Abstract: A surface acoustic wave device includes a quartz rotated Y-cut plate and at least one interdigital transducer disposed on the quartz rotated Y-cut plate. The quartz rotated Y-cut plate has a Euler angle represented by (0, .theta., .phi.). The angle .theta. is within a range of about 125.degree.<.theta.<130.degree. or equivalents thereto, and the angle .phi. is approximately 90 degrees. The interdigital transducer is made of tungsten.

Abstract: The system of the present invention includes, briefly, a point source speaker system, comprising a processor which produces a left minus right (L-R) audio signal, a right plus left (R+L) and a right minus left (R-L) audio signal; left, center and right speakers for audibly transmitting one of the L-R, R+L and R-L audio signals, respectively; left and right acoustically reflective surfaces proximate to the left and right speakers, respectively; and a point source speaker enclosure for housing the three speakers in a single enclosure.

Abstract: The invention relates to a loudspeaker system for omni-directional sound emission consisting of a elongate member forming an air column and a plurality of annular speaker units mounted in axially spaced relationship on the elongate member. Diffusors also mounted on the elongate member are provided with conical surfaces facing the speaker units. Electrical wiring and auxiliary speaker components such as crossover networks may be mounted in the elongate member.

Abstract: A sound focusing speaker system includes a sound focusing lens having an upper parabolic portion and a coaxial lower parabolic portion, each defined by different parabolic equations. A conical skirt is also provided adjacent the lower parabolic portion, and a lower lip is provided around the conical skirt. A speaker driver system is provided within the sound focusing lens. The speaker system includes a high frequency driver, a low frequency driver, and a sound dispersion lens into which the low frequency driver fires. The high frequency driver is vertically aligned with the focus of the upper parabolic portion, and a central portion of the sound dispersion lens is vertically aligned with the focus of the lower parabolic portion. The conical skirt contains reflected waves. The coaxial dual parabolic sound focusing speaker system is optimized to accurately reproduce a broad frequency spectrum of sound and to reflect the sound into a substantially vertical beam.

Abstract: Attractive furniture which encloses a speaker system for improved functionality of both the furniture and speaker system. The furniture is hollow and can be lamps, tables or other pieces, allowing placement of a speaker system unobtrusively and attractively within a room. The speakers are arranged vertically within the hollow furniture, emitting sound vertically upwards and or downwards. Sound directing devices having parabolic surfaces are placed adjacent the speakers to redirect the sound horizontally over a 360 degree range. The furniture may enclose a single speaker and sound directing device or multiples of the same so as to achieve the desired sound output and aesthetic appearance.

Abstract: A surface acoustic wave device includes a quartz rotated Y-cut plate and at least one interdigital transducer disposed on the quartz rotated Y-cut plate. The quartz rotated Y-cut plate has a Euler angle represented by (0, .theta., .o slashed.). The angle .theta. is within a range of about 125.degree.<.theta.<130.degree. or equivalents thereto, and the angle .o slashed. is approximately 90 degrees. The interdigital transducer is made of tungsten.

Abstract: A loudspeaker box for faithfully reproducing stereophonic sound. The box is divided into at least two chambers hermetically sealed from each other and provided with loudspeakers for propagating sound in directions substantially orthogonal of each other. The speakers may be alike or different and they may be controlled independently of each other in respect of their relative output volumes or frequencies.

Abstract: A directional microphone intended for use in a computer visual display monitor, and methods for construction of same. The integral directional microphone assembly comprises a cardioid electret microphone capsule retained therein by acoustically transparent foam. The microphone housing is mounted internally within a display monitor housing facing the user and adjacent to the top surface of the monitor housing. The microphone housing comprises a frontal opening and a plurality of nonfrontally facing openings which together maximally preserve sound pressure gradient applied to the microphone capsule, resulting in a hypercardioid spatial response.

Abstract: A television set speaker system enables stereophonic audio reproduction with a "live" feeling when a television set receives programming in stereo. Such a system includes two front speakers for radiating sound in a forward direction from a cathode ray tube screen and reflection type directional intensifier speakers provided on the right and left sides of the top of the television set for radiating sound diagonally forward and outward in relation to the cathode ray tube screen.

