DE102019209438B4 - Motor vehicle with a system for reducing a sound pressure level in a motor vehicle interior and method for reducing the sound pressure level - Google Patents

Abstract

Motor vehicle (10), having at least one motor vehicle ventilation opening (26), with a system (12) for reducing a sound pressure level (32') in an interior (14) of the motor vehicle (10), comprising a microphone device (18), the microphone device ( 18) is set up to detect a sound (32) penetrating from outside the motor vehicle (10) into the interior (14) of the motor vehicle (10) inside the motor vehicle (10) at at least one predetermined penetration point (26) and to to transmit the signal (40) corresponding to the detected sound (32) to at least one sound-generating device (24) for the motor vehicle (10), the signal (40) being set up to be transmitted by means of the sound-generating device (24) in the interior (14) of the motor vehicle (10) to generate an anti-sound (42) to reduce the sound pressure level (32') of the sound (32) that has penetrated, the at least one predetermined point of penetration (26) being the motor vehicle vent vent opening (26) and is located in the area of a wheel suspension of the motor vehicle (10) and/or in the area of a bumper of the motor vehicle (10), the microphone device (18) having at least one microphone which is used to record the air entering the interior (14 ) of the motor vehicle (10) and is arranged in an air path (36) running between the interior (14) and the motor vehicle ventilation opening (26) on the motor vehicle ventilation opening (26) behind an interior paneling of the motor vehicle (10). , wherein the interior paneling is designed to filter high-frequency components of the penetrating sound (32) in terms of low-pass filtering.

Description

The invention relates to a motor vehicle with a system for reducing a sound pressure level of a sound that has penetrated into an interior of the motor vehicle, and a corresponding method. For this purpose, the system according to the invention has a microphone device.

Sound is defined as a mechanical wave in an elastic medium. Correspondingly, airborne sound is in particular such a mechanical wave in the medium of air and thus a pressure wave. The pressure fluctuation caused by sound at an observed location is called sound pressure. The sound pressure level is the ratio of the observed sound pressure to a reference sound pressure and can be specified in decibels (dB). The sound pressure level determines the loudness of a sound event or noise.

Sound or a sound wave can be converted into an electrical signal by means of an electrical sound transducer, for example by means of a microphone device with at least one microphone. Conversely, an electrical signal corresponding to the sound can also be converted into a sound by means of an electroacoustic converter, for example by means of a sound generating device with at least one loudspeaker.

Opposing sound waves, also referred to as sound and anti-sound, can interfere negatively or destructively when superimposed, resulting in a reduction of the remaining or summed sound. This effect underlies the active noise reduction (ANR) or active noise cancellation (ANC) method.

The invention relates in general to the reduction or suppression of a noise in a motor vehicle interior by means of generating counter-sound that corresponds to a detected sound.

Systems and methods for active noise suppression in the vehicle interior are known in principle. These are preferably concerned with noise suppression in spatially limited, in particular channel or tubular, volumes.

the DE 198 32 517 A1 for example generally describes a method for active soundproofing in a duct through which a medium can flow.

the U.S. 2018/0320922 A1 describes an active soundproofing system that can dampen sound entering a room through a window gap by counter-noise.

the GB 2563346A describes a system for active soundproofing in a motor vehicle interior. Various parameters are recorded which can provide information regarding the sound sources of a sound to be damped, for example a driving speed or an unevenness in the roadway. The sound attenuation system can then be selectively adjusted to the individual sources.

the DE 10 2017 200 822 A1 deals with the ventilation of a motor vehicle interior and with the noise pollution associated with the ventilation. In this case, it is provided that interference noises generated by the ventilation device in the motor vehicle are suppressed by sound converters installed within a duct system of the ventilation device.

the DE 10 2010 014 819 A1 in turn describes a system for active noise cancellation in the vehicle interior. The system described is in this case in a vehicle with an electric drive mode. In order to make this electrically powered vehicle audible to other road users, it is provided to synthesize an outwardly directed sound, which in turn is to be suppressed in the passenger compartment by using the signal generated for synthesizing the sound to generate an opposing sound.

A disadvantage with the known systems for active noise cancellation is that the noise cancellation must necessarily be limited to a spatially restricted area, namely spatially restricted ducts or tubes. This results from the frequency spectrum of the sound to be reduced, since directional synchronization of the sound and the counter-sound must be guaranteed in order to obtain destructive interference in an entire specified room area. Another disadvantage is that only the waveform characteristics of a sound synthesized according to clear specifications are processed, but not the waveform characteristics of such a sound as it is generated by sound events that actually occur.

