Method and vehicle for masking unwanted and annoying noises

Abstract

The invention relates to a method for masking an undesired unpleasant noise (2) occurring during the operation of a vehicle (1) by a synthetic noise (3), which is generated from an unmodulated synthetic noise (3.1) by multiplication by at least one filter (5) and / or amplifier (6) depending on vehicle parameters (4) in order to adjust the desired acoustic characteristics, the pitch of all sound signals (8) constituting the modulated synthetic noise (3.3) being kept constant during the output of the modulated synthetic noise (3.3). The method according to the invention is characterized in that the unmodulated synthetic noise (3.1) is formed as 1 / f noise and is pre-modulated by at least one static filter (7) before modulation by at least one filter (5) and / or amplifier (6) depending on the vehicle parameters (4).

Description

[Technical Field]

[0001] The present invention relates to a method for masking unwanted, unpleasant noises occurring during the operation of a vehicle by means of a synthetic noise, as well as to a vehicle for implementing this method, as defined in the preamble of claim 1. [Background technology]

[0002] Vehicles emit various noises during their operation. Some of these noises, such as a light engine or exhaust sound, are perceived as pleasant, while others, such as rattles, clatters, hums, or V-belt friction, are perceived as unpleasant. Particularly in electric vehicles, the noise emitted by the vehicle plays an important role in the comfort of the vehicle and the safety of road users. Electric vehicles are often quieter than vehicles with internal combustion engines, making electrically powered vehicles less noticeable to road users. Therefore, methods and devices for generating synthetic vehicle noises are already generally known in the prior art. Such synthetic vehicle noises are used, for example, to add a sound to the corresponding vehicle acceleration, thereby alerting road users to the electric vehicle and, on the other hand, to increase the comfort of the person driving the electric vehicle by generating a particularly futuristic and pleasant engine sound.

[0003] Electric motors typically produce mid- and high-frequency vibrations that can only be attenuated to a limited extent by typical noise, vibration, and harshness (NVH) measures. Noise caused by vibrations is quiet in principle, but is audible due to its tonal nature and correlation of pitch with electric motor RPM or vehicle speed.

[0004] For example, from the patent application WO 02 / 04999, a method and a device are known for generating synthetic noise to add to the sound of vehicle acceleration, but such noise related to vehicle acceleration is not well suited for masking noise that is independent of vehicle acceleration. In contrast, Patent Document 2 discloses a method for masking unwanted noises emanating from a vehicle powertrain, which method is suitable for masking noises not related to the vehicle's acceleration. According to the method disclosed in this publication, an unmodulated synthetic noise is multiplied and modulated by a vehicle parameter-dependent filter and a vehicle parameter-dependent amplifier to generate a particularly natural-sounding noise for masking unpleasant noises. The pitch of all sound signals constituting the synthetic noise is maintained constant. In this case, broadband noise, also known as white noise, is used as the source of the unmodulated synthetic noise. To generate a particularly natural-sounding synthetic noise, the acoustic characteristics of the synthetic noise are adapted, so that the synthetic noise sounds like wind noise and / or tires rolling on a surface. However, a drawback is that the generated synthetic noise is not integrated into the vehicle's acoustic characteristics and acts as a "patch" for masking unwanted noises. Therefore, comfortable masking of unwanted noises is not achieved. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] EP3514790A1 [Patent Document 2] DE102020004974A1 Summary of the Invention [Problem to be solved by the invention]

[0006] SUMMARY OF THE INVENTION It is an object of the present invention to provide an improved method for masking unwanted noises generated during vehicle operation with synthetic noise, which improves the comfort of vehicle occupants during vehicle operation. [Means for solving the problem]

[0007] According to the invention, this problem is solved by a method for masking unwanted, unpleasant noises occurring during the operation of a vehicle by means of a synthetic noise, with the features of claim 1. Advantageous configurations and developments as well as a vehicle for carrying out the method become apparent from the claims dependent thereon.

