METHOD FOR MASKING UNWANTED DISTURBING NOISES AND VEHICLE

Description

[0001] The invention relates to a method for masking unwanted noises occurring during the operation of a vehicle by means of synthetic noises of the type defined in more detail in the preamble of claim 1, as well as to a vehicle for carrying out the method.

[0002] Vehicles emit a variety of different noises during operation. Some of these noises, such as a crisp engine or exhaust note, are perceived as pleasant, whereas others such as rattling, clattering, humming, or a grinding V-belt are unpleasant. Particularly in electrified vehicles, the noise emitted by the vehicle plays a significant role in the comfort of use and the safety of road users. Because electrified vehicles are generally quieter than vehicles with combustion engines, electrically powered vehicles are often difficult for road users to hear. Therefore, methods and devices for generating synthetic vehicle noises are already known from the state of the art.By means of such a synthetic vehicle sound, for example, the acceleration of the corresponding vehicle is given a soundtrack, which on the one hand warns road users about the electrified vehicle and on the other hand, by generating a particularly futuristic and pleasant engine sound, increases the comfort for the person driving the electrified vehicle.

[0003] Electric motors typically emit medium- and high-frequency vibrations, which can only be dampened to a limited extent by typical noise, vibration, and harshness (NVH) measures. The noise generated by these vibrations is generally quiet, but is clearly audible due to its tonality and the correlation of pitch with the electric motor's speed or vehicle speed.

[0004] For example, EP 3 514 790 A1 discloses a method and device for generating a synthetic sound to accompany the acceleration of a vehicle. However, such a sound, which is related to the vehicle's acceleration, is only inadequately suited to masking sounds that are not dependent on the vehicle's acceleration.

[0005] DE 10 2020 004 974 A1, on the other hand, discloses a method for masking unwanted noise generated by a vehicle's drivetrain, which method is suitable for masking noises not related to vehicle acceleration. According to the method disclosed in the document, an unmodulated synthetic noise is multiplied by multiplication with a filter dependent on a vehicle parameter and an amplifier dependent on a vehicle parameter, and is thereby modulated to generate a particularly natural-sounding noise for masking an interfering noise. The pitch of all acoustic signals comprising the synthetic noise remains constant. Broadband noise, also known as white noise, is used as the source for the unmodulated synthetic noise.To create a particularly natural-sounding synthetic noise, the synthetic noise's sound characteristics are adjusted to resemble the sound of wind and / or tires rolling on a surface. The disadvantage, however, is that the synthetically generated noise is not embedded in the vehicle's acoustic behavior, but rather acts like a "plaster" to mask the unwanted noise. Thus, comfortable masking of the unwanted noise is not possible.

[0006] A vehicle with Ambisonic surround sound is known from US 2021 / 197667 A1.

[0007] EP 3 757 986 A1 discloses a method for masking noise from a vehicle by dynamically generating a masking audio signal based on drive and background noise.

[0008] DE 10 2020 004974 A1 discloses a method for masking noise from a vehicle. This method comprises pre-modulating a synthetic noise corresponding to wind noise with a static filter and modulating it with an adaptive amplifier. The filter can be any filter, such as a low-pass, high-pass, or band-pass filter, or any combination thereof. The filter removes acoustic signals containing unwanted frequencies from the unmodulated synthetic noise. The amplifier increases the volume of a modulated synthetic noise. The filter and amplifier are adaptive and adapt to input variables encompassing vehicle parameters.

[0009] The present invention is based on the object of providing an improved method for masking unwanted noise occurring during the operation of a vehicle by means of synthetic noise, with the aid of which the user comfort of vehicle occupants during the operation of the vehicle is improved.

[0010] According to the invention, this object is achieved by a method for masking unwanted noises occurring during the operation of a vehicle by means of synthetic noises having the features of claim 1. Advantageous embodiments and further developments as well as a vehicle for carrying out the method emerge from the dependent claims.

