EP0002413A1 - Method and apparatus for recording sound in a room - Google Patents

Abstract

The apparatus comprises for example four microphones (M1-M4) connected to a phase changing system (D) driven by an address system (14) so as to delay certain of the electrical signals generated by certain of the microphones, by amounts which are specified and stored in a memory (15), so as to phase balance the components of the signals emitted by the microphones which correspond to sounds coming from the relevant location, so as to amplify these components in an adder circuit (A). The invention applies in particular to the soundproofing of conference halls. <IMAGE>

Description

The invention relates to sound recording in a room and in particular a conference room. The invention is remarkable in that it makes it possible to selectively favor a location in the room, where there is a congressman wishing to speak, so that the sounds emitted at this location are more amplified than those that are emitted everywhere else in the room.

The sound recording in a conference room, in particular with a view to soundproofing this room, poses many problems. Particularly, when it is a congress where all the participants may have to speak, we come up against a major difficulty linked to a certain indiscipline of the delegates. If the speaker is an important personality, he is generally in a forum which benefits from preferential means of taking his sound and therefore has therefore little difficulty in being heard. On the other hand, when one wishes to temporarily give the floor to a congressman located in the room, the sound of his voice is very often drowned in the hubbub of neighboring conversations or contradictory interpellations, if this congressman does not benefit at this precise moment. '' a particular means of amplification. Until Now, we had no other solution than to ask this congressman to move to a desk with a microphone or on the contrary to have recourse to an operator bringing a mobile microphone near the congressman. These two solutions are detrimental to the progress of the debates, due to the downtime they imply. Furthermore, the solution which consists in providing a microphone near each seat for the congressman, the microphones being individually switchable on the general sound installation, obviously leads to very expensive equipment.

The invention is remarkable in that it makes it possible to amplify the sound of the voice of a participant located at a very precise location in the room, with relative attenuation of the sounds emitted everywhere else in the same room, without said participant. have to leave their seat or without having to bring them a microphone. On the other hand, the invention uses only a limited number of microphones and therefore results in inexpensive sound systems.

• - à sélectionner un emplacement déterminé eà se trouve un participant désirant prendre la parole, déphasant les signaux électriques engendrés par lesdits microphones desdites valeurs de déphasage, correspondant audit emplacement déterminé, préalablement mises en mémoire, de façon que les composantes desdits signaux électriques représentatifs des sons émis audit emplacement déterminé soient en concordance de phase dans lesdits signaux électriques ainsi déphasés,
• - à additionner tous lesdits signaux électriques ainsi déphasés, et
• - à appliquer le signal électrique résultant de cette addition à un système d'amplification.

More specifically, the invention therefore relates to a process for taking sound in a room such as, for example, a conference room; said room comprising a certain number of microphones and a certain number of locations of participants or conventioneers, said locations being for example materialized by individual armchairs, characterized in that it consists, after having determined and stored for each aforementioned location the values relative training of the sounds picked up by all of said microphones when a sound source is located at said location,

• - to select a specific location eà is a participant wishing to speak, phase shifting the electrical signals generated by said microphones of said phase shift values, corresponding to said determined location, previously stored, so that the components of said electrical signals representative of sounds emitted at said determined location are in phase agreement in said electrical signals thus phase shifted,
• - adding all of said electrical signals thus out of phase, and
• - to apply the electrical signal resulting from this addition to an amplification system.

• - une pluralité de microphones situés dans ladite salle à des emplacements choisis,
• - un système déphaseur comportant une pluralité d'entrées reliées auxdits microphones et un même nombre de sorties, ledit système déphaseur comportant des moyens pour retarder les signaux appliqués à ces entrées de valeurs respectives sélectivement ajustables,
• - une mémoire préprogrammée pour contenir plusieurs groupements de valeurs de déphasage, chaque groupement correspondant à un emplacement déterminé de ladite salle,
• - un système d'adressage connecté audit système déphaseur et à ladite mémoire pour introduire un groupement de valeurs de déphasage choisi dans ledit système déphaseur et pour piloter lesdits moyens pour retarder, et
• - un circuit additionneur comportant un même nombre d'entrées que ledit système déphaseur a de sorties, chaque entrée dudit circuit additionneur étant reliée à une sortie dudit système déphaseur.