[0008] According to the present invention, in the method for masking unwanted unpleasant noise as mentioned in the introduction, 1 / f noise is used as an output source for the unmodulated composite noise, and the unmodulated composite noise is pre-modulated by at least one static filter before being modulated by at least one filter and / or amplifier depending on the vehicle parameters.

[0009] The method according to the present invention allows the generation of a particularly natural-sounding synthetic noise for masking unpleasant noises. This natural-sounding synthetic noise can be integrated particularly pleasantly into the acoustics of the vehicle, so that the synthetic noise is perceived as particularly natural and part of the vehicle by vehicle occupants and road users outside the vehicle. The key idea here is to use 1 / f noise as an output source for the unmodulated synthetic noise. "Unmodulated" here means that the corresponding output signal is not manipulated. 1 / f noise, also known as pink noise, corresponds to a linearly decreasing function when considered in frequency space. This means that the amplitude, i.e., the level of each frequency, decreases with increasing frequency. In a log-log plot, 1 / f noise has a negative slope of approximately 3 dB per octave. In contrast, with white noise, the noise amplitude remains nearly constant across all frequencies. However, white noise sounds like it emphasizes high frequencies, meaning that high frequencies are perceived more strongly by humans. In contrast, the amplitude of high frequencies is reduced in 1 / f noise, so that 1 / f noise is perceived as a noise with approximately the same loudness across all frequencies in the audible sound spectrum, which allows the generation of particularly natural-sounding synthetic noises for masking unpleasant noises.

[0010] The 1 / f noise is modulated using a static filter so that the synthesized noise pre-modulated using the static filter has a peak in the frequency range where the nuisance noise to be masked resides. The transfer function of the static filter is constant and therefore independent of any acceleration and / or speed of the vehicle or the vehicle's powertrain.

[0011] The 1 / f noise is a normalized standard function and is used as the only signal source to form the unmodulated synthetic noise. This minimizes the computational resources and memory space required to generate the synthetic noise. For example, the 1 / f noise can be stored in a memory device such as a flash memory in the form of a WAV file, and the unmodulated synthetic noise can be sampled from the WAV file.

[0012] A possible unpleasant noise to be masked using the synthetic noise may originate, for example, from the vehicle's powertrain. In particular, the powertrain may be that of an at least partially electric vehicle. In an electric vehicle, a feedback noise having a defined frequency spectrum may be generated, particularly by the electric portion of the powertrain, in a specific speed range, i.e., at a specific rotational speed of a powertrain component. This feedback noise is unpleasant and should be masked. Since the generation of the feedback noise depends on the rotational speed of at least one component of the powertrain, the feedback noise also occurs in a fairly specific range of vehicle speeds. To mask the unpleasant noise in a very comfortable manner, the synthetic noise is incorporated into the acoustic characteristics of the vehicle so that the masking synthetic noise is output in a range of vehicle speeds where the feedback noise also occurs.

[0013] Here, it is useful to adapt the volume of the synthetic noise to the volume of the unpleasant noise that one wants to cancel. If the synthetic noise is too quiet, the unpleasant noise will still be perceptible. On the other hand, if the synthetic noise is too loud, the synthetic noise itself may be perceived as unpleasant by the vehicle occupants. By multiplying the pre-modulated synthetic noise with an amplifier, the volume of the synthetic noise can be adjusted to the desired target volume.

[0014] In an advantageous development of the method, the unmodulated synthetic noise is premodulated using at least one static filter so that the premodulated synthetic noise comprises at least two acoustic signals, the first acoustic signal having a first spectral width and the second acoustic signal having a second spectral width, the first spectral width corresponding to a frequency range from 0 to a maximum of 2200 Hz, and the second spectral width being in a higher frequency range than the first spectral width and completely encompassing the spectral width of at least one unpleasant noise to be masked. By generating the premodulated synthetic noise to comprise at least the first and second acoustic signals, the perceptual naturalness of the synthetic noise is improved. The low-frequency components make the synthetic noise sound particularly like natural wind noise and / or rolling noise. This further improves the comfort for vehicle occupants during vehicle operation. The first spectral width can be any width within the frequency range from 0 to 2200 Hz. For example, the first spectral width can be 0 to 500 Hz, 0 to 1500 Hz, 200 to 600 Hz, or 1700 to 2200 Hz. The sound of the "ground noise" of wind noise or rolling noise can be adjusted as desired over the first spectral width.

