Abstract: A method for producing an acoustical ceiling tile or panel faced with a distortion free decorative thin plastic film is accomplished by first embossing the acoustical base to form a picture frame surrounding a recessed area, stretching the thin decorative plastic film over the picture frame portion and adhesively securing the film to the side and/or back of the acoustical base and subsequenytly heat shrinking the film to produce a distortion free decorative surface.

Abstract: A broad band acoustic attenuator particularly useful for attenuating gas turbine engine noise utilizes a plurality of axially extending, open-ended, perforated cylinders concentrically arranged within the exhaust duct of the gas turbine engine for attenuating noise therefrom without imposing significant back pressure penalties.

Abstract: This invention is a new and improved muffler for use on the exhaust of noise producing machines such as automotive engines, and the like. It is particularly characterized by utilization of a single inlet into a chamber from which there are a multiplicity of louvered or otherwise appropriately configured exhaust tubes appropriately wrapped with noise entrapping material, and in a preferred form utilizing a ceramic fiber material, and wherein the multiplicity of tubes ultimately open into a chamber from which the ultimate outlet is ducted.

Abstract: An exhaust gas silencing system wherein standing waves are utilized in a silencing chamber to reduce low frequency components of noise, and a downstream muffler is utilized to reduce the high frequency components of noise. An expansion chamber can be utilized further to reduce the pressure of the sound waves.

Abstract: This invention is directed to an apparatus and method for treating a flowing gas so as to decrease the back pressure of the flowing gas and the noise of the flowing gas.

Abstract: A sound attenuator for transformers comprises a rigid plate fixedly attached to a resilient mass. The sound attenuator is attached to the transformer outer wall in the vicinity of highest sound production. The characteristics of the metal plate and the resilient mass are chosen to produce acoustical radiation out of phase with the noise emitted at the transformer wall surface.

Abstract: Two acoustical wall panels are secured together back-to-back to form an acoustical wall baffle installable perpendicularly to a wall of an office space in abutting relationship to the wall, ceiling, and floor. Each of the wall panels includes a fibrous glass board mounted in an extruded aluminum frame and covered on the front and edges with a decorative fabric. Each frame includes a rear mounting foot strip for spacing a wall panel from a wall and enabling the wall panel to be hung by the top frame member on concealed brackets, and a rear groove for anchoring the fabric covering by a rubber or plastic cord. The two wall panels are clipped together at the mounting foot strips of the frames by generally U-shaped metal or plastic strips. On the exposed vertical front edge of the wall baffle, a decorative trim strip is inserted between the two wall panels at the fabric anchoring grooves. The wall baffles are mounted by sliding them onto T-shaped mounting strips adhered to the ceiling and floor.

Abstract: Acoustic energy is absorbed from a moving fluid by passing the fluid, which is typically a gas, through a tube of closely-woven material defining a gas passage, the tube of material being in contact with a surface covered with a multiplicity of fibers or filaments, each filament having one end attached directly or indirectly to the surface. Automobile or marine mufflers or silencers effective in reducing or eliminating objectionable noise, but with only nominal back pressure, are disclosed.

Abstract: Acoustic energy is absorbed from a moving fluid by passing the fluid, which is typically a gas, over a surface covered with a multiplicity of loops of fibers or filaments, each loop having one portion thereof fixed to a suitable backing material, the backing material attached directly or indirectly to a conduit or the like and the other free portions extending into the moving fluid stream. Automobile mufflers or silencers effective in reducing or eliminating objectionable noise, but with at most only nominal back pressure, are disclosed.

Abstract: Acoustic energy is absorbed from a moving fluid by passing the fluid, which is typically a gas, through a liner comprising a closely woven textile-like material which serves as an acoustically transmitting inner lining. Anchored either directly or indirectly to the acoustically transmitting inner liner is a sound absorbing material the surface of which is covered with a multiplicity of fibers or filaments, each filament having one end attached directly or indirectly to the surface and its outer end free and contacting the inner wall of a casing in which the tube and sound absorbing material are contained. Automobile or marine mufflers or silencers effective in reducing or eliminating objectionable noise, but with only nominal back pressure, are disclosed.

Abstract: Acoustic energy is absorbed from a moving fluid by passing the fluid, which is typically a gas, over a surface covered with a multiplicity of fibers or filaments, each filament having one end attached directly or indirectly to the surface and its other end free and extending into the fluid stream. Automobile or marine mufflers or silencers effective in reducing or eliminating objectionable noise, but with only nominal back pressure, are disclosed.

Abstract: In situ oil shale retorts are formed in formation containing oil shale by excavating at least one void in each retort site. Explosive is placed in a remaining portion of unfragmented formation within each retort site adjacent such a void, and such explosive is detonated in a single round for explosively expanding formation within the retort site toward such a void for forming a fragmented permeable mass of formation particles containing oil shale in each retort. This produces a large explosion which generates seismic shock waves traveling outwardly from the blast site through the underground formation. Sensitive equipment which could be damaged by seismic shock traveling to it straight through unfragmented formation is shielded from such an explosion by placing such equipment in the shadow of a fragmented mass in an in situ retort formed prior to the explosion.