Abstract: The loudspeaker particularly comprises two-aperture radiator (1) containing paired in-phase counter-radiating apertures (4) and reproducing middle frequencies. Apertures (4) face each other, and their geometrical axis F is positioned vertically, while the distance between apertures (4) equals to at least the radius of aperture (4) but does not exceed the wavelength of the lowest frequency reproduced by paired apertures (4).

Abstract: Electroacoustical transducing apparatus includes an input for receiving an audio electrical signal. A first electroacoustical transducer is constructed and arranged to radiate first sound waves in a first direction in a first frequency range in response to an audio electrical signal on the input. A second electroacoustical transducer is constructed and arranged to radiate sound energy in a second direction in a second frequency range. A third electroacoustical transducer is constructed and arranged to radiate sound energy in a third direction within the second frequency range.

Abstract: A vent loudspeaker system is provided which has at least one active driver and a port opening in a speaker cabinet. Disks or baffle plates are mounted a predetermined distance to and concentric to the port opening, resulting in a vented system achieving an equivalent performance as would result from a flared, ducted port, but with several performance advantages and simpler construction.

Abstract: A speaker is adapted to transmit sound waves in an omni-directional manner relative to an installation surface upon which the speaker is mounted. The speaker includes an oscillator having a hemispherical oscillating body comprising a piezoelectric body polarized in a thickness direction thereof, a pair of electrodes provided on an inner surface and an outer surface of the oscillating body, input terminals connected to the electrodes via lead wires, an end portion of the oscillator being connected to spacers in a groove to cover a projecting portion of a horn, a cavity communicating with a hole of the horn and being defined between the oscillator and the horn and support members fixed to a flange portion of the horn whereby a sound transmission path communicating with the hole of the horn is defined between the horn and the installation surface upon which the speaker is mounted such that the sound transmission path extends in all directions relative to the installation surface.

Abstract: An electronic device includes an electronic component and a chassis to support the electronic component. The electronic device also includes a non-supporting chassis component that is integrally formed along with and as part of the chassis. The non-supporting chassis component is functionally operable in cooperation with the electronic component to enhance performance of the electronic component. In one example, the electronic component is an electronic speaker and the non-supporting chassis component is a resonance chamber positioned adjacent to the speaker to improve the speaker's sound qualities. The chassis and non-supporting chassis component (i.e., the resonance chamber) are integrally formed together via a single injection molding process using expanded polypropylene.

Abstract: This disclosure relates to a sound system that provides high quality sound notwithstanding extreme background noise. Preferably implemented in amusement ride vehicles, such as roller coasters, the present sound system mounts left and right channel sets of speakers in each seat back, one on each side of a center section that supports the passenger's back. These speakers are mounted in a wing-back relationship, such that they direct their sound away from one another and toward laterally extending arms that extend forward from the seat back, outside of the speakers. These arms mount an inward-facing spherical reflector, which reflects and disperses sound toward a range of positions associated with height variance of the passenger. Using this arrangement, all passengers will experience the same high quality sound, whatever the passenger's height. The left and right channels speakers are each coaxially-mounted, two-way speakers.

Abstract: The invention comprises a device capable of emitting either acoustic or electromagnetic radiant energy. The device has at least one movable transducing element for producing this energy, and at least one reflector with a smooth concave surface which reflects the energy emitted from the transducing element. The shape of the reflector surface is preferably defined by either a rotated ellipse or a rotated parabola. A reflector surface of either shape is characterized by a continuum of distinct focal points that define a focal curve, such that each distinct focal point of the continuum is a unique focal point of each ellipse or parabola in the continuum forming the reflector surface. The radius of curvature of the parabolic surface of revolution can be extended up to an infinite length, causing the focal curve to appear as a straight line.

