Methods for playing digital audio data in a motor vehicle and motor vehicle

Abstract

Within the scope of the invention, digital audio data are subjected to a bandpass filter (20) to filter out data that would be acoustically absorbed in a motor vehicle interior. To nevertheless make the corresponding sound audible, harmonics and / or subharmonics are generated or amplified for the filtered data, and these harmonics and / or subharmonics are played back together with the digital audio data.

Description

[0001] The invention relates to a method for playing digital audio data in a motor vehicle. It also relates to a motor vehicle in which the method can be implemented.

[0002] The digital preprocessing of digital audio data in a motor vehicle is well known.

[0003] For example, EP 1 130 577 B1 relates to a method for reconstructing previously omitted low-frequency speech components (e.g., during data transmission) from medium-high frequency components. The low-frequency speech components are synthetically generated from the entire spectrum of the input signal. A frequency difference between two components with increased amplitude is used to determine a fundamental frequency of a speech signal and to determine the low-frequency frequency range for this fundamental frequency.

[0004] EP 1 367 566 B1 is concerned with an improvement of source coding for audio data using spectral band replication, whereby an input signal thought to be truncated is extended as a whole by low-frequency and high-frequency components.

[0005] While previous techniques aim to expand the originally limited data provided, the present invention has a different goal. In particular, the sound quality of playing digital audio data in a motor vehicle is not always satisfactory.

[0006] US 2018 / 0 278 882 A1 discloses the addition of harmonics to an audio signal from the bandpass filtered audio signal.

[0007] It is accordingly the object of the present invention to show a way in which the sound of digital audio data played in a motor vehicle can be improved.

[0008] The object is achieved by a method for playing digital audio data in a motor vehicle having the features according to claim 1 and by a motor vehicle having the features according to claim 4.

[0009] Within the scope of the invention, the digital audio data (in particular for compensating a resonance gap in a motor vehicle) are filtered in a bandpass filter, and overtones and / or subharmonic tones are generated and / or amplified for the output signal of the bandpass filter, and these overtones and / or subharmonic tones are played back together with the digital audio data (as they were preferably available as a complete input signal before the bandpass filter).

[0010] This approach is based on the knowledge that such resonance gaps typically exist in motor vehicle interiors, which can be compensated for by this process. In particular, the vehicle doors and / or other components in the vehicle interior absorb sound more strongly in a certain frequency band. Such a drop in frequency results in the sound in that frequency band not being heard, regardless of whether the corresponding energy in that frequency band is increased. A particular problem area lies between approximately 120 and 290 Hz, possibly up to 300 Hz.

[0011] The bandpass filter is somewhat narrower than the problem range; in a defined first alternative of the invention, it has a lower limit of between 125 and 175 Hz and / or an upper limit of between 200 and 275 Hz. The bandpass filter can, for example, filter between 150 and 230 Hz.

[0012] Accordingly, the bandpass filter can preferably have a bandwidth of between 40 and 120 Hz, particularly preferably between 60 and 100 Hz, in the example mentioned it has 80 Hz bandwidth.

[0013] Within the scope of another defined alternative of the invention, a resonance gap in the motor vehicle is additionally or alternatively determined (also understood as the absorption maximum, i.e., where a resonance dip occurs), and this determines the bandpass filter. (These problem areas may vary slightly from vehicle to vehicle.)

[0014] Typically, a digital audio file is in MP3 format, but MPEG format or another audio format such as AIFF, etc. is also possible.

[0015] The motor vehicle according to the invention comprises a vehicle interior and a device for playing digital audio data in the vehicle interior. The device has a digital bandpass filter for filtering the original digital audio data. It further comprises a harmonic generator and / or a subharmonic generator to which an output of the bandpass filter is fed. The device further comprises an adder for adding the output of the generator and / or the generators to the original audio data.

[0016] The motor vehicle according to the invention implements the method according to the first alternative of the invention.

[0017] The invention also includes further developments of the motor vehicle according to the invention that have features already described in connection with the further developments of the method according to the invention. For this reason, the corresponding further developments of the motor vehicle according to the invention are not described again here.

