FR3076941A1 - CALIBRATION METHOD FOR ACOUSTIC FOCUSING SYSTEM - Google Patents

Abstract

A method of calibrating an acoustic focusing system for a vehicle passenger compartment (10), in which at least one focusing zone (56) is positioned, comprises the following steps: a) a first wave (60) is emitted from a calibration device (42) comprising at least one acoustic source (44) positioned in the at least one focusing zone (56), - b) at least one signal, corresponding to the first wave (60) having diffused in the passenger compartment (10) is received by at least one transducer (46), - c) the received signal is processed by a processing module (48) comprising means for calculating (50) the temporal reversal of the signal and increasing the informative nature of this signal, and - d) the signal received by the transducer (46) and processed by the processing module (48) is integrated in a database (54) of sound information. Application to the field of the automobile

Description

CALIBRATION METHOD FOR ACOUSTIC FOCUSING SYSTEM

The field of the present invention is that of public address systems for vehicles, and in particular that of motor vehicles.

The sound level inside a passenger compartment, whether that of an automobile, a bus or any other vehicle, is a determining factor in the quality of the user experience. Improving the well-being of the user of a vehicle therefore involves, among other things, controlling the noise level inside the passenger compartment. Some of the tracks developed are geared towards mastering and personalizing the sound environment for different users.

This solution comes up against the multiplication of informative or desired sound sources within the vehicle: film projection system, music, users' telephones, to which are added the various unwanted sounds propagated inside the vehicle (system of propulsion, tire-road contact, aeroacoustics, ...).

Most of these sounds are intended or useful only for some of the vehicle users. However, there is no applied way to effectively individualize the sounds intended for each user.

The aim of the present invention is therefore to propose an effective solution to this problem, by making it possible to individualize the sound perceived by each user, by creating acoustic focusing zones specific to each, so as to control and personalize the sound environment for different users.

The subject of the invention is therefore a method of calibrating an acoustic focusing system for a passenger compartment of a vehicle in which at least one focusing zone is positioned, said calibration method comprising steps during which a first wave originating from an acoustic signal is emitted from a calibration device comprising an acoustic source positioned in the at least one focusing zone, at least one audible signal, corresponding to the first wave having diffused in a passenger compartment, is received by at least one transducer, the received signal is processed by a processing module comprising means for calculating the time reversal of the signal and increasing the

WFR2966 informative nature of this signal, and the signal received by the transducer and processed by the processing module is integrated into a sound information database.

An acoustic focusing system calibrated via the calibration method according to the invention makes it possible to individualize the sound space for at least one user of the vehicle. In this context, the time reversal function relies on constructive interference generated in a vehicle interior to improve focusing, as opposed to existing methods of controlling the sound field, developed for propagation of sound waves in free field, and whose performance in individualizing the sound space is degraded by interference due to reflections in the passenger compartment.

The process according to the invention advantageously comprises any one of the following characteristics, taken alone or in combination.

The database is provided with a plurality of sound information. The database includes a plurality of data, each associated with one or more sound information, this data being either pre-returned signals for calibration, or impulse responses. More particularly, the data included in the database and associated with sound information can comprise a first wave and the sound information that this wave aims to transmit, a signal received by a transducer, a signal processed by a processing module and / or its calculation means, a second wave to be emitted, if necessary by the addition of several processed signals, a particular focusing area, the need to restore a binaural signal, or else the transducer by which the second wave must be issued.

The database is at least partly constituted by a transfer of data from a terminal external to the vehicle. In particular, the constitution of the database can be done by downloading, periodically or not, the data. The download can be caused by a user of the vehicle, or by a manufacturer of the vehicle or of the acoustic focusing system. The passenger compartment of the vehicle includes in particular the passenger compartment of a motor vehicle. Alternatively, the vehicle interior includes the cockpit of an air vehicle or the cockpit of a marine vehicle.

The processing module is linked to the transducer (s). In this arrangement, the signals collected by the transducer (s) are sent to the processing module so as to be processed separately from each other by the processing module.

WFR2966 processing, and more particularly by its calculation means.

The processing module is linked to the database. The signals processed by the processing module, and more particularly by its calculation means, are stored in the database, so as to allow the subsequent emission of a second wave.

The processing module may in particular include means for calculating signal shape recognition, averaging, in order to improve the signal to noise ratio of the signal which will be emitted after time reversal.

The database is linked to at least one transducer. This link is arranged so as to allow the signals processed to be sent in the form of a second wave to be transmitted by the at least one transducer.

