EP0297975B1 - Vorrichtung zur Tonaufnahme und Tonwiedergabe, insbesondere für Audiokonferenzen - Google Patents

Vorrichtung zur Tonaufnahme und Tonwiedergabe, insbesondere für Audiokonferenzen Download PDF

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Publication number
EP0297975B1
EP0297975B1 EP19880401654 EP88401654A EP0297975B1 EP 0297975 B1 EP0297975 B1 EP 0297975B1 EP 19880401654 EP19880401654 EP 19880401654 EP 88401654 A EP88401654 A EP 88401654A EP 0297975 B1 EP0297975 B1 EP 0297975B1
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EP
European Patent Office
Prior art keywords
loudspeaker
microphone
sound
reference plane
disposed
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
EP19880401654
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English (en)
French (fr)
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EP0297975A1 (de
Inventor
Larvor René
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.)
Orange SA
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France Telecom SA
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Publication date
Application filed by France Telecom SA filed Critical France Telecom SA
Publication of EP0297975A1 publication Critical patent/EP0297975A1/de
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Publication of EP0297975B1 publication Critical patent/EP0297975B1/de
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
    • H04R27/00—Public address systems

Definitions

  • the present invention relates to a device for picking up and reproducing sound in broadband, in particular for ensuring effectively and with high quality in listening comfort, the transmission of words or sounds pronounced by a group of people distributed in a conference room of any geometry and therefore comprising acoustics not specially adapted.
  • the multiplication of microphones and loudspeakers inside, in the same room leads to coupling effects in the acoustic transmission between these devices by creating what we in the technique calls for the LARSEN effect, characterized by a particularly unpleasant whistle which appreciably disturbs the atmosphere.
  • the quality of the sound recording depends directly on the value of the ratio established between the direct acoustic field and the reverberant field picked up by a microphone, this ratio being all the better that in the same space the number of microphones in service is more limited.
  • FR-A-2 377 735 describes an apparatus combining a microphone and a loudspeaker for use in a conference room, mounted on a common vertical axis, the loudspeaker being directed upwards.
  • the microphone used does not make it possible to obtain a significant reduction in the acoustic coupling with the loudspeaker, while simultaneously allowing normal perception of the speakers arranged around the device.
  • GB-2 008 359 also illustrates a teleconferencing system but in which a single loudspeaker is associated with a plurality of directional microphones each arranged in front of a speaker, these microphones being mounted with a determined spacing and fixed between them by means of a rigid elongated support. In this case, there is no association of a loudspeaker and a single microphone, hence a distribution of the restored sound which is not homogeneous for all the participants.
  • the present invention relates to a device which takes into account the necessary compromise between the contradictory imperatives stated above, by allowing appreciable omnidirectionality of the recording and reproduction of the sound, while minimizing the number of microphones used, the mounting of these microphones and speakers which are associated with them to restore the received sound, being arranged to best limit looping with each other, by reducing to the lowest level the amount of energy captured by the microphones from the speakers.
  • the invention also aims to produce a compact assembly, where a microphone and an associated loudspeaker together occupy a minimum volume, the device being able to operate in a wide frequency band, being easy to use, inexpensive and capable of being lent easily to construction adaptations improving its exterior aesthetic appearance.
  • the device for picking up and reproducing sound in particular for audio conference between several speakers distributed in any room, substantially around a central point arranged in the reference plane, in particular around a table, comprising a directional microphone and a loudspeaker, the membrane of which is arranged opposite the microphone, the loudspeaker and the microphone being placed in an orientation substantially perpendicular to the reference plane, the microphone being of the cardioid type and having a directivity s extending perpendicular to the reference plane and omnidirectionality parallel to this plane, the microphone being arranged at the top of the device and the speaker at the bottom, the microphone and the speaker being mounted coaxially inside '' a common support, resting on a base extending parallel to the reference plane or resting on it, is because operates in that an intermediate transverse separation, improving the acoustic decoupling between the microphone and the loudspeaker is provided between the microphone and the loudspeaker, this loudspeaker being associated, in the vicinity of the reference plane, with a cone of revolution forming
  • the loudspeaker is secured to a support plate, open at its center for the passage of sound towards the reflective cone located under the loudspeaker at a determined distance from it.
  • the spacing between the loudspeaker and the reflective cone is determined by vertical spacers providing a plurality of lateral passages for the sound returned by the reflective cone, parallel to the reference plane.
  • the passages between the spacers are closed by a layer of sound-transparent protective foam.
  • the microphone is arranged in the axis of the loudspeaker at the top of the support, and is held vertically in the latter by a block of material made of compact acoustic foam, resting on the intermediate transverse separation.
