less than 90 .mu.m, is made from an open-pored PU (polyurethane) foam of a thickness of at least 3 mm and about 15 mm at the most. The core comprises cavities (2-4) originating on the bottom face and formed by the injection molding process, said cavities being open only towards the bottom face (5) and having different cavity volumes and different heights (11) measured from the bottom face (5).

Abstract: An EMR-absorbing anechoic chamber absorber (22, 42) uses a block of honeycomb material with a lossy material, such as carbon, applied to the sheets (4) of material from which the honeycomb is made to create wedges (36) or pyramids (44) of lossy material. Preferably, the lossy material is applied to the sheets of material in a repeating wedge-shaped pattern (16) to create the wedges of lossy material within the solid rectangular block of honeycomb material. Parallel, wedge-shaped grooves (43) are formed in the block of honeycomb material to create the pyramids of lossy material. If the lossy material is applied to the entire sheet, a set of parallel, wedge-shaped grooves are formed in the block of honeycomb material to create wedges of lossy material; two sets of parallel, wedge-shaped grooves are formed at 90.degree. angles to one another to create pyramids of lossy material.

Abstract: A noise damper comprising a molded part of polymer material having at least two chambers which are designed as resonators with resonant frequencies that differ from one another. The molded part consists of a closed-cell material. The resonators are formed of essentially cup-shaped protrusions that open toward the sound source, the molded part on the side facing the sound source being covered by an orifice plate comprising at least two openings leading into each chamber. The molded part and the orifice plate are detachably joined together.

Abstract: An airborne-sound-absorbing shaped component is disclosed. The element comprises at least two chambers that are arranged adjacent to one another in the direction of the vibrations that are to be introduced into the system. These chambers help delimit a shared cavity that is hermetically sealed with respect to the environment which also operates as a pneumatic spring. Each of the chambers is delimited by a delimiting wall made of a polymer material, the delimiting walls being configured integrally and continuously with one another and joined to one another in a transition region, in a manner allowing relative movement by at least one spring element that is resilient in the direction of the introduced vibrations.

Abstract: A sound absorber arrangement includes a plurality of sound absorbing layers of porous materials such as glass wool, rock fiber or cellular plastic, and high-polymer films, are alternately laminated in a direction perpendicular to a sound incidence plane. The layer thicknesses are increased in order in a direction away from the sound incidence plane. The sound absorber arrangement makes it possible to make a sound absorbing coefficient constant over the low to high frequency sound range.

Abstract: Free-standing sound absorber consisting of an open-cell foam body designed in the manner of a board, having at least one opening in a lateral face for plugging together another, similarly designed foam body. The opening has a height corresponding approximately to half the height of the foam body. The depth of the opening corresponds to the thickness of the foam body.

Abstract: This invention is an improved bass trap for controlling standing waves in the listening room. It is cylindrical in shape, with a curved diffuser around one half of the length of the cylinder. The interior of the cylinder is divided into two hemi-cylinders, with one hemi-cylinder made of an absorbing material positioned opposite the curved diffuser, and one hemi-cylinder, which is an air cavity, defined by the boundary of the absorbing material on one side and the diffuser on the other. This device features a ported top, with the ports positioned over the air cavity, which allow tuning pipes of varying length and diameter to be inserted, in order to permit further tuning of the device.

Abstract: A new and improved method and apparatus for an acoustical partition are presented. The acoustical partition comprises a wall section defining an enclosed space, a frame structure contained within the wall section, and an insulation layer contained within the frame structure such that an air cavity is created at the centermost area within the wall section. The acoustical partition may also include a sound absorption layer placed on a front side of the wall section, and a fabric layer positioned over the sound absorption layer in such a way as to provide an airspace between the sound absorption layer and the fabric layer.

Abstract: A two-dimensional primitive root diffusor includes a two-dimensional pattern of wells, the depths of which are determined through operation of primitive root sequence theory. A prime number N is chosen such that N-1 has two coprime factors which are non-divisible into each other. From the prime number, a primitive root is determined and, in the preferred embodiment, an algorithm is used to determine sequence values for each well. Each sequence value is proportional to the well depth, with each sequence value being multiplied by the design wavelength and then divided by 2N to arrive at the actual well depth value.

