Abstract: A heat molded, transparent baffle for instrumental sound deflection is disclosed. The Baffle is a single, molded shield that reflects the sound in any direction the audio engineer decides. It is quickly mounted in one minute, transparent, and ready for sound check.

Abstract: An active acoustic meta material system with micro-perforated sheets embedded between porous layers and air gaps, around the output region in front of a speaker, perpendicular to the direction of wave propagation of the sound is disclosed. Sound input is split into two frequency ranges by an active controller, such that a higher frequency range is sent to a traditional speaker which outputs sound via a diaphragm which vibrates in response to electromagnetic signals generated based on the sound input. The sound waves in the lower frequency range are sent to piezoelectric or other type of motion-creating transducers which are mounted to an outer housing or casing containing a plurality of meta material sheets with insulative layers between each meta material sheet. The combination of meta material sheets and insulation layers are calibrated to focus and amplify the vibrational waves which are outputted by the transducers.

Abstract: An active acoustic meta material system with micro-perforated sheets embedded between porous layers and air gaps, around the output region in front of a speaker, perpendicular to the direction of wave propagation of the sound is disclosed. Sound input is split into two frequency ranges by an active controller, such that a higher frequency range is sent to a traditional speaker which outputs sound via a diaphragm which vibrates in response to electromagnetic signals generated based on the sound input. The sound waves in the lower frequency range are sent to piezoelectric or other type of motion-creating transducers which are mounted to an outer housing or casing containing a plurality of meta material sheets with insulative layers between each meta material sheet. The combination of meta material sheets and insulation layers are calibrated to focus and amplify the vibrational waves which are outputted by the transducers.

Abstract: The invention provides a high-frequency acoustic waveguide for use in coaxial loudspeaker systems. The waveguide is made up of a plurality of walls that define a conduit with an input end and an output end. Each of the walls includes a mask layer and a perforation layer. The mask layer has a plurality of holes sized and shaped to make the mask layer acoustically transparent to sound waves below a crossover frequency. The perforation layer has a plurality of micro-perforations sized and shaped to make the perforation layer acoustically opaque to sound waves above the crossover frequency. The waveguide directs sound waves above the crossover frequency, and is acoustically transparent to sound waves below the crossover frequency.

Abstract: An acoustical phase plug for use in loudspeakers produces a planar rectangular wavefront, or a wavefront with a desired amount of curvature, from the output aperture of the phase plug device when presented with a planar circular wavefront at the input aperture. The phase plug utilizes a waveguide that equalizes the travel paths from the input aperture to the output aperture. The waveguide essentially eliminates surface discontinuities thereby resulting in the reduction of diffraction of the wavefront travelling through the phase plug device.

Abstract: A phasing plug for a compression driver includes a base portion and a hub portion. The base portion includes a first side, a second side, and a plurality of apertures extending between the first and second sides. The hub portion extends from the base portion along an axis. The hub portion includes an outer surface and a plurality of ribs disposed on the outer surface. A plurality of recesses are defined by the outer surface and respective pairs of adjacent ribs. At least one aperture fluidly communicates with at least one of the recesses.

Abstract: A waveguide configured to function as a high frequency waveguide for a high frequency sound source mounted to the waveguide, and to function as an acoustical low pass filter for a low frequency sound source mounted behind the waveguide in a multi-way loudspeaker system. The waveguide includes openings that overlay the vibrating surface of the low frequency source. The openings are configured by selection of various geometrical parameters to tailor filtering characteristics as desired.

Abstract: A speaker module and a mobile device having the speaker module are provided herein. The speaker module includes a speaker unit and a speaker box. The speaker box has a wall defining an aperture receiving the speaker unit therein. The speaker box has a first speaker chamber, a second speaker chamber and a connecting section connecting the first speaker chamber and the second speaker chamber. The cross-sectional height of the space of the connecting section is lower than that of the first speaker chamber or the second speaker chamber. In other option, the space of the connecting section is smaller than that of the first speaker chamber or the second speaker chamber.

Abstract: A parametric loudspeaker system is described which is based upon the FM-modulation of an ultrasound carrier. Known systems work with AM-modulation. The FM-modulation produces a good matching to the resonant transducer such as the conventionally employed piezo-ceramic transducers. The resonance slope of the transducers is used for FM/AM-conversion. This FM-resonance principle can advantageously be employed in a multi-path loudspeaker system, in which the transducer works in the optimal resonance range in each of the paths. With the conventional AM-modulation this is not possible. The FM-resonance principle can also be used in resonance-free or resonance-poor transducers, such as for example electrostatic transducers.

