Immersive seat-centered soundstage for vehicle interiors

Abstract

The invention relates to an audio system and a corresponding method for generating a virtual sound stage in a vehicle interior. A loudspeaker array with at least a first and second central loudspeaker is used, which is arranged centrally between two vehicle seats. In addition, pairs of seat loudspeakers are located near the head areas of the occupants. A signal processing unit receives an input signal and controls the loudspeakers. The central loudspeakers are controlled with inverted and time-shifted signals in order to generate null points in the radiation pattern. These null points are directed towards the ear areas of the head areas and thus center the perception of the virtual sound stage. The seat loudspeakers create spatial sound envelopes around the head areas.By combining the central speaker array with targeted control and side seat speakers, an optimized seat-position-centered sound reproduction with an immersive sound impression is achieved.

Description

Technical field

[0001] The present invention relates to the field of audio system technology, in particular to an audio system and a method for generating a virtual sound stage in a vehicle interior. background

[0002] In modern vehicles, there is increasing interest in providing occupants with an immersive sound experience. Traditional automotive audio systems utilize multiple speakers placed throughout the vehicle cabin to deliver the best possible sound. However, these systems can have limitations in terms of precisely localizing sounds and creating a coherent soundstage that surrounds the listener. The soundstage perceived by listeners can often be mapped to the positions of speakers. Therefore, conventional systems can struggle to ensure an immersive envelopment of a seat-centered soundstage for a passenger at individual seating positions in the vehicle.

[0003] There is therefore a need for improved systems and methods for generating a virtual soundstage for vehicle interiors that enable a more precise and immersive sound experience. Summary

[0004] This object is achieved by the subject matter of the independent claims. Further advantageous features are the subject matter of the dependent claims.

[0005] In the following, the inventive solution is described with reference to the claimed audio systems and the claimed methods for generating a virtual sound stage, as well as with reference to corresponding computing devices, computer programs, and computer-readable data carriers. Features, advantages, or alternative embodiments can be assigned to the other categories, and vice versa. In other words, the methods can be improved by features described and / or claimed within the context of the audio systems, and conversely, the audio systems can comprise any steps or features described within the context of the methods.

[0006] An audio system is configured to generate a virtual soundstage, particularly in a vehicle interior. The audio system comprises a loudspeaker array including at least a first and a second central loudspeaker. The loudspeaker array is arranged between a first and a second vehicle seat with respect to a lateral positioning in the vehicle interior. The loudspeaker array can be positioned centrally with respect to a transverse direction in the listening environment.

[0007] In some examples, the center point or center plane of the loudspeaker array may be centered with respect to the listening environment and / or with respect to the two vehicle seats, which may define listening positions, particularly head positions or head regions of listeners or occupants. A head region may refer to the ideal or typical spatial region in which the head of a person sitting in the vehicle seat, particularly sitting centrally on the seat and facing forward, is located, thereby assuming an ideal or typical listening pose, i.e., looking straight ahead.

[0008] In some examples, the loudspeaker array may be located laterally between two head regions that may be associated with vehicle seats, which may be listening positions, in particular head positions of listeners or passengers. For example, the central loudspeaker array may be positioned longitudinally in front of the seats and transversely between two vehicle seats in the vehicle interior. The loudspeaker array, in particular the center of the loudspeaker array, may therefore be offset transversely from the position of the head region of a vehicle seat, i.e. transversely offset with respect to the center of the loudspeaker array. The vehicle seat may be positioned laterally offset from the center of the listening environment. The loudspeaker array may be arranged centrally in the listening environment, for example in front of the driver's seat and / or the front passenger seat, for example in a dashboard.

[0009] In some examples, the loudspeaker array may be arranged, with respect to the transverse direction, between two head regions associated with two vehicle seats, in particular centrally therebetween. The head regions are associated with different vehicle seats, in particular a first head region is associated with a first vehicle seat, and a second head region is associated with a second vehicle seat, wherein the vehicle seats may be arranged to the left and right of the central loudspeaker array. In other words, the head regions of the vehicle seats may correspond to listening positions in which the head of an occupant or listener is typically positioned when sitting in the vehicle seat. The head of a listener may have a central ear pointing towards the center and an ear facing away from the center.

[0010] Transverse (in other words, lateral, sideways, or transverse) can refer to a direction perpendicular to the longitudinal axis of the vehicle, hence perpendicular to a central axis of the audio system in the longitudinal direction, in other words, transverse to the typical direction of travel and / or the orientation of the vehicle's seats. Front, or a forward direction, can refer to a typical direction of travel, or to an orientation or viewing direction of the vehicle's seats. A vehicle's dashboard can be located at the front of the vehicle, in the typical viewing direction of the occupants.

[0011] Longitudinal can refer to a direction that runs along the length of the vehicle from front to rear, i.e. along the longitudinal axis of the vehicle, for example in the typical direction of travel and / or along the orientation of the vehicle seats or typical viewing direction of the occupants. For example, the directions can also refer to a typical seating position of an occupant of the vehicle seat, while transversal can describe a lateral direction or orientation across the seat or typical orientation / pose of the occupant or listener. Likewise, longitudinal can describe a direction or orientation in the lengthwise direction of the seat or along the typical orientation / pose of the occupant or listener.

[0012] The audio system further comprises a pair of seat speakers in each of the two vehicle seats, wherein the corresponding pair of seat speakers is arranged in each of the two vehicle seats so that an ideal or typical head region of a person sitting on the respective vehicle seat is arranged between the corresponding pair of seat speakers.