The acoustic source of the calibration device may be a device independent of the vehicle, for example a helmet or an acoustic mannequin, or else this device is supplied with the vehicle, in particular in the headrest. This acoustic source is necessary during the calibration process, and can then be moved and / or removed from the vehicle interior.

The first wave is transmitted for a first duration, the corresponding signal being recorded for a second duration greater than the first duration.

The signal received by at least one transducer is recorded.

The data compiled in the database are specific to each transducer.

A plurality of first waves are transmitted and processed successively. Each first wave corresponds to different sound information.

The first wave is returned in time with respect to a characteristic wave corresponding to sound information.

The method includes a step of updating the sound information database by the processing module.

The update step is implemented following the reception by the processing module of modification information relating to the focus area and / or the passenger compartment.

The calibration method employs at least one transducer, the processing module deducing for each transducer a signal which is specific to it.

The first wave is an acoustic wave. The term acoustic here has a meaning

WFR2966 general, and cannot be reduced to only frequencies audible to humans. Artifacts can be added to the signal of the first wave so that the final subjective rendering corresponds to the expected perception.

The calibration process can be operated simultaneously or consecutively for at least one additional user of the vehicle.

The invention also relates to a system for calibrating an acoustic focusing system intended to equip a passenger compartment of a vehicle, comprising at least one calibration device, a transducer configured to receive at least one signal from a first transmitted wave. in a focusing area of the passenger compartment by an acoustic source carried by the calibration device, and at least one processing module comprising means for calculating the time reversal of this signal and for increasing the informative nature of this signal associated with the transducer.

The calibration system according to the invention advantageously comprises any one of the following characteristics, taken alone or in combination:

The processing module further comprises calculation means for generating a second wave in response to said signal.

Artifacts can be added to the signal of the second wave so that the final subjective rendering corresponds to the expected perception.

The system includes at least one sound information database.

The database is configured to associate a wave obtained by the calculation of said processing module with a type of event related to the vehicle and / or an occupant of this vehicle, and at least one transducer of the passenger compartment of the vehicle, configured to receive the transmission instruction from the processing module and transmit the wave corresponding to the detected event.

The calibration device is portable, and in particular comprises at least one system provided with at least one acoustic source at each ear of the listener or of the mannequin.

The calibration device can be physically connected to the passenger compartment of the vehicle.

The calibration device can be independent of the passenger compartment. In this arrangement, the calibration device can be moved or removed from the passenger compartment of the vehicle once the calibration process is completed without disturbing the operation of the acoustic focusing system.

The transducer is a system for setting in motion a surface

WFR2966 radiating acoustics from an electrical signal or transforming the movement of a surface into an electrical signal. This system can be a vibrating pot, a microphone, a loudspeaker or any other type of system corresponding to the preceding description. The radiating surface of the acoustics may be the diaphragm of a loudspeaker, a dashboard of a vehicle cabin or any other surface corresponding to the preceding description.

The transducer is of point, linear, surface or volume type

The transducer is fixed.

The transducer is orientable or towards a reflector.

The invention also relates to a road vehicle comprising such a calibration system. By road vehicle, we generally understand cars, trucks, buses in particular.

Other characteristics, details and advantages of the invention will emerge more clearly on reading the description given below by way of indication in relation to the drawings in which:

- Figure 1 is a schematic representation of a passenger compartment of a vehicle where the method of the invention is implemented,

- Figure 2 is a diagram detailing the calibration method of the invention,

FIGS. 3a and 3b are schematic representations of the technical means allowing the implementation of the method of the invention within the passenger compartment of a vehicle,

- Figures 4a and 4b are representations of a wave before and after its processing by time reversal,

- Figures 5 to 7 are schematic representations of different stages of a scenario where the acoustic focusing system calibrated by the method according to the invention is used.

it should first be noted that the figures show the invention in detail to implement the invention, said figures can of course be used to better define the invention if necessary.

FIG. 1 shows a passenger compartment 10 comprising an acoustic focusing system and a system for calibrating such a system.

The acoustic focusing system comprises at least one transducer 12. The

WFR2966 transducer 12 of the acoustic focusing system can be of the type of a speaker. The transducer 12 of the acoustic focusing system is integrated into an element of the passenger compartment 10 of the vehicle, and in particular a steering wheel 14, an instrument panel 16, a dashboard 18, a rear view mirror 20, a central console 22, a seat 24, an armrest 26 of the seat 24, an upright 28 of the windshield, a door 30 of the vehicle, a rear shelf, a ceiling, a ceiling lamp, or any other element of the vehicle.