[0011] In a method for masking unwanted noise of the type mentioned at the outset, 1 / f noise is used according to the invention as the output source for an unmodulated synthetic noise and, before modulation of the unmodulated synthetic noise by the at least one filter and / or amplifier dependent on the vehicle parameter, the unmodulated synthetic noise is pre-modulated by means of at least one static filter.

[0012] This process makes it possible to generate a particularly natural-sounding synthetic noise to mask background noise. This natural-sounding synthetic noise can be easily embedded into the acoustic behavior of a vehicle, so that the synthetic noise is perceived by vehicle occupants and external road users as particularly natural and part of the vehicle. A key concept is the use of 1 / f noise as the source for the unmodulated synthetic noise.

[0013] Unmodulated means that the corresponding output signal has not been manipulated. 1 / f noise, also known as pink noise, is a noise which, viewed in frequency space, corresponds to a linearly decreasing function. This means that the amplitude, or level of the respective frequencies, decreases with increasing frequency. In a double-logarithmic plot, 1 / f noise has a negative slope of approximately 3 dB per octave. In white noise, on the other hand, the amplitude of the noise is approximately constant across all frequencies. To humans, however, white noise sounds more treble-emphasized. This means that high frequencies are perceived more strongly by humans. Since the amplitude of the high frequencies decreases in 1 / f noise, 1 / f noise is perceived as a noise in which all frequency ranges of the audible sound spectrum sound approximately the same.This allows the creation of a particularly natural-sounding synthetic noise to mask background noise.

[0014] The static filter modulates the 1 / f noise so that the synthetic noise pre-modulated by the static filter has a peak in the frequency range in which the noise to be masked is present. The transfer function of the static filter is constant and thus independent of any acceleration and / or speed of the vehicle or its drivetrain components.

[0015] 1 / f noise is a standardized function and is used as the sole signal source for generating the unmodulated synthetic noise. This minimizes the computing power and memory requirements for generating the synthetic noise. For example, the 1 / f noise can be stored as a WAV file in a storage device such as flash memory, and the unmodulated synthetic noise can be sampled from the WAV file.

[0016] A possible disturbing noise that can be masked with the help of the synthetic noise can, for example, be generated by a vehicle's drivetrain. In particular, this is the drivetrain of an at least partially electrified vehicle. In electrified vehicles, it can happen that the electrified part of the drivetrain in particular generates a whining sound with a defined frequency spectrum in a certain speed range, i.e. at a certain speed of a drivetrain component. This whining sound is disturbing and should be masked. Since the generation of the whining sound depends on the rotational speed of at least one component of the drivetrain, the whining sound also occurs in a very specific travel speed range of the vehicle.For particularly convenient masking of the disturbing noise, the synthetic noise is embedded in the acoustic behavior of the vehicle in such a way that the synthetic noise for masking is emitted in the vehicle's travel speed range in which the wailing sound also occurs.

[0017] The goal is to adjust the volume of the synthetic noise to the volume of the background noise it is trying to mask. If the synthetic noise is too quiet, the background noise will still be audible. If the synthetic noise is too loud, however, the synthetic noise itself may be perceived as disturbing by a vehicle occupant. By multiplying the pre-modulated synthetic noise by an amplifier, the volume of the synthetic noise can be precisely adjusted to a desired level.

[0018] The method according to the invention provides that the unmodulated synthetic noise is pre-modulated by means of the at least one static filter such that the pre-modulated synthetic noise comprises at least two acoustic signals, wherein a first acoustic signal has a first spectral width, a second acoustic signal has a second spectral width, and the first spectral width corresponds to a frequency range from 0 to a maximum of 2200 Hz, and the second spectral width lies in a frequency range higher than the first spectral width, wherein the second spectral width completely encompasses a spectral width of at least one interference noise to be masked. By generating the pre-modulated synthetic noise such that it comprises at least the first and second acoustic signals, a natural-sounding perceptibility of the synthetic noise is improved.The low-frequency components make the synthetic noise sound like a particularly natural wind and / or rolling noise. This further improves the comfort of the vehicle's occupants during operation. The first spectral width can be any width within the frequency range of 0 to 2200 Hz. For example, the first spectral width can take on a value of 0 to 500 Hz, 0 to 1500 Hz, 200 to 600 Hz, or 1700 to 2200 Hz. The first spectral width can be used to specifically adjust the sound of a "background noise" of the wind or rolling noise.

