FR3115103A1 - Device and method for measuring and displaying a sound field - Google Patents

Abstract

The invention relates to a device (10) for measuring and displaying at least one acoustic characteristic, comprising: - a means for measuring (30) the acoustic characteristic which comprises an acoustic sensor (31), - a reality system (20), - an interface (32), and - a computer (40) programmed for, when the operator requires it by means of the interface and while the acoustic sensor is placed at a measurement point (P1) , acquiring the acoustic characteristic instantaneously measured by the measuring means and subsequently controlling the display by the augmented reality system of a pattern (F1) illustrating the acoustic characteristic. Figure for abstract: Fig.1

Description

Device and method for measuring and displaying a sound field

Technical field of the invention

The present invention generally relates to the field of acoustic measurements.

It relates more particularly to a method and a device for measuring and displaying an acoustic characteristic, or even a sound field.

The invention finds a particularly advantageous application in the measurement of the acoustic properties of a motor vehicle, but it relates more broadly to all fields where acoustic measurements must be carried out.

State of the art

Currently, to make acoustic measurements, it is necessary to place in a known environment an element on which one wishes to carry out measurements (for example a car), to carry out acoustic measurements in several predetermined points of the car (in the passenger compartment , in the engine compartment, etc., taking into account the characteristics of said environment, then processing the results of the measurements.

The positioning of the measurement points and the processing of the results require the development of a three-dimensional model of the car, in particular to fully understand where the measured sound field is located in relation to the car.

It is therefore understandable that the process of measuring the sound field is tedious, long and expensive to implement.

Presentation of the invention

In order to simplify this process, the present invention proposes a simple device making it possible to carry out the measurement and the representation of the measurement results almost simultaneously, and which does not require any prior preparation for this.

More particularly, according to the invention, a device for measuring and displaying at least one acoustic characteristic is proposed, comprising:
- a means of measuring the acoustic characteristic, which is portable by an operator and which comprises an acoustic sensor,
- an augmented reality system that is portable by the operator,
- an interface available to the operator, and
- a computer programmed for, when the operator requires it by means of the interface and while the acoustic sensor is placed at a measurement point, to acquire the acoustic characteristic instantly measured by the measurement means at the measurement point, and for consecutively controlling the display by the augmented reality system, at the measurement point, of a pattern illustrating the acoustic characteristic.

Thus, thanks to the invention, it is possible for the operator to place the sensor where he wishes, then to trigger a measurement so that the result of this measurement is instantly displayed in his field of vision, in superposition of the view he has of his environment, using the augmented reality headset.

This system therefore makes it possible to characterize a sound field without requiring prior knowledge of the environment in which the measurement is carried out, nor any external measurement device.

In practice, the augmented reality helmet makes it possible, thanks to its sensors, to scan in a three-dimensional way the environment in which the measurements are taken and to determine the positions where these measurements are taken.

It is then possible to deduce from these data many parameters characterizing the sound field.

Other advantageous and non-limiting characteristics of the device in accordance with the invention, taken individually or according to all the technically possible combinations, are the following:
- the acoustic characteristic is a sound intensity vector;
- the pattern is an arrow whose geometry and/or color depend on the sound intensity vector;
- the computer is programmed to, when the operator requires it by means of the interface, to acquire temporal variations of the acoustic characteristic measured by the measuring means, and to control the display of the pattern so that its geometry and /or its color vary according to said temporal variations of the acoustic characteristic;
- the computer is programmed to control the display by the augmented reality system of several measurement points where the acoustic sensor can be successively placed, and to calculate an acoustic parameter according to the measurements of the acoustic characteristic carried out at the measurement points, said acoustic parameter preferably being an acoustic power;
- the computer is programmed to measure the positioning errors between the acoustic sensor and each measurement point and to deduce an error coefficient therefrom;
- the error coefficient is then used to correct the value of the acoustic parameter;
- the computer is programmed to filter the measurement of the acoustic characteristic frequency-wise and/or temporally, and the pattern displayed is determined as a function of the filtered measurement of the acoustic characteristic;
- an acoustic sensor is provided located at a determined point, and the computer is programmed to determine the contribution of the acoustic characteristic measured at the measurement point in the sound field measured at the point determined by the acoustic sensor, and to subsequently control the display by the augmented reality system of an element illustrating said contribution;
- a vibration sensor is provided located at a reference point, and the computer is programmed to determine the relationship between the acoustic characteristic measured at the measurement point and the measurements made by said sensor, and to subsequently control the display by the augmented reality system of an element illustrating said relationship.

