US3903989A - Directional loudspeaker - Google Patents

Directional loudspeaker Download PDF

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Publication number
US3903989A
US3903989A US471267A US47126774A US3903989A US 3903989 A US3903989 A US 3903989A US 471267 A US471267 A US 471267A US 47126774 A US47126774 A US 47126774A US 3903989 A US3903989 A US 3903989A
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United States
Prior art keywords
baffle
loudspeaker
longer
generally
edge
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US471267A
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English (en)
Inventor
Benjamin B Bauer
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
CBS Broadcasting Inc
Original Assignee
CBS Inc
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Filing date
Publication date
Application filed by CBS Inc filed Critical CBS Inc
Priority to US471267A priority Critical patent/US3903989A/en
Priority to NL7504014A priority patent/NL7504014A/
Priority to AU80099/75A priority patent/AU8009975A/en
Priority to GB17471/75A priority patent/GB1499407A/en
Priority to FR7515268A priority patent/FR2272563A1/fr
Priority to DE19752521950 priority patent/DE2521950A1/de
Priority to BE2054348A priority patent/BE829157A/xx
Priority to LU72503A priority patent/LU72503A1/xx
Priority to JP6013275A priority patent/JPS5616998B2/ja
Application granted granted Critical
Publication of US3903989A publication Critical patent/US3903989A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
    • H04R1/00—Details of transducers, loudspeakers or microphones
    • H04R1/20—Arrangements for obtaining desired frequency or directional characteristics
    • H04R1/22—Arrangements for obtaining desired frequency or directional characteristics for obtaining desired frequency characteristic only 
    • H04R1/26—Spatial arrangements of separate transducers responsive to two or more frequency ranges
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
    • H04R1/00—Details of transducers, loudspeakers or microphones
    • H04R1/20—Arrangements for obtaining desired frequency or directional characteristics
    • H04R1/32—Arrangements for obtaining desired frequency or directional characteristics for obtaining desired directional characteristic only
    • H04R1/323—Arrangements for obtaining desired frequency or directional characteristics for obtaining desired directional characteristic only for loudspeakers
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
    • H04R2201/00—Details of transducers, loudspeakers or microphones covered by H04R1/00 but not provided for in any of its subgroups
    • H04R2201/02—Details casings, cabinets or mounting therein for transducers covered by H04R1/02 but not provided for in any of its subgroups
    • H04R2201/025—Transducer mountings or cabinet supports enabling variable orientation of transducer of cabinet

