Abstract: A sound diffuser assembly for use with a compressive driver. The sound diffuser assembly has a sound reflector for receiving and redirecting sound energy from the compressive driver. A sound diffuser having a plurality of curved shaped concentric rings is also provided and positioned to receive reflected sound energy and to direct the sound energy in a predetermined pattern. Mounting apparatus is further provided to mount the compressive driver to the assembly so that sound energy from the compressive driver is directed into the sound reflector.

Abstract: A microphone baffle apparatus having a baffle member having first and second sides with the first side shaped to form a sound baffling surface to absorb sound energy. The baffle member has an opening therethrough in the center portion thereof and has an elastic material attached around the opening so that a microphone can be slipped through the opening and the baffle member held to the microphone by the elastic material around the opening. The baffle member may be made of a plurality of sectors connected with ductile hinges to allow the baffle member to be bent into a plurality of shapes. In addition, each baffle sector may be made of a plurality of laminated layers of ductile material and bent to a variety of desired shapes. One layer may be a thin layer of lead and one side of the baffle may have a waffle shaped surface thereon.

Abstract: A cover system covers the radiating faces of a loud speaker enclosure. It includes a sheet of flaccid material, such as a sheet of textile fabric printed with an ornamental design and provided with a border of "VELCRO" felt. The speaker radiating face carries either a complete peripheral border or segments of the hook component of a "VELCRO" fastener that is engagable with the felt. In use, the borders of the sheet are rolled up and stuck onto the hook strips to hold the sheet in place. The system makes the customizing of domestic and other loud speaker enclosure very simple.

Abstract: To fasten metallic or plastic covers or panels to supporting surfaces, snapping-in lugs are formed on these covers. These lugs are inserted into the slots of the supporting surface.

Abstract: A focussing element for use in a lenseless, focussed transducer for producing a semi-focussed, ultrasonic beam comprises a body formed of electrical insulating material and a plurality of piezoelectric elements disposed in one end of the body, each element being planar, extending outwardly from a common axis, and being disposed at a predetermined angel to the common axis whereby to define a common focal point on the axis, and electrical conductors secured to the piezoelectric element for electrically exciting the elements.

Abstract: An acoustic characteristics changing device includes a frame member disposed in an acoustic energy field, electro-acoustic conversion means attached to the frame member to constitute at least a portion of the device, variable impedance means connected as an electrical load to the electro-acoustic conversion means, and impedance control means for controlling an equivalent impedance of the variable impedance means. The equivalent impedance is variably controlled, so that an acoustic impedance and then its decrease frequency or decrease amount can be electrically, continuously and finely controlled.

Abstract: A speaker grille is provided which protects the speaker diaphragm from tampering or vandalism. Speakers which are used in public places for intercoms, message transmission, voice synthesis instructions, or the like will be covered by the speaker grille which has two sets of misaligned sound transmitting apertures, which will allow sound to emanate from the speaker, but will prevent objects from being pushed through the grille apertures to the diaphragm. Each set of apertures is found in a separate grille component, and the components are then assembled to form the improved grill. The construction of the grilled assembly is such that it will resist most attempts to break it with commonly carried items.

Abstract: A reflector disperses the audio waves from a loudspeaker acoustic source in a substantially 180 degree pattern. The reflector, coupled with a speaker, forms a loudspeaker system producing a wide dispersion of audio waves in a listening area. The reflector can be adjusted to alter the direction of the dispersal pattern in the listening area.

Abstract: A speaker grille assembly (800) includes a speaker grille 410), a felt (200), and a speaker (300). The speaker grille has a front surface (420), and a rear surface (430). The speaker grille (410) has plurality of equally spaced channels (440) for passage of sound. The sound channels (440) are formed such that that the rear surface port (422) is substantially larger than front surface port (411) thereby enhancing acoustic power transfer by increasing the effective sound passage space.The sound channels (440) can be formed such that the passage through the grille (410) are provided with either gradual or sudden transition from front port (411) to the rear port (422) resulting in a larger rear surface apertures.