The invention also relates to a method for measuring and displaying at least one acoustic characteristic, comprising steps of:
a) positioning, at a measurement point, of an acoustic sensor of a measurement means suitable for measuring said acoustic characteristic,
b) control, by means of an interface, of a measurement of said acoustic characteristic by the measuring means,
c) instantaneous acquisition, by a computer, of said acoustic characteristic, and
d) control, by the computer, of the display by an augmented reality system, at the measurement point, of a pattern illustrating the acoustic characteristic measured.

Preferably, the pattern having a geometry and/or a color which vary according to the acoustic characteristic measured, an operation of searching for a sound source is provided during which steps a) to d) are repeated in a loop until until the geometry and/or the color of said pattern are optimized.

Of course, the different characteristics, 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.

Detailed description of the invention

The following description with reference to the accompanying drawings, given by way of non-limiting examples, will make it clear what the invention consists of and how it can be implemented.

On the attached drawings:

is a schematic perspective view of an operator using a measurement and display device according to the invention, on which is illustrated an arrow representative of a measured sound intensity vector;

is a view similar to that of FIG. 1, in which several arrows representative of several measured sound intensity vectors are illustrated.

As a preliminary, a “sound field” will be defined as a zone of space in which at least one acoustic characteristic has been measured at several points. This acoustic characteristic will preferably be the sound intensity, expressed in Wm ^-2 .

The sound intensity describes the energy flow in the measurement area, i.e. the energy passing through the homogeneous surface located perpendicular to the direction of energy radiation, per unit time. Unlike sound pressure, sound intensity is a vector quantity and therefore has an amplitude and a direction. This is the reason why we will speak hereafter of sound intensity vector . This "vector of sound intensity will be defined as being a vector whose origin is the measurement point, whose norm corresponds to the measured sound intensity, and whose direction and direction correspond to the direction and direction of propagation of the sound waves at the point of measure.

An element will be qualified as "portable" if it can be worn by an individual.

A measurement will be qualified as "instantaneous" if it is carried out immediately or in a short time (less than a second), depending on the capabilities of the measuring means.

Two steps will be qualified as “consecutive” if they are carried out one after the other, in a very short period of time (less than a second) and which is preferably as short as possible.

In Figures 1 and 2, there is shown an individual, hereinafter called "operator 100", who uses a measurement and display device 10.

This measurement and display device 10 includes at least one acoustic sensor and an augmented reality system.

In the embodiment shown in these figures, this device comprises a greater number of components, described below.

All of these components are portable. Therefore, the device includes a rechargeable power supply battery to power the components that require it.

The measurement and display device 10 also comprises a measurement means equipped with an acoustic sensor 31 whose dimensions and technology allow the measurement of an acoustic characteristic, such as for example a sound intensity in the near field (the vector sound intensity ).

This vector is equal to the product of the acoustic pressure p and the acoustic velocity .

In a first embodiment of the invention, the acoustic sensor 31 comprises a “probe PU” (for example marketed by the company Microflown Technologies) which makes it possible to directly measure the acoustic pressure p and the acoustic speed .

In a second embodiment, the acoustic sensor 31 comprises a pressure gradient probe, also called "PP probe", which makes it possible to measure the acoustic pressure p at two different places using two microphones mounted directly one next to each other. The phase shift between the measured pressures thus makes it possible to obtain the acoustic velocity and therefore to deduce the sound intensity.

As shown in the figures, the measuring means is preferably in the form of a pole 30 equipped, at its free end, with the acoustic sensor 31 and the other end of which is intended to be held in the hand by the operator 100 (or by a robot). This pole 30 is therefore portable. It weighs in practice less than 5 kg.