Definitions

  • a loudspeaker system having a cabinet with two compartments, a first of which contains a low-frequency loudspeaker for producing an omnidirectional radiation pattern, and the second compartment, above the first, containing a rotationally adjustable vertically oriented baffle on which are supported additional loudspeaker motors designed to cover the midand highfrequency bands of the audio frequency spectrum.
  • the baffle is so shaped and the additional loudspeaker motors located in positions thereon that they operate as high-efiiciency gradient or dipole loudspeakers over a significant portion of their respective frequency ranges, whereby the directivity of the loudspeaker system can be controlled by adjustment of the position of the baffle relative to the cabinet.
  • the sound field produced by an output signal from a given loudspeaker driver is increasingly narrower with increase in the signal frequency, with the consequence that the midand high-frequency signals are severely attenuated in directions oflset greater than about 30 to 60 from the central axis of the loudspeaker array, depending on the dimensions of the driver and the frequency of the signal.
  • the nature of this problem is described in detail in a paper by applicant entitled Broadening the Area of Stereophonic Perception" which appeared in the Journal of the Audio Engineering Society, Vol. 8, No. 2, pp. 9l94 (I960), and a loudspeaker arrangement representing a solution to the problem is described and claimed in applicants Pat. No. 3,080,012 assigned to the assignee of the present application.
  • FIG. 1 of the drawings shows a listening area 98 in which are placed two loudspeakers 100 and 102 carrying a sterophonic program consisting of left and right channel signals, L and R, applied to the respective loudspeakers, together with a center channel signal, C, which is applied equally to both loudspeakers.
  • L and R left and right channel signals
  • C center channel signal
  • a center signal, C When a center signal, C, is applied to both loudspeakers, a listener located at position 108, in front of the loudspeakers and on a line midway between the loudspeakers, is subjected to equal sound pressures from the respective loudspeakers represented by the vectors 110 and 112. Therefore, the signal C appears to originate from a point midway between the loudspeakers, as indicated by the dashed line circle 114.
  • the listener moves in the direction of the arrow 116 to a new position 118, he now receives a lower level signal from loudspeaker than from loudspeaker 102 because of two factors: (I) the radiation in the direction of position 118 from loudspeaker 100 is now represented by the shortened arrow 120, while the radiation in the direction of position 118 from loudspeaker 102 is as indicated by the longer arrow 122, and (2) the distance from the loudspeaker 100 to position 118 is greater than the distance from loudspeaker 102, thus further increasing the relative difi'erence in sound intensity from the two loudspeakers. In short, to a listener at position 118, the majority of the sounds from the system will appear to arrive from loudspeaker 102; this destroys the stereophonic sound stage in between the loudspeakers.
  • a significant improvement in the positional freedom of the listener can be achieved by providing the loudspeakers with a circular or similar directional characteristic and by positioning the loudspeakers at an angle of approximately 120 with respect to each other as shown in FIG. 2.
  • Such a circular characteristic can be provided, over a wide range of frequencies by utilizing a dipole action.
  • a dipole directional action is obtained by mounting a loudspeaker driver in a small baffle so as to enable it to radiate equally backwardly and forwardly of the baffle.
  • the baffle is specially shaped and the mid-and upperfrequency range loudspeakers are mounted in positions thereon such that the baffle complements the frequency range of the respective loudspeakers to thereby produce high-efficiency operation of the additional loudspeakers and desirable directional characteristics for the individual additional loudspeakers.
  • Adjustment of the movable baffle supporting the directional loudspeakers permits the loudspeaker cabinet to be placed in the most appropriate place to suit the room decor while orienting the sound field of the gradient loudspeakers in a direction to achieve optimum acoustical performance.
  • the rotationally adjustable baffle together with the gradient loudspeakers supported thereon are confined between parallel planes to further improve the performance and efficiency of the gradient transducer.
  • the baffle may be pivotally supported on the parallel planes, or may be supported in a frame which, in turn, is mounted on trunnions supported on one of the parallel planes, so that the plane of the baffle may be varied universally.
  • the disclosed loudspeaker system can be used alone, and it is particularly useful in pairs in a stereophonic array for achieving the aboveoutlined objectives, or in a quadraphonic array.
  • FIGS. 1 and 2 are schematic plan views of prior art loudspeaker system arrangements
  • FIG. 3 is a perspective view of a loudspeaker system embodying the present invention.
  • FIG. 4 is a fragmentary front elevation view of the adjustable baffle of the loudspeaker system of FIG. 3;
  • FIG. 4A is a cross-sectional view taken along line 4A4A of FIG. 4;
  • FIG. 4B is a cross-sectional view taken along line 4B-4B of FIG. 4;