Each transducer 12 of the acoustic focusing system is here mounted in an original position, in which it is oriented to emit sound waves in a determined direction towards the interior of the passenger compartment 10, and in particular a focusing area 56. The transducer 12 of the acoustic focusing system is fixed, that is to say that its orientation cannot be modified.

It will however be understood that in an alternative, at least one transducer 12 of the acoustic focusing system is mounted mobile, its orientation can thus be modified at the time of the emission of sound waves.

The acoustic focusing system is coupled to a calibration system according to one aspect of the invention. The calibration system comprises a calibration device 42, a transducer 46 and at least one processing module 48.

In the example illustrated, the calibration device 42 takes the form of a helmet. The device is integrated and automated in the passenger compartment or worn by the user or a mannequin on his ears, during the calibration phase of the process described below. The helmet comprises at least one acoustic source 44, preferably two, each disposed in a focusing zone 56 of the passenger compartment 10, at the level of the ears of the user or of the mannequin.

The calibration device 42 is arranged to emit at least a first wave 60 by its acoustic source 44. The calibration device 42 therefore comprises the means allowing it to store, or to recover by wired or wireless link, prior to the method of calibration of the first 60 Waves to be sent.

It will be understood that the calibration device 42 could be of another type, without questioning the inventive concept of the calibration process and of the calibration system. In particular, the calibration device 42 may be integrated into a headrest of a seat 24 of the vehicle, without being modified however by the fact that the calibration device is configured to emit first waves 60 to initiate a process of

WFR2966 calibration of the focused emission function in the vehicle cabin. The first wave 60 corresponds to sound information previously processed by the time reversal function and stored in the calibration device 42.

The transducer 46 of the calibration system is integrated in an element of the passenger compartment 10 of the vehicle, and in particular a steering wheel 14, a dashboard 16, a dashboard 18, a rear view mirror 20, a central console 22, a seat 24 , an armrest 26 of the seat 24, an upright 28 of the windshield, a door 30 of the vehicle, a rear shelf, a ceiling, a ceiling lamp, or any other element of the vehicle. The transducer 46 of the calibration system is positioned close to the transducer 12 of the acoustic focusing system, that is to say that they are in the vicinity of one another. It will be understood that the transducer 12 of the acoustic focusing system and the transducer 46 of the calibration system can be fused into a single element, using for example the same transducer in its two modes of energy transformation (acoustic / mechanical <- > electric). Furthermore, if two separate transducers are formed, the proximity means that they are less than twenty centimeters apart. Alternatively, the transducer 12 of the acoustic focusing system and the transducer 46 of the calibration system are arranged in the same housing.

The transducer 46 of the calibration system can be of the type of a piezoelectric sensor or a microphone or any other type of system making it possible to set in motion a structure radiating an acoustic wave. Other types of transducers can be used, as long as they are suitable for detecting a first Wave 60 or a signal corresponding to the first Wave 60.

A given wave, here a first wave 60, comprises a plurality of components. In the case of the first wave 60, this first wave 60 comprises a plurality of first components 62. The components of a wave represent each part of the wave, the wave representing the whole of a sound emitted by an element. any sound source 44 or transducer 12 for example.

The components will propagate in the passenger compartment 10, undergo disturbances such as refractions or reflections, and reach at least one transducer 46 of the calibration system. It should be noted that the disturbances of waves due to the environment can be amplified by the addition of complex acoustic materials in the environment in order to improve the focusing phenomenon.

The transducer 46 of the calibration system will pick up a signal, the sum of all

WFR2966 components received by transducer 46 of the calibration system and modified by the disturbances suffered.

In the case of a single transducer 46 of the calibration system arranged in the passenger compartment 10, a first wave 60 gives a single signal for the transducer 46.

In the case of a passenger compartment comprising a plurality of transducers 46, and in particular a first transducer 46, a second transducer 46 and a third transducer 46, a first wave 60 gives a first signal for a first transducer 46, a second signal for a second transducer 46 and a third signal for a third transducer 46.

If a first additional Wave 60 is emitted, this first additional Wave 60 gives a first additional signal for the first transducer 46, a second additional signal for the second transducer 46 and a third additional signal for the third transducer 46. The term additional denotes here a first additional Wave 60 separate from the first Wave 60 mentioned above, the first Wave 60 and the first additional Wave 60 being treated separately.