The measurement and display device 10 also includes an interface allowing the operator 100 to interact with it. It could be a microphone coupled with a voice recognition system, allowing the operator to give oral instructions.

In the embodiment shown in the figures, it is rather a remote control 32 which is removably mounted on the pole 30 and which comprises at least one button.

The measurement and display device 10 also includes an augmented reality system, which here takes the form of a mask 20 worn on the head by the operator 100.

This mask 20 comprises for example two liquid crystal screens located opposite the two eyes of the operator, and through which the operator can observe his environment. The screens then make it possible to display elements superimposed on the environment, in such a way that the operator has the impression that these elements are located in this environment, in a determined position.

The mask 20 also comprises a three-dimensional measurement system, which comprises for example two stereoscopic cameras making it possible to determine the positions of the various elements of the environment of the operator 100.

Finally, it preferably comprises two microphones 21 allowing binaural measurement. These two microphones 21 are located on the helmet 20 so as to be close to the ears of the operator 100 when the latter wears the mask 20.

Preferably, the measurement and display device 10 comprises means for determining the attitude (position and orientation) of the acoustic sensor 31. These means for determining can for example be formed by the two stereoscopic cameras of the mask 20, in order to allow the position and orientation of this sensor to be determined in a frame of reference attached to the mask 20.

The measurement and display device 10 further comprises a data processing computer system.

This system could be in the form of a single block located in the pole or in the augmented reality mask or even in the form of a remote central unit.

In practice, it rather comprises several units which communicate together by means of wired or wireless communication.

One of these units, commonly called “measurement front end”, is used to supply the acoustic sensor 31 with electric current (via the storage battery) and to read and format the signals picked up by this sensor.

Another of these units is integrated in the augmented reality mask 20 and makes it possible to process the data coming from the cameras and to control the display of elements on the liquid crystal screens.

A third of these units, hereinafter called the computer, is provided to perform complex operations in order to jointly control the acoustic sensor 31 and the mask 20. This third unit is adapted to communicate with the remote control 32.

It is here separate from the other two units but it could alternatively be integrated into the mask 20.

The computer is also adapted to communicate with other entities. Examples of other entities are for example other sensors, or display screens or other augmented reality or virtual reality headsets.

In practice, this computer comprises a processor, a memory and various communication interfaces. Thanks to its memory, the computer stores a computer application, consisting of computer programs comprising instructions whose execution by the processor allows the computer to implement the process described below.

This measurement and display device 10 can be used to perform a large number of measurements simply and intuitively, without requiring modeling of the environment.

In the rest of this presentation, we will be able to give examples of the use of this device, then examples of processing the data measured by this device.

In these examples, it may be considered by way of illustration that it is desired to carry out acoustic measurements in the passenger compartment of a motor vehicle, in order to know the noise which will be felt by the driver or by a passenger of the vehicle in different configurations ( stationary, engine started, engine at high speed, ventilation on, etc.).

In a first mode of operation, the measurement and display device 10 will be used to instantly measure an acoustic characteristic, namely the sound intensity vector at a point in the passenger compartment chosen by the operator 100, then to illustrate this measurement in real time in the field of vision of the operator 100.

For this, the operator places the pole 30 so that the acoustic sensor 31 is located at a measurement point P1.

Then he makes a short press on the button of the remote control 32, so that the computer 40 commands the measurement, at the current instant, of the sound intensity vector . As a variant, it could be designed to control the acquisition of only one component of this vector.

Following this measurement, the computer 40 controls the display, by the mask 20, of a three-dimensional pattern in the field of vision of the operator 100, at the level of the measurement point P1.

This pattern could come in different forms.

As shown in FIG. 1, it is preferably formed by an arrow F1 which is superimposed on the environment seen by the operator 100, the origin of which is located at the measurement point P1, the direction and sense of which are identical to the direction and sense of the sound intensity vector measured, and whose length is proportional to the norm of this vector.

As a variant, the length of the arrow could be invariable, and it would be its color which would depend on the norm of this vector.

Still as a variant, the arrow could be of invariable length but be surmounted by a number indicating the norm of the vector.