Abstract: This invention provides a radiation boundary integrator (“RBI”) for integrating sound radiation from mid-range and high-frequency sources in multi-way loudspeakers. The RBI is a substantially solid boundary that is placed over the mid-range speakers to provide smooth, wave-guiding side walls to control the angular radiation of the high-frequency sound waves emanating from the high-frequency sound sources. To allow the mid-range frequency sound waves generated from mid-range sound sources to pass through the RBI, the RBI is designed with openings. To further prevent the possibility of having high-frequency sound radiate through the openings in the RBI, the RBI may be designed with porous material in the openings of the RBI. The porous material would be transparent to the mid-range sound radiation, but would prevent the high-frequency sound radiation from being disturbed by the openings in the RBI.

Abstract: An acoustic enclosure for a single sound transducer has sound pressure apertures near the end where the transducer is located, and sound apertures in a wall at the other end. The sound apertures enable the low, mid-range, and high frequency sounds to exit the enclosure along different paths. The sound aperture end can be flat or contoured with one or two outwardly extending members having straight or tapered end walls in which the mid-range and high frequency sound apertures are formed. One or two inwardly extending members can also be provided in the interior of the enclosure. The sound pressure apertures can be fixed or adjustable.

Abstract: An electric fan system has a first electric blower 10, which utilizes a brushless motor, and a second electric blower, which utilizes a brushed motor, for distributing the cooling air to the radiator and the condenser. The system has an electronic engine control unit which activates only the first electric blower when it determines that the cooling water temperature is less than T2, and activates both the first and second electric blowers when it determines that the cooling water temperature is T2 or higher. The water temperature is based on a detection output from a cooling water temperature sensor. Thus, since the electric blower is not activated unless the cooling water temperature becomes T2 or higher, use of the brushed motor is limited and its life is increased.

Abstract: An electroacoustical transducer has an enclosure having a thickness substantially smaller than the width and the depth. The transducer includes a first rigid sheet, a second rigid sheet, and a spacing structure for spacing the first rigid sheet from the second rigid sheet to define an acoustic enclosure, having a top, a bottom and a side edge. The top includes the first rigid sheet and the bottom includes the second rigid sheet. The transducer includes an acoustic transducer for exchanging sound waves with the acoustic enclosure. The enclosure has a plurality of outlet points.

Abstract: In an adapted to be used in an on-ear mode and in an off-ear mode a holder compartment (6)accommodates a first transducer (20)and a second transducer (25)and the holder compartment (6)is bounded by a bounding wall (7)formed with internal sound ports (10, 11)and at least one additional internal sound port (22), and an outer wall (3)formed with external sound ports (15, 16)is spaced at a distance from the bounding wall (7), and at least one additional external sound port (19)is provided between the bounding wall (7)and the outer wall (3), and the two transducers (20, 25)can be driven with useful signals of the same phase in the off-ear mode and with useful signals of opposite phase in the on-ear mode.

Abstract: An apparatus (1) is constructed for operation in an on-ear mode and an off-ear mode and includes a housing wall (6) having passages (15) to allow useful sound waves to pass through, and additional passages (16) to allow the passage of sound waves which are in phase opposition to the useful sound waves and includes, behind the housing wall (6), an electroacoustic transducer (7) having a diaphragm (12), the transducer (7) being accommodated in an acoustically substantially impervious holder compartment (17). Sound-pressure frequency response influencing structures (18, 19) are arranged both in the sound path between the frontside (13) of the diaphragm (12) and the passages (15), and in the sound path between the rearside (14) of the diaphragm (12) and the additional passages (16).

Abstract: An improved acoustic horn for loudspeakers is provided. The acoustic horn of the referred embodiment of the present invention includes a one piece body that incorporates damping material within the body. Preferably, the one piece body is slotted and vibration damping material is provided within the slots. The horn is fabricated by casting from suitable metals and metal alloys. In the preferred embodiment, the body comprises four outwardly curved and flared side walls and is generally rectangular. Each wall of a pair of the opposed side walls is cast with a slot. Vibration damping material is provided in each slot to substantially reduce the structural resonances of the one piece body, so that the acoustic horn has enhanced vibration damping. Various vibration damping materials that are flexible relative to the body and have a high loss tangent are used. Suitable materials include hot melt adhesives, epoxy resins, and commercially available elastomeric materials.

Abstract: An acoustic horn imparts energy at a selected wavelength, frequency, and amplitude. The horn has at least one nodal plane and a natural frequency of vibration. The horn has an outer surface and at least one cutout located in the outer surface. The cutout is located at a longitudinal location on the surface that does not contact the nodal plane. The horn length is a function of the shape, size, number, and location of the cutouts, and is less than the length of a solid horn having the same natural frequency of vibration. The horn can vibrate at a natural frequency and the length of the horn can be less than one-half wavelength of vibration.