  • the microphone is mounted in a cavity formed inside a foam cover, transparent to sound, disposed at the upper part of the support and covering the microphone.
  • connection connector mounted in the base for connection to electronic amplification assemblies, filtering and adaptation, necessary for its operation.
  • electronic assemblies include a gain variation circuit and / or suppression of acoustic echoes.
  • the reference 1 designates the envisaged device, comprising in particular a microphone 2, preferably of the type with cardioid directivity, mounted vertically at the upper part of the assembly.
  • This microphone 2 itself known in the art but whose assembly and mode of implementation constitute in combination with the other provisions of the proposed system, the object of the present invention, is in particular arranged so that the acoustic waves coming in a determined direction from any point in a horizontal plane, induce vibrations in phase in the membrane (not shown) of the microphone.
  • the microphone 2 is held in a vertical position inside a block of compact acoustic foam 3, immobilized in a support 4, comprising a cylindrical body 5 at the top of which the block 3 is mounted.
  • the microphone 2 is housed, above the block 3, in a chamber 6, delimited inside a foam cover 7, made of a material transparent to sound and covering the assembly, protecting it from the external environment.
  • the block 3 also rests inside the body 5, on a transverse separation member, constituted by a plate 8 extending horizontally.
  • a speaker 9 there is mounted inside the support 4, opposite the microphone 2 in the same vertical direction, a speaker 9 whose membrane is directed downwards.
  • This loudspeaker 9 can be of a type known per se, in particular electrodynamic or electrostatic and is secured to a support plate 10, pierced in its center in order to facilitate the emission downwards of the sound reproduced by the speaker.
  • the support plate 10 is supported by means of vertical spacers 11 by a lower support base 12.
  • the spacers 11 laterally delimit passages, closed by a cylinder 13 of foam transparent to sound.
  • the device in order to facilitate the reflection of the sounds emitted vertically by the loudspeaker 9, the device according to the invention comprises a part 14 of conical shape mounted on the top of the base 12 substantially in the common axis of the microphone 2 and the speaker 9, the cone 14 thus allowing the sound returned by the speaker to undergo an appropriate deflection, to escape through the layer of foam 13, substantially in the plane horizontal.
  • the support 12 is usually placed on a table or the like which thus constitutes a reference plane.
  • the equipment of the device is completed by a connector 15 mounted inside the base 12 and to which electrical conductors, respectively 16 and 17 are connected, making it possible to connect the microphone 2 on the one hand, the speaker on the other part, to one or more electronic assemblies (not shown), advantageously arranged under the table which receives the device 1.
  • These electronic assemblies make it possible in particular to ensure amplification, filtering and adjustment of the sound level, or even elimination parasitic echoes, with control of the gain variation according to the conditions of use.
  • a particularly simple device is thus produced, making it possible for a group of speakers distributed around the table and on the central part of which the device rests, to take and reproduce the sound in a very wide frequency band, possibly ranging, or even exceed 7 kHz, omnidirectionality in the plane of the pickup table and the sound reproduction being optimally ensured.
  • the mounting opposite the other of the microphone and the loudspeaker provides an effective acoustic decoupling between these two devices, by eliminating any possible parasitic effects.
  • the device can be particularly reduced in its size, the volume of the assembly not exceeding 10 dm3 for a maximum height of approximately 35 cm.
  • the weight of the device can be reduced, under normal operating conditions, to less than 2.5 kg, the directivity of the assembly, however, making it possible to ensure an audio conference with great listening comfort, even with a number high speakers distributed around the table and away from the center of it by a distance between and 1 and 5 m.
  • the device thanks to its central position in the middle of the table, at substantially equal distances from all the speakers allows in all cases an omnidirectional reception of the sound emitted by the different speakers towards the microphone; in the same way, the sound reproduced by the loudspeaker is returned by the reflective cone substantially at the level of the plane of the table, or even slightly above the latter, allowing perfect listening by all users.
  • the mounting of the microphone and the loudspeaker opposite each other in the same vertical direction also limits to the maximum the coupling of the sound to reception and to retransmission, the device being able to be used in a band of frequency which can extend to the vicinity or beyond 7 kHz, without requiring, in the circuit of the loudspeaker, any system of pre-accentuation of the treble which makes it possible to reduce in particularly sensitive conditions the price and the size of the device.
  • the angle at the top of the reflective cone is determined by construction according to the conditions of use of the device.
  • this angle is chosen to be 112 °.
  • the transverse separation plate, mounted between the microphone and the loudspeaker improves the separation between microphone and loudspeaker, by further reducing their acoustic coupling, while the omnidirectionality of the sound recording remains maintained in the reference plane, by allowing it to retain its full effectiveness.