Abstract: An apparatus and method are disclosed for reducing electromagnetic or acoustic energy scattered in both the near and more generalized vicinity of a source thereof by various phenomena including atmospheric and weather-related effects and diffraction at the top edge of heretofore known barriers. The apparatus includes a member configured for engagement with the top edge of a barrier, with the member having a patterned edge defining a plurality of portions jutting away from the top edge of the barrier and in a direction having a component toward the source, preferably substantially in a more or less horizontal plane with the top edge.

Abstract: An apparatus for enhancing the environmental quality of work and living spaces which combines a high efficiency particulate air filter and an optional gas element and electric blower and a sound-masking device for generating pink noise. The sound-masking device is designed to improved the affective state, and thereby the task-performance, of persons in the space being treated.

Abstract: A masking unit for bowling lanes equipped with automatic pinsetters, comprising a vertically moving masking panel and a series of stepped panels in front of the moving panel and extending from the top thereof to the ceiling of the bowling establishment. Stanchions at each end of a panel hold wheeled carriages which engage tracks on the back of the moving panel so that the panel may be vertically raised and lowered. Chain driven control means assures that one end of the panel does not get ahead of the other when the panel is being moved, and spring biasing means aid in raising the panel.

Abstract: A substantially enclosed sound absorbing unit for an anechoic chamber is disclosed. The sound absorbing unit includes a substantially flat panel member comprising a layer of sound absorptive material. An anechoic member is disposed adjacent to the flat panel member. The anechoic member is disposed adjacent to a base and a generally spaced apart sound transparent wall member. The wall member includes a layer of sound absorptive material and a cover sheet made of perforated, substantially sound reflective material. The free space of the perforated cover sheet is at least 7 percent of the total area of the cover sheet.

Abstract: An acoustical equalization device is designed to be attached to the front of a stereo speaker and includes a plurality of moveable baffles which may be used to either reflect or absorb sound waves being emitted from the speaker. The baffles can be slidably positioned along a plurality of rods forming a part of the device and may be pivoted into a desired sound adjusting position. Modified baffles include through-extending apertures into which sound modifying cones may be removably positioned, while the cones may be provided with pivotal closures to further affect sound quality. The device is used as an aid in equalizing a sound system so as to obtain the best audio response curve without the use of electronic equalization systems.

Abstract: A file cabinet is disclosed which has a door with high sound absorption properties. The door has metal front and rear panels and an intermediate layer of sound absorbing material sandwiched therebetween. An array of openings are cut through both the front and rear panel. Sound impinging on the front panel enters the cabinet via the door and is attenuated in the door and cabinet. Preferably, paper files are stored within the file cabinet with their peripheral edge surfaces disposed towards the rear panel to assist in attenuating sound within the cabinet.

Abstract: A tubular sound absorbent device includes the cylindrical wall closed by top and bottom end walls to define an internal chamber. Located within the chamber are various sound wave attenuating devices including those of tubular configuration as well as those of frust-conical shape. The sound wave attenuating components may also include perforated tubes entirely confined within the sound absorbent unit or with a tube extending outwardly for termination in a companion structure.

Abstract: An apparatus for enhancing the environmental quality of work and living spaces is provided. The apparatus combines a high efficiency particulate air filter, a gas-adsorbent element, a means for moving air, a means for releasing a pleasant odor and a means for sound masking. The odor-releasing means and sound-producing means are designed to improve the affective state, and thereby the task-performance, of persons working in the space being treated. Preferred fragrances are citrus, floral, eucalyptus and mint, released at about 1 to 20 mg/hr. The sound masking is preferably accomplished by a sound-generating device which generates pink noise.

Abstract: A performance shell is disclosed which includes a plurality of modular components which may be assembled together to surround a performing entity ranging from a single soloist to a full orchestra. Modular components may be added and subtracted as desired to adapt the size of the shell to the size and type of the performance entity. The structure of the invention includes a plurality of rectangular recesses each one of which is designed to receive an acoustical device such as a reflective device, a diffusive device or an absorbing device. By carefully arranging the locations of these various devices in the shell, the performers will be better able to hear themselves and other musicians resulting in a performance which the audience perceives as louder, being more rhythmically in unison, and containing better loudness balance between sections than would be the case without the features of the shell.

Abstract: A trapezoidal-shaped acoustic absorber is designed for use in music recording studios. The absorber is configured in the shape of a right trapezoidal prism and has an internal transverse pegboard partition which divides the absorber into a plurality of chambers. Each of the chambers is lined with fiberglass sound insulation padding and is resonant to a different frequency. The unit as a whole is resonant to still another frequency. A plurality of the modules are assembled together to line the walls or ceiling of a room so as to render the room suitable for mixing and recording musical sounds. The modular units are portable and allow audio recording and mixing to be formed in virtually any room without the necessity for access to a specially designed recording studio.