  • FIG. 4C is a cross-sectional view taken along line 4C-4C of FIG. 4;
  • FIG. 5 is a schematic diagram depicting typical ranges of frequencies covered by the various loudspeakers of the system
  • FIG. 6 is a polar plot illustrating the polar patterns of the individual loudspeakers utilized in the system
  • FIG. 7 is a fragmentary perspective view of the loudspeaker system illustrating a modification of the system of FIG. 3;
  • FIG. 8 is a fragmentary front elevation view of the adjustable baffle of the system of FIG. 3, showing an alternative mounting thereof.
  • a preferred form of a loudspeaker system embodying the invention consists of a generally cubical cabinet having two compartments: a lower compartment 302 which is essentially a rectangular shaped box closed on all six sides, constructed of wood or other suitable material, and an upper compartment defined by the plate 326 forming the upper surface of the lower compartment and by a cover plate 322, also preferably formed or wood, supported at its corners by posts 324.
  • the upper compartment is closed at the top and bottom but has generally open sides; acoustically transparent grilles or panels (not shown) may be aflixed to the walls of the cabinet for ornamental purposes, and felt or similar sound absorbent material may be applied to the upper surface of the plate 326 and to the lower surface of plate 322, to minimize sound reflections therefrom.
  • a conventional woofer or low-frequency loudspeaker driver 306 is supported in a hole 304 in the front wall of the lower compartment 302 so as to constitute, when the lower compartment is completely sealed, an infinite baffle".
  • the lower compartment may be provided with an opening or tube 308 communicating with the upper compartment and proportioned relative to the volume of the lower compartment and the acoustical properties of the loudspeaker 306 to provide the desired low-frequency response. It having been experimentally determined that low frequency sounds up to approximately 200 Hz. do not significantly contribute to the sense of direction, the low-frequency portion of the loudspeaker system is designed to be omnidirectional and to perform most efficiently up to a frequency of about 2001-12. It will be understood that this frequency is not exact and may be selected to have different values, depending upon the application.
  • the upper compartment encloses the gradient portion of the loudspeaker system, which consists of a specially shaped planar baffle 310 supported in a vertical position between the upper plate 326 of the lower compartment and the lower surface of the cover plate 322 and mounted on suitable pivots 318 and 320 respectively secured to the top surface of the lower compartment and the under surface of cover plate 322 for rotational adjustment about a vertical axis Y-Y, and upon which are mounted, for movement with the baffle, a desired number of loudspeaker drivers, in this example, four.
  • the baffle 310 has parallel upper and lower edges, the lower edge 310a being appreciably shorter than the upper 3I0b for reasons which will become apparent, and the upper and lower edges are joined by curved side edges 310C and 310d located symmetrically on opposite sides of the axis YY.
  • the illustrated cur vature of the side edges 3I0c and 310d in effect divides the area of the baffle into two generally rectangular zones of different sizes: a smaller zone defined by the lower edge 310a and the generally perpendicular portion of the side edges 3l0cand 310d extending approximately one-third the vertical height of the baffle, and a second, larger zone defined by the upper edge 3l0b and the remaining portion of the side edges 310C and 310d.
  • the aforementioned Bauer patent teaches that a loudspeaker provided with a small baffle constitutes a suitable dipole radiator for sound energy. It is important to keep in mind, however, that when a loudspeaker is installed in an open baffle, the sounds radiated from the back part of the cone tend to cancel those radiated from the front, making it important that the front-to-back distance defined by the baffle be properly related to the wavelength of the sound being considered so as to avoid undue cancellation.
  • the front-to-back path should be no less than onesixth wavelength, and no more than three-fourths wavelength; this, in effect, defines that the frequency range handled by a gradient loudspeaker in general should cover a frequency range of approximately 4 to 5: i. It follows that if several loudspeakers, designed to cover different frequency ranges, and to be operated in a gradient manner, are to be mounted on a single baffle, the baffle must be so shaped, and the loudspeakers appropriately placed thereon, that the baffle provides for each loudspeaker the appropriate front-to-back acoustical distance.
  • the width of the baffle for the loudspeaker 312 based on the lowest frequency of 200Hz. (for which the wavelength is l72cm.), should be l72cm./6 29cm, or approximately lft.
  • the width of the baffle should be approximately 2% inches. It will be understood that these calculations are based on the velocity of sound in air of 34,400cm. per second.
  • the upper and lower edges of the baffle are 12 inches and 2% inches long, respectively, and are joined by side edges that are curved so as to provide the appropriate front-to-back distances for the loudspeakers 312 and 314. It is, of course, to be understood that these dimensions are appropriate for the frequency ranges assumed for loudspeakers 312 and 314 and would be suitably adjusted for loudspeakers designed to cover different frequency ranges.
