Method and vehicle for masking unwanted and annoying noises - Patents.com

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 and unpleasant noises occurring during the operation of a vehicle by means of a synthetic noise, as specified in the preamble of claim 1, and to a vehicle for implementing said method. [Background technology]

[0002] Vehicles emit different noises during their operation: some of these noises, for example light engine or exhaust sounds, are perceived as pleasant, whereas others, such as rattles, clatters, buzzes or V-belt friction, are perceived as unpleasant. Particularly in electric vehicles, the noise emitted by the vehicle plays an important role for the comfort of the vehicle and for the safety of road users. Electric vehicles are often quieter than vehicles with internal combustion engines, which often makes electrically driven vehicles less noticeable to road users. Therefore, methods and devices for generating synthetic vehicle noises are already generally known from the prior art. With such synthetic vehicle noises, for example, a sound is added to the corresponding vehicle acceleration, which on the one hand alerts road users to the electric vehicle and, on the other hand, increases the comfort for the person driving the electric vehicle by generating a particularly futuristic and pleasant engine sound.

[0003] Typically, electric motors produce mid- and high-frequency vibrations that can only be attenuated to a limited extent by typical noise, vibration and harshness (NVH) measures. Noises caused by vibrations are in principle quiet, but are nevertheless audible due to their tonal nature and due to the correlation of pitch with electric motor rpm or vehicle speed.

[0004] For example, from the patent US 2005 / 0133999 a method and device are known for generating synthetic noise to add to the sound of the acceleration of a vehicle. However, such noise related to the acceleration of the vehicle is not well suited for masking noises that are independent of the acceleration of the vehicle. In contrast, US Pat. No. 5,399,633 discloses a method for masking unwanted noises originating from a vehicle powertrain, which method is suitable for masking noises that are not related to the acceleration of the vehicle. 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, while the pitch of all sound signals that make up the synthetic noise remains constant. In this case, a broadband noise, also called white noise, is used as the source of the unmodulated synthetic noise. In order to generate a particularly natural-sounding synthetic noise, the acoustic properties of the synthetic noise are adapted so that it sounds like wind noise and / or tires rolling on a surface. However, it is a disadvantage that the synthetic noise generated is not integrated into the acoustic properties of the vehicle but acts like a "patch" for masking unwanted noises. A pleasant masking of unwanted noises is therefore 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] It is an object of the present invention to provide an improved method for masking undesirable noises occurring during operation of a vehicle with a synthetic noise, which improves the comfort of vehicle occupants during operation of the vehicle. [Means for solving the problem]

[0007] According to the invention, this problem is solved by a method for masking unwanted, unpleasant noises occurring during 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 emerge from the claims dependent thereon.

[0008] According to the invention, in the method for masking unwanted unpleasant noise as mentioned at the beginning, 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 it is modulated by at least one filter and / or amplifier depending on the vehicle parameters.

[0009] With the method according to the invention, a particularly natural-sounding synthetic noise is generated for masking unpleasant noises. This natural-sounding synthetic noise can be integrated particularly comfortably into the acoustics of the vehicle, so that the synthetic noise is perceived by the vehicle occupants and road users outside the vehicle as particularly natural and part of the vehicle. The central 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 called pink noise, is a noise that corresponds to a linearly decreasing function when considered in frequency space. This means that with increasing frequency the amplitude, i.e. the level of each frequency, decreases. In a log-log plot, 1 / f noise has a negative slope of about 3 dB per octave. In contrast, in white noise the amplitude of the noise is approximately constant over the entire frequency range. However, white noise sounds to humans with an emphasis on high frequencies. This means 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. This allows the creation of particularly natural-sounding synthetic noises for masking unpleasant noises.

[0010] The 1 / f noise is modulated with a static filter such that the synthetic noise premodulated with the static filter has a peak in the frequency region 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 powertrain of the vehicle.

[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 reduces the computational resources and memory space required to generate the synthetic noise to a minimum. 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] Possible unpleasant noises to be masked with synthetic noises can come, for example, from the powertrain of a vehicle. In particular, the powertrain is the powertrain of an at least partially electric vehicle. What can happen in an electric vehicle is that, in particular, the electric parts of the powertrain generate howling sounds with a defined frequency spectrum in a certain speed range, i.e. at certain rotational speeds of the powertrain components. This howling sound is unpleasant and should be masked. Since the generation of the howling sound depends on the rotational speed of at least one component of the powertrain, the howling sound also occurs in a fairly specific travel speed range of the vehicle. In order to mask the unpleasant noises very comfortably, the synthetic noise is integrated into the acoustic characteristics of the vehicle in such a way that the synthetic noise for masking is output in a travel speed range of the vehicle where the howling sound also occurs.