In the embodiment considered here, the arrow F1 is displayed for the duration of pressing the button on the remote control and then it disappears. As a variant, it could be displayed for a predetermined duration, or even until the button on the remote control is pressed again.

Thanks to this first mode of operation of the measurement and display device 10, the operator 100 can search for the location of a sound source 200.

For this, the operator moves the pole 30 according to the orientation of the arrow (in the opposite direction) to get as close as possible to this source.

It can thus detect the exact position of the sound source when the length of the arrow is maximum (or when its color indicates that the norm of the vector is maximum).

A second mode of operation of the device consists in acquiring and representing in the field of vision of the operator 100 no longer a fixed vector, but a temporal variation of the sound intensity vector .

In this second mode, the operator performs an acoustic measurement over a period greater than a tenth of a second, at a fixed point, then the computer illustrates the result of the measurements in the field of view of the operator 100.

For this, the operator places the pole 30 so that the acoustic sensor 31 is located at a measurement point P1 that he chooses.

Then he performs a long press on a dedicated button of the remote control 32, which controls the measurement, for the entire duration of the press (or for a predetermined duration), of the sound intensity vector .

In parallel with these measurements, the computer 40 controls the display, by the mask 20, of the arrow F1, the direction, direction and length of which vary this time according to the variations of the sound intensity vector measure.

This mode of operation of the device makes it possible, for example, in the case where the sound source 200 generates a cyclic and slow sound signal, to observe this cycle.

Of course, the operator 100 can also move the pole 30 during the measurement.

A third mode of operation of the device, illustrated in FIG. 2, consists in successively carrying out several acoustic measurements and simultaneously illustrating these measurements in the field of vision of the operator 100.

For this, as in the first mode of operation, the operator places the pole 30 so that the acoustic sensor 31 is located at a measurement point P1, then he briefly presses a dedicated button on the remote control 32 to control the measurement of the sound intensity vector and the display of a first arrow F1 illustrating the characteristics of this vector.

It repeats this operation several times, in different measurement positions P2, P3, P4, P5, so that the computer can command the display of several other arrows F2, F3, F4, F5.

These arrows are displayed simultaneously, allowing the operator 100 to observe several patterns describing the sound field.

In this way, the operator 100 can better apprehend the zones where the sound intensity is high, which gives him, for example, a first indication as to the positions of the sound sources.

In the example of Figure 2, he can observe the presence of a sound source 200 and deduce that it is directive, since the arrows are longer on one side of this source than on the other.

It is understood at this stage that the idea is to allow the operator to place the acoustic sensor 31 where he wishes, for example initially randomly then then in zones which seem to him more interesting to describe, so as to obtain a precise idea of the shape of the sound field.

A fourth mode of operation of the device aims to allow the operator to perform measurements in predetermined positions, according to a mesh adapted for example to the calculations that one wishes to perform.

To do this, the computer begins by acquiring the shape of a mesh (each measurement point being at the intersection of several meshes).

This grid responds preferentially to the conditions laid down by a standard (a house standard or a standard responding to a standard).

By way of example, this grid can be based on the measurement codes by intensimetry of the acoustic power emitted by a source (ISO 9614-3:2002 or ISO 3743 or ISO 3744 or ISO 3745 standard).

For example, the mesh can indicate to the operator where to successively place the acoustic sensor 31 to obtain the data necessary for calculating the acoustic power emitted by a source.

In practice, the operator can use a dedicated button to point to the position of a sound source, then, given this position, the computer will control the display, thanks to the helmet 20, of a mesh placed in the field of vision. of the operator.

The operator will then be able to place the acoustic sensor 31 in each of these positions to carry out the required measurements.

These measurements are then preferably stored in a database provided for this purpose.

In this example, the computer will store in its memory the coordinates of each measurement point, combined with the coordinates of each sound intensity vector measure.

It may also store other data, including the instant t of each measurement, as well as possibly photos or a video of the environment as it was seen by the operator at the time of the measurements.

The storage of all of this data will make it possible, as will be described later, to process the results of the measurements, for example to perform acoustic power calculations.

