EP0474548A1 - Verfahren und Gerät zur Verbesserung der Wiedergabequalität eines stereophonisches Raumklanges - Google Patents

Verfahren und Gerät zur Verbesserung der Wiedergabequalität eines stereophonisches Raumklanges Download PDF

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Publication number
EP0474548A1
EP0474548A1 EP91402349A EP91402349A EP0474548A1 EP 0474548 A1 EP0474548 A1 EP 0474548A1 EP 91402349 A EP91402349 A EP 91402349A EP 91402349 A EP91402349 A EP 91402349A EP 0474548 A1 EP0474548 A1 EP 0474548A1
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EP
European Patent Office
Prior art keywords
zones
spectra
sets
transducers
spectrum
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.)
Withdrawn
Application number
EP91402349A
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English (en)
French (fr)
Inventor
Pierre Piccaluga
Claude Annie Perrichon
André Augros
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Individual
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Individual
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Publication date
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04S—STEREOPHONIC SYSTEMS 
    • H04S1/00—Two-channel systems
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
    • H04R3/00—Circuits for transducers, loudspeakers or microphones
    • H04R3/12—Circuits for transducers, loudspeakers or microphones for distributing signals to two or more loudspeakers
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04S—STEREOPHONIC SYSTEMS 
    • H04S1/00—Two-channel systems
    • H04S1/002—Non-adaptive circuits, e.g. manually adjustable or static, for enhancing the sound image or the spatial distribution