  • FIG. 4B which is a cross-section taken along line 4B4B of FIG. 4
  • FIG. 4C which is a cross-sectional view taken along line 4C-4C of P10. 4
  • the location of the upper mid-range loudspeaker 314 in the narrower portion of the baffle provides the desired front-to-back path length D for its freuqncy range.
  • tweeter or high-frequency loudspeakers 316 designs are commercially available which will normally provide the desired directional pattern, approximating a circle of revolution, and which therefore may be used in conventional manner by mounting them in openings in the baffle 310. That is, the shape of the baffle is not critical to their operation, and therefore they can be mounted at any convenient location on the baffle, in the illustrated example at either side of the lower mid-range loudspeaker 312.
  • FIG. 3 Another advantageous feature of the structure illustrated in FIG. 3 is that containment of the baffle 310 between the upper surface 326 of compartment 302 and the under surface of cover plate 322 causes the radiation from the gradient or dipole loudspeakers to be guided around the side edges of the baffle board as depicted in FIGS. 43 and 4C rather than travelling over the upper edge or under the lower edge of the baffle board, this contributing to the overall efficiency of the loudspeaker system.
  • the incoming signal is preferably divided between the four types of loudspeaker motors by coupling it through suitable dividing and frequency compensating networks, as schematically shown in FIG. 5.
  • FIG. 6 shows the polar patterns of the individual loudspeakers with the baffle 310 positioned to radiate from the front of the cabinet.
  • the omnidirectional pattern of the woofer or low-frequency loudspeaker 306 is depicted by the circle 600
  • the polar patterns of the low mid-range and high mid-range loudspeakers 312 and 314 are in the form of cosine or figure-8 patterns as depicted at 602
  • the polar pattern of the tweeters 316 over their operating range is illustrated as the somewhat narrowed circle 604.
  • the baffle 310 in the preferred embodiment is mounted with its longer edge 3l0b adjacent the cover plate 322, it is possible to invert it as shown in FIG. 8 so that its wider portion will be down and the narrower portion adjacent the cover plate.
  • This alternative position of the bafile gives somewhat less satisfactory operation, however, because the upper midrange loudspeaker 314 would tend to be shielded from the listener whose cars would normally be at a level higher than the level of the cover plate 322.
  • mount the loudspeaker driver in planes other than the planes of the baffle 310 and to construct the baffle itself so as to be non-planar; however, in the interest of simplicity and ease of manufacture, the illustrated construction is to be preferred.
  • the loudspeaker system illustrated in FIG. 3 is subject to significant modification without departing from the spirit of the invention.
  • the cabinet may be only as long as it is deep.
  • Another modification, illustrated in F K]. 7 and especially applicable to this modifled cabinet construction is to pivotally mount the baffle 310 in an open rectangular frame 701 having a height corresponding generally to the spacing between the plates 322 and 326, which, in turn, is pivotally supported by trunnions 703 joumalled in a pair of supports 702 which are affixed to the top plate 326 of the lower enclosure.
  • This alternative form of mounting the baffle permits the plane of the baffle and, accordingly, the di rectivity of the radiation pattern produced by the loud speaker drivers mounted thereon, to be varied universally, including the possibility of laying the cabinet over on one of its sides.
  • the frame 701 would be rotationally adjusted to lie in a plane parallel to the floor so as to maintain a substantially vertical orientation of the baffle 310.
  • a directional loudspeaker system comprising:
  • a cabinet having a substantially closed lower compartment having a baffle board at the front thereof and a separate generally open-sided upper compartment,
  • a first loudspeaker driver for the low frequency range mounted on the front baffle board of said lower compartment to cause sound emanating therefrom to be essentially omnidirectional
  • a generally planar baffle having substantially parallel upper and lower edges of unequal length joined by side edges supported vertically within said upper compartment and mounted for rotational adjustment relative to the cabinet about a generally vertical axis, and
  • a third loudspeaker driver for the upper midrange of frequencies is mounted on said baffle between the side edges and generally adjacent the shorter of the other two edges.
  • the system of claim 2 further including fourth and fifth loudspeaker drivers for the high range of frequencies mounted on said baffle one on each side of said second loudspeaker and generally adjacent the longer of said other two edges.
  • the system of claim 8 further including fourth and fifth loudspeaker drivers for the high range of frequencies mounted on said baffle in said second zone one on each side of said second loudspeaker driver.
  • the means for supporting said baffle comprises an open frame mounted for rotational adjustment about a generally horizontal axis, and means for pivotally supporting said baffle on said frame for rotational adjustment about a generally vertical axis.