Abstract: To manufacture an anechoic coating which prevents a wall from reflecting acoustic waves, the wall is coated with an elastic material of low compressibility, which is highly absorbent under shear stresses, and then with a highly compressible layer of material. A set of plates covers the second layer and vibrates under the effect of the acoustic waves. Rods fixed to these plates transmit these vibrations to the first layer which is thus subjected to shear stresses and dissipates the energy of the vibrations, thus making it possible to avoid the sonar detection of submarines.

Abstract: An acoustic lens for use in an acoustic microscope including a solid state medium for propagating an acoustic wave having a wavelength .lambda. and having opposed end surfaces, an electric-acoustic transducer applied on one end surface of the solid state medium and having a radius a, and a spherical lens portion formed in the other end surface of the solid state medium and having an aperture of a radius w. The length l and the aperture radius w are normalized by the transducer radius a such that Z=l.lambda./a.sup.2 and W=w/a. Values of Z and W are selected from such a region in a first quadrant of the Z-W coordinate system that desired power and/or phase are obtained. The region neighboring the point Z=1 and W=1 is excluded.

Abstract: A noise reducing apparatus is disclosed, comprising a lens-type hollow body consisting of a plurality of inclined hollow tubular passages. The lens-type hollow body has a plane incident surface and a curved emission surface and the length L.sub.2 of the hollow tubular passage is optimized in accordance with relevant dimensional parameters of setting of the lens-type hollow body in a sound field, to reduce noise from a spot sound source efficiently.

Abstract: An acoustic filter is provided for attenuating or suppressing the negative pressure half-waves of an elastic wave, comprising an enclosure containing a liquid whose saturating vapor tension is close to the atmospheric pressure. A pump causes the liquid to flow and a regulator fixes its temperature.

Abstract: A dripping sound generating apparatus which comprises a dripping sound echoing or resonating member having a cavity inside and a hole at least at the top portion of the member. The apparatus is adapted to allow liquid to enter the member and positively retain the liquid at a lower inside portion of the member. The apparatus also includes a dripping device for producing liquid drops and permitting the liquid drops to fall from the top portion of the member onto a pool of the liquid retained at the lower inside portion of the member and a device for recycling the liquid having dripped for repeated dripping. The apparatus is capable of providing varied dripping sounds over a long time by controlling the amount of the dripping liquid.

Abstract: An improved outdoor warning siren comprising an electromechanical siren together with a multi-segment horn which effects an exceptionally smooth transition from a small high pressure area at the horn inlet to a larger low pressure area at the horn outlet thereby producing increased sound output with reduced power requirements.

Abstract: A lens incorporates two reflective shells. One shell's surface is generated when a parabola is rotated around a line which lies in the parabolic plane perpendicular to its axis of symmetry. The other shell's surface is generated when an ellipse is rotated about a line lying in the elliptic plane and passing through one focal point at a finite angle to its major axis. The parabolically-generated shell has a characteristic focal curve while the elliptically-generated shell has both a characteristic focal curve and a focal point. The lens incorporates these shells which are aligned so that they have coincident focal curves and axes of rotation. Plane wave radiation travelling parallel to the axis of rotation of the lens will be focused at the focal point of the elliptically-generated shell. Conversely, a transducer placed about this common focal point and can produce radiation which will be converted into a plane wave radiation.

Abstract: An acoustical impedance inducing device is created for axial insertion into the longitudinal air column of a wind musical instrument. The device includes a first annular band of first predetermined thickness and a second annular band of approximately twice the thickness of the first band. A first web interconnects the first and second bands and maintains the bands at a predetermined axial spacing. The web is formed of strips diagonally disposed between the first and second bands and defining a triangle shaped aperture between adjacent bands, with the base of the triangle being colinear with an edge of one of the first and second bands. A third annular band, twice the thickness of the second, may be separated from the second band by a second web; or the device may be placed in a tubular portion of the instrument at a location where an end of the tubular portion is spaced from the second band by the axial width of the web.