[0018] In one example, the device for playing digital audio data comprises a radio receiver for receiving the digital audio data. Alternatively or additionally, the device for playing the data can have a digital interface for a data storage device containing a digital audio file. The digital interface can, for example, read the digital audio data from a data stick plugged into a corresponding mechanical interface ("socket"). The digital interface can also be part of a CD player in the motor vehicle.

[0019] According to a preferred embodiment, the playback device is further configured to delay playback after the arrival and / or reading of the digital audio data by a time required for bandpass filtering and summing. Accordingly, a clock generator can be provided in the motor vehicle, which is used by the playback device.

[0020] For use cases or application situations that may arise during the method and which are not explicitly described here, it may be provided that, in accordance with the method, an error message and / or a request to enter user feedback is issued and / or a default setting and / or a predetermined initial state is set.

[0021] The invention also includes the control device for the motor vehicle. The control device can have a data processing device or a processor device that is configured to carry out an embodiment of the method according to the invention. For this purpose, the processor device can have at least one microprocessor and / or at least one microcontroller and / or at least one FPGA (Field Programmable Gate Array) and / or at least one DSP (Digital Signal Processor). In particular, a CPU (Central Processing Unit), a GPU (Graphical Processing Unit), or an NPU (Neural Processing Unit) can be used as the microprocessor. Furthermore, the processor device can have program code that is configured to carry out the embodiment of the method according to the invention when executed by the processor device. The program code can be stored in a data memory of the processor device.The processor device can be based, for example, on at least one circuit board and / or on at least one SoC (System on Chip).

[0022] The motor vehicle according to the invention is preferably designed as a motor vehicle, in particular as a passenger car or truck, or as a passenger bus or motorcycle.

[0023] As a further solution, the invention also encompasses a computer-readable storage medium comprising program code which, when executed by a computer or computer network, causes the computer to carry out an embodiment of the method according to the invention. The storage medium can be provided at least partially as a non-volatile data memory (e.g. as a flash memory and / or as an SSD - solid state drive) and / or at least partially as a volatile data memory (e.g. as a RAM - random access memory). The storage medium can be arranged in the computer or computer network. However, the storage medium can also be operated on the Internet, for example, as a so-called app store server and / or cloud server. The computer or computer network can provide a processor circuit with, for example, at least one microprocessor.The program code may be provided as binary code and / or as assembly code and / or as source code of a programming language (e.g. C) and / or as a program script (e.g. Python).

[0024] The invention also encompasses combinations of the features of the described embodiments. The invention therefore also encompasses implementations that each comprise a combination of the features of several of the described embodiments, unless the embodiments are described as mutually exclusive.

[0025] Exemplary embodiments of the invention are described below. Shown are: Fig. 1 shows the problem solved by the invention based on a frequency response of the resonances typical for a motor vehicle interior; and Fig. 2 shows a schematic structure of the components that can be used in a motor vehicle according to an embodiment of the invention for carrying out an embodiment of the method according to the invention.

[0026] The exemplary embodiments explained below are preferred embodiments of the invention. In the exemplary embodiments, the described components of the embodiments each represent individual features of the invention that can be considered independently of one another, each of which also develops the invention independently of one another. Therefore, the disclosure is intended to encompass combinations of the features of the embodiments other than those shown. Furthermore, the described embodiments can also be supplemented by further features of the invention already described.

[0027] In the figures, the same reference symbols designate elements with the same function.

[0028] Fig. Figure 1 illustrates a measurement curve K showing a resonance level P as a function of an audio frequency f. The frequency f is given in Hz, and the level in arbitrary units. Here, it is assumed that an input signal is fed in that has a predetermined level, which can be essentially constant for each frequency. Curve K illustrates that the resonance generally decreases with higher frequencies. However, a noticeable resonance dip RE (absorption maximum of elements in the vehicle interior, such as the vehicle doors) is observed between approximately 120 and 290 Hz.

[0029] If an audio file is played inside a vehicle, the resonance drop results in frequencies between 120 and 290 Hz not being perceived sufficiently. Amplifying the sound in this frequency range is of little use. Another solution has been found: Fig. 2 shows the schematic structure of the components of the motor vehicle designated as a whole by 1, as they can be used in an embodiment of the method according to the invention.