[0019] The second spectral width encompasses at least the frequency range in which the noise to be masked occurs. In a frequency range adjacent to the noise to be masked, for example, ±100 Hz, the amplitude of the second acoustic signal can gradually decrease or increase. This further enhances the natural sound of the synthetic noise.

[0020] According to an advantageous development of the method according to the invention, at least one adaptive filter is formed by a low-pass filter, wherein a cutoff frequency of the low-pass filter depends on the vehicle's speed of travel. With the help of the low-pass filter, the natural sound of the synthetic noise can be further improved. For example, a natural wind or rolling noise of a vehicle depends on the vehicle's speed of travel. As the speed of travel increases, the proportion of high frequencies in the wind or rolling noise also increases. The low-pass filter is designed as an adaptive filter and depends on the vehicle's speed of travel. The cutoff frequency of the low-pass filter is shifted to higher frequencies as the vehicle's speed of travel increases.The pitch of the acoustic signals of the modulated synthetic sound remains constant, but the low-pass filter can be used to control the frequency up to which acoustic signals, i.e., tones, are to be integrated into the modulated synthetic sound. This allows more tones with higher frequencies to be recorded as the vehicle's speed increases. This allows the sound characteristics of the modulated synthetic sound to be adapted to create a particularly natural-sounding wind or rolling noise.

[0021] A further advantageous embodiment of the method according to the invention further provides that an amplification factor of at least one adaptive amplifier depends on a travel speed of the vehicle, wherein the amplification factor assumes a maximum value in at least one speed range in which an interference noise occurs. As already mentioned, the volume of the modulated synthetic noise can be adjusted with the aid of an amplifier. The amplification factor of the adaptive amplifier is coupled to the travel speed of the vehicle. In a speed range in which the interference noise to be masked does not occur, this amplification factor is preferably 0 or a very low value such as 0.01. In the travel speed range in which the interference noise to be masked does occur, however, the amplification factor of the amplifier is in particular 1 or higher.

[0022] According to a further advantageous embodiment of the method, the amplification factor assumes a minimum value at a predetermined interval before the start and after the end of the speed range in which the disturbing noise occurs, and in particular continuously increases from the minimum value to the maximum value or decreases. In other words, the volume of the modulated synthetic noise for masking the disturbing noise is gently increased as the vehicle's speed increases and is gently reduced again when the vehicle leaves the speed range in which the disturbing noise is present. This allows the synthetic noise for masking the disturbing noise to be particularly conveniently embedded in the vehicle's acoustic behavior. The modulated synthetic noise can thus be seamlessly integrated into the wind or rolling noise perceived by the vehicle occupants in the vehicle interior.During vehicle use, there is only a minimal increase in the overall noise level in the vehicle interior. This increase is also limited to the vehicle's problematic speed range. The vehicle occupants therefore perceive the synthetic noise as particularly authentic. The synthetic noise begins to increase in volume 10 km / h before the actual noise occurs and returns to its minimum volume 10 km / h after the noise subsides. This smooth integration of the synthetic noise into the vehicle's acoustic behavior makes the synthetic noise appear even more natural.

[0023] A further advantageous embodiment of the method according to the invention further provides that the synthetic noise, after modulation by the at least one adaptive filter and / or an amplifier, preferably configured to adjust an attenuation (relative volume level of the fed-back signal), experiences a feedback delay whose transfer function corresponds to a comb filter. By imposing a feedback delay on the synthetic noise, the natural sound of the synthetic noise can be enhanced even further. Comparatively little computational effort is required to impose the feedback delay. Furthermore, slight flanging, i.e. the imposition of non-linearities, can be generated in the synthetic noise. The feedback level must be less than 0 dB, otherwise instabilities will occur. This attenuation level can be adjustable in the vehicle. This enables the vehicle occupants orAn authorized technician can adjust the sound of the synthetic noise based on personal preferences. The feedback delay can be used to make it more difficult to recognize repetitive patterns. Since the human ear is very good at recognizing repetitive patterns, this can further enhance the natural sound of the synthetic noise. In particular, the synthetic noise undergoes the feedback delay several times.