[0015] The second spectral width includes at least the frequency range in which the unpleasant noise to be masked occurs. In the frequency range adjacent to the unpleasant noise to be masked, for example, the frequency range of ±100 Hz, the amplitude of the second acoustic signal can be gradually reduced or increased. This further supports the natural sounding of the synthesized noise.

[0016] According to an advantageous development of the method according to the invention, at least one adaptive filter is formed by a low-pass filter, the cutoff frequency of which depends on the vehicle's moving speed. Using the low-pass filter, the natural-sounding of the synthesized noise can be further improved. That is, the natural wind or rolling noise of the vehicle depends on the vehicle's moving speed. As the moving speed increases, the proportion of high frequencies in the wind or rolling noise also increases. The low-pass filter is formed as an adaptive filter and depends on the vehicle's moving speed. The cutoff frequency of the low-pass filter is shifted toward higher frequencies as the vehicle's moving speed increases. The pitch of the acoustic signal of the modulated synthesized noise remains constant. However, the low-pass filter can be used to control up to which frequencies of the acoustic signal, i.e., the pitch, should be integrated into the modulated synthesized noise. That is, as the vehicle's moving speed increases, higher frequencies can be included more. Thus, the acoustic characteristics of the modulated synthesized noise can be adapted to a particularly natural-sounding wind or rolling noise.

[0017] In a further advantageous embodiment of the method according to the invention, the gain of the at least one adaptive amplifier depends on the vehicle's speed, with the gain being maximum in at least one speed range in which the unpleasant noise occurs. As already mentioned, the amplifier can be used to adapt the volume of the modulated composite noise. Here, the gain of the adaptive amplifier is linked to the vehicle's speed. In speed ranges in which the unpleasant noise to be masked does not occur, this gain is preferably 0 or a very low value such as 0.01. In contrast, in speed ranges in which the unpleasant noise to be masked occurs, the gain of the amplifier is 1 or greater.

[0018] According to a further advantageous configuration of the method, the amplification factor is set at a predetermined value before and after the start and end of the speed range in which the annoying noise occurs. intervalThe synthetic noise has a minimum value at a speed of 10 km / h and continuously increases or decreases from the minimum to the maximum. In other words, the volume of the modulated synthetic noise for masking the unpleasant noise increases gradually with the vehicle's speed and decreases gradually again once the speed range in which the unpleasant noise is present is over. This allows the synthetic noise for masking the unpleasant noise to be integrated into the acoustic behavior of the vehicle in a particularly pleasant way. The modulated synthetic noise can thus be seamlessly inserted into the wind or rolling noise that is perceptible by the vehicle occupants in the vehicle cabin. Therefore, only a minimal increase in the overall level in the vehicle cabin occurs while the vehicle is in use. This increase is again limited to the speed range in which the vehicle is problematic. The vehicle occupants therefore perceive the synthetic noise as particularly authentic. Particularly preferably, the synthetic noise starts to increase in volume 10 km / h before the unpleasant noise actually occurs and decreases again to a minimum volume after 10 km / h, when the unpleasant noise subsides. This gradual integration of the synthetic noise into the vehicle's acoustic characteristics allows the synthetic noise to appear even more natural.