Abstract: A jet engine test cell capable of dissipating infrasound. The test cell includes an engine test section, an augmentor and an exhaust stack having a structure near its open end for dissipating infrasound.

Abstract: An electroacoustical transducing system for exchanging pressure wave energy with a medium that propagates pressure waves includes an electroacoustical transducer having a vibratile surface. At least one low-loss pressure waveguide has one end adjacent to the vibratile surface and the other end adjacent to the medium. At least one acoustic immittance element is imposed in the length of the waveguide dimensioned and positioned to alter the transfer characteristic of the waveguide between the vibratile surface and the medium at the other end.

Abstract: The purpose of the invention is to direct, in a coherent fashion, audible frequencies, particularly, low frequencies and especially those below 90 cycles. The advantage to directing low frequencies to acute projection patterns previously thought impossible is to reduce low frequency feedback in live performance applications and to reduce low frequency room reverberation in all applications which results in a faster decay time of the low frequency produced. Acute directivity of low frequencies is achieved by using a rectangular enclosure in the vertical axis and by placing a rectangular port on the horizontal axis centrally located between two transducers. The three-point projection pattern is established so that the three points of projection can act to set up a carrier wave and side band waves effect. Alternatively, one transducer can be centrally located between two rectangular ports.

Abstract: The present invention relates to an acoustical transducer enclosure which is particularly adapted for directing sound waves and is housed in a multisided enclosure. The enclosure has a cylindrical hollow tube, held in position by a pair of forward baffles, with a speaker housed within. Forward wave guides line the interior area of the enclosure. A wave form vent is located on a horizontal plane with the speaker at one end of the cylindrical hollow tube. A rear back pressure booster baffle is located at the end of the cylindrical hollow tube with a wave splitter which is located proximate the rear back pressure booster.

Abstract: A horn loudspeaker has an opening formed in a wall of a horn, and a tubular duct is provided along the horn and communicated with the opening. The length L of the duct is expressed as, L.perspectiveto.c/4fr-0.4d where c is a velocity of sound, fr is a frequency a sound pressure of which is to be reduced, and d is an inner diameter of the duct.

Abstract: A baseball bat having the functions of resonators and microphones is designed to be hollow and has a receiver cup disposed at its inner top end in such a manner that a spring may be hooked to its bottom while the other end of the spring is hooked to a tuning bar fixed at an end cap fittedly adhered to the bottom end of the bat. Besides, a plurality of sound-amplifying holes are formed on the surface of the bat at proper positions. Whenever the bat is vibrated by external force, the spring inside it shall vibrate accordingly and the sound-wave so produced resonates within the hollow bat which serves as a resonance box. When the sound-wave passes through the sound-amplifying holes on the surface of the bat, a special striking tone shall be produced. Such special tone can be produced either when the bat stikes a ball or when the bat is purposely vibrated or waved. When speaking into the receiver cup, the wave of voice may be amplified through the resonance effect of the hollow bat.

Abstract: An acoustic apparatus (10) adapted for use as either a sound projector or a ound receiver. The apparatus (10) comprises a bundle (20) of individual sound tubes (21, 22) disposed in a tube array unit (14) which rests on a support unit (13) operatively engaged with an acoustic unit (11). Only the ends of the individual sound tubes (21, 22) are provided with a plurality of spaced discrete sound ports (25).

Abstract: A horn shaped baffle is provided in the front of a loudspeaker. Escape holes are formed in the horn shaped baffle so as to emit sound waves deviated from the axis of the loudspeaker. A sound absorptive panel is provided on the outside of the baffle so as to cover the holes.

Abstract: An acoustic apparatus comprises a resonator, a vibrator, and a vibrator drive circuit for an improved bass sound reproduction. The resonantor has a resonance radiation unit for radiating an acoustic wave by resonance, and the vibrator has a diaphragm constituting a part of the resonator and disposed in the resonator. The vibrator drive circuit for driving the vibrator has a negative impedance component in an output impedance, and a reaction from the resonator to the diagram is canceled upon driving of the resonator. Accordingly, the presence of the vibrator is invalidated as viewed from the resonator, and the vibrator and the resonator can be independently designed. As a result, the resonator can be realized in a compact size, and the resonance acoustic wave can be radiated powerfully.

Abstract: An acoustic apparatus comprising a resonator having a resonance radiation unit for radiating an acoustic wave by resonance, a vibrator arranged in the resonator, and a vibrator drive means for driving the vibrator. The vibrator has a diaphragm having a direct radiator portion for directly radiating an acoustic wave, and a resonator driver portion for driving the resonator. The vibrator drive means has a drive control means for controlling the drive condition so as to equivalently reduce or invalidate the internal impedance inherent to the vibrator.