[0024] According to a further advantageous embodiment of the method, a delay time reciprocal to the frequency of the noise to be masked is imposed on the synthetic noise in the feedback delay. The corresponding transfer function thus has the equation delay time = 1 / frequency. The transfer function can also be adjusted so that a multiplication by a multiple of the frequency 1 / (n*f) occurs, for example, 1 / (2 xf). The multiplication factor n is ideally taken from a number range of 2 x<, where X contains positive or negative integers. The factor n therefore ideally has values ​​of, for example, 0.25, 0.5, 1, 2, 4, etc. From an acoustic perspective, this sets the transfer function of the comb filter to octaves of the noise frequency, which contributes to the naturalness of the synthetic masking noise.The set frequency f can also be freely adjusted in the vehicle and only needs to be roughly based on the frequency of the noise to be masked. A variance can also be included in the formula for calculating the delay time, which is reciprocal to the set frequency. For example, the formula could be: Delay time = 1 / (frequency + variance) or Delay time = 1 / (frequency - variance). Multiplication factors and variances can also be used simultaneously, for example: Delay time = 1 / (N*frequency + / - variance). If the dominant frequency at which an interference noise occurs is in a range around 3500 Hz, for example, the variance can be 500 Hz, or fractions or multiples thereof.

[0025] A further advantageous embodiment of the method according to the invention further provides that at least one synthetic sound is distributed across at least two loudspeakers for output in the vehicle. By distributing the synthetic sound across at least two loudspeakers, preferably more than two loudspeakers, its source becomes difficult for vehicle occupants to locate. This makes the synthetic sound appear to come from different directions, further enhancing the natural sound.

[0026] According to a further advantageous embodiment of the method, the at least one synthetic noise is output via at least two loudspeakers such that a position of an apparent noise source, from which the synthetic noise appears to a vehicle occupant to be coming, is positioned at a predetermined location in a vehicle interior, in particular using an Ambisonics algorithm. A slight time offset in the output of the synthetic noise between the at least two loudspeakers makes it possible to freely position a position of an apparent noise source, from which the synthetic noise appears to be coming to a vehicle occupant, in the vehicle interior. Particularly preferably, more than two loudspeakers, for example three, four or five loudspeakers, are used for this purpose. The time offset of the output of the synthetic noise is determined individually for each of the loudspeakers.For even better application of delay times and speaker output levels, an Ambisonics algorithm is particularly preferred. Ambisonics is a method for recording and / or reproducing a sound field. Ambisonics enables the particularly simple and convenient placement of virtual, i.e., apparent, sound sources in the room. This allows a developer to specify the position from which the synthetic sound appears to be coming relative to the vehicle. For the vehicle occupants, the synthetic sound no longer appears to be coming from the corresponding speakers, but instead, for example, from a fictitious sound source behind the vehicle's dashboard, from the direction of the vehicle's exterior mirrors, or the like.Because the vehicle occupants perceive the synthetic noise not from the direction of the loudspeakers, but from any other direction, the synthetic noise appears to belong even more naturally to the vehicle.

[0027] A further advantageous embodiment of the method according to the invention further provides that at least two synthetic sounds provided with a feedback delay are output in the vehicle, and the apparent positions of their noise sources are positioned at different locations in the vehicle interior, wherein the two synthetic sounds have a different feedback delay time. This further improves the natural sound of the synthetic sound. The two synthetic sounds can also be identical except for their feedback delay. However, the two synthetic sounds can also differ at least partially in their frequency bandwidth.