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  • Health & Medical Sciences (AREA)
  • Otolaryngology (AREA)
  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Acoustics & Sound (AREA)
  • Signal Processing (AREA)
  • Obtaining Desirable Characteristics In Audible-Bandwidth Transducers (AREA)
US471267A 1974-05-20 1974-05-20 Directional loudspeaker Expired - Lifetime US3903989A (en)

Priority Applications (9)

Application Number Priority Date Filing Date Title
US471267A US3903989A (en) 1974-05-20 1974-05-20 Directional loudspeaker
NL7504014A NL7504014A (nl) 1974-05-20 1975-04-04 Luidsprekerstelsel.
AU80099/75A AU8009975A (en) 1974-05-20 1975-04-14 Directional loudspeaker
GB17471/75A GB1499407A (en) 1974-05-20 1975-04-28 Directional loudspeaker
FR7515268A FR2272563A1 (enrdf_load_html_response) 1974-05-20 1975-05-15
DE19752521950 DE2521950A1 (de) 1974-05-20 1975-05-16 Lautsprecheranordnung mit richtwirkung
BE2054348A BE829157A (fr) 1974-05-20 1975-05-16 Enceinte acoustique directive
LU72503A LU72503A1 (enrdf_load_html_response) 1974-05-20 1975-05-16
JP6013275A JPS5616998B2 (enrdf_load_html_response) 1974-05-20 1975-05-20

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US471267A US3903989A (en) 1974-05-20 1974-05-20 Directional loudspeaker

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US3903989A true US3903989A (en) 1975-09-09

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US471267A Expired - Lifetime US3903989A (en) 1974-05-20 1974-05-20 Directional loudspeaker

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JP (1) JPS5616998B2 (enrdf_load_html_response)
AU (1) AU8009975A (enrdf_load_html_response)
BE (1) BE829157A (enrdf_load_html_response)
DE (1) DE2521950A1 (enrdf_load_html_response)
FR (1) FR2272563A1 (enrdf_load_html_response)
GB (1) GB1499407A (enrdf_load_html_response)
LU (1) LU72503A1 (enrdf_load_html_response)
NL (1) NL7504014A (enrdf_load_html_response)

