Classifications

• • G—PHYSICS
  • G10—MUSICAL INSTRUMENTS; ACOUSTICS
  • G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
  • G10K11/00—Methods or devices for transmitting, conducting or directing sound in general; Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
  • G10K11/16—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
  • G10K11/175—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general using interference effects; Masking sound
• • G—PHYSICS
  • G10—MUSICAL INSTRUMENTS; ACOUSTICS
  • G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
  • G10K11/00—Methods or devices for transmitting, conducting or directing sound in general; Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
  • G10K11/02—Mechanical acoustic impedances; Impedance matching, e.g. by horns; Acoustic resonators
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; ELECTRIC HEARING AIDS; PUBLIC ADDRESS SYSTEMS
  • H04R1/00—Details of transducers, loudspeakers or microphones
  • H04R1/20—Arrangements for obtaining desired frequency or directional characteristics
  • H04R1/32—Arrangements for obtaining desired frequency or directional characteristics for obtaining desired directional characteristic only
  • H04R1/40—Arrangements for obtaining desired frequency or directional characteristics for obtaining desired directional characteristic only by combining a number of identical transducers
  • H04R1/403—Arrangements for obtaining desired frequency or directional characteristics for obtaining desired directional characteristic only by combining a number of identical transducers loud-speakers
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; ELECTRIC HEARING AIDS; PUBLIC ADDRESS SYSTEMS
  • H04R1/00—Details of transducers, loudspeakers or microphones
  • H04R1/20—Arrangements for obtaining desired frequency or directional characteristics
  • H04R1/32—Arrangements for obtaining desired frequency or directional characteristics for obtaining desired directional characteristic only
  • H04R1/40—Arrangements for obtaining desired frequency or directional characteristics for obtaining desired directional characteristic only by combining a number of identical transducers
  • H04R1/406—Arrangements for obtaining desired frequency or directional characteristics for obtaining desired directional characteristic only by combining a number of identical transducers microphones
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; ELECTRIC HEARING AIDS; PUBLIC ADDRESS SYSTEMS
  • H04R29/00—Monitoring arrangements; Testing arrangements
  • H04R29/001—Monitoring arrangements; Testing arrangements for loudspeakers
  • H04R29/002—Loudspeaker arrays
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; ELECTRIC HEARING AIDS; PUBLIC ADDRESS SYSTEMS
  • H04R3/00—Circuits for transducers
  • H04R3/002—Damping circuit arrangements for transducers, e.g. motional feedback circuits
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; ELECTRIC HEARING AIDS; PUBLIC ADDRESS SYSTEMS
  • H04R3/00—Circuits for transducers
  • H04R3/005—Circuits for transducers for combining the signals of two or more microphones
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; ELECTRIC HEARING AIDS; PUBLIC ADDRESS SYSTEMS
  • H04R3/00—Circuits for transducers
  • H04R3/12—Circuits for transducers for distributing signals to two or more loudspeakers

Definitions

• TITLE PROCEDURE AND DEVICE FOR CONTROLLING THE PROPAGATION OF ACOUSTIC WAVES ON A WALL
• the present invention relates to a method and a device for controlling the propagation of acoustic waves in the vicinity of a wall.
• the techniques used for acoustic treatment are generally based on the use of absorbent materials such as foam or structured cellular materials.
• acoustic liners having a distribution of Helmholtz resonators at low frequencies and foam at high frequencies are used.
• the reduction obtained remains less than a few decibels at low frequencies.
• the technique deployed makes it possible, in a thickness reduced to a few centimeters, to guarantee good absorption efficiency of acoustic nuisances for complex waves (grazing or diffuse waves for example) and for a wide range of frequencies including low frequencies or passive treatments. are inoperative.
• the invention proposes to implement a method and a device making it possible to control locally and not locally and adaptively the generalized acoustic impedance of a wall.
• the acoustic impedance is a usual and known physical quantity which corresponds to the ratio between the acoustic pressure and the acoustic speed.
• the device consists of a first layer of acoustic transducers, each consisting of microphones and a loudspeaker.