[0028] In a vehicle with a computing unit, at least one sensor for detecting vehicle speed, and at least one loudspeaker, the computing unit, the sensor, and the loudspeaker are configured according to the invention to carry out a method as described above. The vehicle can be any vehicle, such as a car, truck, van, bus, or the like. The computing unit comprises hardware and software for implementing the method according to the invention. Thus, the computing unit comprises at least one memory element, for example a flash memory, for storing a sound file used to generate the 1 / f noise and / or program code, the execution of which on a processor allows the method according to the invention to be carried out. Individual signal processing elements such as filters and / or amplifiers can be implemented by hardware components and / or software.The sensor allows at least the detection of the vehicle speed. This allows the volume of the synthetic noise to be adjusted depending on the vehicle speed, so that the synthetic noise is emitted at a sufficient volume precisely when the background noise to be masked also occurs. The synthetic noise for masking at least one background noise is emitted via at least one loudspeaker, preferably via multiple loudspeakers. The loudspeakers can be arranged anywhere in the vehicle.

[0029] Multiple noises may also occur during vehicle operation, with the various noises occurring at different vehicle speeds. Using the method according to the invention, all occurring noises can be individually masked. Accordingly, various synthetic noises are generated using the method according to the invention.

[0030] Particularly preferably, the vehicle has an at least partially electrified drivetrain. The vehicle is thus designed as a hybrid vehicle or a purely battery-electric vehicle. Especially with an electrified drivetrain, whining noises occur at various operating points, which can be particularly conveniently masked using the method according to the invention.

[0031] Further advantageous embodiments of the method according to the invention for masking unwanted noise and the vehicle also emerge from the exemplary embodiments which are described in more detail below with reference to the figures.

[0032] Showing: Fig. 1 shows a schematic diagram of several diagrams of noises occurring during operation of a vehicle in a frequency domain; Fig. 2 shows a schematic diagram of an inventive processing of a synthetic noise; and Fig. 3 shows a plan view of a vehicle according to the invention in which noises occurring during operation are masked using a method according to the invention.

[0033] Figure 1 shows four different acoustic diagrams in which a volume LEVEL of different sounds is plotted against a frequency F. Figure 1a ) a specific operating point during the operation of a Figure 3 shown vehicle 1, as well as a background noise 15 present during operation. The noise 2 occurs in a Figure 3 The noise 2 becomes perceptible in the vehicle interior 12 shown when the vehicle 1 is traveling at a speed within a certain speed range, for example, between 110 km / h and 120 km / h. The noise 2 has a comparatively narrow spectral width SB, thus comprising only a few acoustic signals, each with a characteristic frequency F, and can thus be perceived as an annoying "whining noise." The noise 2 is emitted in particular by an electrified part of a drive train of the vehicle 1.

[0034] In order to improve the comfort of vehicle occupants during operation of the vehicle 1, a method according to the invention is used to Figure 1b) is generated to mask the noise 2. The synthetic noise 3 is characterized by a particularly natural sound and is embedded in the acoustic behavior of the vehicle 1 in such a way that the synthetic noise 3 does not stand out as a "plaster" to drown out the noise 2 during operation of the vehicle 1, but rather blends seamlessly into the soundscape perceptible in the vehicle interior 12. In particular, the synthetic noise 3 sounds like wind and / or rolling noise of a tire on a road. The synthetic noise 3 has a maximum volume value for the spectral width SB of the noise 2, which in Figure 1b ) is indicated by a peak. In Figure 1b ) the maximum volume between synthetic noise 3 and background noise 2 has a comparatively large distance a, which means that synthetic noise 3 is too quiet to adequately mask background noise 2.

[0035] Particularly preferably, the synthetic noise 3 comprises at least two acoustic signals 8.1 and 8.2. The first acoustic signal 8.1 is in the low-frequency range and serves to generate a particularly natural-sounding background noise. For this purpose, the first acoustic signal 8.1 has a comparatively large first spectral width SB1. The second acoustic signal 8.2 serves to mask the background noise 2 and accordingly has a second spectral width SB2, which is adapted to the spectral width SB of the background noise 2.