As is known, a sound wave that penetrates into the interior of the motor vehicle from outside a motor vehicle passes through body components and/or an interior paneling of the motor vehicle on its way. This causes the sound wave, which is usually made up of a lot number of superimposed sound waves of different frequencies is filtered. In particular, high-frequency components are filtered or suppressed in the sense of low-pass filtering by the vehicle body and/or the interior paneling and/or by so-called absorber fleece. This applies in particular to components from frequencies greater than 100 Hz. As a rule, low-frequency sound components remain, which lead to a sound pressure level in the passenger compartment, which is disadvantageously perceptible, for example, as a rumbling or droning.

The invention is based on the object of reducing a sound pressure level of an penetrating sound, in particular the sound pressure level generated by the low-frequency components mentioned, in a motor vehicle interior.

The object is solved by the subject matter of the independent patent claims. Advantageous developments of the invention are described by the dependent patent claims, the following description and the figures.

The invention is based on the finding that sound penetrates into the passenger compartment in particular at clearly defined and known penetration points and is filtered there in accordance with low-pass filtering.

The invention provides a motor vehicle with a system for reducing a sound pressure level in an interior of the motor vehicle. The interior is in particular the passenger compartment or passenger compartment of the motor vehicle. The system includes a microphone device. The microphone device is set up to detect a sound penetrating from outside the motor vehicle into the interior of the motor vehicle at at least one predetermined penetration point inside the motor vehicle. The sound can be recorded, for example, by means of a microphone. According to the invention, the microphone device is therefore not arranged at any arbitrary point within the motor vehicle and/or the motor vehicle interior, but rather at a predetermined sound penetration point. The penetrating sound is thus advantageously detected directly where it penetrates into the passenger compartment.

The predetermined penetration point at which the sound penetrating the interior of the motor vehicle is detected is advantageously defined in such a way that the above-mentioned low-frequency sound components in particular occur at it, which after the filtering of the penetrating sound by means of the vehicle body and/or the interior paneling and/or by means of so-called absorber fleece. The detection therefore takes place inside or inside the motor vehicle, i.e. within the area delimited by the outer skin or the outer panel of the motor vehicle. In the area of the predetermined penetration point, the penetrating sound preferably comprises sound waves which are in a frequency range below 100 Hz (low-frequency frequency range), in particular in a frequency range between 8 Hz and 100 Hz, in particular between 20 Hz and 80 Hz. In other words, the location for sound detection is selected in such a way that there is no automatic cancellation for frequencies in this frequency range, e.g. due to the vehicle geometry. This achieves reliable detection of this frequency range.

Assuming that the speed of sound propagation in air is 343 m/s, sound waves in the frequency range mentioned have wavelengths between 3 m and 45 m. These wavelengths are therefore at least in the order of magnitude of the room dimensions of a typical motor vehicle interior and thus in the order of magnitude of the room volume within which a reduction in the resulting sound pressure level is to occur. This is an advantageous prerequisite for a successful reduction of a sound pressure level by means of counter-noise, since the propagation direction of the counter-noise can be aligned less precisely in relation to the sound which has penetrated. The damping of higher-frequency sound components or sound waves, in particular those sound waves whose wavelengths are smaller than the dimensions of the room volume within which the resulting sound pressure level is to be reduced, is known to only succeed by means of counter-noise if the penetrating sound and the counter-noise are in the same direction.

According to the invention, the microphone device is set up to generate a signal corresponding to the recorded sound, ie an electrical and/or digital signal. In other words, the microphone device is an electroacoustic converter or a sound converter that works according to the electromagnetic or electrodynamic or electrostatic principle or according to another known principle of converting sound into the signal. Furthermore, the microphone device is designed to transmit or transmit the generated signal to at least one sound generating device for the motor vehicle, ie it has a corresponding interface to be selected by the person skilled in the art. The transmission or transmission of the signal to the sound generating device can, for example, take place wirelessly, ie via a radio link, or by cable.