[0019] In a further advantageous configuration of the method according to the invention, the synthesized noise further undergoes a feedback delay after modulation by at least one adaptive filter and / or amplifier designed, inter alia, to adjust the attenuation (relative volume level of the feedback signal), the transfer function of which corresponds to a comb filter. Applying a feedback delay to the synthesized noise can further enhance the natural-sounding of the synthesized noise. The amount of calculation required to apply the feedback delay is relatively small. Furthermore, slight flanging can be generated in the synthesized noise, i.e., nonlinearity can be applied to the synthesized noise. The feedback level must be less than 0 dB, since otherwise instability would occur. This attenuation level can be adjusted in the vehicle, thereby enabling the vehicle occupant or an authorized technician to adjust the sound quality of the synthesized noise according to personal preferences. The feedback delay can be used to make repetitive patterns difficult to recognize. Since the human ear is very good at repetitive patterns, this can further improve the natural-sounding of the synthesized noise. In particular, the synthesized noise is subjected to multiple feedback delays.

[0020] According to a further advantageous configuration of the method, in the feedback delay, a delay time is applied to the synthesized noise that is the reciprocal of the frequency of the unpleasant noise to be masked. The corresponding transfer function therefore has the formula: delay time = 1 / frequency. Here, the transfer function can also be adapted to be multiplied by a frequency multiple 1 / (n*f), i.e., for example, 1 / (2*f). The multiplication factor n is ideally 2 Xwhere X can be a positive or negative integer. Therefore, the coefficient n ideally takes a value such as 0.25, 0.5, 1, 2, or 4. Acoustically, this adjusts the transfer function of the comb filter to an octave of the interference frequency, which is beneficial for the naturalness of the synthesized masking noise. Furthermore, the adjusted frequency f can be freely adjusted within the vehicle and only needs to roughly match the frequency of the unpleasant noise to be masked. The formula for calculating the delay time, which is the reciprocal of the adjusted frequency, can also include variance. That is, the formula can be, for example, delay time = 1 / (frequency + variance) or delay time = 1 / (frequency - variance). It is also possible to use the multiplication factor and variance simultaneously, that is, delay time = 1 / (N*frequency + / - variance). If the dominant frequency at which unpleasant noise occurs is in the region around 3500 Hz, for example, the variance can be, for example, 500 Hz, or a fractional part or multiple thereof.

[0021] In a further advantageous embodiment of the method according to the invention, at least one synthetic noise is split and output to at least two loudspeakers in the vehicle. Splitting the synthetic noise to at least two loudspeakers, preferably more than two, makes it more difficult for vehicle occupants to identify the source of the synthetic noise. This makes the synthetic noise seem to come from different directions, which further improves the natural sound.

[0022] According to a further advantageous embodiment of the method, at least one synthetic noise is output via at least two loudspeakers, particularly using an Ambisonics algorithm, so that the position of a pseudo-noise source, which appears to the vehicle occupants as the origin of the synthetic noise, is located at a defined location in the vehicle cabin. A slight time offset in the output of the synthetic noise between the at least two loudspeakers allows the position of the pseudo-noise source, which appears to the vehicle occupants as the origin of the synthetic noise, to be freely positioned within the vehicle cabin. For this purpose, it is particularly preferred to use two or more loudspeakers, for example, three, four, or five loudspeakers. The time offset of the output of the synthetic noise is determined individually for each loudspeaker. The Ambisonics algorithm is particularly preferred for better adaptation of delay times and loudspeaker output levels. Ambisonics is a method for recording and / or reproducing sound fields. Ambisonics allows for particularly simple and convenient positioning of virtual noise sources, i.e., pseudo-noise sources, in space. Thus, the developer can define the location relative to the vehicle from which the synthetic noise appears to originate. That is, to the vehicle occupant, the synthetic noise no longer appears to come from the corresponding speaker, but instead from an imaginary source, for example, from behind the vehicle dashboard, in the direction of the vehicle's exterior mirrors, etc. By having the vehicle occupant perceive the synthetic noise not from the direction of the speaker, but from any other direction, the synthetic noise appears to belong even more naturally to the vehicle.

[0023] In a further advantageous embodiment of the method according to the invention, at least two feedback-delayed composite noises are output to the vehicle, and the simulated noise sources of the composite noises are positioned at various locations in the vehicle interior, with the two composite noises having mutually different feedback delay times. This further improves the natural sound of the composite noises. The two composite noises may be identical except for the feedback delay times. However, the two composite noises may also at least partially differ in frequency bandwidth.