[0036] In Figure 1c ) the volume LEVEL of synthetic noise 3 was increased, thereby decreasing the distance a. This achieves optimal masking of background noise 2 from a comfort perspective.

[0037] In Figure 1d), however, the volume LEVEL of the synthetic noise 3 was increased too much. Due to this overcompensation, there is a risk that the synthetic noise 3 itself may be perceived in the vehicle interior 12 as not belonging to the natural soundscape of the vehicle 1 and thus as disturbing.

[0038] For optimal masking, the volume LEVEL of synthetic noise 3 should be sufficiently high, but not too loud. A volume LEVEL just below the volume LEVEL of background noise 2 is sufficient to achieve an optimal psychoacoustic level difference between background noise 2 and synthetic noise 3.

[0039] Figure 2serves to illustrate how the synthetic noise 3 is generated. For example, an acoustic signal 8 in the form of 1 / f noise, also referred to as pink noise, is provided by a signal source 16. The signal source 16 can contain the 1 / f noise, for example, as a WAV file, after which an unmodulated synthetic noise 3.1 is generated by sampling. The volume of the unmodulated synthetic noise 3.1 can optionally be adjusted after generation using a static amplifier 17.

[0040] The unmodulated synthetic noise 3.1 is then multiplied by a static filter 7. The static filter 7 can be formed by any signal filter or any combination thereof. For example, the static filter 7 is a low-pass filter, high-pass filter, band-pass filter, comb filter, or combinations thereof. By means of the static filter 7, the unmodulated synthetic noise 3.1 is pre-modulated and converted into a pre-modulated synthetic noise 3.2 in order to impose on the synthetic noise 3 at least the peak in the spectral width SB in which the interference noise 2 occurs. Since the spectral width SB of the interference noise 2 does not change or changes only marginally during operation of the vehicle 1, a static filter 7 is sufficient to impose the peak.The frequencies covered by the noise 2 can be determined, for example, during the development of the vehicle 1 using acoustic measurements and the static filter 7 can be adjusted accordingly.

[0041] Preferably, the synthetic noise 3 is pre-modulated such that, in addition to the peak frequencies of the noise 2, it also includes a low-frequency component, i.e., in addition to the second acoustic signal 8.2, it also includes the first acoustic signal 8.1. With the aid of acoustic signals in the low-frequency range, in a range from 0 to 2200 Hz, the natural sound of the synthetic noise 3 is improved. This makes it possible to make the noise emitted in the vehicle interior 12 sound more like a natural wind and / or rolling noise.

[0042] The unmodulated synthetic noise 3.1 can also be split into multiple signal paths, with each signal path assigned a different static filter 7 (not shown). The individual signals are then recombined.

[0043] Following the static filter 7, the pre-modulated synthetic noise 3.2 is multiplied by at least one adaptive amplifier 6 and / or at least one adaptive filter 5, thereby converting it into a modulated synthetic noise 3.3. A gain factor f of the adaptive amplifier 6 depends on a vehicle parameter 4. The vehicle parameter 4 is a parameter dependent on the speed of travel of the vehicle 1. For example, the vehicle parameter 4 can be a rotational speed of a tire, a shaft, or the like, or even the speed of travel itself.

[0044] With the help of the adaptive amplifier 6, the output of the synthetic noise 3 in the vehicle interior 12 is controlled such that the synthetic noise 3 is emitted exclusively in the speed range in which the disturbing noise 2 also occurs, plus / minus a certain speed transition range. Thus, the synthetic noise 3 also has its maximum volume in the speed range in which the disturbing noise 2 occurs, for example, in the range between 110 km / h and 120 km / h. In the speed transition range, for example, + / - 5 km / h, 10 km / h, 20 km / h, or the like, above or below 110 km / h or 120 km / h, respectively, the volume of the synthetic noise 3 is then gradually increased or decreased.The volume of the synthetic noise 3 is increased and decreased in such a way that the synthetic noise 3 appears particularly natural to the vehicle occupants and is part of the acoustic behavior of the vehicle 1. For example, the volume of the synthetic noise is increased and decreased linearly or parabolically in the speed transition range.