[0013] It is useful here to adapt the volume of the synthetic noise to the volume of the unpleasant noise that is to be masked. If the synthetic noise is too low, the unpleasant noise is still perceptible. On the other hand, if the synthetic noise is too high, the synthetic noise itself may be unpleasant for the vehicle occupants. By multiplying the pre-modulated synthetic noise by 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 with at least one static filter such 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 compared to the first spectral width, the second spectral width completely comprising the spectral width of at least one unpleasant noise to be masked. By generating a premodulated synthetic noise to comprise at least the first and the second acoustic signals, the perceptibility of the natural sound of the synthetic noise is improved. Due to the low-frequency components, the synthetic noise sounds in particular like natural wind and / or rolling noise. This further improves the comfort for the vehicle occupants during the operation of the vehicle. The first spectral width can be any width within the frequency range from 0 to 2200 Hz. For example, the first spectral width can take a value of 0 to 500 Hz, 0 to 1500 Hz, 200 to 600 Hz, or 1700 to 2200 Hz. Over the first spectral width, the sound of the "ground noise" of the wind noise or rolling noise can be adjusted as desired.

[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 expanded. This further supports the natural sounding of the synthetic 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 cut-off frequency of which depends on the travel speed of the vehicle. With the low-pass filter, the natural sounding of the synthetic noise can be further improved. That is, the natural wind or rolling noise of the vehicle depends on the travel speed of the vehicle. With an increase in the travel speed, the proportion of high frequencies in the wind or rolling noise also increases. The low-pass filter is formed as an adaptive filter and also depends on the travel speed of the vehicle. The cut-off frequency of the low-pass filter is shifted towards higher frequencies with an increase in the travel speed of the vehicle. The pitch of the sound signal of the modulated synthetic noise remains constant, however, with the low-pass filter, it is possible to control up to which frequency the sound signal, i.e. the pitch, should be integrated into the modulated synthetic noise. That is, with an increase in the travel speed of the vehicle, sounds of higher frequencies can be included more. The acoustic properties of the modulated synthetic noise can thus 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 amplification factor of the at least one adaptive amplifier is furthermore dependent on the travel speed of the vehicle, the amplification factor being a maximum value 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 synthetic noise. Here, the amplification factor of the adaptive amplifier is linked to the travel speed of the vehicle. In speed ranges in which the unpleasant noise to be masked does not occur, this amplification factor is preferably 0 or a very low value such as 0.01. In contrast, in travel speed ranges in which the unpleasant noise to be masked occurs, the amplification factor of the amplifier is 1 or more.

[0018] According to a further advantageous configuration of the method, the amplification factor assumes a minimum value at a predefined distance before the beginning and after the end of the speed range in which the unpleasant noise occurs and in particular increases or decreases continuously from the minimum value to the maximum value. In other words, the volume of the modulated synthetic noise for masking the unpleasant noise increases gradually with the moving speed of the vehicle and decreases gradually again when the speed range in which the unpleasant noise is present is left. This allows the synthetic noise for masking the unpleasant noise to be integrated in a particularly pleasant way into the acoustic behavior of the vehicle. 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 compartment. Thus, only a minimal increase in the overall level in the vehicle compartment occurs during the use of the vehicle. This increase is again limited only to the speed range in which the vehicle problem occurs. The vehicle occupants therefore perceive the synthetic noise as particularly authentic. Particularly preferably, the synthetic noise starts to grow louder 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 gentle integration of the synthetic noise with the vehicle's acoustics makes the synthetic noise appear much more natural.