Landscapes

  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Acoustics & Sound (AREA)
  • Signal Processing (AREA)
  • Obtaining Desirable Characteristics In Audible-Bandwidth Transducers (AREA)
  • Details Of Audible-Bandwidth Transducers (AREA)
  • Circuit For Audible Band Transducer (AREA)

Claims (7)

  1. Vorrichtung zur Tonaufnahme und Tonwiedergabe, besonders für Audio-Konferenzen zwischen mehreren Sprechern, die in einem beliebigen Raum im wesentlichen um einen in einer Bezugsebene befindlichen Mittelpunkt, insbesondere um einen Tisch verteilt sind, mit einem Richtmikrofon (2) und einem Lautsprecher (9), dessen Membran entgegengesetzt zum Mikrofon angeordnet ist, wobei der Lautsprecher und das Mikrofon in einer zur Bezugsebene im wesentlichen senkrechten Richtung angeordnet sind, das Mikrofon ein Kardioid-Mikrofon mit einer Richtcharakteristik senkrecht zur Bezugsebene und einer Kugelcharakteristik parallel zu dieser Ebene ist, das Mikrofon im oberen Teil und der Lautsprecher im unteren Teil der Vorrichtung angeordnet und das Mikrofon (2) und der Lautsprecher (9) koaxial im Inneren eines gemeinsamen Halters (4) montiert sind, der auf einem sich parallel zur Bezugsebene erstreckenden oder auf dieser aufsitzenden Sockel (12) ruht, dadurch gekennzeichnet, daß eine quer verlaufende trennende Zwischenwand (8), welche die akustische Entkoppelung zwischen dem Mikrofon und dem Lautsprecher verbessert, im Halter (4) zwischen dem Mikrofon (2) und dem Lautsprecher (9) vorgesehen ist, wobei dem Lautsprecher (9) in der Nähe der Bezugsebene ein Kreiskegel (14) zugeordnet ist, der einen Reflektor für seine Abstrahlung bildet und die vom Lautsprecher ausgesandten Schallwellen im wesentlichen in die Richtung dieser Ebene lenkt.
  2. Vorrichtung nach Anspruch 1, dadurch gekennzeichnet, daß der Lautsprecher (9) fest mit einer Auflageplatte (10) verbunden ist, die in ihrer Mitte offen ist für den Durchtritt von Schall in Richtung des unter dem Lautsprecher in einem bestimmten Abstand von diesem angeordneten Reflektorkegels.
  3. Vorrichtung nach einem der Ansprüche 1 oder 2, dadurch gekennzeichnet, daß der Abstand zwischen dem Lautsprecher (9) und dem Reflektorkegel (14) durch senkrechte Stege (11) bestimmt ist, die eine Mehrzahl von seitlichen Durchlässen für den vom Reflektorkegel parallel zur Bezugsebene umgelenkten Schall bilden.
  4. Vorrichtung nach Anspruch 3, dadurch gekennzeichnet, daß die Durchlässe zwischen den Stegen (11) durch eine Schutzschicht (13) aus einem schalldurchlässigen Schaumstoff abgeschlossen sind.
  5. Vorrichtung nach einem der Ansprüche 1 bis 4, dadurch gekennzeichnet, daß das Mikrofon (2) in der Achse des Lautsprechers (9) im oberen Teil des Halters (4) angeordnet und in diesem durch einen Block (3) aus einem akustisch dichten Schaumstoff gehalten ist, der sich auf der quer verlaufenden trennenden Zwischenwand (8) abstützt.
  6. Vorrichtung nach einem der Ansprüche 1 bis 5, dadurch gekennzeichnet, daß das Mikrofon (2) in einem im Inneren eines Deckels (7) aus schalldurchlässigem Schaumstoff ausgebildeten Hohlraum angeordnet ist, wobei der Deckel im oberen Teil des Halters (4) angeordnet ist und das Mikrofon überdeckt.
  7. Vorrichtung nach einem der Ansprüche 1 bis 6, dadurch gekennzeichnet, daß die elektrischen Verbindungsdrähte (16, 17) des Mikrofons (2) und des Lautsprechers (9) mit einem Anschlußstück (15) verbunden sind, das im Sockel (12) für den Anschluß an elektronische Anordnungen zur Verstärkung, Filterung und Anpassung montiert ist, die für seinen Betrieb notwendig sind.
EP19880401654 1987-06-30 1988-06-28 Vorrichtung zur Tonaufnahme und Tonwiedergabe, insbesondere für Audiokonferenzen Expired - Lifetime EP0297975B1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR8709205 1987-06-30
FR8709205A FR2617660B1 (fr) 1987-06-30 1987-06-30 Dispositif de prise et de restitution du son, notamment pour audio-conferences