[0045] Furthermore, the pre-modulated synthetic noise 3.2 or the synthetic noise 3.3 already modulated by the adaptive amplifier 6 can be multiplied by an adaptive filter 5. The adaptive filter 5 can, analogous to the static filter 7, be any combination of typical signal filters. Particularly preferably, the adaptive filter 5 comprises at least one low-pass filter. The adaptive filter 5 is also dependent on the vehicle parameter 4. For example, the cutoff frequency of the low-pass filter is selected depending on the speed of the vehicle 1. Particularly preferably, the cutoff frequency is adjusted proportionally with the speed of travel. Therefore, if the vehicle 1 travels faster, more high-frequency components are integrated into the modulated synthetic noise 3.3.The pitch of the individual acoustic signals of the synthetic noise 3 remains constant during operation of the vehicle 1. Only more or fewer acoustic signals from the high-frequency range are incorporated into the synthetic noise 3. This takes into account the fact that a natural-sounding wind or rolling noise also includes more high-frequency components as the vehicle 1's speed increases. This allows the natural sound of the synthetic noise 3 to be further enhanced.

[0046] Subsequently, a feedback delay is applied to the modulated synthetic noise 3.3 by a feedback delay module 9. A delay time can be set using a delay block 18. Particularly preferably, the delay time is the inverse of a particularly dominant frequency F of the noise 2. The feedback level should be less than 0 dB to avoid instabilities. For this purpose, multiplication by an amplifier 6 is performed, whose gain f has a value less than -0.01 dB. This value can be freely set in the vehicle 1.

[0047] The synthetic noise 3 can also be passed through the feedback delay multiple times. A transfer function of the feedback delay can also resemble or be based on a comb filter.

[0048] In a particularly advantageous embodiment, at least one synthetic noise 3 is transmitted via at least two Figure 3 shown loudspeakers 10 in the vehicle interior 12. In doing so, a virtual sound object is generated from the synthetic sound(s) 3, which can be placed anywhere in the vehicle interior 12 or even outside the vehicle 1. Thus, the synthetic sound(s) 3 no longer appears to come directly from the loudspeakers 10, but rather from a position of one or more apparent noise sources 11. To generate the virtual sound object and freely place the sound object in the room, an Ambisonics algorithm is preferably used. For this purpose, the modulated synthetic sound 3.3 is first processed by an Ambisonics encoder 19.1 and then by an Ambisonics decoder 19.2.

[0049] To generate multiple sounds to be output in the vehicle interior 12, the combination of feedback delay module 9 and Ambisionics encoder 19.1 can also be provided multiple times, as indicated by the dashed boxes. If multiple noise sources 2 exist, multiple synthetic noises 3 can also be generated to mask the noise sources 2, as indicated by the dotted boxes. To output the individual synthetic noises 3 in the vehicle interior 12, the individual synthetic noises 3 are then combined.

[0050] The vehicle 1 may have additional devices for generating artificial sounds (not explained in detail). For example, an artificial engine sound 20 is combined with the synthetic sounds 3 to be emitted in the vehicle interior 12.

[0051] Figure 3shows a plan view of a vehicle 1 according to the invention. The vehicle 1 preferably has an at least partially electrified drive train. A plurality of loudspeakers 10 for outputting at least one synthetic sound 3 are arranged in the vehicle interior 12. Particularly preferably, at least one loudspeaker 10 is located in front of a vehicle occupant in the direction of travel of the vehicle 1 and at least one loudspeaker 10 is located behind the respective vehicle occupant. In this way, a particularly natural-sounding surround sound can be generated. Particularly preferably, a position of an apparent noise source 11, from which the synthetic noise 3 appears to come, is placed at a desired position in the vehicle interior 12. This allows the noise source 11 to be freely positioned, thus enabling an even more natural sound experience when reproducing the synthetic noise 3.For example, a synthetic sound 3 is placed near the exterior mirrors of the vehicle and a synthetic sound 3 is located behind a dashboard of the vehicle 1.