Definitions

  • the present invention relates to stereophony and, more particularly, to an improvement made to the stereophonic system with the aim of improving the quality of the sound environment reproduced in stereophony.
  • stereophony is a process of reproducing the acoustic atmosphere of a recorded sound scene which allows a listener to reconstruct the spatial distribution of the sound sources forming this scene.
  • stereophonic of directivity and depth
  • the two electrical audio frequency signals from these two microphones are recorded respectively on two separate tracks from which they can be read, processed and applied respectively by a right channel and by a left channel to a right speaker and a loudspeaker.
  • left speaker which reproduces the sounds recorded by the microphones by giving a listener facing them the impression of the sound relief that a listener listening to the sound scene would have felt at the time of recording.
  • Every human being has the ability to locate in direction, that is to say in width and depth, a sound source thanks to the analysis carried out by his brain from the differences between the messages received respectively by the ear. right and left ear.
  • the localization in depth is obtained by the unconscious appreciation of the intensity of the source, which decreases with the distance, while the localization in width is obtained thanks to the fact that the sound waves reaching the right ear and the left ear will be felt there differently. Indeed, the waves emitted on the right side will arrive at the right ear before arriving at the left ear and their intensity will be greater for the right ear than for the left ear. Likewise their relative phase will be different.
  • These three characteristics are reinforced by the presence of the head between the two ears. This, in fact, constitutes an obstacle and plays the role of a frequency filter: the sounds arriving from the right will be noisier for the right ear and more deaf for the left ear because the head absorbs the high sounds .
  • the present invention therefore relates to a method for improving the quality of reproduction of the acoustic environment of a sound scene in a stereophonic reproduction system comprising two sets of electro-acoustic reproduction transducers arranged at a distance from one of the other for simultaneously reproducing the sound information contained in two audio frequency signals which they receive via a right channel and a left channel and which correspond respectively to a right part and to a left part of said sound scene.
  • each of the frequency spectra of the right and left channels is cut into successive and contiguous zones before applying the audio frequency signals of the latter to the sets of transducers, the number of zones of one of the spectra being equal. to the number of zones of the other spectrum, and the sound information of the two spectra is reproduced simultaneously at the rate of one zone out of two in each of them and in such a way that, when one zone of one of the spectra is acoustically reproduced, the corresponding area of the other spectrum is not, the two spectra thus being reproduced acoustically simultaneously but in an alternating and complementary manner.
  • the number of zones is at least equal to three.
  • each transducer in each set is tuned to the frequency range or ranges which correspond to them.
  • the present invention also relates to a stereophonic device arranged so as to improve the quality of reproduction of the acoustic environment of a sound scene, this device comprising two sets of electro-acoustic reproduction transducers arranged at a distance from one the other to simultaneously reproduce the sound information contained in two audio-frequency signals which they receive separately and simultaneously via a right channel and a left channel and which correspond respectively to a right part and to a left part of said recorded sound scene.
  • means divide into successive and contiguous zones each of the frequency response spectra of said channels before applying these signals to the two sets of electro-acoustic transducers, the number of zones of one of the spectra being equal. to the number of zones of the other spectrum, the zones of the spectra being applied selectively and simultaneously to the respective sets of electro-acoustic transducers at the rate of one zone out of two in each spectrum and in such a way that when one of the zones of one of the spectra is reproduced the corresponding zone of the other spectrum is not, the two spectra thus being reproduced acoustically and simultaneously but in an alternating and complementary manner.
  • the number of zones in each spectrum is at least equal to three.
  • each transducer is formed by a loudspeaker and by a resonator tuned over the frequency range of the zone or zones which correspond to them.
  • the means for dividing the spectra into zones are right and left sets of electronic filters connecting the right and left channels to the right and left sets of electroacoustic reproduction transducers.
  • means selectively apply the audio frequency signals to the respective sets of electro-acoustic transducers and these sets are series of electrical contactors, the order of opening and closing of one series of contactors being the reverse of the order of opening and closing of the other series of contactors.
  • a switching means is provided for reversing the opening and closing order of each of the contactor assemblies.
  • the acoustic information stored on the medium is read in a reading device L which may be a recorder, a tape recorder or other similar device or, in the case of a radio transmission, a broadcasting receiver, and the electrical signals of audio frequencies obtained from these devices are appropriately processed in right and left Crd and Crg sound reproduction channels to be applied to two speakers Hpd and Hpg which reproduce the sounds recorded by the microphones Md and Mg by reconstructing, for a listener in zone A ′ shown in broken lines, the sound environment which was that of zone A at the time of recording.
  • a localized sound source for example a musical instrument
  • a listener P2 located in the reproduction area A ′, facing the loudspeaker will reconstruct in his brain thanks to the stereophonic effect, the sound of the sound source S by locating it in space, both in direction and in "width". It can be seen, however, that the sound of the localized sound source S in zone A is emitted from a single point in this zone while in zone A the same sound of the sound source S, which has been recorded by the two microphones, is finally emitted by the speakers from two separate points.
  • the auditory sensory system of the listener at point P2 will not reconstruct the sound of the sound source S in the same way as it would have reconstructed it in the case of the listener at point P1, and the listener at point P2 will not obtain the quality of stereophonic acoustic reproduction to which he could claim.
  • the object of the present invention is to provide the solution to this problem which will be described in detail below.
  • FIG. 2 the sound reproduction part of the stereophonic system of FIG. 1 has been represented.
  • the right and left audio frequency signals Sid and Sig applied to the inputs Ed and Eg from the playback device L, or of a radio receiver in the case of radio transmission, are amplified and appropriately processed in the Crd and Crg channels. There is shown in Figure 2, at the output of these channels, the frequency response spectra of the latter.
  • the signals Sid and Sig are then applied, via sets of filters Fd and Fg to two respective sets Trd and Trg of electro-acoustic transducers.
  • transducers are usually loudspeakers fitted with resonators and are designed to operate in particular frequency ranges for which their geometry has been studied. In the example shown, these transducers are five in number, but this figure is completely arbitrary and could be different. However, for the implementation of the present invention, it is not less than three. In the latter case, the loudspeakers and their resonators are designed to reproduce, respectively, the audio frequency ranges which correspond in the register of sounds to bass, medium and treble, as is conventional in the reproduction of sounds with good high fidelity quality.
  • the number of filters Fd1 to Fd5 and Fg1 to Fg5 of each set of filters Fd and Fg is equal to the number of transducers Hd1 to Hd5 and Hg1 to Hg5 of the sets Trd and Trg, respectively, and these filters are generally active filters which cut out the frequency response spectrum in as many zones Zd1 to Zd5 and Zg1 to Zg5 as there are transducers in the sets Trd and Trg, as shown by the frequency response spectra represented above and below these sets Trd and Trg in Figure 2.
  • the sound content of the two frequency response spectra of the right and left channels for the two signals Sid and Sig recorded by the microphones Md and Mg are therefore reproduced in their entirety simultaneously by the sets of speakers Trd and Trg with, for a listener facing the transducer sets, the aforementioned drawback of reproducing a sound source emitted from two points in space during reproduction when it was only emitted from a single point in the space when recording.
  • FIG 3 shows schematically the basic principle of the present invention.
  • the device shown in this figure has the same components as the device in Figure 2, namely an input terminal block (Ed, Eg) from which two right and left audio frequency signals Sid and Sig are routed to two sets of filters right and left Fd and Fg by two right and left channels Crd, Crg where they are applied to two right and left sets Trd and Trg of electro-acoustic transducers after the frequency response spectra Spd and Spg of the two channels have been cut , that is to say divided, into as many zones as there are transducers Hd1 to Hd5 and Hg1 to Hg5 in the respective sets Trd and Trg.
  • an input terminal block Ed, Eg
  • two right and left audio frequency signals Sid and Sig are routed to two sets of filters right and left Fd and Fg by two right and left channels Crd, Crg where they are applied to two right and left sets Trd and Trg of electro-acoustic transducers after the frequency response
  • the filters Fd1 to Fd5 and Fg1 to Fg5 are not all connected to the respective acoustic transducers Hd1 to Hd5 and Hg1 to Hg5 in the two sets as c ' was the case in the previous device.
  • the filters Fd1, Fd3 and Fd5 are connected to the electro-acoustic transducers Hd1, Hd3 and Hd5.
  • the filters Fg2 and Fg4 are connected to the acoustic transducers Hg2 and Hg4.
  • Trg will give rise to a sound reproduction of the acoustic information contained in the audio frequency signals Sid and Sig.
  • These active areas of the spectra have been shown hatched in the figure.
  • zones Zid1, Zid3 and Zd5 of the Spd spectrum will be the subject of a sound reproduction for the right channel Crd and only the zones Zg2 and Zg4 of the Spg spectrum are the subject of a sound reproduction for the channel left Crg.
  • each of the sets Trd and Trg of electro-acoustic transducers comprises “active” transducers and “inactive” transducers. In fact, the presence of the latter is maintained in the sets Trd and Trg in order to use the resonance of these transducers to the harmonics of the sounds emitted by the neighboring active transducers.
  • the authors of the present invention have found that the quality of the stereophonic reproduction of a recorded sound scene is improved in a surprising way, thereby bringing to the problem mentioned previously a solution which places the sensory system hearing of a listener in conditions closer to listening in a natural sound environment than in the case of conventional stereophonic listening.
  • FIG. 4 shows an alternative embodiment of the apparatus according to the present invention.
  • the zones giving rise to a sound reproduction that is to say the zones Zd1, Zd3 and Zd5 for the spectrum Spd of the right channel and Zg2, Zg4 for the spectrum Spg have been chosen arbitrarily in the example chosen.
  • FIG. 4 additional means have been provided for the right and left channels, in the form of two right and left sets Cd and Cg of contactors between the filters Fd and Fg, on the one hand, and the sets respective Trd and Trg of electro-acoustic transducers, on the other hand.
  • These sets Cd and Cg comprise series of contactors Cd1 to Cd5 and Cg1 to Cg5 which, in each of these sets, are open and closed alternately, as can be seen in this FIG. 4, the order of opening and of closing the contactors of the assembly Cd being the reverse of the order of opening and closing of the other assembly Cg.
  • each spectrum Spd and Spg could be divided into a higher number of zones and it is not beyond the scope of the present invention for the number of transducers to be less than the number of zones.
  • the complementary areas of the Spg spectrum would then be applied to the complementary transducer of the other set Trg.
EP91402349A 1990-09-04 1991-09-03 Verfahren und Gerät zur Verbesserung der Wiedergabequalität eines stereophonisches Raumklanges Withdrawn EP0474548A1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR9010979A FR2666473B1 (fr) 1990-09-04 1990-09-04 Procede et appareil pour ameliorer la qualite de la restitution d'une ambiance sonore en stereophonie.
FR9010979 1990-09-04