In one and/or the other of the aforementioned operating modes, the computer 40 will be able to filter the measurements of the sound intensity vector frequency-wise and/or temporally, so that the displayed arrow(s) have geometries and/or colors depending on this vector once filtered.

A first example of filtering consists in filtering the sound intensity vector in frequency.

In this example, the measurement and display device 10 has a functionality allowing the operator 100 to select a given frequency band in which he wishes to carry out the measurements.

For this, the operator can begin to enter, for example by means of the remote control, the frequency band in which he wishes to carry out the measurements. It can be a predetermined frequency or octave band corresponding to a button on the remote control, or a frequency band whose limits are manually configured by the operator.

Any type of filter can be used to perform the filtering, for example a frequency filter (typically band-pass), a temporal filter, an adaptive filter, a parametric filter...

It should be noted that the frequency filtering can be carried out during the acquisition of the sound signal, or by post-processing by the computer.

A second example of filtering consists in filtering the sound intensity vector temporally, ie to perform (or select) the measurement in a given time window.

For this, the measurement and display device 10 will preferably be equipped with an external sensor which will make it possible to trigger the moment of the start of the measurement and possibly also that of the end.

This functionality will be of particular interest when the sound signal is cyclical or cyclostationary (i.e. presenting a more complicated periodic rhythm than a simple periodic function).

By way of example, the external sensor may be formed by an accelerometer placed on an internal combustion engine and connected to the computer, or by an angular position sensor placed on the crankshaft of this engine and connected to the computer.

Then, the measure of the sound intensity vector (or variations of this vector) may be carried out during a particular period of engine operation, for example during the explosion of the fuel and air mixture.

Once the measurements have been taken and the arrows displayed in the field of vision of the operator 100, the computer 40 is preferably programmed to reprocess the results of the measurements. We will talk here about post-processing.

The first example of post-processing that can be carried out by the computer 40 is the calculation of the acoustic power of a surface in which various measurements have been carried out.

To perform this calculation, the calculator uses the coordinates of the measurement points and the sound intensity vectors measures.

The integration of the intensity (eventually filtered) for each surface element dS makes it possible to estimate the acoustic power Lw according to the formula:

This calculation can be carried out when different measurements have been successively performed randomly by the operator 100.

However, preferably, this calculation will be carried out when the measurements have been carried out according to a predetermined mesh meeting a defined standard, as explained above. Thus, the result of the calculations will be particularly reliable.

However, it may happen that the operator 100 does not place the acoustic sensor 31 exactly at the measurement points P1, P2, P3, P4, P5 of the mesh displayed by his augmented reality headset 20.

In this eventuality, the computer 40 is programmed to measure the positioning errors between the acoustic sensor 31 and each measurement point and to deduce therefrom one or more positioning error coefficients. This or these coefficients can then be used to:
- inform the operator that the calculated power is reliable, except for an error calculated according to said coefficients, and/or
- inform the operator that he must repeat one and/or the other of the measurements, and/or
- correct the calculated power according to these coefficients.

A second example of post-processing that can be performed by the computer 40 consists, when several measurements of sound intensity vectors have been carried out, to provide a mapped representation of any acoustic parameter, such as for example the sound intensity, the acoustic pressure or the acoustic power.

For this, the computer 40 will carry out an interpolation calculation between the various measurement points in order to obtain a continuous representation of the entire acoustic field in the measurement zone.

This representation may take the form of a map of colors located in a measurement plane (if all the measurements considered were carried out in a plane or close to it), or a vector field.

A third example of post-processing that can be performed by the computer 40 consists in determining the participation of a particular sound source in the signal measured at a determined point P21.

As shown in FIG. 1, the determined point P21 is for example located at the level of the right ear of the operator 100 (more precisely at the level of the right microphone 21 of the augmented reality helmet 20).

The idea is then for example to determine, in the sound signal perceived by the operator at the level of his right ear, the part which is coherent with the sound source considered.

This example of post-processing therefore requires a measurement of the sound intensity at the level of the right ear, here by means of the microphone 21, and at least one measurement of the sound intensity at the level of the sound source considered thanks to pole 30.