[0052] To detect the speed of travel of the vehicle 1 or a value representative of the speed of travel, the vehicle 1 comprises at least one sensor 14. The synthetic noise 3 is generated by means of a computing unit 13. A measured value generated by the sensor 14 is fed to the computing unit 13 as an input variable in order to control the volume of the synthetic noise 3 as a function of the speed of travel of the vehicle 1 and / or to integrate more higher-frequency components into the synthetic noise 3 as the speed of travel increases.

Claims

1. Method for masking unwanted background noises (2), occurring during operation of a vehicle (1), using synthetic noises (3), wherein the synthetic noise (3) is generated from an unmodulated synthetic noise (3.1) to adjust a desired sound characteristic by multiplication with at least one filter (5) and / or amplifier (6) dependent on a vehicle parameter (4), wherein a pitch level of all acoustic signals (8) of which the modulated synthetic noise (3.3) is composed is kept constant during an output of the modulated synthetic noise (3.3), characterized in that the unmodulated synthetic noise (3.1) is formed as 1 / f noise and is pre-modulated by means of at least one static filter (7) before being modulated by the at least one filter (5) and / or amplifier (6) dependent on the vehicle parameter (4), wherein the unmodulated synthetic noise (3.1) is pre-modulated by means of the at least one static filter (7) such that the pre-modulated synthetic noise (3.2) comprises at least two acoustic signals (8.1, 8.2), wherein a first acoustic signal (8.1) has a first spectral width (SB1), a second acoustic signal (8.2) has a second spectral width (SB2) and the first spectral width (SB1) corresponds to a frequency range from 0 to a maximum of 2200 Hz and the second spectral width (SB2) is in a higher frequency range than the first spectral width (SB1), wherein the second spectral width (SB2) completely comprises a spectral width of at least one background noise (2) to be masked.

2. Method according to claim 1, characterized in that at least one adaptive filter (5) is formed by a low-pass filter, wherein a cutoff frequency of the low-pass filter depends on a travel speed of the vehicle (1).

3. Method according to any of claims 1 to 2, characterized in that an amplification factor (f) of at least one adaptive amplifier (6) depends on a travel speed of the vehicle (1), wherein the amplification factor (f) assumes a maximum value in at least one speed range in which a background noise (2) occurs.

4. Method according to claim 3, characterized in that the amplification factor (f) assumes a minimum value at a predetermined distance before the start and after the end of the speed range in which the background noise occurs, and in particular continuously rises and falls from the minimum value to the maximum value.

5. Method according to any of claims 1 to 4, characterized in that the synthetic noise (3), after modulation by the at least one adaptive filter (5) and / or an amplifier (6), experiences a feedback delay, in particular with an adjustable attenuation, the transfer function of which corresponds to a comb filter.

6. Method according to claim 5, characterized in that a delay time reciprocal to a frequency (F) of the background noise (2) to be masked is applied to the synthetic noise (3) in the feedback delay.

7. Method according to any of claims 1 to 6, characterized in that at least one synthetic noise (3) is distributed to at least two loudspeakers (10) for output in the vehicle (1).

8. Method according to claim 7, characterized in that the at least one synthetic noise (3) is output via at least two loudspeakers (10) such that a position of an apparent noise source (11), from which the synthetic noise (3) appears to a vehicle occupant to originate, is positioned at a specified location in a vehicle interior (12), in particular using an ambisonics algorithm.

9. Method according to claim 8, characterized in that at least two synthetic noises (3) provided with a feedback delay are output in the vehicle (1) and the apparent positions of the noise sources (11) thereof are positioned at different locations in the vehicle interior (12), wherein the two synthetic noises (3) have a feedback delay time that differs from one another.

10. Vehicle (1) comprising a computing unit (13), at least one sensor (14) for detecting a vehicle speed, and at least one loudspeaker (10), characterized in that the computing unit (13), the sensor (14) and the loudspeaker (10) are designed to carry out a method according to any of claims 1 to 9.