The transducer 46 of the calibration system is connected to a processing module 48. This processing module 48 comprises at least one calculation means 50, arranged to allow the processing of a signal received by the transducer 46 of the calibration system. The processing module 48 and its calculation means 50 are here represented in the passenger compartment 10 of the vehicle, but at least one of these elements can be arranged in another space, and in particular an engine compartment of the vehicle, or else on a remote server, these elements in this case being provided with appropriate radio communication means to allow remote data exchanges.

The processing module 48 is arranged to receive information relating to the focusing area 56, the conditions within the passenger compartment 10 and the wishes of the users of the vehicle.

The processing module 48 is also connected to a database 54 of sound information.

It is understood from the above that the calibration system comprises at least one transducer 46, paired with the at least one transducer 12 of the acoustic focusing system, the transducers 12, 46 being arranged close to each other, c that is to say within twenty centimeters, or within the same housing. It will be understood that the

WFR2966 transducer 12 of the acoustic focusing system and transducer 46 of the calibration system can be merged into a single element, using for example the same transducer in its two modes of energy transformation (acoustic / mechanical <=> electrical) . More particularly, provision may be made for a plurality of transducers 46 of the calibration system and a corresponding plurality of transducers 12 of the acoustic focusing system to equip the passenger compartment 10, each transducer of the calibration system being paired with a transducer of the system acoustic focus. As illustrated in the exemplary embodiment of FIG. 1, it is possible in particular to provide at least one pair of transducer of the calibration system - transducer of the acoustic focusing system which is arranged on a left side of the passenger compartment, at the front of this passenger compartment, and at least one pair of transducer of the calibration system - transducer of the acoustic focusing system which is arranged on a right side of the passenger compartment at the front thereof. In addition to these pairs, at least one pair of transducer of the calibration system - transducer of the acoustic focusing system which may be arranged on a left side of the passenger compartment at the rear of the passenger compartment, at least one other pair of transducer of the transducer calibration system of the acoustic focusing system which can be arranged on a right side at the rear of the passenger compartment.

Due to the fact that they are arranged in different places in the passenger compartment, and due to the disturbances linked to the environment of the wave originally emitted from the focusing zone 56 by the calibration device, each transducer 46 of the calibration system receives one or more signals relating to the first wave 60 which is different from that received by the transducer 46 adjacent to the calibration system.

A focusing area 56 corresponding to an area close to the ears of an occupant of the passenger compartment 10. The calibration device 42 is arranged in this focusing area 56 for the emission of the first wave 60 during the calibration process.

If a specific focus area 56 is desired for one of the users, for example for the passenger of a motor vehicle distinct from the driver for which a first focus area 56 has been defined, a calibration phase is carried out. with the calibration device 42 placed in this specific focusing area 56.

Alternatively, the calibration device 42 comprises at least two acoustic sources 44 disposed respectively in the vicinity of one of the ears of the user brought to wear the calibration device 42.

WFR2966

Such a calibration system makes it possible to implement the calibration method according to the invention. This calibration process, illustrated in FIG. 2, comprises at least the following steps:

a step 100 during which a first wave 60 is emitted from a calibration device 42 comprising an acoustic source 44 positioned in the at least one focusing area 56,

a step 110 during which at least one signal, corresponding to the first wave 60 having diffused in the passenger compartment, is received by at least one transducer 46 of the calibration system,

a step 120 during which the received signal is processed by a processing module 48 comprising calculation means 50 for time reversal of the signal, and

a step 130 during which the signal received by the transducer of the calibration system and processed by the processing module 48 is integrated into a database 54 of sound information.

Steps can be added to the previous steps, and in particular a step 140 for updating the database 54 of sound information by the processing module 48. This updating step involves a modification of the database developed during step 130.

This updating step occurs following the reception by the processing module 48 of modification information 150 relating to the focusing zone 56 and / or to the passenger compartment 10 of the vehicle. This information 150 may for example relate to an increase in temperature capable of modifying the propagation of the waves within the passenger compartment 10, this variation being taken into account to modulate the signal and / or the orientation of the transducer 12 of the focusing system. acoustics, so as to allow sound to be focused.

The precise location of the focusing area 56 can be obtained by detection of the calibration device 42, in particular optical. This detection can be done by visual, infrared, ultrasonic, computer vision, or any other effective means. This detection can for example be implemented to determine whether or not there is a change of user, and allows the step of updating the database to be implemented, the adjustment of certain parameters, or even to restart one or more steps of the calibration process.

WFR2966

Once the first wave 60 emitted by the acoustic sources 44, the focusing area 56 is frozen. The calibration device 42 can be moved into the passenger compartment 10 or even removed from the passenger compartment 10, without affecting the position of the focusing zone 56.