Publications (1)

Publication Number Publication Date
EP0474548A1 true EP0474548A1 (de) 1992-03-11

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EP91402349A Withdrawn EP0474548A1 (de) 1990-09-04 1991-09-03 Verfahren und Gerät zur Verbesserung der Wiedergabequalität eines stereophonisches Raumklanges

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Country Link
EP (1) EP0474548A1 (de)
JP (1) JPH06121397A (de)
KR (1) KR920007490A (de)
CA (1) CA2050622A1 (de)
FR (1) FR2666473B1 (de)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2691867A1 (fr) * 1992-06-02 1993-12-03 Thouzery Jean Procédé pour répartir spatialement une source sonore monophonique.
EP0653897A2 (de) * 1993-11-12 1995-05-17 SPHERIC AUDIO LABORATORIES, Inc. Verfahren und Gerät zur Erzeugung von Raumklangeffekten
FR2746247A1 (fr) * 1996-03-14 1997-09-19 Bregeard Dominique Systeme electronique programmable restituant des effets de deplacement expressif de sources sonores et de perception tri-dimentionnelle

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2394222A1 (fr) * 1977-06-08 1979-01-05 Cote Georges Ensemble acoustique a effet spatial ameliore
EP0282017A2 (de) * 1987-03-13 1988-09-14 Ohno Matsuo Stereobearbeitungssystem

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2394222A1 (fr) * 1977-06-08 1979-01-05 Cote Georges Ensemble acoustique a effet spatial ameliore
EP0282017A2 (de) * 1987-03-13 1988-09-14 Ohno Matsuo Stereobearbeitungssystem

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2691867A1 (fr) * 1992-06-02 1993-12-03 Thouzery Jean Procédé pour répartir spatialement une source sonore monophonique.
EP0653897A2 (de) * 1993-11-12 1995-05-17 SPHERIC AUDIO LABORATORIES, Inc. Verfahren und Gerät zur Erzeugung von Raumklangeffekten
EP0653897A3 (de) * 1993-11-12 1996-02-21 Spheric Audio Lab Inc Verfahren und Gerät zur Erzeugung von Raumklangeffekten.
FR2746247A1 (fr) * 1996-03-14 1997-09-19 Bregeard Dominique Systeme electronique programmable restituant des effets de deplacement expressif de sources sonores et de perception tri-dimentionnelle

Also Published As

Publication number Publication date
FR2666473B1 (fr) 1993-07-30
FR2666473A1 (fr) 1992-03-06
JPH06121397A (ja) 1994-04-28
KR920007490A (ko) 1992-04-28
CA2050622A1 (fr) 1992-03-05

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