[0030] A radio receiver 12 receives audio data from an antenna 10. Alternatively or additionally, there is a data source 14 in the vehicle (data stick, CD), which is read by a reader 16. To carry out the method, it would be sufficient if only the radio receiver 12 or only the reader 16 were present. The received or read data is collected in unit 18. (Filtering by frequency can only occur once data has been received over a predetermined period of time, corresponding to playback over a predetermined period of time.) The collected data can optionally be converted in a unit 18opt into a format required for further processing (filtering, etc.). They preferably remain digital, but can theoretically already be converted into analog signals.

[0031] Bandpass filtering is performed in unit 20, preferably based on the digital data. The digital bandpass filter 20 filters out, for example, a range between 150 and 230 Hz, thus hitting the minima M1 and M2 in the resonance dip region RE ( Fig. 1). The bandpass filter filters out precisely that range from the audio data that is typically barely audible due to absorption. For the filtered-out range, harmonics are then generated by a generator 22a, and subharmonics are generated by a generator 22b. Units 22a and 22b can be implemented as a single component, but can also be separate components. The units can also be split up; for example, there can be a subunit of unit 22a for harmonics that generates the first overtone, one that generates the second overtone, etc.

[0032] The output signals of generators 22a and 22b are added to the input signal of bandpass generator 20, for which purpose an adder 24 is shown here. Other signal processing options besides pure addition are possible. Adder 24 outputs an output signal 26, which is optionally conditioned before being fed to the actual playback device 28, such as a loudspeaker control device.

[0033] In order to ensure reliable processing of the data, which is time-critical, a clock generator 30 can be provided which sends clock signals to the units 18, 20, 22a and 22b, 24, 26 and 28 (or only to some of the units in this group).

[0034] As a result, a sequence of overtones and / or subharmonic tones are generated for the frequency range in which the resonance gap RE exists. The human brain processes the resulting sound signal in such a way that the sounds that would otherwise be acoustically absorbed are reconstructed based on the overtones and / or subharmonic tones, thus becoming audible in a sense.

[0035] Overall, the examples show how the following can be provided: The “Bridge of the Valley of Death” is a signal processing technique that allows sound loss due to resonances in the body of a vehicle (for example, due to its doors) to be compensated “via a bridge” into adjacent frequency bands.

Claims

[1] Method for playing digital audio data in a motor vehicle (1), in which the digital audio data are subjected to filtering in a bandpass filter (20) to compensate for a resonance gap (RE) in the motor vehicle (1), and overtones and / or subharmonic tones are generated and / or amplified for the output signal of the bandpass filter, and wherein these overtones and / or subharmonic tones are played back together with the digital audio data, characterized by that the bandpass filter (20) has a lower limit of between 125 and 175 Hz and / or an upper limit of between 200 and 275 Hz and / or that a resonance gap (RE) is determined in the motor vehicle (1) and this specifies the bandpass filter. [2] Method according to claim 1, characterized by that the bandpass filter (20) has a bandwidth of between 40 and 120 Hz, preferably between 60 and 100 Hz. [3] Method according to claim 1 or 2, characterized bythat a digital audio file is in MP3 format or MPEG format. [4] Motor vehicle (1) with a vehicle interior and a device for playing digital audio data in the vehicle interior, the device comprising: a digital bandpass filter (20) for filtering the original digital audio data, a harmonic generator (22a) and / or a subharmonic generator (22b) to which an output of the bandpass filter (20) is supplied, and an adder (24) for adding the output of the generator and / or the generators (22a, 22b) to the original audio data, characterized by that the bandpass filter (20) has a lower limit of between 125 and 175 Hz and / or an upper limit of between 200 and 275 Hz. [5] Motor vehicle according to claim 4, characterized by that the bandpass filter (20) has a bandwidth of between 40 and 120 Hz, preferably between 60 and 100 Hz. [6] Motor vehicle (1) according to claim 4 or 5, wherein the device for playing comprises a radio receiver (12) for receiving the digital audio data and / or a digital interface (16) for a data carrier (14) with a digital audio file. [7] Motor vehicle (1) according to one of claims 4 to 6, in which the device for playing back is designed to delay playing back after arrival and / or reading out of the digital audio data by a time required for bandpass filtering and adding.

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