Abstract: The surface of an acoustic reflector faces the source, and has a plurality (N) of wells, where N is an odd prime number. Each well has a depth D.sub.n =(n.sup.2 rem N)* unit depth (0<=N<=N-1), governed by a Quadratic Residue Sequence. Acoustic energy directed from the source to the reflector, and reflected along a length direction of the reflector, has substantially equal acoustic energy in all angular directions from the reflector within plus and minus .pi./2 from the direction of radiation. The surface above can be used for the surface of a loudspeaker, where either it is the surface of the loudspeaker or has speakers positioned at the bottom of the wells. The surface above can also be used for drag reduction in moving vehicles when it is positioned either at the front or rear of the vehicle.

Abstract: An acoustic signal receiving apparatus comprising a housing having an acoustically reflecting surface and a directional acoustic sensor unit having first-order gradient characteristics. The sensor unit is coupled to the housing with use of a retractable member having a retracted position and an extended position. When the member is extended, the sensor unit is positioned relative to the reflecting surface such that the acoustic interaction between the sensor unit and the reflecting surface causes the output of the sensor unit to have second-order gradient response characteristics. In accordance with one illustrative embodiment, in a notebook computer with a "flip-back" lid, the sensor element automatically extends to the desired position when the lid is opened, and automatically retracts to be flush with the housing surface when the lid is closed.

Abstract: An acoustic transducer including an acoustical reflecting surface of a finite dimension and at least one sensor having an output which produces a first-order differential response pattern. The sensor is located proximate to the reflecting surface, wherein acoustical waves propagating from the reflecting surface, acoustically interact with the sensor to produce a second-order differential response pattern at the output of the sensor at a predetermined frequency. The second-order differential response pattern at the output of the sensor occurs at the predetermined frequency when the finite dimension of the reflecting surface is at least one-half of an acoustic wavelength.

Abstract: Either a tweeter or a woofer diffuser may alternatively be detachably secured to a driver holder of a speaker base through axial engagement of lugs carried by the holder with guide grooves formed in a skirt of the driver and thereafter rotating the driver to dispose the lugs in a circumferential groove and out of alignment with the guide grooves.

Abstract: A speaker system includes a vertically oriented elongated tube supported on a ground surface, and open at upper and lower ends thereof; a woofer, mid-range speaker and tweeter mounted at a lower end of the tube, the woofer having a front driving face with an effective driving area, the woofer providing an in-phase audio signal directed upwardly through the tube and an out-of-phase ground wave audio signal directed in an opposite direction therefrom; an enclosure enclosing the woofer and mounting the tube on the ground surface; a restricted open area formed between a lower edge of the enclosure and the ground surface and being less than the effective driving area, the restricted open area being arranged to transmit the out-of-phase ground wave audio signal from the woofer in a direction transverse to the axial direction; and a driving circuit for driving the woofer and including a power amplifier for amplifying an input signal with a variable gain and supplying the amplified input signal to the woofer, a circu

Abstract: A loudspeaker system includes a flexible compressible tube having a woofer mounted at one end with its cone directed outward, and a vented baffle mounted at the other end. A first sound dispersion element is mounted with its apex facing the cone of the woofer and a midrange speaker is mounted in the base of the dispersion element with its cone facing away from the tube. A second sound dispersion element is mounted with its apex facing the cone of the midrange speaker, and at least one tweeter is mounted on the base of the second sound dispersion element with its cone facing away from the tube. According to one embodiment, a plurality of tweeters are mounted in an enclosure mounted on the base of the second dispersion element. According to another embodiment, a single tweeter is mounted in the base of the second dispersion element and a third dispersion element is mounted with its apex facing the cone of the tweeter.

Abstract: A loudspeaker unit for producing wide dispersion sound for use in wide imaging stereo has a plastic case defined by a front onto which a separate sound mirror fits, and a back. A drive unit fits into a housing located opposite to the sound mirror. A frame of metal or other rigid material provides a mechanical connection between the drive unit and a load-bearing plinth on which the sound mirror is supported. The case front and back together define an upper space behind drive unit that is connected to a lower space beneath the sound mirror by a passage behind a wall of the case front. The three spaces provide a combined volume of gas that provides a reflex load for the drive unit. The overall size of the unit can be reduced without corresponding loss of bass frequency response, and, because the sound mirror is separate from the plinth, a range of drive units of different dispersion patterns can be provided, requiring only alteration in the surface profile of the sound mirror.