An additional method of time reversal of the signal and emission of a second wave 70 temporally returned, to generate a focused sound emission as will be described, therefore makes it possible to direct a processed signal corresponding to the first wave 60 in direction of focus area 56.

This method of focused sound emission in a passenger compartment 10 of the vehicle of at least one sound information associated with a first wave 60, by an acoustic focusing system comprising at least one transducer 12 located in the passenger compartment 10 of the vehicle, comprises at minus a step of diffusion from the transducer 12 of the acoustic focusing system of a second wave 70 associated with the sound information.

The transducer 12 of the acoustic focusing system returns the second wave 70, resulting from the time reversal of the signal corresponding to the first wave 60 specifically received by the transducer 46 of the calibration system associated with the transducer 12 of the acoustic focusing system, in the same direction but in a reverse direction from that of arrival of the signal to the transducer 46 of the calibration system. In other words, one or more signals arrive on the transducer of the calibration system in one or more directions and corresponding signals forming the second wave are emitted, after time reversal, in these same directions and in opposite directions. It should be recalled here that the transducers of the

The use of the calibration and sound emission methods specific to the vehicle's acoustic focusing system will now be described. This usage is illustrated in particular in Figure 3.

For a given focusing area 56, there is an acoustic source 44, several transducers 46 of the calibration system and several transducers 12 of the acoustic focusing system. The following description will focus on the operation of an acoustic source 44, a transducer 46 of the calibration system and a transducer 12 of the acoustic focusing system, and it will be understood subsequently that this can be declined. operating with a plurality of transducers 46, 12.

It is understood that in the case where the calibration device 42 comprises several acoustic sources 44, each acoustic source 44 emits the same first wave 60, and the

WFR2966 transducers 46 of the calibration system receive a plurality of signals emanating from the emission of the first wave 60 respectively by several acoustic sources 44.

In the case with several acoustic sources 44, the same first wave 60 is sent, the transducers 46 of the calibration system receiving different components depending on whether the first wave 60 is emitted by a first acoustic source 44 and a second source. acoustic 44.

A first wave 60, comprising a plurality of first components 62, emitted from a first source located in a focusing area 56, propagates in a medium, here the cabin 10 of the vehicle. The first Wave 60 corresponds to the sound information previously processed by the time reversal function and stored in the calibration device 42.

During its propagation in the environment, each of the first components 62 of the first wave 60 follows a defined path during which it is reflected, refracted, diffused and / or diffracted by the environment of the passenger compartment 10, and in particular here the glass walls of the vehicle, before reaching a first transducer 46 of the calibration system arranged in the passenger compartment. Each of the first components 62 captured by the first transducer 46 of the calibration system is representative of the route taken, all of these first components 62 thus giving a representation of the environment in which they have evolved. The set of first components 62 of the first wave 60 captured by the first transducer 46 of the calibration system thus generates a first image waveform associated with the first wave 60 which is specific to the first transducer 46 of the calibration system.

In the case with several acoustic sources 44, the transducers 46 of the calibration system receive a plurality of signals emanating respectively from the emission of the first wave 60 by several acoustic sources 44 and resulting from disturbances linked to the environment.

All of the first components 62 of the first wave 60 picked up by the transducer 46 of the calibration system are then processed by the processing module 48, so as to obtain a second wave 70, resulting by time reversal of the signal picked up by the transducer. 46 of the calibration system and associated with the first Wave 60.

For each first component 62, there is an analysis of the shape and the direction of the received signal, which makes it possible to deduce the path taken by the first component 62

WFR2966 between the emission source and the transducer 46 of the calibration system, and a processing is applied to this first component 62 so that a second component 72, participating in forming a second wave 70, is returned from the transducer 12 of the acoustic focusing system paired with the transducer 46 of the calibration system, so as to travel the returned path of the first corresponding component 62, between the transducer pair 46 of the calibration system - transducer 12 of the acoustic focusing system and the focusing area 56 The processing carried out corresponds to a Flipping of the Wave, the beginning of the first Wave 60 becoming the end of the second Wave 70 while the end of the first Wave 60 becomes the beginning of the second Wave 70.

This inversion by time reversal is illustrated in FIGS. 4a and 4b.

In FIG. 4a, a reference wave 80 illustrates a waveform before its time reversal, namely a wave returned from the first wave resulting from the addition of the signals received by the transducer 46 of the calibration system. For a given period of time, the reference wave 80 comprises a first amplitude 82 at an instant t1, a second amplitude 84 at an instant t2 and a third amplitude 86 at an instant t3. In FIG. 4b, a transformed wave 90 illustrates a waveform after its time reversal.