The invention also covers the material means necessary to implement the method defined above. In this spirit, a room sound installation according to the invention is characterized in that it comprises:

• - a plurality of microphones located in said room at selected locations,
• a phase-shifting system comprising a plurality of inputs connected to said microphones and the same number of outputs, said phase-shifting system comprising means for delaying the signals applied to these inputs of respective values which are selectively adjustable,
• a memory preprogrammed to contain several groups of phase shift values, each group corresponding to a determined location in said room,
• an addressing system connected to said phase-shifting system and to said memory for introducing a grouping of phase-shifting values chosen in said phase-shifting system and for controlling said means for delaying, and
• - an adder circuit comprising the same number of inputs as said phase shifter system has outputs, each input of said adder circuit being connected to an output of said phase shifter system.

• La figure 1 représente schématiquement l'agencement général d'une salle de conférence équipée d'une installation de prise de son et de sonorisation conformément au principe de l'invention;
• la figure 2 est un schéma bloc de l'installation de prise de son équipant la salle de conférence;
• la figure 3 représenτe les composantes des signaux électriques représentatifs d'un son émis à un emplacement déterminé de la salle, telles qu'elles sont captées par les microphones dans cette salle; la figure 4 représente ces mêmes composantes à leur sortie d'un système déphaseur;
• et la figure 5 représente le signal résultant à la sortie d'un additionneur recevant à ses entrées les composantes de la figure 4.

The invention will be better understood and other objects, characteristics, details and advantages thereof will appear better in the light of the explanatory description which follows, of a sound installation in accordance with the principle of the invention, given only by way of example and with reference to the attached nonlimiting drawing in which:

• Figure 1 schematically shows the general arrangement of a conference room equipped with a sound recording and sound system in accordance with the principle of the invention;
• FIG. 2 is a block diagram of the sound installation for equipping the conference room;
• FIG. 3 represents the components of the electrical signals representative of a sound emitted at a determined location in the room, as they are picked up by the microphones in this room; FIG. 4 represents these same components at their output from a phase-shifting system;
• and FIG. 5 represents the signal resulting from the output of an adder receiving at its inputs the components of FIG. 4.

Referring to Figure 1, there is shown a conference room 11 arranged of conventional Aacon with a number of chairs for participants or delegates and a table with a platform 12 behind which are arranged a number of chairs F for participants most important of the assembly. The grandstand table 12 can be equipped with microphones (not shown) favoring the participants installed in the seats F; this is however not essential in the context of the invention. Advantageously, a public address booth 13 is arranged near the room 11. This booth includes a console 18 which can group together certain elements of the installation according to the invention at the same time as a luminous call board or the like making it possible to immediately identify a participant installed in any of the f chairs who has asked to speak. This type of call panel is conventional and is not part of the invention. On the other hand, the invention uses only a limited number of microphones (four microphones M ₁ , M ₂ , M3 ^, M ₄ according to the example shown) arranged in the room so as to be relatively distant from each other and which capture all the sounds emitted in the room. As shown in FIG. 2, the microphones M ₁ -M ₄ are connected to four corresponding inputs e ₁ -e4 of a phase-shifting system D. This phase-shifting system D is connected to be controlled by an addressing system 14 from data stored once and for all in a memory 15 also connected to the addressing system 14 and of which an output S is connected to the phase shifter system D to introduce data there. The outputs s ₁ -s ₄ of the phase shifter system D are connected to corresponding inputs e ' ₁ -e' ₄ of an adder circuit A whose output S 'is connected to a sound system comprising for example a amplifier 16 and one or more speakers 17. The entire installation shown diagrammatically in FIG. 2 can be housed in the cabin 13 with the exception of the microphones M ₁ -M ₄ and the speaker (s) 17 which are obviously placed in conference room 11.