Abstract: A vented loudspeaker system is provided which has at least one active driver and a port opening in a speaker cabinet, Disks or baffle plates are mounted a predetermined distance to and concentric to the port opening, resulting in a vented system achieving an equivalent performance as would result from a flared, ducted port, but with several performance advantages and simpler construction. Flow guides are provided, attached to the disks or baffle plates, extending back into the port to block areas of stagnant air and enhance laminar air flow.

Abstract: In an audio mirror speaker, an uneven area is formed on a planar mirror surface and a directivity distribution is controlled by changing a relative position of a diaphragm facing the mirror surface and the mirror. The directivity distribution of such a speaker is determined by a radius of curvature of the uneven area. Since the directivity changes with various movements of the planar mirror, a freedom in setting the directivity distribution is enhanced.

Abstract: A speaker apparatus includes a speaker having a diaphragm, a frame having a mouth and a reflector. The speaker is mounted inside a cylindrical box, and the frame is formed cylindrically and covers over the diaphragm. The mouth opens perpendicular to an axis along the center of the diaphragm. The reflector is positioned opposite the diaphragm in the frame and is formed roughly conically but asymmetrically between a side of the mouth and the opposite side of the cylindrical box. Sound waves radiated from the diaphragm are reflected by the reflector and an inner surface of the frame, and are released to the outside of the mouth.

Abstract: A loudspeaker unit is provided for attachment at an elevated position within a listening space. It has a drive unit for producing a beam of treble sound, and a sound mirror that distributes a beam from the sound unit over a wide angular extent both horizontally and vertically with a generally consistent amplitude of perceptible sound. The unit may further comprise an angled mid range and low frequency drive unit. The unit demountably clips into a support bracket that can be carried by a post or fixed directly to the wall. Signal supply is via connectors in the bracket so that as the unit is clipped in place, the electrical connections are established. The speaker is quadrant shaped when viewed in plan and lends itself to installation in groups and clusters (FIG. 13).

Abstract: A speaker system designed to use wider resonant sound waves by two conventional speakers which are symmetrically and oppositely disposed to face one another along a co-axis on which both axes of the cone paper vibrator of the speakers are aligned. A sponge like sound wave absorbing material with cone-shaped recesses may be disposed in between the speaker and spherical speaker case.

Abstract: A high fidelity loudspeaker having a driver, e.g., a woofer in a housing, is rear-loaded by a folded passage, i.e., a transmission line, closed at one end by a loudspeaker and open to the environment at the other end. The line has a length equal to the quarter-wave length of the lowest desired frequency. Angled 45.degree. reflectors are used in the transmission line whereby an advancing planar wave from the rear of the speaker is produced from the rear hemispherical wave. The transmission line is conventionally stuffed with fibrous material, such as long fiber wool, which attenuates resonances, absorbs high frequencies and acts as a low pass filter. The acoustic output at the open end of the transmission line has high frequencies filtered out and a low frequency planar wave at maximum possible amplitude emitted in close phase with the front wave of the loudspeaker.

Abstract: A loudspeaker system is arranged to house an electromagnetic loudspeaker driver of the type having both front and back acoustic waves. The loudspeaker driver is reversed mounted such that its weaker back waves are emitted directly to the outside, while its stronger front waves are directed through an internal passageway of the loudspeaker enclosure before adding in phase and exiting with the back waves. The front waves are phase-shifted by half a wavelength through the internal passageway which acts as a transmission line. The attenuation suffered through the transmission line is offset somewhat by the stronger front waves such that the differential amplitudes of the front and back exiting waves are minimized. Throughout the transmission line, the flow of the sound waves is kept circular and laminar in order to maintain coherence and to further minimize loss of energy due to turbulence. These are accomplished by the use of a cylindrical passageway, a streamlining reflecting cone, and an outer reflecting ring.

Abstract: A loudspeaker has a magnetic circuit and a speaker frame attached to the magnetic circuit, which is mounted on a rear tray of an automobile. A grille is attached to the speaker frame so as to reflect sound generated from the magnetic circuit. The grille has a slit so as to radiate the sound in a forward horizontal direction.