The first amplitude 82 of the reference wave 80, the first of the reference wave 80 along a first time axis 88, becomes a third amplitude 92 transformed from the transformed wave 90, the last from the transformed wave 90 along a second time axis 98 equivalent to the first time axis 88. Similarly, the third amplitude 86 of the reference wave 80, the last of the reference wave 80 along the first time axis 88, becomes a first transformed amplitude 96 of the transformed wave 90, the first of the transformed wave 90 along the second time axis 98. Finally, the second amplitude 84 of the reference wave 80 is also transformed into a second transformed amplitude 94 of the transformed wave 90.

The second wave 70 is then transmitted from a transducer 12 of the acoustic focusing system associated with the transducer 46 of the calibration system. The second wave 70, comprises a plurality of second components 72 corresponding respectively to a first component 62 of the first wave 60. Each second component 72 is emitted in a direction which takes account of the directivity of the transducers 12 and 46 and of the direction d arrival of the first wave.

WFR2966

If a first component 62 (FIG. 3a) results in a signal received by a transducer 46 from the calibration system corresponding to the reference wave 80 illustrated in FIG. 4a, then the second component 72 (FIG. 3b) resulting from the time reversal of the first component 62 will have a waveform corresponding to the transformed wave 90 illustrated in FIG. 4b.

Each second component 72 propagates in the passenger compartment, each of its second components 72 following its own course during which it undergoes a certain number of disturbances. More particularly, the second components 72 of the second wave 70 undergo the same phenomena as the first components 62 of the first wave 60 have undergone, but in an inverted chronology. The disturbances undergone by the second wave 70 during the inverted propagation cancel the disturbances undergone by the first components 62.

The fact of going back in time and reemitting in the same direction will make it possible to route the second wave 70 at the level of the focusing zone 56 with which an acoustic source 44 was specifically associated.

as a result, all of the second components 72 of the second wave 70 focus in the area from which the acoustic sources 44 emitted during the calibration phase, namely at the level of the focusing area 56 or in its close vicinity. At the focusing area 56, all of the second components 72 have the same waveform as the first components 62 at the time of their emission by the acoustic source 44.

Thus, all of the components of the second wave 70 form at the level of the focusing zone 56 or in its close vicinity a sound, corresponding to the sound information emitted and audible by the user or an acquisition system located at the level of the first source or in its close vicinity. The set of components of the second wave 70 obtained at the level of the focusing area 56 or in its close vicinity is directly deduced from the set of components of the first wave 60 by the time reversal function.

So that the sound information is finally delivered correctly at the level of the focusing area 56, that is to say that it corresponds to a signal known to the user, it is understood that the second wave 70 corresponds to the sound identifiable by the user and that the first Wave 60 is a wave corresponding to this sound but processed

WFR2966 initially by a time reversal function. In this way, this double time reversal operation (before the emission of the first wave, then before the emission of the second wave by the processing module 48) delivers the signal in the same temporal direction as the initial signal.

According to one aspect of the invention, the second waves 70 emitted by each of the transducers 12 of the acoustic focusing system can be generated so as to reproduce a binaural sound. Binaural synthesis is a sound spatialization technique consisting of reproducing at the level of a user's ears all the information necessary for the construction of a sound image so as to allow the auditory system to locate a sound source in space. This binaural synthesis is based on the use of filters called binaural filters, which reproduce the acoustic transfer functions between the sound source and the user's ears. These filters are used to simulate auditory location cues that allow a user to locate sound sources in real listening situations. The techniques related to binaural synthesis are therefore based on a pair of binaural signals which feeds a restitution system. This pair of signals is obtained by signal processing, by filtering a signal by binaural filters which reproduce the properties of the acoustic propagation between the source placed at a given position and the two ears of a user. As a result, the user perceives a sound not from his actual emission source, but from a fictitious location determined by the transfer functions applied by the binaural filters.

Other binaural synthesis methods can be used, and the invention cannot be reduced to binaural synthesis as described above.

The acoustic focusing system described here is calibrated during the calibration process according to the invention. A nonlimiting example of calibration is described below.