Abstract: A wide dispersion baffle for a vertically oriented loudspeaker includes a first semi-conical reflective section that is concave toward the speaker and has a semicircular rim positioned at the periphery of the speaker. It extends at an angle of about 45.degree. to the radiation axis of the speaker to its apex on the speaker axis. A second semi-conical reflective section is convex toward the speaker and extends from the apex of the first semiconical section at substantially the same 45.degree. angle with respect to the speaker radiation axis. Sound emanating from the vertically directed speaker is reflected by both the concave and convex semi-conical reflector sections in a pattern centered about a substantially horizontal plane, but the sound is reflected through widely diverging angles in such horizontal plane. Baffle arrangements can provide horizonal dispersion patterns of any angular width between about 180.degree. and 360.degree..

Abstract: An enclosure for a transduction element incorporates a geometrically shaped acoustically reflective shell. This acoustically reflective shell is shaped so that the inner surface thereof is at a least a section of that shape generated when a parabolic structure is rotated around a line which, lies in the plane of the parabolic structure, is perpendicular to the major axis of the parabolic structure. Such geomtrically generated shapes will have one distinct focal curve. A transduction element placed about this focal curve will, in operation, cause acoustic radiation to be produced which will be characterized by a plane wavefront of coherent radiation. Said device may alternately act as a transducer which produces a 360 degree beam width by placement of a plane wavefront producing transduction means at a position above the acoustically reflective shell and parallel to the plane of the distinct focal curve.

Abstract: A human sound muffler and indicator for placement around the mouth of a user to absorb most of the sound emanating from the user's mouth including a microphone and associated electrical circuit for receiving unabsorbed sound and providing an indication of the intensity of the unabsorbed sound.

Abstract: A sound-permeable loudspeaker cover including a frame in which are arranged mutually crossing webs of a synthetic plastic material delimiting sound passage openings. A sound-permeable material, for instance a fleece, a textile fabric or a knitting, covers the sound passage openings, and is arranged approximately in the middle of the webs. The webs are produced as a single part according to the injection molding process, and penetrate the sound-permeable material to anchor it at a plurality of individual locations.

Abstract: A parametric loudspeaker utilizes nonlinearity of air relative to ultrasonic waves for producing an audio frequency having super directivity, and to thus provide a limited listening area public address system subject to a large listening area by safeguarding listeners by the provision of a framework for intercepting powerful ultrasonic waves and an acoustic filter. The depth and energy consumption of the parametric loudspeaker are reduced by the use of a reflective plate. Arbitrary directivity is obtained by the provision of a mechanism to move an ultrasonic wave radiator or the reflective plate. The parametric loudspeaker and any other loudspeaker may be combined.

Abstract: An acoustic damper for substantially reducing the reverberation echoes at the junction between an acoustic signal propagating fluid and a material having an acoustic impedance substantially different from that of the fluid. The damper, which is particularly adapted for use in ultrasonic transducers, is formed of a material having an acoustic impedance which substantially matches the acoustic impedance of the fluid, such material preferably being a foam plastic material having sufficient hardness to be acoustically stable. For preferred embodiments, the damper is formed of a laminate of the layer described above and a second layer of a material which provides high acoustic attenuation, such as cork material.

Abstract: In a sound emitter including an emitting piston powered by a three phase asynchronous electric motor, the torque curve of the motor may be adjusted to suit any temperature, causing variations in the emitted resonance frequency by using a motor having its maximum torque at less than half the maximum speed. This may be done by using an alloy of silicon and aluminum in the rotor winding.

Abstract: An acoustical reflector is positioned in such manner relative to a loudspeaker as to reflect all of the indirect sound waves generated as a necessary concomitant to the generation of direct sound waves by the loudspeaker substantially only to the audience area receiving said direct sound waves from the loudspeaker. In an array of a plurality of loudspeaker, each serving one of a plurality of audience areas, acoustical reflectors are positioned relative to said plurality of loudspeakers so that indirect sound waves, generated as a result of the generation of direct sound waves by each of said loudspeakers, are reflected substantially only to the audience area served by said loudspeaker and not to audience areas served by other loudspeakers.