Abstract: The noise emanating from a noise-generating source, such as a machine tool or a stock tube, is reduced by covering the surface from or through which the noise emanates with a cladding comprising a first layer, an intermediate layer, and an outer layer. The first layer, 1 to 5 mm thick, of a resilient vibration-isolating material, being plastic foam, rubber foam, rubber, or fibrous material, has the function of decoupling the intermediate layer from the surface. The intermediate layer, 0.25 to 2.5 mm thick, of lead or metal-loaded plastic material in contact with and supported by the first layer, has the function of a sound-insulating barrier. The outer layer, resistant to impact, wear, and abrasion, has the function of surface protection. The total thickness of the three layers need be no more than 6 mm.

Abstract: A muffler incorporates a tubular shell that has an acoustically reflective interior circumferential surface. In successive sections taken transversely through the shell, the acoustically reflective surface has at least a portion of its circumference shaped to define at least part of an ellipse or a parabola. Between an inlet into and an outlet from the shell, a fluid flow path extends along an axis lengthwise through the shell. A sound absorptive treatment is disposed along a second axis extending lengthwise through the shell. The treatment is spaced from but communicates with the fluid flow path. At least one of the two axes is defined by corresponding focal points of successive transverse sections taken through the curvilinear portion of the circumference of the acoustically reflective shell surface. In operation, sound emitted from fluid flowing along the fluid flow path is reflected by the reflective shell surface to the sound absorptive treatment.

Abstract: There is disclosed a muffler for an internal combustion engine, particularly an automobile engine, which includes a heavy steel outer casing formed from a section of cylindrical tubing together with an internal baffle structure of two sections of smaller diameter cylindrical steel tubing at least one of which is perforated to create a plurality of louvered openings extending along and around the tubing section. Each of the tubing sections has an end that is offset by reason of a pair of opposite-direction bends in the tubing, and the offset ends of the two sections of tubing are overlapped and joined together by welding or other suitable means to produce an extended baffle structure of approximately the same length as the outer casing. The offset ends of the sections of tubing which are joined together are preferably flattened on the sides adjacent to each other to reduce the maximum dimension of the baffle structure along the portion thereof where the two tube sections overlap.

Abstract: For obtaining a noiseless or substantially noiseless process of a flow passing through a throttle or damper device, the flow is given a speed increase with increasing acceleration in the direction of flow. Further, at least a substantial part of the dynamic component of the energy state of the flow is quenched within or immediately after the device by means of a counter-directed flow having a similar dynamic component. The invention also concerns a throttle or damper device for such a noiseless or substantially noiseless process of a flow.

Abstract: This invention covers a hollow, sound-dampened structure capable of reducing propagation of high frequency sound waves, in which a hollow, walled structure is covered with sound-transmission barrier material and an outer wrapping of a thin flexible plastic material capable of maintaining the sound-transmission barrier material adjacent to the outer surface of the structure.

Abstract: A plurality of passageways, each having its longitudinal axis substantially parallel to the flight path of an aircraft, extend through the wings, fuselage, horizontal elevators, and rudder for the purpose of permitting air to pass through these areas. The passageways diverge from front to rear on either side of the longitudinal axis. The front openings leading into the passageways are of such size and so spaced as to exhibit considerable reduction in parasite drag generated at the leading edges of the wings, elevators, and rudder, as well as at the front end of the fuselage.

Abstract: A noise silencer for an internal combustion engine has a hollow pipe serving as an air intake for the internal combustion engine and having a length L which is an even submultiple of the wavelength at the lowest of a range of noise frequencies from the internal combustion engine which are to be attenuated. The hollow pipe attenuates noise at the lowest frequency and at certain other frequencies throughout the range. Intervening frequencies are attenuated by at least one expansion chamber coupled to the pipe and having extended inlets and outlets the lengths of which are even submultiples of L. In certain preferred arrangements of the silencer the hollow pipe extends into one expansion chamber forming an extended outlet, a second hollow pipe extends between and within the expansion chamber and a second expansion chamber forming an extended inlet and an extended outlet and a third hollow pipe extends into the second expansion chamber from the internal combustion engine to form an extended inlet.

Abstract: A muffler incorporates a tubular shell that has an acoustically reflective interior circumferential surface. In successive sections taken transversely through the shell, the acoustically reflective surface has at least a portion of its circumference shaped to define at least part of an ellipse or a parabola. Between an inlet into and an outlet from the shell, a fluid flow path extends along an axis lengthwise through the shell. A sound absorptive treatment is disposed along a second axis extending lengthwise through the shell. The treatment is spaced from but communicates with the fluid flow path. At least one of the two axes is defined by corresponding focal points of successive transverse sections taken through the curvilinear portion of the circumference of the acoustically reflective shell surface. In operation, sound emitted from fluid flowing along the fluid flow path is reflected by the reflective shell surface to the sound absorptive treatment.