[0024] According to the present invention, a vehicle includes a computing unit, at least one sensor for detecting vehicle speed, and at least one speaker, the computing unit, the sensor, and the speaker being designed to implement the above-described method. The vehicle may be any vehicle, such as a car, truck, transporter, or bus. The computing unit includes hardware and software for implementing the method according to the present invention. That is, the computing unit includes a memory element, such as a flash memory, for storing sound files and / or program code used to generate 1 / f noise. The program code is executed by a processor to implement the method according to the present invention. Individual signal processing elements, such as filters and / or amplifiers, can be implemented by hardware components and / or software. The sensor can detect at least the vehicle speed. Therefore, the volume of the synthesized noise can be adapted depending on the vehicle speed, so that even if an unpleasant noise to be masked occurs, the synthesized noise is output with sufficient volume and accuracy. The synthesized noise for masking at least one unpleasant noise is output via at least one speaker, preferably via multiple speakers. The speakers can be located anywhere in the vehicle.

[0025] Furthermore, multiple nuisance noises may occur during the operation of the vehicle, with different nuisance noises occurring at different vehicle speeds. By using the method according to the invention, all the nuisance noises that occur can be masked individually. Accordingly, different synthetic noises are generated using the method according to the invention.

[0026] Particularly preferably, the vehicle has an at least partially electric powertrain, and thus the vehicle is designed as a hybrid vehicle or a purely battery-electric vehicle. In particular, in an electric powertrain, feedback noises occur at various operating points, and these feedback noises can be particularly conveniently masked using the method according to the invention.

[0027] Further advantageous configurations of the method and vehicle according to the invention for masking unwanted, unpleasant noises will become apparent from the detailed description of exemplary embodiments which follows with reference to the figures. [Brief explanation of the drawings]

[0028] [Figure 1] 1 shows a schematic diagram of multiple graphs of noise generated during vehicle operation in frequency space; [Figure 2] 1 shows a schematic diagram of the processing of synthetic noise according to the invention; [Figure 3] 1 shows a plan view of a vehicle according to the invention, the unpleasant noises generated during operation of which are masked using the method according to the invention; DETAILED DESCRIPTION OF THE INVENTION

[0029] FIG. 1 shows four different acoustic graphs in which the volume levels of various noises are plotted across a frequency F. Here, FIG. 1a) shows an unpleasant noise 2 generated at a specific operating point during the operation of a vehicle 1 shown in FIG. 3, as well as background noise 15 present during operation. The unpleasant noise 2 is perceptibly generated in a passenger compartment 12, also shown in FIG. 3, when the vehicle 1 is traveling within a predetermined speed range, for example, between 110 km / h and 120 km / h. The unpleasant noise 2 has a relatively narrow spectral width SB. That is, the unpleasant noise 2 contains only a few acoustic signals, each with a characteristic frequency F, and is therefore perceived as a disturbing "feedback sound." The unpleasant noise 2 is particularly emitted from the electrified parts of the powertrain of the vehicle 1.

[0030] To improve the comfort of vehicle occupants during operation of the vehicle 1, a synthetic noise 3, shown in FIG. 1b), is generated using the method according to the present invention to mask the unpleasant noise 2. The synthetic noise 3 is characterized by a particularly natural sound and is therefore inserted into the acoustics of the vehicle 1 so that it blends seamlessly into the perceptible soundscape within the passenger compartment 12 during operation of the vehicle 1, rather than standing out as a "patch" to drown out the unpleasant noise 2. In particular, the synthetic noise 3 sounds like wind noise and / or the rolling of tires on the road in this case. The synthetic noise 3 has a maximum volume value relative to the spectral width SB of the background noise 2, which can be identified by a peak in FIG. 1d. In FIG. 1b), the maximum volume is achieved with a relatively large distance a between the synthetic noise 3 and the unpleasant noise 2, which means that the synthetic noise 3 is too quiet to adequately mask the unpleasant noise 2.