• a second layer is formed by the electronic part of signal conditioning and real-time command / control.
• the device is cellular, each cell incorporating a loudspeaker, microphones as well as electronics for calculating and managing signals.
• each cell is autonomous and executes a control law whose parameters can be determined and updated by an integrated interface. It is used to manage the cell network and to access the inputs and outputs of the entire system.
• the power supply of the device is coated through all the elements.
• the invention relates more precisely to the distributed and modular nature of the system.
• the subject of the invention is in particular a method for controlling the propagation of acoustic waves in the vicinity of a wall, the method comprising: - a step a) in which a number Ne of cells is affixed on the wall mainly consisting of a loudspeaker connected to a set of Nm microphones, said microphones and loudspeaker being designed to be controlled by a control unit,
• each microphone of each cell measures the acoustic pressure of the acoustic waves, each measurement being returned to the cell control unit,
• step c) in which the control unit estimates the acoustic pressure and / or its spatial derivative at the level of the loudspeaker, then defines the control law which fixes the intensity of the electric current which must be sent to the loudspeaker. loudspeaker so as to obtain a determined generalized acoustic impedance Zdet for the loudspeaker,
• step d) in which the control unit sends the electrical signal to the loudspeaker, so that a fraction of the acoustic waves is absorbed by the loudspeaker membrane.
• control unit in step c) estimates either the acoustic pressure at the level of the loudspeaker, or its spatial derivative, or both.
• a master device controls all the control units following a learning loop so as to adjust the generalized acoustic impedance determined Zdet for each cell.
• the parameters of the control law are adapted as long as the value of the insertion loss is below a predetermined threshold, then when the threshold is reached, step c is carried out ) of claim 1, which applies the appropriate control law (defined by the adaptation of the parameters) in order to obtain the determined generalized acoustic impedance (ie targeted) Zdet for the loudspeaker.
• the loop has the following steps: BEGIN: start
• A2 attribution of a control law to at least one of the cells
• A3 calculation of the parameters associated with the control law
• A5 generation of a calibrated signal (white noise or swept sine wave for example)
• A6 acquisition of the signal by the microphones
• A9 return to A3 to adapt the parameters of the control law to minimize the error on the measured impedance, in the case where IL ⁇ ILO.
• each cell has between 3 and 5 microphones, preferably 4.
• the fraction of the acoustic waves absorbed by the speaker membrane is converted into electrical energy to supply all of the cells.
• the generalized acoustic impedance is modified by means of the control law defined as follows:
• the method consists in imposing a physical dynamic on the system on the sole knowledge of the measurement of the physical state of the system (pressure, and / or pressure gradient in the vicinity of the loudspeaker membrane).
• the method therefore does not require resorting to a theoretical model of the behavior of technological components (for example the loudspeaker).
• control unit is a microcontroller, preferably of the ARM type.
• This type of microcontroller comes under an external architecture of the 32-bit RISC type (ARMvl to ARMv7) and 64 bits (ARMv8) l developed by ARM Ltd since 1983 and introduced from 1990 by Acorn Computers.
• control law is defined at a frequency between 25 and 150 kHz.
• the subject of the invention is also a device for controlling the propagation of acoustic waves in the vicinity of a wall, characterized in that it comprises a number Ne of cells consisting mainly of a loudspeaker, of a set of Nm microphones connected to said loudspeaker, to a control unit, and to a power supply, said microphones and loudspeaker being provided to be controlled by said control unit, a fraction of the acoustic waves absorbed by the membrane of the loudspeaker.
• each microphone of each cell being able to measure the acoustic pressure of the acoustic waves, each measurement being returned to the control unit of the cell, the control unit being able to estimate the acoustic pressure and / or its tangential spatial derivatives at the level of the loudspeaker, and able to apply the control law which fixes the intensity of the electrical signal which must be sent to the loudspeaker so as to obtain a determined generalized acoustic impedance Zdet for the loudspeaker, the device further comprising a master device for controlling all of the control units according to a loop comprising the following steps: BEGIN: start
• A2 attribution of a control law to at least one of the cells
• A3 calculation of the parameters associated with the control law
• A4 application of the control law to the cell
• A5 generation of a calibrated signal (white noise or sine wave swept for example)
• A6 signal acquisition by microphones
• A9 return to A3 to adapt the parameters of the control law to minimize the error on the measured impedance, in the case where IL ⁇ ILO.