A user of a vehicle, here a driver of a passenger car, gets behind the wheel 14 of his vehicle and makes adjustments to the seat of his seat 24, his mirrors and any other system. Once installed, the driver places the calibration device 42 on his ears, here in the form of a helmet, before starting the calibration process, by pressing a command, by voice command or any other interaction. The acoustic sources 44 of the calibration device 42 then successively emit one or more first waves 60, each corresponding to a given sound information previously processed by the time reversal function. For example, the acoustic sources 44 will emit the noise of a flashing light, the noise of a third vehicle 4 arriving from the rear, the

WFR2966 noise from a third-party vehicle 4 passing the vehicle, and a warning that the authorized speed limit has been exceeded, each processed by a time reversal function prior to transmission. Each of these first waves 60 is broken down into first components 62, which will reach a plurality of transducers 46 of the calibration device arranged in the passenger compartment 10 of the vehicle, here the passenger compartment, after having undergone disturbances as illustrated in FIG. Figure 3a. Each transducer 46 of the calibration device will receive a different signal for each of the first waves 60 emitted, each signal then being sent to the processing module 48 to be processed by the calculation means 50. The processing of each of the signals by the function of time reversal gives a processed signal which is stored in the database 54 of sound information. The signal 54 associated with sound information is associated with the signal processed with sound information, and in particular a first signal processed corresponding to the activation of a flashing light, a second signal processed corresponding to the arrival of a third vehicle 4 from the rear, a third processed signal corresponding to exceeding a third vehicle 4 and a fourth processed signal corresponding to exceeding the authorized speed limit. It will be understood that additional signals can be associated with additional audio information.

In an alternative to the calibration method, the acoustic sources 44 of the calibration device 42 emit a single first wave 60, corresponding to sound calibration information. The signals resulting from the broadcasting of this first wave 60 will then be directed to the processing module 48. The processing module 48 will use the signals received to develop second waves 70 corresponding to the sound information stored in the database 54 of audio information.

In addition to the calibration process, there may be added a method of focused sound emission in a vehicle interior of at least one sound information by an acoustic focusing system comprising at least one emission member, or fixed transducer located in the passenger compartment, and a control module, said method comprising at least one step of reception by the control module of data relating to an event related to the vehicle and / or with a user / occupant of this vehicle and a step of broadcasting from the stationary transmitting member of a second wave 70 associated with the sound information, this broadcasting step being associated with an event. The second wave 70 and its second components, as described above, will diffuse into the passenger compartment 10 in the opposite direction from the components of the first wave 60 during the calibration step and will converge towards a focusing area 56 of the passenger compartment 10.

WFR2966

Applied to a motor vehicle traveling on a road scene 6, the operation of the acoustic focusing system calibrated by the calibration process or by the calibration system is set out below and illustrated in FIGS. 5 to 7. Obviously, the Use of an object of the invention cannot be reduced to the example given below, other scenarios being possible.

Vehicle 2 equipped with the acoustic focusing system is traveling on a road scene 6, here on the right lane of a departmental road, at a speed slightly lower than the maximum authorized speed. A detection system is fitted to vehicle 2, such a system consisting of a plurality of detection devices arranged to locate and identify elements of the road scene 6, in particular signaling devices, other vehicles and users of the scene route 6, obstacles and weather conditions. The detection system identifies a third vehicle 4 arriving from the rear of the vehicle 2 and traveling in the same direction of circulation as the vehicle 2, at a speed greater than that of the vehicle 2. This situation is illustrated in FIG. 5. The detection system sends detection information relating to the detection of the third vehicle 4. The processing module 48 determines the need to send the sound information to the driver, and chooses from the entries in the sound information database the second wave 70 to be emitted by the transducers 12 of the acoustic focusing system, as well as the binaural filters to be applied so as to spatialize the sound information in an approach direction of the third vehicle 4, here towards the rear and towards the left, estimated position of the third-party vehicle 4. The different audio information chosen here corresponds to the approach and passage of a vehicle .

The different transducers 12 of the acoustic focusing system will each emit a second wave 70, specific to each, so that the different second components 72 of the different second waves 70 reach and are concentrated in the determined focusing area or areas 56, here the driver's ears. The different second components 72 of the different second waves 70 concentrated on the focusing areas 56 make it possible to recreate only in these focusing areas 56 the chosen sound information, namely the noise of approaching a vehicle. The other users of vehicle 2 do not perceive any sound coming from the acoustic focusing system.

In the rest of the scenario, the third vehicle 4 continues its course, and is overtaking vehicle 2. This situation is represented by FIG. 6. The information of

WFR2966 detection are updated by the detection system and sent to the vehicle processing module 48 2. The processing module 48 indicates the need to send the overtaking sound information to the driver, and selects the sound information to send in the form of the second Wave 70. The acoustic focusing system emits a second Wave 70 as well as the binaural filters necessary for the spatialization to the left of the sound information.