According to the invention, the signal corresponding to the detected sound is set up to generate counter-sound in the interior of the motor vehicle by means of the sound-generating device in order to reduce the sound pressure level of the sound that has penetrated. The signal therefore not only carries information about the sound that corresponds to it, but also information about a corresponding counter-sound. This anti-sound information can be generated or calculated in the microphone device or in the sound generation device. In other words, it is provided that the counter-sound generated from the signal by the sound-generating device interferes negatively or destructively with the sound that has penetrated. For this purpose, the phase information of the detected sound can be taken as a basis in a manner known per se. Such a negative interference of sound and anti-noise results, as mentioned at the outset, in a significant reduction, in particular in mutual cancellation, of sound and anti-noise (ANR/ANC—active noise reduction/active noise cancellation).

The sound-generating device for the motor vehicle can advantageously already be permanently installed in the motor vehicle and, for example, be part of an entertainment system in the motor vehicle. Manufacturing costs can be reduced as a result.

According to the invention, at least one microphone of the microphone device is arranged in an air path running between the interior of the motor vehicle and at least one motor vehicle ventilation opening. In this case, the predetermined penetration opening is therefore a motor vehicle ventilation opening. The motor vehicle ventilation opening is located in the area of the wheel suspension of the motor vehicle and/or in the area of a bumper. The area between this ventilation opening and the interior of the motor vehicle, ie the area within which sound penetrating through the motor vehicle ventilation opening propagates, is referred to here as the air path. The air path can be formed or delimited by a ventilation pipe, for example. A microphone of the microphone device is therefore arranged within this air path. A respective microphone is arranged on the ventilation opening or, for example, in the area of the motor vehicle trunk and/or behind an interior paneling of the motor vehicle. This results in the advantage that the sound penetrating through the ventilation opening can be specifically detected by the microphone.

The invention, in particular the selection of the predetermined penetration point within the motor vehicle, results in the advantage that the method of active noise suppression can be used in an irregularly shaped spatial volume, namely a motor vehicle interior. The invention uses in particular the synergetic effect between the low-pass filtering of the sound penetrating from the outside into the motor vehicle interior through parts of the bodywork and/or the interior lining and/or through absorber fleece and the physical effect that sound waves with frequencies in the above-mentioned low Hertz range (less than 100 Hz) can also be reduced in the volume of a passenger compartment by the method of generating counter-noise.

The invention also includes embodiments that result in additional advantages.

According to one embodiment, the system includes a control unit that is designed to detect a deviation of the sound pressure level in the interior of the motor vehicle from a predetermined target sound pressure level. In other words, the control unit monitors the sound pressure level that occurs in the motor vehicle interior as a result of the reduction by means of the generation of counter-noise described. This actual value of the sound pressure level is compared by the control unit with a predetermined target value for the sound pressure level. The controller unit is also designed to adjust said signal intended for the sound generating device in order to minimize the detected deviation. In other words, the control unit is able to modulate or adapt the signal so that it generates an adapted or corrected or tracked counter-sound when it is reproduced by means of the sound generating device. As a result, the deviation between the actual value of the sound pressure level and the predetermined setpoint sound pressure level can be minimized. A control unit can be implemented by a microcontroller, for example. A PID control (PID—proportional, integral, differential), for example, can be used as the basis for the control algorithm.

According to an advantageous development, the system comprises at least one loudspeaker which is set up to receive the signal corresponding to the sound detected by the microphone device and to use the signal to generate counter-sound in the interior of the motor vehicle to reduce the sound pressure level of the sound that has penetrated. In other words, there is at least one additional loudspeaker, that is to say an additional electroacoustic converter, in addition to the sound generating device already present in the motor vehicle (for example that of the infotainment system). This additional electroacoustic converter can be used be partially limited to a predetermined frequency range that is only necessary for the generation of counter-noise, e.g. to frequencies less than 300 Hz or less than 150 Hz Entertainment system or infotainment system of the motor vehicle can be belonging speaker, and complement each other from the additional speaker. The additional loudspeaker can advantageously be placed anywhere within the passenger compartment. As a result, the available installation space can be optimally utilized. A system according to this embodiment can be advantageously used as an aftermarket or retrofit kit for a motor vehicle. The additional loudspeaker can be a subwoofer, for example. The additional loudspeaker can be arranged in a trunk or under a back seat or under a vehicle seat of the motor vehicle. By means of the additional loudspeaker and/or by means of the sound generating device for the motor vehicle, a low-frequency counter-noise, in particular counter-noise in a frequency range below 100 Hz, can preferably be generated.