When the conference room is put into operation, the memory 15 is preprogrammed, which will be established once and for all. For each location f corresponding to a conference chair, the relative phase shifts of the sounds picked up by the microphones M1-M ₄ are determined or measured when a sound source is located at one of the predetermined locations (for example the chair f ₁ ). In FIG. 3, the components of the sound signals picked up by the four microphones are represented, which correspond to a sound emitted from the location f ₁ . If we take as a reference the component which reaches the microphone M ₁ (maximum delay), we see that this same component arrives at the microphone M ₂ with a phase advance t ₂ , that it arrives at the microphone M ₃ with a phase advance t ₃ and that it arrives at the microphone M ₄ ^. with a phase advance t ₄ . Consequently, at the time of programming the memory 15, for the location f ₁ , the microphone considered as reference (M ₁ ) and the values of the phase shifts t ₂ , t ₃ , t ₄ corresponding to the microphones M will be stored in memory. ₂ , M ₃ , M ₄ . We proceed in the same way for all the locations f by choosing for example for reference microphone the one which records a maximum delay, that is to say generally the most distant from the location f considered, and by noting in the memory 15 the values of the relative phase shifts of the sounds picked up by the other microphones, with respect to the reference microphone. As a first approximation, we can consider that the delays recorded between the emission of a sound at a location f considered and its perception by the microphones M ₁ -M ₄ , depends on the distance of said microphones from said location. Once the memory 15 has been programmed in the manner just indicated, the installation is ready to operate. When the participant or conventioneer in the chair f ₁ requests to speak, an operator located in the cabin 13 performs a selection operation from the addressing system 14 and then the memory 15 communicates to the phase-shifting system D the values of the phase shifts t ₂ , t ₃ and t ₄ taken with respect to the signal picked up by the microphone M ₁ . The role of the phase shift system D is then to delay the sound picked up by the microphone M ₂ by a time t ₂ , to delay the sound picked up by the microphone M ₃ by a time t ₃ and to delay the sound picked up by the microphone M ₄ of a time t ₄ . From this moment, the components of the sounds picked up by the microphones M ₁ -M ₄ which are representative of the sound emitted from the location f ₁ are in phase concordance (FIG. 4). Consequently, the adder circuit A receiving the signals coming from the microphones M ₁ -M ₄ by means of the phase shift system D will automatically carry out an amplification of said components of the electrical signals representative of the sounds emitted at the location f ₁ . In other words, these components are added so that the sound emitted in f ₁ is practically amplified by a factor 4 (the number of microphones) while the components of the sounds emitted everywhere else in the room are algebraically added. so that the sound system only transmits these parasitic sounds, a background noise which is not really amplified like that which is produced at the particular location f ₁ (FIG. 5). By acting on the addressing system 14, it is possible to modify the values of the phase shifts as well as the reference microphone so as to favor another location f corresponding to another participant wishing to speak.

Furthermore, the installation shown in FIG. 2 can be easily modified to allow selective picking up of two (or more) chosen locations. It then suffices to double the circuits of the phase-shifting system D and to provide for example two adding circuits such as A whose outputs would be connected to the same amplification means of the room. Of course, the memory 15 would be capable of simultaneously communicating two groups of data to the phase shifting system.

In addition, in some cases, the selection can be made by the participants themselves, if each has a push button allowing him to select his own location; another pressure where ^. pressing a second push button cancels the selection. Finally, the system according to the invention is also compatible with a simultaneous translation installation. The loudspeakers are replaced by individual headphones broadcasting the message of the selected participant, translated by an interpreter.

Of course, the invention is in no way limited to the embodiment of the installation which has just been described, it includes all the technical equivalents of the means involved if these are in the context of the claims which follow .

Claims (3)

1. Method for taking sound in a room such as for example a conference room; said room comprising a certain number of microphones and a certain number of locations of participants or congress participants, said locations being for example materialized by individual armchairs, characterized in that it consists, after having determined and stored for each location the values of the relative phase shifts of the sounds picked up by all of said microphones when a sound source is located at said location, - selecting at least one determined location where a participant wishing to speak is located by phase shifting the electrical signals generated by said microphones by said phase shift values corresponding to said determined location, previously stored, so that the components of said electrical signals representative of sounds emitted at said determined location are in phase agreement in said electrical signals thus phase shifted, - adding all of said electrical signals thus out of phase, and - to apply the electrical signal resulting from this addition to an amplification system. 2. Method according to claim 1,
characterized in that it consists, for each aforementioned location, in taking for reference the electrical signal whose said component has the greatest delay with respect to the sound emitted at said location, in determining the phase shifts of the other electrical signals with respect to said reference so to store said phase shifts in memory then, when said location cement is selected, to delay said other electrical signals by the respective values of said phase shifts previously stored in memory, before effecting said addition of all these electrical signals. 3. Sound recording installation in a room, in particular for implementing the method according to claim 1 or 2, comprising in particular a plurality of microphones located in said room at selected locations, a phase shift system comprising a plurality of inputs connected to said microphones and at least one group with the same number of outputs, said phase shifting system comprising means for delaying the signals applied to its respective selectively adjustable value inputs and at least one adder circuit comprising the same number of inputs as said phase shifter system has outputs, each input of said adder circuit being connected to an output of said phase shifter system, characterized in that it further comprises a memory preprogrammed to contain several groups of phase shift values, each group corresponding to: a determined location of said room and an addressing system connected to said phase shift system and to said memory for i ntroducing a grouping of phase shift value chosen in said phase shifting system and for controlling said means for delaying.

Images