Thanks to these data, the computer 40 is programmed to determine the contribution of the sound intensity measured at the level of the sound source in the sound field measured by the microphone 21, then to consecutively control the display by the augmented reality headset 20 20 of an element illustrating this contribution.

It will be noted here that the microphone 21 is designed to measure a binaural sound pressure, which may possibly be corrected to take into account the fact that the noise perceived at the level of the microphone is different from that perceived in the ear.

More generally, in this third example of post-processing, the computer is designed to acquire simultaneously, or in a reduced duration, several sound intensity data corresponding to several sound sources (called reference channels).

The computer can also acquire other data characterizing these reference channels (acceleration, speed, displacement and/or acoustic pressure).

Then, the computer will be able to calculate the transfer functions between each reference channel and the ear considered, based on the measured intensity field.

The analysis of these transfer functions will then allow him to deduce the causality of the noise perceived by the ear of the operator, that is to say the responsibility of each source in this noise.

The measured intensity field will then be represented in the field of vision of the operator 100, thanks to the helmet 20. This representation could for example be in the form of arrows positioned at the level of each sound source considered, and whose sizes are a function of the responsibility of each sound source in the noise perceived by the operator at the level of his right ear.

A fourth example of post-processing that can be performed by the computer 40 consists in calculating and representing the relationship between a vibration measurement performed at a reference point and an acoustic measurement performed at a distance from this reference point.

For this, the measurement and display device 10 is equipped with a vibration sensor which can be placed on an object subjected to vibrations, for example on the engine of the vehicle.

The computer 40, connected to this sensor, will then be able to detect the part of the sound field measured by the pole 30 at a measurement point chosen by the operator (for example at the level of the driver's headrest) which is consistent with the measured vibration.

The computer 40 will then be able to display, thanks to the augmented reality headset 20, an element illustrating said relationship. This representation may for example take the form of an arrow positioned at the measurement point, and whose color will depend on said relationship.

A fifth example of post-processing that can be performed by the computer 40 consists in evaluating the type of acoustic field in the measurement zone.

Three types of fields will be considered here.

The first type of field is the “free field”. It is the one in which the sound waves propagate freely, no variation of the medium opposing the propagation of the waves.

The second type of field is the “near field”. It is the one located near the sound source and where the acoustic speed decreases more rapidly than in a free field (with a preponderant term which is a function of the inverse of the square of the distance to the source).

The third type of field is the “reverberant field”. In this type of field, the sound waves from the same source come from at least two different directions, since they are reflected.

To determine whether the measurements taken are characteristic of a free field or a reverberated field, the computer 40 observes how the waves emitted by one or more sources propagate in space.

The measurement of several vectors of sound intensity in the zone considered makes it possible to obtain a description of the precise geometry of this field.

Then, by observing the direction of the sound intensity vector with respect to the source or by calculating the characteristics of the radiation at a given distance from a source, the computer 40 can deduce therefrom whether the source studied radiates in a free field or in a free field. reverberated.

To determine whether the measurements taken are characteristic of a free field or a near field, the computer can rely on the particle velocity measurements.

In fact, in a free field, the attenuation of sound intensity decreases proportionally to the square of the distance traveled, whereas it decreases much more rapidly in a near field.

More generally, the computer 40 can, to determine the type of field, be based on the measurements of acoustic pressure and particle velocity carried out for several reference channels (that is to say here several sources), as well as than on the far-field pressure measurements made by the microphones 21.

This operation will require the acoustic sensor 31 to include a probe of the P-U type since, as explained above, such a probe is able to determine the particle velocity.

On this basis and on the basis of the coordinates of the measurement points, the computer 40 will be able to solve wave equations, and deduce the type of acoustic field therefrom.

In this way, it will be possible to better understand the effect of each sound source in the sound field.

A functionality of the measurement and display device 10 will also consist in allowing the operator 100 to share his observations with a third party equipped with a virtual reality mask or a display screen.

This functionality is obtained by exploiting a video output from the augmented reality headset 20 of the operator 100, which will then be used as a source for the device used by the third party.

In this context, the third party may be located close to the operator 100, or remotely from it, for example using the Internet network to communicate the various necessary data.

It should be noted here that this data will include not only the displayed arrows, but also a video of the environment seen by the operator.