According to one advantageous development, the system includes an activation device that is set up to receive operating data relating to an operating state of the motor vehicle. Such an operating state can be, for example, an engine operating state and/or an operating state of assistance systems, for example a navigation system and/or other media systems of the motor vehicle. The activation device is set up to automatically activate the system as a function of a predetermined operating state. For example, it can be provided that the activation device activates the system in an engine operating state which indicates, for example through an engine speed in combination with a transmission state, that the motor vehicle is being moved at a speed greater than 50 km/h. This results in the advantage that the system is only activated when an increased input of sound (for example due to an increased speed of the motor vehicle) is to be expected through the predetermined penetration point. Otherwise the system remains in an inactive state, which advantageously reduces the fuel consumption of the motor vehicle.

It can be provided that the activation device has a manual operating unit and is set up to receive a switching state and/or a switching signal from the manual operating unit. The manual control unit can be designed as a mechanical switch (for example as a toggle switch or button) and/or capacitive (as a touchscreen or other touch-sensitive surface). Provision can be made for the activation device to activate and deactivate the system independently of the operating state of the motor vehicle when it receives the switching signal and/or when it detects a predetermined switching state. In other words, the system can be switched on and off manually, for example by a vehicle occupant, overriding the automatic activation of the system.

According to an advantageous development of the motor vehicle according to the invention, at least one of the motor vehicle ventilation openings is arranged in the trunk of the motor vehicle. In this case, the microphone device is set up to detect a sound penetrating from outside the motor vehicle into the trunk of the motor vehicle at the at least one motor vehicle ventilation opening in the trunk of the motor vehicle.

The motor vehicle according to the invention is preferably designed as a motor vehicle, in particular as a passenger car or truck, or as a passenger bus.

The invention also relates to a method for reducing a sound pressure level in an interior of a motor vehicle using a system. The method is characterized in that the microphone device detects a sound penetrating from outside the motor vehicle into the interior of the motor vehicle at at least one predetermined penetration point inside the motor vehicle and transmits a signal corresponding to the detected sound to at least one sound generating device for the motor vehicle, the signal counter-sound is generated in the interior of the motor vehicle by means of the sound-generating device in order to reduce the sound pressure level of the sound that has penetrated.

The invention also includes developments of the method according to the invention, which have features as have already been described in connection with the developments of the motor vehicle according to the invention. For this reason, the corresponding developments of the method according to the invention are not described again here.

The invention also includes the combinations of features of the described embodiments.

• 1 eine schematische Darstellung eines Kraftfahrzeugs mit einem erfindungsgemäßen System zur Reduktion eines Schalldruckpegels in dem Innenraum des Kraftfahrzeugs, und
• 2 eine schematische Darstellung des erfindungsgemäßen Verfahrens.

Exemplary embodiments of the invention are described below. For this shows:

• 1 a schematic representation of a motor vehicle with a system according to the invention for reducing a sound pressure level in the interior of the motor vehicle, and
• 2 a schematic representation of the method according to the invention.

The exemplary embodiments explained below are preferred embodiments of the invention. In the exemplary embodiments, the described components of the embodiments each represent individual features of the invention to be considered independently of one another, which also develop the invention independently of one another and are therefore also to be regarded as part of the invention individually or in a combination other than the one shown. Furthermore, the described embodiments can also be supplemented by further features of the invention that have already been described.

In the figures, the same reference symbols designate elements with the same function.

1 shows a motor vehicle 10 with a system 12 and an interior 14. The interior 14 includes the area of the motor vehicle 10 in which motor vehicle occupants are typically present. The interior space 14 generally has a length of between 1 m and 8 m, in particular between 2 m and 4 m, measured in the longitudinal direction of extent of the motor vehicle 10 .

in the in 1 In the exemplary embodiment shown, the system 12 is arranged in the rear area of the motor vehicle 10 . The system 12 can have a microphone 16 as part of the microphone device 18 not shown here. Furthermore, the system 12 in the example shown here includes a controller unit 20, which is equipped with an additional filter 22 (not in 1 shown) may be equipped to filter incoming signals. A loudspeaker 24 is shown as a further component of the system 12 in the example shown here. The predetermined penetration point 26 can be located in the area of a ventilation grille 28 which is arranged, for example, behind a bumper 30 of the motor vehicle 10 . The microphone 16 as part of the microphone device 18 (not shown here) is arranged in the immediate vicinity of the predetermined penetration point 26 and thus the ventilation grid 28 in the example shown here. The microphone 16 can be designed to detect a sound 32 penetrating from outside the motor vehicle 10 into the interior 14 of the motor vehicle 10 at the predetermined penetration point 26 .