The third vehicle 4 ends its overtaking of the vehicle 2, as illustrated in FIG. 6. The detection information is updated once again, and the processing module 48 selects a new second wave 70 to be transmitted to report on the new situation. The acoustic focusing system emits a second Wave 70 as well as the binaural filters necessary for the spatialization at the front and to the left of the sound information.

In an alternative application of the acoustic focusing system, the detection information can be updated continuously rather than at regular intervals. The acoustic focusing system can also emit only a second wave 70, which will be spatialized to represent the passage of the third vehicle 4, without resorting to a plurality of second waves 70.

It will be understood that the acoustic focusing system can be adapted to allow differential acoustic focusing between several users of the vehicle. In particular, while the driver receives audio information related to driving, a passenger seated in the front passenger seat can receive audio information related to navigation. A third passenger, for example seated in a rear seat, can receive audio information related to entertainment, such as a soundtrack from a movie that the user is watching on a portable device. Thus, each user receives the sound information which is useful to him, without raising the noise level inside the passenger compartment of the vehicle.

The foregoing description clearly explains how the invention makes it possible to achieve the objectives which it has set for itself, and in particular to propose a method for calibrating an acoustic focusing system using an acoustic reversal function making it possible to individualize the sound of an audio information inside a passenger compartment of a vehicle.

Of course, various modifications can be made by the skilled person to the entire cabin and the calibration and focusing system which have just been

WFR2966 described by way of nonlimiting example, as soon as a calibration method is implemented comprising at least one step of transmitting a first wave, a step of receiving, a step of processing by a function of time reversal and a step of integration into a sound information database.

In any event, the invention cannot be limited to the embodiment specifically described in this document, and extends in particular to all equivalent means and to any technically operative combination of these means.

Claims (13)

1. Method for calibrating an acoustic focusing system for a passenger compartment (ΐθ) of a vehicle, in which at least one focusing zone (56) is positioned, said calibration method comprising steps during which: - a first wave (6θ) is emitted from a calibration device (42) comprising at least one acoustic source (44) positioned in the at least one focusing zone (56), - at least one signal, corresponding to the first wave (6θ). having diffused in the passenger compartment (1Ô), is received by at least one transducer (46), the received signal is processed by a processing module (48) comprising calculation means (50) for time reversal of the signal and for increasing the informative nature of this signal, and - the signal received by the transducer (46) and processed by the processing module (48) is integrated into a database (54) of sound information. 2. Calibration method according to the preceding claim, during which the emission and the processing of a plurality of first waves (60) are carried out successively. 3. Calibration method according to any one of the preceding claims, in which the first wave (6θ) is returned in time relative to a characteristic wave corresponding to sound information. 4- Calibration method according to any one of the preceding claims, further comprising a step of updating the database (54) of sound information by the processing module. 5- calibration method according to the preceding claim, the updating step being implemented following the reception by the processing module (48) of modification information relating to the focusing area (56) and / or in the passenger compartment (10) · WFR2966 6. Calibration method according to any one of the preceding claims, comprising a plurality of transducers (46), the processing module (48) by deducing for each transducer (46) a signal which is specific to it. 7. Calibration system of an acoustic focusing system intended to equip a passenger compartment (10), comprising at least: a calibration device (42), a transducer (46) configured to receive at least one signal from a first wave (6θ) emitted in a focusing zone (56) of the passenger compartment by an acoustic source (44) carried by the calibration device (42), at least one processing module (48) comprising calculation means (50) for time reversal of this signal and for increasing the informative nature of this signal associated with the transducer (46). 8. Calibration system according to the preceding claim, the processing module (48) further comprising calculation means (50) for generating a second wave (70) in response to said signal. 9- Calibration system according to the preceding claim, wherein the second wave (70) is returned in time relative to the first wave (6θ). 10. Calibration system according to any one of claims 7 to 9, comprising at least one database (54) of sound information. 11. Calibration system according to any one of claims 7 to 10, in which the calibration device (42) is portable, and in particular comprises at least one system provided with an acoustic source (44) at each ear d 'an auditor or a model. 12. Calibration system according to any one of claims 7 to 11 in which the calibration device (42) is physically connected to the passenger compartment (10) of the vehicle. WFR2966 13 · Calibration system according to any one of claims 7 to 11 wherein the calibration device (42) is independent of the passenger compartment (10).