• Optional, complementary or substitute characteristics of the invention are set out below.
• each cell of the device has between 3 and 5 microphones, preferably 4.
• the power supply of the device is coated through all the elements.
• the invention relates more precisely to the distributed and modular nature of the distributed system.
• the distributed nature of the microphones makes it possible to reconstruct spatial derivatives and to measure a pressure field in real time.
• the distributed nature of the actuators makes it possible to have a control law that is variable in space.
• control units make it possible to have a high level of robustness (the system can operate in degraded mode, even with several malfunctioning elements).
• All control units are autonomous, but can be reconfigured in real time by a master device which allows self-learning to adapt to new ambient conditions.
• the assembly can be mounted directly on the wall or in the form of nesting on a support mesh, which allows modularity in order to adapt to various geometries.
• the subject of the invention is also an acoustic panel coated with a set Ne of cells consisting mainly of a loudspeaker, a set of Nm microphones connected to said loudspeaker, and a control unit, said microphones and loudspeakers.
• the speaker being designed to be driven by said control unit, a fraction of the acoustic waves absorbed by the membrane of the loudspeaker being converted into electrical energy to supply the set Ne of the cells, the generalized acoustic impedance of each loudspeaker being subject to a control law, so as to locally define on the surface of said panel an absorbing or reflecting behavior, the panel being furthermore connected to a master device to drive all the control units according to a loop such as the one detailed above.
• FIG.1 This figure represents a schematic view of an acoustic control device according to the invention.
• FIG.2 This figure shows a detail of an acoustic cell according to the invention.
• variants of the invention comprising only a selection of characteristics described, isolated from the other characteristics described (even if this selection is isolated within a sentence. including these other characteristics), if this selection of characteristics is sufficient to confer a technical advantage or to differentiate the invention from the state of the prior art.
• This selection comprises at least one characteristic, preferably functional without structural details, or with only part of the structural details if this part alone is sufficient to confer a technical advantage or to differentiate the invention from the state of the prior art. .
• the device according to the invention aims to transform an electroacoustic transducer into a versatile electroacoustic resonator making it possible to absorb sound energy in a space or else to contain this energy between two adjacent spaces without using sensors in order to achieve noise reduction. desired.
• the technological innovation includes in particular a modification of the internal dynamics of the electroacoustic transducer by means of an electrical load impedance connected to its terminals, adapted to the electroacoustic transducer used as well as to the acoustic radiation conditions and to the desired acoustic performances.
• This impedance is to adjust the losses, and to compensate for the reactive parts of the transducer, with a view to enabling it to present performance that meets acoustic requirements.
• the acoustic impedance presented by the membrane of the electroacoustic transducer to the surrounding sound field can thus be rendered transparent, absorbent or insulating to incident sound waves, depending on the transfer function performed by the electrical impedance of the load.
• the synthesized electrical impedance constitutes the functional link between the voltage induced by the electroacoustic transducer subjected to an exogenous pressure field and the current necessary to absorb or contain the incident sound energy.
• the object of the invention relates, among other things, to an electroacoustic system regulated in a closed loop and permanently according to a self-adjustment, the control laws of which are based on a prior knowledge of the internal model, that is to say of the transduction mechanisms and dissipative and reactive mechanisms inherent in the transducer mounted on an enclosure or baffle.
• a moving part of the loudspeaker (for example the membrane, the dust cover and the coil) is set in motion when subjected to an exogenous sound pressure field, oscillates by front to back along the axis of symmetry of the transducer, and brought back to a position of equilibrium under the action of a spider and peripheral suspensions.
• the movement of the coil, itself immersed in a magnetic field generated by a permanent magnet creates an electromotive force, reflected in an induced voltage at the electrical terminals of the transducer.