The present invention is in no way limited to the embodiment described and represented, but those skilled in the art will know how to make any variant in accordance with the invention.

In particular, it would be possible to use not an augmented reality headset, but rather a virtual reality headset, provided that the latter is equipped with cameras and that it permanently displays in the operator's field of vision the environment as the latter would see it if he was not wearing the helmet. Thus, this mask will work under an augmented reality mode.

Claims (10)

Device for measuring and displaying (10) at least one acoustic characteristic ( ), including:
- a means of measuring (30) the acoustic characteristic ( ), which is portable by an operator (100) and which comprises an acoustic sensor (31),
- an augmented reality system (20) which is portable by the operator (100),
- an interface (32) available to the operator (100), and
- a computer (40) programmed to, when the operator requires it by means of the interface (32) and while the acoustic sensor (31) is placed at a measurement point (P1), acquire the acoustic characteristic ( ) instantaneously measured by the measuring means (30) at the measuring point (P1), and for consecutively controlling the display by the augmented reality system (20), at the level of the measuring point (P1), of a pattern (F1) illustrating the acoustic characteristic ( ). A measuring and display device (10) according to claim 1, in which the acoustic characteristic ( ) is a sound intensity vector and in which the pattern (F1) is an arrow whose geometry and/or color depends on the sound intensity vector. Measurement and display device (10) according to claim 1 or 2, in which the computer (40) is programmed to, when the operator (100) so requires by means of the interface (32), acquire temporal variations of the acoustic characteristic ( ) measured by the measuring means (30), and for controlling the display of the pattern (F1) such that its geometry and/or its color vary as a function of said temporal variations of the acoustic characteristic ( ). Measurement and display device (10) according to one of Claims 1 to 3, in which the computer (40) is programmed to control the display by the augmented reality system (20) of several measurement points (P1, P2, P3) where the acoustic sensor (31) can be successively placed, and to calculate an acoustic parameter according to the measurements of the acoustic characteristic ( ) carried out at the measurement points (P1, P2, P3), said acoustic parameter preferably being an acoustic power (Lw). Measurement and display device (10) according to claim 4, in which the computer is programmed to measure the positioning errors between the acoustic sensor (31) and each measurement point (P1, P2, P3) and to deduce a error coefficient. Measurement and display device (10) according to one of Claims 1 to 5, in which the computer (40) is programmed to filter the measurement of the acoustic characteristic ( ) in a frequency and/or temporal manner, and in which the pattern (F1) displayed is determined according to the filtered measurement of the acoustic characteristic ( ). Measurement and display device (10) according to one of Claims 1 to 6, in which an acoustic sensor (21) is provided located at a determined point (P21), and in which the computer (40) is programmed to determine the contribution of the acoustic characteristic ( ) measured at the measurement point (P1) in the sound field measured at the determined point (P21) by the acoustic sensor (21), and to control the display by the augmented reality system (20) of an element illustrating said contribution . Measuring and display device (10) according to one of Claims 1 to 7, in which a vibration sensor is provided located at a reference point, and in which the computer (40) is programmed to determine the relationship between the acoustic characteristic ( ) measured at the measurement point (P1) and the measurements made by said sensor, and to control the display by the augmented reality system (20) of an element illustrating said relationship. Method for measuring and displaying at least one acoustic characteristic ( ), comprising steps of:
a) positioning, at a measurement point (P1), of an acoustic sensor (31) of a measuring means (30) suitable for measuring said acoustic characteristic ( ),
b) control, by means of an interface (32), of a measurement of said acoustic characteristic ( ) by the measuring means (30),
c) instantaneous acquisition, by a computer (40), of said acoustic characteristic ( ), And
d) control, by the computer (40), of the display by an augmented reality system (20), at the measurement point (P1), of a pattern (F1) illustrating the acoustic characteristic ( ) measured. Method according to the preceding claim, in which the pattern (F1) having a geometry and/or a color which vary according to the acoustic characteristic ( ) measured, a sound source search operation (200) is provided during which steps a) to d) are repeated in a loop until the geometry and/or the color of said pattern are optimized.