Abstract: A sound absorber has a column shape defined by a hollow, substantially cylindrical wire frame with a filler of uniformly distributed fused parallel filaments having high surface area to mass ratio, such as bloomed cellulose acetate. The sound absorber gives efficient absorption in the articulation frequency range.A method of manufacture of the sound absorber includes determining the sound response of an acoustic environment, determining the reciprocal of the sound response of that environment, and matching the absorption characteristics of the sound absorber to the reciprocal of the sound response.Each sound absorber has a linear absorption spectrum above the center frequency so that clusters of the sound absorbers exhibit a similar spectrum.

Abstract: A sound absorptive structure for installation on room wall structure to reduce low frequency wave energy and enhance room acoustics. A fibrous, sound absorptive member is of curved section and terminates in tapered side edges for inserted engagement with wall mounted strips. The structure may be segmented with partitions between the segments. Alternatively T-shaped divider strips may interconnect adjacent segments. A further modification utilizes a flat base for wall attachment with end portions of the base folded perpendicularly to the base to provide closures for the ends of a sound member. Intersections between segments of a sound absorptive structure may be accomplished by corner mounted box structures or may be mitered for endwise abutment with one another. Openings in the room wall structure increase the volume of the present wall mounted structure.

Abstract: Apparatus for reducing acoustic transmission from mechanical or acoustic sources by means of a double wall partition, within which an acoustic pressure field is generated by at least one secondary acoustic source. The secondary acoustic source is advantageously placed within the partition, around its edges, or it may be an integral part of a wall of the partition.

Abstract: A movable, prefabricated wall panel having a rigid frame. Internal to the rigid frame is a structural acoustical core, consisting of a grid with a plurality of individual cells, each filled with insulation media, such as a loose, discrete insulation such as fiberglass, cellulose, etc. The outer surfaces of the cell grid are covered with a skin or screen mesh for confining the loose discrete insulation. This skin or mesh can be a finished decorative outer cover or an intermediate component that is later covered with a decorative outer cover of fabric or other suitable material. A septum may be provided in the panel in the grid and may be made of a pliable, sound absorbing material. Additional acoustic barrier panels may be sandwiched on either side of the cellular grid.

Abstract: A space unit for the recording and/or reproduction of acoustic signals on and/or from sound carriers is described. The space unit is formed as transportable space cell which is adapted to be installed in closed rooms or out of doors. Recording means and/or reproduction means for the acoustic signals are located within the space unit, and the same offers space for at least one person. The space unit is in the shape of a sphere, of a regular, sphere-like polyeder or of a part thereof.

Abstract: A readily removable and replaceable acoustical absorber for mounting in a channel that utilizes a flexible grid within the absorber to support the absorber on flanges of angles mounted on the channel walls.

Abstract: A volumetric sound absorber for audible sound frequencies is made from a thin sheet material that is permeable to air with thickness mass, and flow resistance within specified ranges.

Abstract: An acoustic tile that provides soundproofing in a modular wall, such as is used in a modular panel office system, comprises a rigid rectangular metallic frame, a septum formed of a calcium carbonate-filled molded synthetic rubber polymer, a layer of low-density fiberglass and a layer of high-density fiberglass. The front of the frame is covered by fabric, and the back of the frame has fittings to attach the acoustic tile to a wall panel.

Abstract: A soundproof structure is provided at its surface with a lining of a catadioptric material which forms a light source when a light beam impinges on it.

Abstract: A multi-tubular acoustic absorber panel system suited particularly for use in open office environments or workspaces with unwanted echoes, excessive noise, or the need for enhanced acoustic privacy. The basic components of the system are a series of sound absorbent tubular members and a structure for holding the members in an array, creating a baffle which can be attached to wall or ceiling surfaces or, in the preferred embodiment, to a manufactured office partition. When installed, the system creates a lightweight, adaptable, highly absorbent enclosure, capable of significant reduction in unwanted noise and increase in acoustic privacy.