[0031] Particularly preferably, the synthetic noise 3 comprises at least two acoustic signals 8.1 and 8.2. The first acoustic signal 8.1 is located in the low frequency range and is used to generate a particularly natural-sounding background noise. To this end, the first acoustic signal 8.1 has a relatively large first spectral width SB1. The second acoustic signal 8.2 is used to mask the unpleasant noise 2 and has a second spectral width SB2 that is accordingly adapted to the spectral width SB of the unpleasant noise 2.

[0032] In Figure 1c) the volume level of the synthetic noise 3 is increased, thereby shortening the interval a, thereby achieving optimal masking of the unpleasant noise 2 from a comfort point of view.

[0033] In contrast, in Fig. 1d) the volume level of the synthetic noise 3 has been increased too much. Due to such excessive compensation, there is a risk that the synthetic noise 3 itself will also not belong to the natural soundscape of the vehicle 1 in the passenger compartment 12 and may therefore be perceived as unpleasant.

[0034] That is, for optimal masking, it is desirable that the volume level of the synthetic noise 3 is high enough, but not too high: in order to achieve an optimal psychoacoustic level difference between the unpleasant noise 2 and the synthetic noise 3, a volume level slightly below that of the unpleasant noise 2 is already sufficient.

[0035] 2 is used to explain how the synthetic noise 3 is generated. An audio signal 8 in the form of 1 / f noise, also known as pink noise, is provided by a signal source 16. The signal source 16 may contain the 1 / f noise, for example as a WAV file, and is sampled to generate the unmodulated synthetic noise 3.1. Optionally, the volume of the unmodulated synthetic noise 3.1 can be varied after its generation using a static amplifier 17.

[0036] 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 can include any combination of signal filters. For example, the static filter 7 can be a low-pass filter, a high-pass filter, a band-pass filter, a comb filter, or a combination thereof. To add the synthetic noise 3 to at least the spectral width SB in which the nuisance noise 2 occurs, the unmodulated synthetic noise 3.1 is pre-modulated and converted into a pre-modulated synthetic noise 3.2 using the static filter 7. Since the spectral width SB of the nuisance noise 2 does not change during the operation of the vehicle 1, or only its edges, the static filter 7 is already sufficient to add the peaks. The frequencies contained in the nuisance 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.

[0037] Preferably, the synthetic noise 3 is pre-modulated so that it contains low-frequency components in addition to the peaks at the frequencies of the unpleasant noise 2, i.e., so that it contains not only the second acoustic signal 8.2 but also the first acoustic signal 8.1. Using an acoustic signal in the low-frequency range, for example, in the range of 0 Hz to 2200 Hz, improves the natural sound of the synthetic noise 3. In other words, the noise output into the vehicle interior 12 can be made to sound like more natural wind noise and / or rolling noise.

[0038] The unmodulated synthetic noise 3.1 can also be split into multiple signal paths, each with a different associated static filter 7 (not shown), and the individual signals are then recombined.

[0039] Following the static filter 7, the pre-modulated composite 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 composite noise 3.3. The amplification factor f of the adaptive amplifier 6 depends on a vehicle parameter 4. The vehicle parameter 4 is a parameter that depends on the moving speed of the vehicle 1. For example, the vehicle parameter 4 may be the rotation speed of tires, shafts, etc., or the moving speed itself.

[0040] Using the adaptive amplifier 6, the output of the combined noise 3 in the vehicle cabin 12 is controlled so that the combined noise 3 is only output in a speed range plus or minus a certain speed transition range in which the unpleasant noise 2 also occurs. That is, the combined noise 3 has a maximum volume in the speed range in which the unpleasant noise 2 occurs, i.e., in the range of 110 km / h to 120 km / h, for example. In speed transition ranges above or below 110 km / h or 120 km / h, for example, ±5 km / h, ±10 km / h, ±20 km / h, etc., the volume of the combined noise 3 is gradually increased or decreased. The volume of the combined noise 3 is increased or decreased so that the combined noise 3 appears particularly natural to the vehicle occupants and is considered to be part of the acoustic characteristics of the vehicle 1. For example, the volume of the combined noise is increased or decreased linearly or parabolically in the speed transition range.