Publications (2)

Publication Number Publication Date
EP0297975A1 EP0297975A1 (de) 1989-01-04
EP0297975B1 true EP0297975B1 (de) 1992-11-04

Family

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Family Applications (1)

Application Number Title Priority Date Filing Date
EP19880401654 Expired - Lifetime EP0297975B1 (de) 1987-06-30 1988-06-28 Vorrichtung zur Tonaufnahme und Tonwiedergabe, insbesondere für Audiokonferenzen

Country Status (3)

Country Link
EP (1) EP0297975B1 (de)
DE (1) DE3875659T2 (de)
FR (1) FR2617660B1 (de)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US10051353B2 (en) 2016-12-13 2018-08-14 Cisco Technology, Inc. Telecommunications audio endpoints
US10863035B2 (en) 2017-11-30 2020-12-08 Cisco Technology, Inc. Microphone assembly for echo rejection in audio endpoints

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2670351B1 (fr) * 1990-12-05 1997-04-30 France Etat Appareil de prise et de restitution du son.
FR2702918B1 (fr) * 1993-03-19 1995-05-12 Prescom Sarl Appareil de prise et de restitution de son, et son application à l'audio-conférence.
FR2743685B1 (fr) * 1996-01-17 1998-02-20 Prescom Sarl Appareils de prise de son et appareils de prise de son et de restitution de son
DE19650522C2 (de) * 1996-12-05 1998-10-22 Lion S Motor Sport Trading Com Kegelförmiger Lautsprechervorsatz

Family Cites Families (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CA1050154A (en) * 1977-01-14 1979-03-06 Conrad D. Lafrance Telephone conferencing apparatus
GB2008359B (en) * 1977-11-03 1982-05-12 Post Office Audio teleconferecing
US4378468A (en) * 1980-10-10 1983-03-29 Darome, Inc. Methods and apparatus for alleviating sound-coupled feedback in conference room sound systems
US4436966A (en) * 1982-03-15 1984-03-13 Darome, Inc. Conference microphone unit
US4620317A (en) * 1984-04-05 1986-10-28 Shure Brothers, Inc. Tabletop speaker assembly
US4574906A (en) * 1984-11-15 1986-03-11 Audio Technica U.S., Inc. Outdoor speaker

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US10051353B2 (en) 2016-12-13 2018-08-14 Cisco Technology, Inc. Telecommunications audio endpoints
US10863035B2 (en) 2017-11-30 2020-12-08 Cisco Technology, Inc. Microphone assembly for echo rejection in audio endpoints

Also Published As

Publication number Publication date
FR2617660A1 (fr) 1989-01-06
DE3875659D1 (de) 1992-12-10
EP0297975A1 (de) 1989-01-04
FR2617660B1 (fr) 1990-06-08
DE3875659T2 (de) 1993-03-25

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