• This induced voltage is like the acoustic disturbance at the origin of the movement of the moving part, but also depends on the internal dynamics of the speaker system and the acoustic radiation conditions (enclosure, position in a room, etc. .). It constitutes the input of the regulator, the role of which is to return a compensating electric current calculated to oppose a mechanical force to the membrane adapted to the desired acoustic effect: sound absorption in a space or sound insulation between two adjacent spaces.
• the control of the generalized acoustic impedance that is to say of the dynamics of the relationship between the pressure, the pressure gradient and the speed at the level of the controlled surface, results in a significant reduction in the energy transmitted along of the treated surface.
• This control is carried out by a distribution of loudspeakers, which act on the speed field, as well as by a distribution of microphones which allow the measurement of the acoustic pressure field and its gradient.
• the value of the intensity being preferably calculated by an infinite impulse response (IIR) filter, as a function of the measured sound pressure and of its gradient.
• the device developed makes it possible to simultaneously control N active loudspeaker cells.
• the architecture of the device also makes it possible to modify in real time the dynamics of each implemented filter.
• Imposing a generalized acoustic impedance on a wall amounts to imposing the dynamics between the acoustic pressure, the acoustic pressure gradient and the air speed at the level of this wall.
• the bandwidth of interest extends from 20 to 20,000 Hertz, and in particular in the context of civil engineering applications from 20 to 1,500 Hertz.
• the wall can be subdivided into local control zones five centimeters apart.
• Each cell has between 3 and 5 microphones 10, preferably 4.
• Each loudspeaker 11 is controlled by the power supply driven by a specifically developed digital computer card.
• the four microphones 10 of each cell 1 make it possible to estimate the average pressure at the center of the membrane of each loudspeaker.
• the pressure difference between the right and left border of the cell makes it possible to evaluate the spatial pressure gradient along the axis of propagation of the waves in the duct.
• the device senses the sound pressure by means of microphones 10.
• the signals are digitized by an analog-to-digital converter (ADC).
• ADC analog-to-digital converter
• the average pressure at the center of the membrane and / or the spatial derivative of the pressure at the level of the membrane is estimated from the measurement of the microphones.
• the control law is then calculated by the calculation unit 12.
• the current setpoint resulting from the previous calculation is generated by a digital to analog converter (DAC).
• DAC digital to analog converter
• a current source controls the current flowing in Loudspeaker 11.
• control method according to the invention comprises the following steps:
• a number Ne of cells 1 is affixed to the wall, consisting mainly of a loudspeaker 11 connected to a set of Nm microphones 10, said microphones and loudspeaker being designed to be controlled by a control unit 12,
• each microphone 10 of each cell 1 measures the acoustic pressure of the acoustic waves, each measurement being returned to the control unit 12 of the cell,
• the control unit 12 estimates the acoustic pressure at the level of the loudspeaker and / or its spatial derivative, then determines the control law which fixes the intensity of the electrical signal which must be sent to the loudspeaker 11 so as to obtain a determined acoustic impedance Zdet for the loudspeaker,
• the control unit in this step, estimates either the acoustic pressure at the level of the loudspeaker, or its spatial derivative, or both.
• control unit 12 sends the electrical signal to the loudspeaker 11, so that a fraction of the acoustic waves is absorbed by the loudspeaker membrane, the remaining second fraction being reflected.
• the calculation of the control laws is carried out locally at a frequency of 50 kHz by a microcontroller preferably of the ARM type.
• the fraction of the acoustic waves absorbed by the membrane of the loudspeaker 11 is converted into electrical energy to supply each of the cells.
• a master device C provided with an interface card makes it possible to advantageously communicate with the control unit 12 of each unit cell from a graphical user interface.
• the coefficients of the equations can then be determined and updated in real time, and cells can be turned on or off separately.
• This type of architecture makes it possible to locally implement control laws requiring different dynamics from one cell to another.
• the master device C can control all of the control units 12 following a learning loop.
• the loop can include a first step “BEGIN” to initiate the process.
• step A1 in which we initiate a generic acoustic model, in the sense that any acoustic model can be suitable and that in the present case, it is in fact defined by the equation [Math3]. Then, in A2, one proceeds to the attribution of a control law for at least one of the cells.