[0019] In a further advantageous configuration of the method according to the invention, the synthetic noise is furthermore subjected to a feedback delay after modulation by at least one adaptive filter and / or amplifier, which is designed, inter alia, to adjust the attenuation (relative volume level of the feedback signal), the transfer function of which corresponds to a comb filter. By applying a feedback delay to the synthetic noise, the natural sounding of the synthetic noise can be further enhanced. The amount of calculations required to apply the feedback delay is relatively small. Furthermore, a slight flanging can be generated in the synthetic noise, i.e. a non-linearity can be applied to the synthetic noise. The level of feedback must be less than 0 dB, since otherwise instabilities would occur. This attenuation level can be adjusted in the vehicle. This allows the vehicle occupant or an authorized technician to adjust the sounding of the synthetic noise according to personal preferences. The feedback delay can be used to make repetitive patterns difficult to recognize. This can further improve the natural sounding of the synthetic noise, since the human ear can recognize repetitive patterns very well. In particular, the synthetic noise is subjected to a feedback delay multiple times.

[0020] According to a further advantageous configuration of the method, in the feedback delay, a delay time is applied to the synthetic noise that is the inverse 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 includes positive or negative integers. The coefficient n therefore ideally takes values ​​such as 0.25, 0.5, 1, 2, 4, etc. 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 synthetic masking noise. The adjusted frequency f can also be adjusted freely in the vehicle and only needs to be roughly aligned with 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 the 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 the variance simultaneously, that is, for example, delay time = 1 / (N*frequency + / - variance). If the dominant frequency at which the unpleasant noise occurs is, for example, in the region around 3500 Hz, the variance can be, for example, 500 Hz, or a fractional part or multiple thereof.

[0021] In a further advantageous configuration of the method according to the invention, at least one synthetic noise is furthermore split and output to at least two loudspeakers in the vehicle. By splitting the synthetic noise to at least two loudspeakers, preferably more than two loudspeakers, it becomes difficult for the vehicle occupants to identify the source of the synthetic noise. As a result, the synthetic noise seems to come from different directions, which further improves the natural sound.

[0022] According to a further advantageous configuration of the method, at least one synthetic noise is output via at least two loudspeakers, in particular by means of an Ambisonics algorithm, in such a way that the position of a pseudo-noise source, from which the synthetic noise appears to the vehicle occupant, is located at a defined location in the vehicle interior. The presence of a small time offset in the output of the synthetic noise between the at least two loudspeakers allows the position of the pseudo-noise source, from which the synthetic noise appears to the vehicle occupant, to be freely located in the vehicle interior. For this purpose, particularly preferably, two or more loudspeakers are used, for example three, four or five loudspeakers. The time offset of the output of the synthetic noise is determined individually for each loudspeaker. For better adaptation of the delay times and the loudspeaker output levels, the Ambisonics algorithm is particularly preferred. Ambisonics is a method for recording and / or reproducing sound fields. Ambisonics allows a particularly simple and comfortable 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, i.e., the synthetic noise to the vehicle occupant no longer appears to come from the respective speaker, but instead from an imaginary sound source, e.g., from behind the vehicle dashboard, in the direction of the vehicle exterior mirror, etc. By the vehicle occupant not perceiving the synthetic noise 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 synthetic noises are output to the vehicle, the pseudo-locations of the noise sources of the synthetic noises being located at various locations in the vehicle interior, the two synthetic noises having mutually different feedback delay times, whereby the natural sound of the synthetic noises is further improved. The two synthetic noises may be identical apart from the feedback delay times. However, the two synthetic noises may also differ at least partially in frequency bandwidth.

[0024] According to the invention, a vehicle with a calculation unit, at least one sensor for detecting the vehicle speed and at least one speaker, the calculation unit, the sensor and the speaker are designed to perform the above-mentioned method. The vehicle may be any vehicle, such as a car, a truck, a transporter, a bus, etc. The calculation unit includes hardware and software for implementing the method according to the invention. That is, the calculation unit includes a memory element, for example a flash memory, for storing sound files and / or program codes used for forming the 1 / f noise, which program codes are executed in a processor to perform the method according to the invention. Individual signal processing elements such as filters and / or amplifiers can be formed by hardware components and / or software. The sensor can detect at least the vehicle speed. Thus, the volume of the synthetic noise can be adapted depending on the vehicle speed, so that the synthetic noise is output accurately with a sufficient volume even if an unpleasant noise to be masked occurs. The synthetic noise for masking the 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] Also, several nuisance noises may occur during the operation of the vehicle, with different nuisance noises occurring for different vehicle speeds. By using the method according to the invention, all occurring nuisance noises can be masked individually. Accordingly, different synthetic noises are generated by using the method according to the invention.