Abstract: A speaker system which has a speaker unit with a diaphragm and an acoustic path provided on the front side of the diaphragm so as to guide sound waves emitted from the diaphragm. The acoustic path is defined by a sound absorbing member. The space in the acoustic path and the sound absorbing member is separated by a partition member which is disposed in such a manner that at least a portion of the sound absorbing member is exposed to the space in the acoustic path, except that the portion of the sound absorbing member just adjacent the diaphragm is not exposed to the acoustic path. This arrangement eliminates peaks and troughs of resonance determined by the length of the acoustic path, so that flat sound pressure frequency characteristics can be obtained over a wide range up to high-pitch tone region.

Abstract: The present invention relates to acoustic filters for use in combination with a multiple transducer system which includes a low frequency transducer subsystem and a high frequency transducer subsystem each mounted with respect to an axis directed towards the listening environment so as to function acoustically as though having coaxial acoustic centers. Preferably, the acoustic filter is constructed from one or more acoustical elements such as small tubes, narrow slits, perforated baffles, enclosed cavities, and the like combined so as to provide an acoustical impedance which is relatively low for the frequencies produced by the low frequency transducer but which is relatively high for the frequencies associated with the high frequency transducer.

Abstract: Highly directional response patterns can be obtained by connecting microphones or loudspeakers with tubular coupling path structures. The coupling paths comprise a plurality of elements (110,111 . . . 157) arranged in pairs (110,111; 112,113; . . . 156,157) so that for every element (110) below a center line (102) there is an element (111) above the line. Furthermore, the relationship between the element pairs is nonlinear. The desired directional response comprises one main lobe and a plurality of substantially smaller lobes below a determinable threshold value. The elements may be a bundle of tubes (90) or a plurality of apertures (110,111, . . . 157) in a single tube (100).

Abstract: An electret transducer comprising a diaphragm (3) arranged between first (1 or 1') and second electrodes with at least one electrode (2) arranged at some distance from the diaphragm as a stationary electrode formed with holes (5). An air gap (4) is formed between the diaphragm (3) and said electrode (2). In the case of one air gap the air gap width d and the area A (7) enclosed by four holes which are situated nearest each other in said electrode (2) are selected so that the following equation is satisfied ##EQU1## where .eta. is the dynamic viscosity of the air in the air gap. In the case of an air gap on each side of the diaphragm, the air gap widths d.sub.1 and d.sub.2 and the said areas A.sub.1 and A.sub.

Abstract: A loudspeaker horn is described, which produces good coupling of sound to the atmosphere, while avoiding perturbations in magnitude and phase that would produce large narrow-frequency losses or transient distortions. The horn includes a major sound-reflective portion of typical horn shape, and also includes a buffer extending around the large end of the horn. The buffer has a sound absorption coefficient about halfway between the almost zero absorption coefficient of the major portion of the boundary walls of the horn and the 100% absorption coefficient of the ambient atmosphere, to couple sound to the atmosphere more efficiently, and with an efficiency that is relatively constant with frequency. A horn of largely rectangular cross-section, has corner regions covered with highly sound absorbing material, to minimize transient distortions such as "ringing".

Abstract: An exponential folded horn loudspeaker enclosure is built so that all of its components are coaxial with respect to a line that is equidistant from three cooperating surfaces, including floor or ceiling, as well as the customary two walls of a corner. Perfect symmetry with all three cooperating surfaces permits a smooth transition to these surfaces, so that they become a balanced extension of the exponential horn, more than doubling its effective length. Approaching the configuration of a large ideal horn, this geometry is uniquely free of discontinuities and artificial resonances that are needed in other enclosures for boosting low frequency response; therefore, efficiency and fidelity of low frequency response are greatly increased over other enclosures of comparable size.

Abstract: The present invention is an acoustic filter for use in combination with a coaxial loudspeaker system which includes a low frequency loudspeaker and a high frequency speaker which is axially aligned with the low frequency loudspeaker. The acoustic filter includes a pair of parallel, perforated sheets which are separated from each other a suitable distance and which are joined together at their peripheries in any appropriate manner so that they enclose an airspace therebetween in order to form a single section filter. The acoustic filter is disposed between the low frequency loudspeaker and the high frequency loudspeaker so the acoustic filter inhibits the high frequency sounds of the high frequency loudspeaker from interacting with the internal sidewall of the conically shaped diaphragm of the low frequency loudspeaker.

Abstract: In a moving-coil type loudspeaker, a tubular member of a length longer than the wave-length of any one of the frequencies in a desired frequency range and having a constant cross-sectional area along its length, is coupled, at one end thereof, with one side of a vibrating plate or diaphragm through an acoustic transformer constituted by a cavity formed therebetween, whereby the loudspeaker is capable of reproducing sounds with high fidelity particularly in extremely low frequency ranges.