Abstract: A reverberating platform structure usable as an exercise floor or, depending upon the configuration thereof, for the support of people or objects thereon wherein the platform is supported by an anchor structure above a foundation such that there is an open space between the foundation and the undersurface of the platform. The anchor structure may be essentially flexible so as to provide a giving or flexible structure to the platform for a person to exercise, dance, or otherwise move thereon. An agitator assembly primarily in the form of a plurality of speakers are disposed within the space immediately adjacent to the space slightly from the undersurface of the supporting platform wherein activation of the speakers causes vibration to be communicated directly to the platform but wherein the platform is further structured not to generate specific sounds therefrom so as to be considered part of the speaker system itself.

Abstract: An echo sound melodeon, in accordance with the principles of this invention, includes a body on which is mounted a keyboard and a holder, and a controlled flow of air into an interior of the body. A propeller is placed in the interior of the body in the path of the controlled flow of air. The spinning of the propeller causes the flow of air to vibrate and the vibrating air creates echo sound effects.

Abstract: A sonar dome having an external wall in which a central layer is formed by a plurality of woven webs of glass fibers impregnated with a resin and by two peripheral layers located on each side of the central layer, the peripheral layers being constituted by a plurality of woven webs of carbon fibers impregnated with a resin.

Abstract: The acoustic transducer system includes an electroacoustic transducer and a flexural oscillator plate which is coupled to the electroacoustic transducer. The flexural oscillator plate is so constructed that at the system operating frequency it is stimulated to flexural oscillations of a higher order at which on the flexural oscillator plate node lines form between which antinode zones oscillating alternately in opposite phase lie. To influence the sound radiation of the flexural oscillator plate a sonic beam shaper is provided. The sonic beam shaper has soundwave barriers which are impermeable for soundwaves and which lie spaced from the flexural oscillator plate and acoustically decoupled therefrom in front of first antinode zones oscillating in equal phase with each other, and soundwave-permeable regions which lie between the soundwave barriers in front of the remaining second antinode zones oscillating in opposite phase to the first antinode zones.

Abstract: A simulated rock speaker cabinet in the form of a natural rock has build-up portions of modeling clay which include a pattern of small diameter holes to form speaker grills at longitudinally spaced positions. A chicken wire ring provides structural reinforcement to the speaker cabinet. The artificial rock cabinet may be molded of various hydrolitic cements, magnesite cement, a suitable catalytic plastic resin to which pigment or other colorants may be added along with glass or rock chips, to provide the simulated rock cabinet with an external appearance which corresponds to various natural rocks. The speaker cabinet has speakers and the various electronic components of the speaker system housed within the speaker cabinet and may be coated with water-proofing and weather-proofing material with the speakers molded into the wells and facing the grills. An end plug may be adhesively sealed to the opening within the base of the speaker cabinet and suitably sealed by Hydrostone or other cementous material.

Abstract: Disclosed herein is a sound wave control device which is shaped in a lens form or a prism form from an acoustically rigid porous material, wherein numerous paths having different path lengths are provided and the apparent medium density is varied. This second wave control device is used to improve the sound quality and the directivity of the sound waves from a speaker and the directional control of noises.

Abstract: A system for detecting and monitoring blast noise, the invention provides ncentrically arranged cylindrical windscreens having a pair of vertically spaced microphones mounted centrally therein, the windscreens acting to reduce interference from wind-generated pseudosound yet being acoustically transparent so as not to interfere with the reception of acoustical data incident on the microphones. The present system also includes a signal processing subsystem which receives the output of the respective microphones for analysis.

Abstract: A neutrally buoyant, wide frequency range underwater acoustic baffle suite for extended depth operation comprising a laminated structure including a rigid inner separator sheet having a plurality of uniformly distributed cavities sandwiched between two flexible outer cover sheets and surrounded along its edges with a waterproof seal to completely encapsulate the separator sheet within the cover sheets and waterproof seal. Entrapped air within the air cavities offers a low effective acoustic impedance compared to water, and the rigid inner separator sheet maintains constant separation between the flexible cover sheets, and therefore low acoustic impedance, even under high hydrostatic pressures.