[0026] Particularly preferably, the vehicle has an at least partially electric powertrain.The vehicle is therefore designed as a hybrid vehicle or a pure battery-electric vehicle.In particular, in an electric powertrain, howling noises occur at various operating points, which can be masked particularly conveniently 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 emerge from the exemplary embodiments which are described in detail below with reference to the respective figures. [Brief description of the drawings]

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

[0029] FIG. 1 shows four different acoustic graphs in which the volume levels of various noises are plotted over a frequency F. Here, FIG. 1a) shows an unpleasant noise 2 occurring at a particular operating point during the operation of the vehicle 1 shown in FIG. 3 as well as a background noise 15 present during the operation. The unpleasant noise 2 occurs perceptibly in the passenger compartment 12, also shown in FIG. 3, when the vehicle 1 is moving at a speed within a certain speed range, for example at a speed between 110 km / h and 120 km / h. The unpleasant noise 2 has a relatively narrow spectral width SB. That is to say, the unpleasant noise 2 contains only a small number of acoustic signals, each with a characteristic frequency F, and is therefore perceived as an annoying "howling sound". The unpleasant noise 2 is radiated in particular from the electrified parts of the powertrain of the vehicle 1.

[0030] In order to improve the comfort of the vehicle occupants during operation of the vehicle 1, a synthetic noise 3, shown in FIG. 1b), is generated using the method according to the invention to mask the unpleasant noise 2. The synthetic noise 3 is characterized by a particularly natural sound and is inserted into the acoustics of the vehicle 1 in such a way that it does not stand out as a "patch" to drown out the unpleasant noise 2 during operation of the vehicle 1, but blends seamlessly into the soundscape perceptible in the passenger compartment 12. In particular, the synthetic noise 3 sounds in this case like wind noise and / or the rolling of tires on the road. 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. Since in FIG. 1b), the maximum volume has a relatively large distance a between the synthetic noise 3 and the unpleasant noise 2, this means that the synthetic noise 3 is too small to sufficiently 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 which is correspondingly adapted to the spectral width SB of the unpleasant noise 2.

[0032] In Fig. 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 also does 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 for the volume level of the synthetic noise 3 to be high enough, but not too high: 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] Fig. 2 is used to explain how the synthetic noise 3 is generated: an audio signal 8 in the form of 1 / f noise, also called pink noise, is provided by a signal source 16, which may contain the 1 / f noise, for example as a WAV file, and is sampled to generate an unmodulated synthetic noise 3.1, the volume of which can optionally 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 is 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 at least in the spectral width SB in which the nuisance noise 2 occurs, the unmodulated synthetic noise 3.1 is premodulated and converted into a premodulated synthetic noise 3.2 by means of 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 changes at the 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 as to include low-frequency components in addition to the peaks at the frequencies of the unpleasant noise 2, i.e. so as to include the first acoustic signal 8.1 in addition to the second acoustic signal 8.2. The natural sound of the synthetic noise 3 is improved by using an acoustic signal in the low-frequency range, for example in the range of 0 Hz to 2200 Hz. In other words, the noise outputted into the vehicle interior 12 can be made to sound like a 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 static filter 7 (not shown) associated with it, and the individual signals are then recombined.

[0039] Following the static filter 7, the premodulated synthetic noise 3.2 is multiplied by at least one adaptive amplifier 6 and / or at least one adaptive filter 5 and is thereby converted into a modulated synthetic 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 synthetic noise 3 in the passenger compartment 12 is controlled so that the synthetic noise 3 is output only in a speed range where the unpleasant noise 2 also occurs plus / minus a certain speed transition range. That is, the synthetic noise 3 has a maximum volume in the speed range where the unpleasant noise 2 occurs, i.e., for example, in the range of 110 km / h to 120 km / h. 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 synthetic noise 3 is gradually increased or decreased. The volume of the synthetic noise 3 is increased or decreased so that the synthetic noise 3 seems 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 synthetic noise is increased or decreased linearly or parabolically in the speed transition range.

[0041] Furthermore, the premodulated 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 comprises at least one low-pass filter. The adaptive filter 5 likewise depends on the vehicle parameters 4. For example, the cut-off frequency of the low-pass filter is selected depending on the moving speed of the vehicle 1. Particularly preferably, an adaptation of the cut-off frequency is made proportional to the moving 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 during the operation of the vehicle 1. More or less only sound signals originating from the high-frequency range are incorporated into the synthetic noise 3. It is thereby taken into account that natural-sounding wind or rolling noise contains more high-frequency components with increasing moving speed of the vehicle 1. This allows the natural sounding of the synthetic noise 3 to be further improved.