in 1 shown embodiment, the bumper 30 acts as a first low-pass filter. As a result, the penetrating sound 32 in the area of the predetermined penetration point 26 essentially comprises sound waves that move in a frequency range between 8 Hz and 100 Hz, in particular between 20 Hz and 80 Hz. Assuming that the speed of sound propagation in air is 343 m/s, sound waves in the frequency range mentioned have wavelengths between 3 m and 45 m. These wavelengths are therefore at least in the order of magnitude of the spatial dimensions of the interior 14 of the motor vehicle 10.

in 1 In the exemplary embodiment shown, the predetermined penetration point 26 is a motor vehicle ventilation opening 34 which is located behind a ventilation grille 28 . In 1 several such motor vehicle ventilation openings 34 are shown as an example. Exemplary air paths 36 are also shown. In addition, penetrating supply air in the front area of the vehicle is shown with arrows 38 .

2 shows with reference to the associated with 1 Components and features described schematically the method according to the invention. The method according to the invention provides that the microphone device 18, in 1 represented in parts by a microphone 16, a sound 32 penetrating from outside the motor vehicle 10 into the interior 14 of the motor vehicle 10 is detected in a first step 1. As already explained, the penetrating sound 32 has already passed through the bumper 30 of the motor vehicle 10, for example, or another part of the interior paneling, for example an absorber fleece. The remaining low-frequency components of the penetrating sound 32 are thus recorded by the microphone 16 of the microphone device 18 . In the manner described above, the microphone device 18 generates a signal 40 corresponding to the sound 32 and modulates the corresponding anti-sound information onto this signal 40 .

In a second step S2, the microphone device 18 transmits the signal 40 to at least one sound generating device 24. The sound generating device 24 can be permanently installed in the motor vehicle 10 and/or can include a loudspeaker 24 of the system 12.

In a third step S3, signal 40 generates counter-sound 42 in interior space 14 of motor vehicle 10 by means of sound-generating device 24 and/or loudspeaker 24 in order to reduce the sound pressure level 32' of the sound 32 that has penetrated.

In a fourth step S4, the controller unit 20 detects a difference or a deviation between tween the reaction to the counter-noise 42 adjusting sound pressure level 32 'in the interior 14 of the motor vehicle 10 and a predetermined target sound pressure level 44. By adjusting the signal 40, the control unit 20 minimizes the recorded difference. This advantageously results in an optimization of the resulting sound pressure level 32 ′ in the interior 14 of the motor vehicle 10 in relation to the predetermined target sound pressure level 44 .

In a specific embodiment, the system 12 is used to actively dampen airborne noise 32 penetrating through the ventilation grille 28 of a motor vehicle 10. In motor vehicles 10, the air from the passenger compartment 14 is typically routed through a ventilation opening/a ventilation grille 28 to the outside for ventilation and ventilation . In the ventilation mode, sound 32 enters the passenger compartment 14 through this opening 28 and can become disturbing. Typically, the noise that penetrates through the ventilation grille 28 into the passenger compartment 14 is attenuated by interior paneling in the manner of a low-pass filter. A rumbling noise remains. If necessary, the passenger compartment 14 and/or the trunk acts as a resonator, so that the rumbling is amplified. The resulting low-frequency noise pollution has a negative effect on driving comfort and can cause pressure on the ears and nausea for those affected.

In the specific exemplary embodiment, by introducing a microphone 16 at the ventilation opening 26, 28 and a loudspeaker 24 in the passenger compartment 14 in conjunction with a filter/control circuit 20, 22, the disruptive noise input 32 can advantageously be damped according to the anti-noise principle. In the simplest embodiment, the signal from the microphone 16 can be inverted (multiplication by the factor −1) in order to obtain a suitable signal for the loudspeaker 24. A motor vehicle 10 typically already has at least one loudspeaker 24 from the car radio installed. This can be used advantageously for the control loop. If there are several ventilation openings 26, 28, one microphone 16 can also be used at the ventilation opening 26, 28, the control loop then having to be expanded for this.

Overall, the example shows how active damping of airborne noise penetrating through the ventilation grille of a motor vehicle can be provided by the invention. In particular, the low-frequency components of the penetrating airborne noise are reduced, which remain in the interior of the motor vehicle after the airborne noise has passed through body components, in particular bumpers and/or interior panels and/or absorber fleeces, where they have a negative effect on motor vehicle occupants.