Abstract: The lightweight underwater acoustic baffle with enhanced performance chareristics particularly at low frequencies is provided by a stiffened resistive screen means affixed in front of a compliant material for allowing the baffle to reflect on the compliant side and on the screen side, a rigid irregular shaped material means with a primary open surface area affixed to the screen as a means for attaining maximum stiffness with a minimum weight, a compliant means affixed behind the screen means, a water fluid sealing and container means within the baffle means for suffusing the stiffening core area and its attached screen for generating miniscule acoustic resistance in the screen and producing a greater impedance mismatch thus enhancing the insertion loss and baffle performance, and, an attachment affixed to the container means for attachment to a vessel.

Abstract: A microphone system comprising a pair of microphone capsules, a pair of planar barriers positioned at an angle to each other, with each microphone capsule secured to the center portion of a barrier positioned between the microphone capsules. A baffle is positioned between the microphones with the sidewalls of the baffle extending angularly toward the barriers forming corners with each of the microphone capsules located at the corner.

Abstract: An acoustic lens for use in an ultrasonographic probe is made of a material including silicone rubber mixed with particles of titanium oxide having diameters ranging from 0.08 to 0.20 .mu.m. The particles are mixed at a ratio in the range of 30 to 65 wt %.

Abstract: Acoustic frictional resistance comprises a plate having at least one laser-formed hole therethrough. The plate is formed by positioning a plate preferably one having a thickness smaller than one and one-half milimeters alongside a laser and directing the laser beam so that it cuts a hole through the plate. During the process of producing the resistance, the value of the acoustic friction is measured as a pressure drop of a constant air stream or as an expenditure of electrical energy for an electrically excited electroacoustic transducer. This measurement is then used as a variable or as a standard for controlling the process. Advantageously, a coherent beam is emitted by the laser which is deflected by mirror from a horizontal to a vertical direction and focused by means of a lens to work in a contact-free manner on a workpiece supported on a support member such as a movable table. By moving the table in two coordinate directions, a plurality of bores are formed in a pattern in a workpiece.

Abstract: The application describes a "jellyfish" acoustic array. The array is housed in a cable suspended container with an open bottom. A series of individual transducer elements are stacked inside the container, and may be deployed in a column hanging from the container. Spacer cables join adjacent transducer elements to limit the separation of the deployed elements. The uppermost of the transducer elements is suspended from the container. Control cables secured to the bottommost of the transducer elements and extend up through the container. Pulling in the control cables raises the bottommost transducer element and sequentially stacks the remaining transducer elements. Lowering the control cables serves to deploy the transducers.

Abstract: An enclosure for a transduction element incorporates a geometrically shaped acoustically reflective shell. This acoustically reflective shell is shaped so that the inner surface thereof is at a least a section of that shape generated when an ellipse is rotated around a line which, lies in the plane of the ellipse, is oriented at any angle to the major axis of the ellipse, and contains one focus of the ellipse, or that shape generated when a continuum of ellipses having identical major axes are placed about a line which, lies in the plane of all the ellipses, is oriented at any angle with respect to the major axes of the ellipses, and contains a focal point common to all the ellipses. Such geometrically generated shapes will have one common focus and one distinct focal line.

Abstract: The present invention relates to a grill comprising one or more acoustic shells to be used in combination with conventional acoustic speakers. The speaker grill of the present invention in it simplest form is an acoustic shell which serves to focus the acoustic emissions generated by the speaker. In a preferred embodiment of the present invention the speaker grill is constructed of a series of acoustic shells. The different acoustic shells may focus different portions of the acoustic spectrum. The speaker grill of the present invention has particular use with an automobile speaker. The speaker grill of the present invention can be used in any listening area and has particular application to small environments, environments having spacial restriction, critical listening environments such as recording studios, and environments which utilize sound reinforcement systems.

Abstract: A flush-dish microphone system for measuring aircraft flyover noise is disclosed. The system includes an acoustically hard base supporting a microphone. The base is configured along its periphery to define a plurality of outwardly extending tapered members. Each of the tapered members includes a pair of converging edges that are each at least in part curved. The curved edges produce a favorable progressive match of acoustic impedance at the ground/tapered member boundary that reduces edge diffraction contamination of the noise signal being measured by the microphone.