[0041] 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. Like the static filter 7, the adaptive filter 5 can be any combination of typical signal filters. Particularly preferably, the adaptive filter 5 includes at least one low-pass filter. The adaptive filter 5 also depends on the vehicle parameters 4. For example, the cutoff frequency of the low-pass filter is selected depending on the vehicle's speed. Particularly preferably, the cutoff frequency is adapted proportionally to the speed. The faster the vehicle 1 travels, the more high-frequency components are incorporated into the modulated synthetic noise 3.3. The pitch of the individual sound signals of the synthetic noise 3 remains constant throughout the vehicle's operation. More or less, only sound signals originating from the high-frequency range are incorporated into the synthetic noise 3. This takes into account the fact that natural-sounding wind or rolling noises tend to contain more high-frequency components as the vehicle's speed increases. This further improves the natural sound of the synthetic noise 3.

[0042] The modulated synthetic noise 3.3 is then subjected to a feedback delay by a feedback delay module 9. The delay time can be adjusted using a delay block 18. Preferably, the delay time is the reciprocal of a particularly dominant frequency F of the unpleasant noise 2. To avoid instabilities, the feedback level should be less than 0 dB. For this purpose, multiplication is performed by an amplifier 6 with an amplification factor f of less than -0.01 dB, which can be freely adjusted in the vehicle 1.

[0043] The composite noise 3 may be subjected to multiple feedback delays, the transfer function of which may be approximated or formed by a comb filter.

[0044] In a particularly advantageous embodiment, at least one synthetic noise 3 is output via at least two loudspeakers 10 in the vehicle interior 12 shown in FIG. 3. From the synthetic noise 3, a virtual sound object is generated, which can be positioned anywhere in the vehicle interior 12 or outside the vehicle 1. The synthetic noise 3 thus no longer appears to originate directly from the loudspeakers 10, but rather from the location of one or more artificial noise sources 11. For the generation of the virtual sound object and for the free positioning of the sound object in the vehicle, the Ambisonics algorithm is preferably used. For this purpose, the modulated synthetic noise 3.3 is first processed by an Ambisonics encoder 19.1 and then by an Ambisonics decoder 19.2.

[0045] There may be multiple combinations of feedback delay modules 9 and Ambisonics encoders 19.1, as indicated by the multiple dashed boxes, to generate multiple noises to be output in the vehicle cabin 12. If multiple unpleasant noises 2 are present, multiple synthetic noises 3 may also be generated to mask the unpleasant noises 2, as indicated by the dotted boxes. The individual synthetic noises 3 are combined to output the individual synthetic noises 3 in the vehicle cabin 12.

[0046] The vehicle 1 may have further devices, not described in detail, for generating artificial noise, i.e., for example, an artificial engine noise 20 is combined with the synthetic noise 3 to be output in the passenger compartment 12.

[0047] FIG. 3 shows a plan view of a vehicle 1 according to the present invention. The vehicle 1 preferably has an at least partially electrified powertrain. A plurality of speakers 10 are arranged in the vehicle interior 12 for outputting at least one synthetic noise 3. Particularly preferably, at least one speaker 10 is provided in front of the vehicle occupants in the direction of travel of the vehicle 1, and at least one speaker 10 is provided behind each vehicle occupant. Thus, a particularly natural-sounding surround sound can be generated. Particularly preferably, the position of the pseudo-noise source 11 from which the synthetic noise 3 appears to be generated is positioned at a target position in the vehicle interior 12. This allows for free positioning of the noise source 11, resulting in a more natural sound experience when the synthetic noise 3 is played back. For example, one synthetic noise 3 is positioned near the vehicle's exterior mirrors, and another synthetic noise 3 is positioned behind the dashboard of the vehicle 1.