Abstract: Monophonic sound is transformed into a stereo pattern by arranging two reflectors on a common axis at a predetermined distance from each other with both facing in the direction of the sound. One reflector has a larger diameter than the other and is provided with a central aperture into which a tone generator is mounted and spaced from the smaller reflector.

Abstract: An audio system includes a speaker unit having an opening in its front surface supporting a speaker and a diffuser with a reflecting surface detachably attached to the speaker unit and positioned opposite to the speaker and in front of the opening such that sound waves from the speaker are diffused by the reflecting surface of the diffuser to propagate radially. A multi-channel amplifier for driving the speaker includes a compensating circuit for correcting the output level and frequency characteristic of the system when the diffuser is attached.

Abstract: A sound output system has a pair of right and left speakers and a pair of audio mirrors for respectively controlling directivities of sounds which are output from the pair of speakers. The shapes or arrangement of the pair of audio mirrors are adjusted such that a difference between arrival times of the sounds which are respectively output from the pair of speakers can be compensated by a sound pressure difference due to the Haas effect in a predetermined area. Alternative means are phase difference, dipole, and asymmetrical horn loading.

Abstract: A sound dispersing system using two or more vertically facing drivers in substantially coaxial alignment on a vertical axis. The drivers face conic reflectors which reflect sound radially over 360 degrees with substantial dispersion in vertical planes that include the vertical axis. Mounting means for drivers and reflectors are spaced vertically apart so that the vertical separation of the effective acoustic centers does not exceed industry standards for coherent sound above and below the horizontal plane equidistant between two drivers assigned adjacent bands of sound frequencies.

Abstract: A speaker housing arrangement which uniquely combines a number of acoustic functions is disclosed in both a simple embodiment and in a more complex embodiment. Each embodiment utilizes a pair of angular deflectors in a tubular or pipe type enclosure to directionally co-align the sound product from both sides of the speaker cone. A slight interval in time of egress between the pressure opposite signals provides sonic contrast and hence sharp imaging. In the simpler embodiment linearity and signal integrity is preserved throughout the sound spectrum. In the more complex embodiment part of the bass signal is momentarily retained for purposes of co-phasing in a partial bass reflex arrangement. Either embodiment permits the production of sound of unusual quality and quantity in relation to input energy and to cost and grade of components. Secondary improvements in high frequency linearity and in overall spectral equalization in the region of the speaker itself are also disclosed.

Abstract: An integrated amplifier and speaker system includes a speaker having an enclosure having a closed end and an open end; an electro-acoustic driver sealingly mounted in the open end; a reflex duct connected acoustically to the enclosure through a port and having a reflex duct open end proximate to the electro-acoustic driver means; and an amplifier assembly that has an inner surface defining an interior surface of the enclosure. The amplifier subassembly further includes a circuit board that extends within the enclosure. The amplifier is electrically connected to drive the electro-acoustic driver means.

Abstract: Omnidirectional electro-acoustical chamber comprising two transducers (4) for low/medium tones and (7) for shrill tones disposed coaxially with their membranes facing one another, the transducer (4) being maintained at the end of the extensions (2) of a compartment (1) and the transducer (7) at the end of the compartment (5), a portion of the sounds emitted by the transducers (4, 7) being diffused by means of a diffuser (9) placed between the membranes, the other portion being reflected on the surfaces (12, 13) of the compartments (1, 5).

Abstract: A mobile stereo speaker unit and assembly includes a central speaker for reproducing both left and right stereo sound channels. The central speaker is in a well in the central portion of the front panel of a vehicle, and a reflector is positioned above the speaker to intercept the sound and reflect it in a desired direction. The direction is selectable vertically or horizontally depending on the particular reflector used and the reflected sound may be directed towards the rear or towards the front windshield.

Abstract: An improved loudspeaker assembly for frequencies higher than approximately 6 kHz, i.e., a tweeter assembly, is disclosed. The tweeter assembly includes a dome tweeter driver for delivering high frequency sound to a listener, and a cylindrical housing for mounting the tweeter driver in a horizontal plane. A centrally located aperture is provided in the top surface of the housing for receiving the dome portion of the tweeter, and a plurality of concentric annular ridges are also provided, and are spaced outwardly from the tweeter dome. The annular ridges function to reflect sound energy transmitted off the dome structure, and are used to disperse the high frequency energy in a horizontal direction within the listening room.