• a reference signal is generated.
• This reference signal is in fact a “noise” initiated by the loudspeaker or by an external device which is collected during step A6 by the microphones to initiate the control loop.
• Step A6 allows the microphones to collect the signal.
• the insertion loss is a usual and known physical quantity which corresponds to the reduction in the sound power level, caused by the insertion of an acoustic control device in a duct instead of a section of duct with rigid walls.
• the master device C loops back to A3 to adapt the parameters of the control law to minimize the error on the measured impedance, in the case where IL ⁇ ILO.
• the master device C restarts the loop in order to refine the control laws.
• the output of the filter depends both on the state of the inputs (pressure and pressure gradient) and outputs (current setpoint) at the instant t and at the preceding instants as a function of the order of the filter.
• the device dynamics are calculated by a microcontroller. This calculation takes place in discrete time, all sampling periods, in the form of a recurrent equation.
• control law can therefore be defined as follows:
• the loudspeakers are controlled by a current source based on 150mA operational amplifiers.
• the chosen shape is an improved Howland source, stable in the case of inductive loads such as loudspeakers.
• yioc usually corresponds to the local value of the output current while ydis corresponds to the distributed value of the output current.
• xioc usually corresponds to the local value of the input current while Xdis corresponds to the distributed value of the input current.
• the pressure gradient is the quantity used in mechanics to represent the variation of the pressure in a fluid (here air).
• Equation [Math 2] and [Math 3] are equations which are classical generic definitions of filtering techniques which make it possible to express with the equation [Math 1] the desired dynamics of the intensity of the current (i) with respect to the sound pressure (p) and its gradient (grad (p)), in the form of a sum of filters with infinite impulse response.
• the method and the electroacoustic control device allow the implementation of a distributed control law based on an advection equation aimed at the attenuation of grazing acoustic waves in a tube.
• the parameters of the control law are adapted as long as the value of the insertion loss is less than a predetermined threshold, then when the threshold is reached, we proceed to step c ) of claim 1, which applies the adequate control law (defined by the adaptation of the parameters) in order to obtain the determined generalized acoustic impedance (ie targeted) Zdet for the loudspeaker.
• the device can be programmed and the preferred direction of treatment can be modified
• the device can be programmed in "self-learning" mode so as to define the optimal acoustic behavior locally and in real time
• the device is modular and can adopt several geometries
• the device allows the synthesis of an acoustic diode (non-reciprocal propagation of waves) and potentially its 2D extension,
• the device allows the measurement of wall pressure fields in real time and therefore offers the ability to analyze sources
• the device is more robust than conventional control approaches due to the distributed nature of the control units
• the device is more efficient than other active systems, in terms of pure efficiency and energy consumption.
• the different characteristics, shapes, variants and embodiments of the invention can be associated with each other, in various combinations insofar as they are not incompatible or exclusive of each other.
• a physical reference quantity other than the insertion loss (for example the transmission loss, a absorption coefficient or a target impedance), is sufficiently close to a predetermined value.

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• Physics & Mathematics (AREA)
• Engineering & Computer Science (AREA)
• Acoustics & Sound (AREA)
• Health & Medical Sciences (AREA)
• Otolaryngology (AREA)
• Signal Processing (AREA)
• General Health & Medical Sciences (AREA)
• Multimedia (AREA)
• Soundproofing, Sound Blocking, And Sound Damping (AREA)
• Circuit For Audible Band Transducer (AREA)
• Building Environments (AREA)

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• 2019
  • 2019-12-16 FR FR1914484A patent/FR3104860B1/fr active Active
• 2020
  • 2020-12-11 JP JP2022536926A patent/JP7691425B2/ja active Active
  • 2020-12-11 WO PCT/EP2020/085832 patent/WO2021122394A1/fr not_active Ceased
  • 2020-12-11 CN CN202080087321.3A patent/CN115136231B/zh active Active
  • 2020-12-11 US US17/757,057 patent/US12230240B2/en active Active
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