Cited By (19)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4054750A (en) * 1976-06-18 1977-10-18 Ralph Montgomery Full range rotatable speaker housing with oppositely directed speakers
US4112256A (en) * 1973-08-24 1978-09-05 Stig Carlsson Loudspeaker and stereophonic loudspeaker system
US4466505A (en) * 1982-04-19 1984-08-21 Temporal Dynamics Research, Inc. Sound reproducing combination
US4598789A (en) * 1982-04-19 1986-07-08 Temporal Dynamics Research, Inc. Sound reproducing
EP0172705A3 (en) * 1984-08-20 1987-08-19 Bose Corporation Loudspeaker system
US4742548A (en) * 1984-12-20 1988-05-03 American Telephone And Telegraph Company Unidirectional second order gradient microphone
US4953223A (en) * 1988-09-08 1990-08-28 Householder George G Speaker mounting system
US6496586B1 (en) * 1998-01-07 2002-12-17 New Transducers Limited Thin Loudspeaker
US20040105559A1 (en) * 2002-12-03 2004-06-03 Aylward J. Richard Electroacoustical transducing with low frequency augmenting devices
US20040112671A1 (en) * 2002-08-17 2004-06-17 Kh Technology Corporation Loudspeaker unit and assembly
US20040196982A1 (en) * 2002-12-03 2004-10-07 Aylward J. Richard Directional electroacoustical transducing
US20090277713A1 (en) * 2005-04-21 2009-11-12 Ambrose Thopson Acoustic Loading Device for Loudspeakers
US20100177921A1 (en) * 2009-01-14 2010-07-15 Richard Bos Response speaker system
EP2043381A3 (en) * 2007-09-28 2010-07-21 Bang & Olufsen A/S A method and a system to adjust the acoustical performance of a loudspeaker
US20100189299A1 (en) * 2009-01-23 2010-07-29 John Grant Microphone
EP2637417A1 (de) * 2012-03-07 2013-09-11 RE-Speakers Gehäuse für Dipollautsprecher, Verfahren zur dessen Herstellung und Dipollautsprecher
US20160173986A1 (en) * 2014-12-15 2016-06-16 Gary Lloyd Fox Ultra-low distortion integrated loudspeaker system
WO2017186312A1 (en) * 2016-04-29 2017-11-02 Burmester Audiosysteme Gmbh Loudspeaker
US20230145186A1 (en) * 2021-11-09 2023-05-11 Fca Us Llc Battery electric vehicle active sound and vibration enhancement systems

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FR2413839A1 (fr) * 1977-12-29 1979-07-27 Setton Jack Ensemble de haut-parleurs a voies multiples
FR2465385A1 (fr) * 1979-09-14 1981-03-20 Pioneer Electronic Corp Enceinte a plusieurs haut-parleurs pour vehicule automobile
JPS59101334A (ja) * 1982-11-30 1984-06-11 Yoshida Kogyo Kk <Ykk> 合成樹脂製務歯を有するスライドフアスナ−チエンの製造装置
JPS62282783A (ja) * 1986-05-31 1987-12-08 Mitsubishi Electric Corp 金属ストリツプの接続方法およびその装置
DE3823482A1 (de) * 1988-07-11 1990-01-25 Bartsch Klaus Lautsprecheranordnung
DE3915204A1 (de) * 1989-05-10 1990-11-15 Magnat Electronik Gmbh & Co Kg Lautsprecherbox
DE3915205A1 (de) * 1989-05-10 1990-11-15 Magnat Electronik Gmbh & Co Kg Lautsprecherbox mit einem basisgehaeuse und einem zweitgehaeuse
GB2350964B (en) * 1999-06-10 2001-08-22 Stefan Gamble Loudspeaker driver high frequency central imaging system

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US3483945A (en) * 1967-08-28 1969-12-16 Musitronic Inc Omnidirectional sound system
US3491204A (en) * 1967-05-12 1970-01-20 Stanley A Sherno Sound system circuit and cabinet assembly
US3754618A (en) * 1970-11-30 1973-08-28 Pioneer Electronic Corp Speaker system

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JPS4863714A (enrdf_load_html_response) * 1971-11-25 1973-09-04
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US2927657A (en) * 1958-01-29 1960-03-08 Louis J Patla Loud speaker system
US3491204A (en) * 1967-05-12 1970-01-20 Stanley A Sherno Sound system circuit and cabinet assembly
US3483945A (en) * 1967-08-28 1969-12-16 Musitronic Inc Omnidirectional sound system
US3754618A (en) * 1970-11-30 1973-08-28 Pioneer Electronic Corp Speaker system