Abstract: An acoustic connector is shown for coupling two devices. One device is provided with a hub while the other has a cylindrical member which mates with the hub to provide a permanent coupling therebetween. The member is hollow to conduct acoustic signals between the devices.

Abstract: A microphone apparatus is disclosed which consists of a plain plate with a constant area and a microphone element located on the plain plate at its peripheral position at least different from the center thereof.

Abstract: An improved siren including means for producing and directing sound energy against a rotatable reflector which directs the sound waves out from the siren in a generally horizontal direction and which due to rotation of the reflector about a vertical axis causes such sound waves to be directed in all horizontal directions. One embodiment includes rotor and stator means which create sound energy that is directed generally downwardly in the manner of a ring radiator, together with a reflector mounted beneath the rotor and stator for rotation about a generally vertical axis, the reflector being tilted relative to its axis of rotation to intercept the downwardly directed sound waves and direct them out horizontally thereby providing a directional siren which covers a 360 degree area due to rotation of the reflector.

Abstract: A bubble silencer for use with scuba equipment is comprised of a flat flexible enclosure attached to a scuba regulator valve. Exhaust bubbles issuing from the regulator into the enclosure coalesce into large air parcels to be expelled at low velocity through a rearward exit port. The large size and low velocity of the exhaust bubbles leaving the enclosure are much quieter than the small high velocity bubbles issuing from the regulator itself.

Abstract: An underwater voice communicator in which the preferred embodiment comprises a pair of tapered tubes in communication with a diver's mouth. The tubes are constructed of a material having a sound impedance similar to the sound impedance of water. Sound energy issuing from the mouth of a diver is reflected down the length of the tapered tubes to an area of the tube that concentrates the sound for injection into the surrounding water.

Abstract: A sound absorbent pad, which comprises an interconnected cellular foam or a fibrous material, has a central hole which houses a microphone whose sound-sensing diaphragm is held flush with the center of the outer surface of the pad. The pad is a shallow dome or other shape which converges from a large base to a vertex and incorporates a plastic or metal plate, which being frusto-conical or another suitable shape. The pad with its plate acts to control noise which would otherwise be reflected from noise reflecting surface onto the microphone, thereby facilitating measurement of freefield noise levels.

Abstract: An acoustical device for reducing sound pressure levels and the potential for noise induced hearing loss comprising an arched shaped acoustic pad having an interior or frontal concave sound absorption panel and an exterior or rear convex sound shield supported by an interior frame member. Sound attenuation is accomplished by enclosing the frame with at least one layer of resilient material having a high sound absorption coefficient. The acoustic pad is affixed to the back of a musician's chair by means of a mounting device which provides a high degree of flexibility in positioning for optimal directional protection of the performer.

Abstract: A loudspeaker system for use in stereo sound reproduction which is adapted to reflect all higher frequency sounds off a reflecting surface before the sounds reach a listener. The system comprises two enclosures, each having two compartments. The lower compartment houses the woofer; the upper compartment contains at least two arrays of at least two acoustic speakers, each array being positioned vertically relative to each other and projecting in the same general direction. The arrays are positioned in the enclosure such that the arrays project at a moderately divergent angle relative to each other and are spaced at least one array width from each other. The portion of the enclosure between the arrays is essentially pervious to sound and thus permits sound generated by the speakers which has been reflected from the reflecting surface to pass through the enclosure.

Abstract: A system for determining optimal selection and positioning of transducers (e.g., loudspeakers or microphones) in an acoustical environment, and relating an acoustic environment to any sound source. The system determines the acoustical dispersion pattern, and the sensitivity or power requirements for transducers or sound sources.The system involves mapping acoustical environment, as viewed from a specific location, in true angles and with attenuation information, onto the surface of a sphere. The transducer or sound source is related to this mapped environment by mapping its angular sensitivity or radiating pattern onto an overlay which is manipulated over the surface of the sphere.A system light source permits the information depicted on the sphere to be projected onto a scale model. Final documentation of all interrelationships may be viewed on the system sphere, or photographed from a system screen.