[0048] In order to detect the speed of movement of the vehicle 1 or a value representative of the speed of movement, the vehicle 1 comprises at least one sensor 14. The generation of the synthetic noise 3 is performed by means of a calculation unit 13. The measurements produced by the sensor 14 are supplied as input quantities to the calculation unit 13, whereby the volume of the synthetic noise 3 is controlled depending on the speed of movement of the vehicle 1 and / or more high frequency components are integrated into the synthetic noise 3 when the speed of movement increases.

Claims

1. A method for masking unwanted and unpleasant noises (2) occurring during operation of a vehicle (1) by a synthetic noise (3), comprising: The synthetic noise (3) is generated from an unmodulated synthetic noise (3.1) by multiplication with at least one filter (5) and / or amplifier (6) depending on vehicle parameters (4) to adjust the desired acoustic characteristics, and the pitch of all acoustic signals (8) that make up the modulated synthetic noise (3.3) is kept constant during the output of the modulated synthetic noise (3.3), the unmodulated synthetic noise (3.1) is generated as 1 / f noise and is pre-modulated by at least one static filter (7) before modulation by the at least one filter (5) and / or amplifier (6) depending on the vehicle parameters (4); and The method is characterized in that the unmodulated synthetic noise (3.1) is premodulated by the at least one static filter (7) so that the premodulated synthetic noise (3.2) comprises at least two acoustic signals (8.1, 8.2), the first acoustic signal (8.1) having a first spectral width (SB1) and the second acoustic signal (8.2) having a second spectral width (SB2), the first spectral width (SB1) corresponding to a frequency range from 0 to a maximum of 2200 Hz, the second spectral width (SB2) being in a higher frequency range compared to the first spectral width (SB1), and the second spectral width (SB2) completely encompassing the spectral width of at least one unpleasant noise (2) to be masked.

2. 2. The method according to claim 1, characterized in that at least one adaptive filter (5) is formed by a low-pass filter, the cut-off frequency of which depends on the speed of movement of the vehicle (1).

3. 3. The method according to claim 1, wherein the amplification factor (f) of at least one adaptive amplifier (6) depends on the speed of movement of the vehicle (1), and the amplification factor (f) has a maximum value in at least one speed range in which annoying noise (2) occurs.

4. 4. The method according to claim 3, characterized in that the amplification factor (f) takes a minimum value at predetermined intervals before the start and after the end of the speed range in which the unpleasant noise occurs, and in particular increases and decreases continuously from a minimum value to a maximum value.

5. 3. The method according to claim 1 or 2, characterized in that the composite noise (3) is subjected to a feedback delay after modulation by the at least one adaptive filter (5) and / or amplifier (6), in particular with adjustable attenuation, the transfer function of which corresponds to a comb filter.

6. 6. The method according to claim 5, wherein the feedback delay applies to the synthesized noise (3) a delay time that is the reciprocal of the frequency of the unpleasant noise (2) to be masked.

7. 3. The method according to claim 1, wherein the at least one synthetic noise (3) is outputted separately to at least two loudspeakers (10) in the vehicle (1).

8. 8. The method according to claim 7, characterized in that at least one synthetic noise (3) is output via at least two loudspeakers (10) in such a way that, in particular using an Ambisonics algorithm, the position of a pseudo-noise source (11), which appears to the vehicle occupants as the point of origin from which the synthetic noise (3) arrives, is positioned at a defined location in the vehicle compartment (12).

9. 9. The method according to claim 8, wherein at least two feedback-delayed composite noises (3) are output in the vehicle (1), the pseudo-positions of the noise sources (11) being positioned at various locations in the passenger compartment (12), and the two composite noises (3) have mutually different feedback delay times.

10. A vehicle (1) comprising a calculation unit (13), at least one sensor (14) for detecting the vehicle speed, and at least one speaker (10), The vehicle (1), characterized in that the calculation unit (13), the sensor (14) and the speaker (10) are designed to implement the method according to claim 1 or 2.

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