This advantageously achieves a reduction in the noise exposure on the vehicle occupants.

Claims (7)

Motor vehicle (10), having at least one motor vehicle ventilation opening (26), with a system (12) for reducing a sound pressure level (32') in an interior (14) of the motor vehicle (10), comprising a microphone device (18), wherein the microphone device (18) is set up to detect a sound (32) penetrating from outside the motor vehicle (10) into the interior (14) of the motor vehicle (10) inside the motor vehicle (10) at at least one predetermined penetration point (26). and to transmit a signal (40) corresponding to the detected sound (32) to at least one sound generating device (24) for the motor vehicle (10), the signal (40) being set up to be transmitted in the interior ( 14) of the motor vehicle (10) to generate counter-sound (42) to reduce the sound pressure level (32') of the sound (32) that has penetrated, wherein the at least one predetermined penetration point (26) is the motor vehicle ventilation opening (26) and is located in the area of a wheel suspension of the motor vehicle (10) and/or in the area of a bumper of the motor vehicle (10), wherein the microphone device (18) has at least one microphone which is designed to record the sound (32) penetrating the interior (14) of the motor vehicle (10) and which is located in an air path ( 36) is arranged on the motor vehicle ventilation opening (26) behind an interior paneling of the motor vehicle (10), the interior paneling being designed to filter high-frequency components of the penetrating sound (32) in the sense of low-pass filtering. Motor vehicle (10) after claim 1 , wherein the system (12) comprises a control unit (20) which is designed to detect a deviation of the sound pressure level (32 ') in the interior (14) of the motor vehicle (10) from a predetermined target sound pressure level (44), and by adjustment of the signal (40) corresponding to the sound (32) detected by the microphone device (18) to minimize the deviation detected. Motor vehicle (10) according to one of the preceding claims, wherein the sound generating device (24) has at least one loudspeaker (24) which is set up to receive the signal (40) corresponding to the sound (32) detected by the microphone device (18) and, by means of the signal (40) in the interior (14) of the motor vehicle (10), to generate an opposing sound (42 ) to reduce the sound pressure level (32 ') of the penetrated sound (32). Motor vehicle (10) according to one of the preceding claims, wherein the signal (40) is set up to generate a low-frequency counter-noise (42) in a frequency range of less than 300 Hz, in particular a counter-noise ( 42) in a frequency range of 8 to 100 Hz. Motor vehicle (10) according to one of the preceding claims, wherein the system (12) comprises an activation device which is set up to receive operating data relating to an operating state of the motor vehicle (10) and to activate the system (12) as a function of a predetermined operating state . Motor vehicle (10) after claim 5 , wherein the activation device has a manual operating unit and is set up to receive a switching state and/or a switching signal from the manual operating unit and upon detection of a predetermined switching state and/or upon receipt of the switching signal, the system (12) independently of the operating state of the motor vehicle (10) enable and disable. Method for reducing a sound pressure level (32') in an interior (14) of a motor vehicle (10) according to one of the preceding claims, wherein the motor vehicle (10) has at least one motor vehicle ventilation opening (26) and a system (12) for reducing the sound pressure level (32 ') in the interior (14) of the motor vehicle (10), comprising a microphone device (18), wherein the microphone device (18) detects (S1) a sound (32) penetrating from outside the motor vehicle (10) into the interior (14) of the motor vehicle (10) inside the motor vehicle (10) at at least one predetermined penetration point (26), wherein the at least one predetermined penetration point (26) is the motor vehicle ventilation opening (26) and is located in the area of a wheel suspension of the motor vehicle (10) and/or in the area of a bumper of the motor vehicle (10), wherein the microphone device (18) transmits (S2) a signal (40) corresponding to the recorded sound (32) to at least one sound generating device (24) for the motor vehicle (10), the signal (40) being transmitted by the sound generating device (24) in the interior (14) of the motor vehicle (10) generates counter-sound (42) to reduce the sound pressure level (32') of the sound (32) that has penetrated (S3), wherein at least one microphone (16) of the microphone device (18) is arranged in an air path (36) running between the interior (14) and the motor vehicle ventilation opening (26) and the sound (32 ) recorded, and wherein the penetrating sound (32) is filtered at the predetermined penetration point (26) by means of a vehicle body and/or the interior paneling of the motor vehicle (10) and/or by means of absorber fleece in terms of low-pass filtering.

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