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

[0043] The synthetic 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 located 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 from the location of one or more pseudo noise sources 11. For the generation of the virtual sound objects and for the free positioning of the sound objects in the room, preferably an Ambisonics algorithm is 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 dashed boxes, to generate multiple noises to be output in the vehicle cabin 12. If multiple nuisance noises 2 are present, multiple synthetic noises 3 may also be generated to mask the nuisance 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 noises, 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 invention. The vehicle 1 preferably has an at least partially electrified powertrain. In the passenger compartment 12, a number of speakers 10 are arranged for outputting at least one synthetic noise 3. Particularly preferably, at least one speaker 10 is arranged in front of the vehicle occupants in the direction of travel of the vehicle 1 and at least one speaker 10 is arranged 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 originate is positioned at a target position in the passenger compartment 12. This allows a free positioning of the noise source 11, so that a more natural sound experience is achieved when the synthetic noise 3 is reproduced. For example, one synthetic noise 3 is positioned near the exterior mirrors of the vehicle and another synthetic noise 3 is positioned behind the dashboard of the vehicle 1.

[0048] In order to detect the moving speed of the vehicle 1 or a value representative of the moving speed, 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 generated by the sensor 14 are supplied as input quantities to the calculation unit 13, whereby the volume of the synthetic noise 3 is controlled in dependence on the moving speed of the vehicle 1 and / or more high frequency components are integrated into the synthetic noise 3 when the moving speed increases.

Claims

Claim 1 A method for masking an undesired unpleasant noise (2) occurring during the operation of a vehicle (1) by means of a composite noise (3), wherein the composite noise (3) is generated from an unmodulated composite noise (3.1) by multiplication by at least one filter (5) and / or amplifier (6) depending on vehicle parameters (4) to adjust desired acoustic properties, and the pitch of all acoustic signals (8) constituting the modulated composite noise (3.3) is maintained constant during the output of the modulated composite noise (3.3), in the method, the unmodulated composite 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 unmodulated composite noise (3.1) is pre-modulated by the at least one static filter (7) such that the pre-modulated composite noise (3.2) includes at least two acoustic signals (8.1, 8.2), a first acoustic signal (8.1) has a first spectral width (SB1), a second acoustic signal (8.2) has a second spectral width (SB2), the first spectral width (SB1) corresponds to a frequency range from 0 to a maximum of 2200 Hz, the second spectral width (SB2) is in a higher frequency range compared to the first spectral width (SB1), and the second spectral width (SB2) completely includes the spectral width of at least one unpleasant noise (2) to be masked, characterized in that, the method. Claim 2 The method according to claim 1, characterized in that at least one adaptive filter (5) is formed by a low-pass filter, and the cut-off frequency of the low-pass filter depends on the moving speed of the vehicle (1). Claim 3 The method according to claim 1 or 2, characterized in that the amplification factor (f) of at least one adaptive amplifier (6) depends on the moving speed of the vehicle (1), and the amplification factor (f) takes a maximum value in at least one speed range where the unpleasant noise (2) occurs. Claim 4 The amplification factor (f) takes the minimum value at a predetermined interval before the start and after the end of the speed range where the unpleasant noise occurs, and is characterized in that it continuously increases and decreases from the minimum value to the maximum value in particular. The method according to claim 3.

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

6. In the feedback delay, a delay time that is the reciprocal of the frequency of the unpleasant noise (2) to be masked is applied to the composite noise (3). The method according to claim 5, characterized in that.

7. At least one composite noise (3) is characterized in that it is output separately to at least two speakers (10) in the vehicle (1). The method according to claim 1 or 2.

8. In particular using an ambisonics algorithm, at least one composite noise (3) is output via at least two speakers (10) such that the position of the virtual noise source (11) that seems to be the origin from which the composite noise (3) arrives at the vehicle occupant is positioned at a prescribed location within the passenger compartment (12). The method according to claim 7, characterized in that.

9. At least two composite noises (3) with feedback delay are output in the vehicle (1), the virtual positions of their noise sources (11) are positioned at various locations within the passenger compartment (12), and the two composite noises (3) have different feedback delay times. The method according to claim 8, characterized in that.

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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