Abstract: A co-oscillating, volume-changing resonator in the form of a silencer, includes a lens-shaped housing formed of a material having a given flexural stiffness, the housing being arched defining an evacuated cup-shaped cavity formed therein, and a coating layer completely surrounding the housing, the coating layer being formed of a material having a flexural stiffness being at most one-third of the given flexural stiffness of the material of the housing.

Abstract: A portable acoustic absorber system which can be used in particular in open office environments or in large spaces with unwanted echoes or excessive noise. The device operates by supporting and arraying panels of efficient sound absorbing materials in a helical configuration in which a majority of the surface area of those panels is exposed. During shipping, or when the device is not in use, it can be reconfigured into a closed position, which occupies much less space.

Abstract: A sound-absorbing structure in a vehicular compartment can prevent the air within the compartment from passing out through the lining and thus prevent deposition of dust onto the inner surface of the lining. The structure includes a panel forming part of a vehicular body and allowing air leakage, a porous sound-absorbing lining separated from the inner surface of the panel by a space and a partition for preventing air leakage, the partition being air-impermeable and disposed in the space. The lining and the partition define an air chamber enhancing the sound-absorbing properties of the lining.

Abstract: A suspended ceiling system for a room comprises a plurality of inverted T-shaped members suspended from the structural ceiling of the room and extending across the room, each T-shaped member having a horizontal base portion and a vertical leg portion; a plurality of open metal ceiling panels having two pairs of opposed sides and a bottom, and acoustical insulation in the panels, at least one pair of opposed sides being perforated; and each panel being supported by the inverted T-shaped members with the panel bottom and the pair of opposed perforated panel sides spaced from and facing the horizontal base portion and the vertical leg portion, respectively, of the pair of inverted T-shaped members.

Abstract: A multidirectional sound absorber which is adapted to be mounted on an exterior surface of a wall and includes a substantially flat base made of a relatively low density, sound absorbing material, and an outer layer made of a relatively high density, sound absorbing material attached to the base and shaped to form a plurality of channels which, together with the base, form enclosed hollow chambers. A substantially flexible sheet of acoustically transparent material covers the outer face of the outer layer, and upper and lower track members which enclose the ends of the base and outer layer and are adapted to attach the assembly to an exterior surface of a wall. The base and outer layer preferably are made of fiber glass insulation material. Also in a preferred embodiment, a woven mat of fiber glass material is attached to the outer face of the outer layer, and the sheet is attached to the mat.

Abstract: A device having a high sound absorption ability and intended for use as floor, wall and/or ceiling facing in so-called echo-free rooms (10), i.e. in acoustic measuring rooms designed according to international standard, ISO-3745, in picture and sound recording studios, in sound laboratories etc., in which a sound propagation as in a free field is desired. The new device is based on sound absorbents in the form of plates (16, 20) forming a substrate support (16) and units (20) projecting obliquely from this which are so placed that they have a wave-like cross-section. The size and reciprocal angular conditions of the sound absorbents (20) projecting from the substrate support (16) are chosen so that at least double reflection is always obtained before a sound wave deriving from a measuring object (12) is directed from the device. The sound absorption ability is further increased by utilizing a low-frequency cavity resonance between the projecting sound absorbents (20) and the substrate support (16).

Abstract: A sound barrier (22) comprising a pair of spaced apart members (24,26), a medium (34) disposed between the members capable of propagating sound waves, and one or more acoustical resonators (30) coupled to the medium and tuned to one or more selected frequencies. The resonators may be disposed between the members or may be disposed around the outer periphery of the members to permit construction of a sound barrier window. The resonators may form an integral part of one of the members or may be suspended between the members by netting or sound insulating material.

Abstract: A sound attenuator formed by a bank of at least three wall mounted tubes extending into a room from which noise originates and also into an adjacent occupied room. Each tube is cylindrical and has a length between one sixth and one third wavelength of sound in air at the highest frequency in the low frequency waveband in which the reactive acoustical properties of the tubes are effective. The diameter of each tube is less than about one sixth wavelength. The size, arrangement and spacing of the tubes are selected to take good advantage of the operative acoustical phenomena, including the quarter wavelength effect, the duct end loss effect and the multiple tube effect.

Abstract: A co-oscillating, volume-changing resonator in the form of a silencer, includes a lens-shaped housing formed of a material having a given flexural stiffness, the housing being arched defining an evacuated cup-shaped cavity formed therein, and a coating layer completely surrounding the housing, the coating layer being formed of a material having a flexural stiffness being at most one-third of the given flexural stiffness of the material of the housing.