Cited By (29)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4112256A (en) * 1973-08-24 1978-09-05 Stig Carlsson Loudspeaker and stereophonic loudspeaker system
US4054750A (en) * 1976-06-18 1977-10-18 Ralph Montgomery Full range rotatable speaker housing with oppositely directed speakers
US4466505A (en) * 1982-04-19 1984-08-21 Temporal Dynamics Research, Inc. Sound reproducing combination
US4598789A (en) * 1982-04-19 1986-07-08 Temporal Dynamics Research, Inc. Sound reproducing
EP0172705A3 (en) * 1984-08-20 1987-08-19 Bose Corporation Loudspeaker system
US4742548A (en) * 1984-12-20 1988-05-03 American Telephone And Telegraph Company Unidirectional second order gradient microphone
US4953223A (en) * 1988-09-08 1990-08-28 Householder George G Speaker mounting system
US6496586B1 (en) * 1998-01-07 2002-12-17 New Transducers Limited Thin Loudspeaker
US20040112671A1 (en) * 2002-08-17 2004-06-17 Kh Technology Corporation Loudspeaker unit and assembly
US20040105559A1 (en) * 2002-12-03 2004-06-03 Aylward J. Richard Electroacoustical transducing with low frequency augmenting devices
US20040196982A1 (en) * 2002-12-03 2004-10-07 Aylward J. Richard Directional electroacoustical transducing
US7676047B2 (en) * 2002-12-03 2010-03-09 Bose Corporation Electroacoustical transducing with low frequency augmenting devices
US20100119081A1 (en) * 2002-12-03 2010-05-13 Aylward J Richard Electroacoustical transducing with low frequency augmenting devices
US8139797B2 (en) 2002-12-03 2012-03-20 Bose Corporation Directional electroacoustical transducing
US8238578B2 (en) 2002-12-03 2012-08-07 Bose Corporation Electroacoustical transducing with low frequency augmenting devices
US20090277713A1 (en) * 2005-04-21 2009-11-12 Ambrose Thopson Acoustic Loading Device for Loudspeakers
US8191674B2 (en) * 2005-04-21 2012-06-05 Martin Audio Limited Acoustic loading device for loudspeakers
EP2043381A3 (en) * 2007-09-28 2010-07-21 Bang & Olufsen A/S A method and a system to adjust the acoustical performance of a loudspeaker
US20100177921A1 (en) * 2009-01-14 2010-07-15 Richard Bos Response speaker system
US8116499B2 (en) 2009-01-23 2012-02-14 John Grant Microphone adaptor for altering the geometry of a microphone without altering its frequency response characteristics
US20100189299A1 (en) * 2009-01-23 2010-07-29 John Grant Microphone
EP2637417A1 (de) * 2012-03-07 2013-09-11 RE-Speakers Gehäuse für Dipollautsprecher, Verfahren zur dessen Herstellung und Dipollautsprecher
US20160173986A1 (en) * 2014-12-15 2016-06-16 Gary Lloyd Fox Ultra-low distortion integrated loudspeaker system
WO2017186312A1 (en) * 2016-04-29 2017-11-02 Burmester Audiosysteme Gmbh Loudspeaker
CN109196876A (zh) * 2016-04-29 2019-01-11 柏林之声音频系统有限公司 扬声器
US10735850B2 (en) 2016-04-29 2020-08-04 Burmester Audiosysteme Gmbh Loudspeaker
CN109196876B (zh) * 2016-04-29 2020-11-20 柏林之声音频系统有限公司 扬声器和操作扬声器的方法
US20230145186A1 (en) * 2021-11-09 2023-05-11 Fca Us Llc Battery electric vehicle active sound and vibration enhancement systems
US12377782B2 (en) * 2021-11-09 2025-08-05 Fca Us Llc Battery electric vehicle active sound and vibration enhancement systems

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AU8009975A (en) 1976-10-21
JPS51326A (enrdf_load_html_response) 1976-01-06
LU72503A1 (enrdf_load_html_response) 1976-03-17
DE2521950A1 (de) 1975-12-11
JPS5616998B2 (enrdf_load_html_response) 1981-04-20
NL7504014A (nl) 1975-11-24
FR2272563A1 (enrdf_load_html_response) 1975-12-19
GB1499407A (en) 1978-02-01
BE829157A (fr) 1975-11-17

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