Abstract: An audio speaker system includes a pair of satellite speakers each having a copper lined pyramidal enclosure formed by four side walls diverging outwardly upwardly from a downwardly facing apex. A speaker mounting support at an upper end of each of the satellite speaker enclosures has a horizontal upper surface through which an upwardly facing speaker is mounted. A plurality of upwardly and inwardly inclined walls connect an upper end of each of the triangular side walls of the satellite speaker enclosures with the horizontal upper surface. A pyramidal speaker grill having four triangular side walls tapering to an upper apex covers the horizontal upper surface and is supported by the inclined walls. A sub-woofer speaker includes a pyramidal enclosure lined with a thin sheeting of copper and has four triangular side walls tapering to an upwardly facing apex.

Abstract: An acoustically shielded speaker enclosure for use in the ear pockets of motorcycle helmets is disclosed wherein parasitic sound waves emitted from the rear side of an enclosed audio loudspeaker are prevented from entering the motorcycle rider's ear and from mixing with and distorting the primary sound waves issued from the audio loudspeaker directed at the rider's ear. The acoustically shielded speaker enclosure consists of a pair of joined together cup-shaped housing assemblies forming a shortened cylinder adapted to enclose and secure an audio loudspeaker, the enclosure having openings in one face of the housing assemblies to allow passage of the primary sound waves from the contained loudspeaker. An acoustic shield attached to the speaker enclosure cylindrical side extends to the edge of the ear pocket and is sealed there.

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 modular microphone assembly housed in a handsfree telephone apparatus provides an environment that is isolated from a loudspeaker installed within the apparatus and through which environment the directional and frequency response characteristics of a directional microphone capsule contained within a closable cavity of a microphone mounting receptacle in the assembly are altered via a predetermined internal surface configuration of the receptacle to improve the performance of the apparatus.

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 dual diverging manifold loudspeaker system includes a generally cubically-shaped outer horn housing and an inner dome-like cap member for encapsulating therebetween a compression driver assembly. The loudspeaker system includes a back plate member which is secured adjacent to the rear end of the housing. The back plate member includes a first diverter member for diverting a planar sound wavefront into two diverging sound wavefronts, a pair of second diverter members for splitting the two diverging sound wavefronts into four separate planar wavefronts, and reflector members for deflecting forwardly the four separate planar wavefronts toward an open mouth of the housing. A manifold formed by the inner surfaces of the housing and the inner cap member is used to recombine the four separate planar wavefronts back into a single composite wavefront emanating from the open mouth of the housing.

Abstract: An omnidirectional sound emitter with separate sound sources (1, 2), each comprising a funnel-shaped horn (4), is characterized in that the sound sources (1, 2) are mutually arranged such that the acoustic main axes (6) of the horns (4) lie in essentially one and the same plane (7) and the sound-emitting open ends (8) of the horns are directed towards the central portion of the sound emitter and located at a distance (B.sub.S ; B.sub.D) from one another. Slot-shaped openings (9) are so arranged between the open ends (8) of adjacent horns (4) that sound emitted by the horns is caused to pass in a direction from the sound emitter through the slot-shaped openings (9), thereby to be dispersed through 360.degree. in the said plane (7) such that the sound representation from the sound emitter corresponds to the sound representation from a line source perpendicular to said plane (7).

Abstract: One or more up-firing woofer loudspeakers (12 or 22) are mounted atop a truncated pyramidal enclosure (1 or 21). A down-firing tweeter (5 or 25) is aligned above the woofer. A sound-reflecting sphere (4 or 24) is disposed between the woofer and the tweeter. When the sphere is aligned there-between omni-directional sound is radiated in both horizontal and vertical planes. When the sphere is positioned to the rear, a medium to high frequency forward hemispherical pattern is obtained. This pattern is desirable when the loudspeaker structure is positioned against a wall. Duct ports (3) or a folded horn (20) within the enclosure enhance very low frequency sound.

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: 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..