[0013] In some examples, the audio system includes at least a first and a second seat loudspeaker, or more generally, near-field loudspeakers, placed at or near a first head region and transmitting near-field sound signals directly to the first head region. In other words, near-field (near-field) loudspeakers or individual head region loudspeakers are positioned near each head region and are individually controlled for the respective seating region or head region. The first head region is thus associated with a first vehicle seat and arranged in a laterally offset position relative to the central loudspeaker array, having respective at least first and second seat loudspeakers associated with the head region. A second vehicle seat may be configured accordingly with a third and a fourth seat loudspeaker. Other vehicle seats, which may be adjacent to the center of the listening environment, may be configured accordingly.

[0014] The audio system further comprises a signal processing unit connected to the loudspeaker array and the seat loudspeakers. The signal processing unit comprises at least one processor and memory for audio signal processing and generation of audio signals, and sends generated audio signals to the loudspeakers to drive them so that they generate sound signals. The signal processing unit is configured to receive an input audio signal. The signal processing unit generates a first central audio signal and a second central audio signal based on or using the input audio signal. Based on processing the input audio signal, the signal processing unit drives the first loudspeaker with the first central audio signal and the second central loudspeaker with the second central audio signal.The second central audio signal is inverted with respect to the first central audio signal and is temporally shifted forward or delayed by a predetermined period of time, as described in more detail with reference to the figures. This delayed actuation of the second central loudspeaker with an inverted audio signal shifts a zero point, or in other words, a minimum in the sound pressure generated by the loudspeaker array, in the radiation pattern of the loudspeaker array toward the head region of the first vehicle seat.

[0015] The first head area can have a central side or a central side area that points or is aligned towards the center of the listening environment and / or points in the direction of the second vehicle seat. The zero point can be aligned or positioned with the central side area of ​​the head area. The zero point can at least partially intersect or overlap the central side area. Typically, an ear of a listener can be located in this area, so that the listener perceives a reduced sound pressure with this ear compared to the other, outward-facing ear. Therefore, the central side area can also be referred to as the ear area or inner ear area. The ear area can therefore be a sub-area of ​​the ideal head area in which the (central, i.e., center-facing) ear of the occupant / listener is located in an ideal or typical seating position.The first zero point can run between the first and second vehicle seats, or be located between the vehicle seats. The second zero point can run between the first and second vehicle seats, or be located between the first and second vehicle seats. The first and second zero points can both run or be located between the first and second vehicle seats. The respective zero point axis that describes the first and / or second zero point can run from the center of the loudspeaker array between the vehicle seats. The loudspeaker axis that connects the centers of the central loudspeakers can run between the first and second vehicle seats.

[0016] In other words, in the described audio system with a central loudspeaker array, the dipole radiation pattern, which is created by superposition of the first and second central loudspeakers by inversion, has a zero point. The zero point is a point or area where the sound pressure is reduced to a minimum due to interference. It can also be referred to as the area or axis with minimum sound pressure or sound pressure cancellation. At the zero point, the sound pressure is greatly attenuated or equal to zero; around the zero point, the sound pressure is attenuated even further. By specifically controlling the loudspeaker array, the position of the zero point and thus the directional characteristic can be influenced. Shifting the zero point leads to a shift in the area with minimized sound pressure. The zero point is used to influence the perception of the virtual sound source center.

[0017] A first zero point in the radiation characteristic of the sound signals from the loudspeaker array hits the ideal head area of ​​the first vehicle seat, not centrally but laterally shifted. The zero point is therefore located at least partially in an area in which a central ear of an occupant is located, i.e. the ear pointing towards the center of the audio system. This area can be referred to as the side area facing the center, which can be positioned adjacent to the head area, or at least partially intersects the head area on the hemisphere of the head area facing the center. This ensures that on the central side of the head area, particularly in the peripheral area where the listener's ear is located, the zero point results in a reduced sound pressure based on a reproduction of the audio input signal and influences the localization of the presented sound event.

[0018] The first zero point hits the ideal head area near one ear of the person sitting in the first vehicle seat, which is facing the other vehicle seat when both people in the two vehicle seats are looking in the same direction.

[0019] The null point creates a reduced sound pressure, resulting in the center of the virtual soundstage, as a listener would perceive it, being centered directly in front of the head area. Additionally, based on the processing of the input audio signal, the signal processing unit drives the first seat loudspeaker with a first seat loudspeaker audio signal and the second seat loudspeaker with a second seat loudspeaker audio signal. The sound signals from the seat loudspeakers overlap with the sound signals from the loudspeaker array, generating a spatial sound envelopment of the virtual soundstage around the head area based on the virtual soundstage, which is perceived as centered in front of the occupant.

[0020] In some examples, the head area, particularly the ear area, may be at least partially located in the near field of the loudspeaker. For example, the near field may refer to a distance in a free field without reflections that is less than 1 / 4 of the wavelength of the lowest frequency to be reproduced. However, the distances for the seat loudspeakers must be smaller due to multiple reflections in the vehicle.

[0021] The first seat loudspeaker can be positioned in a near-field region in a left hemisphere, and the second seat loudspeaker can be positioned in a near-field region in a right hemisphere of the first head region associated with a first vehicle seat. The first seat loudspeaker can therefore be located near the left half of the head region, in other words, in the near-field region of a listener's left ear, and the second seat loudspeaker can be located in the right half, or vice versa. This arrangement can create a spatial sound envelope around the listener's head. The seat loudspeakers are arranged close to the head region, in particular to the central side region (ear region).In some examples, the ear area is less than 20 cm, or 15 cm, or 10 cm, or 5 cm from the seat loudspeakers, where as a reference, for example, a diaphragm (or the center of the diaphragm) of the loudspeaker, or the center of the loudspeaker, or the point of the loudspeaker closest to the head area on the one hand, and the listener's ear, or the center of the ear area, or the point of the ear area closest to the loudspeaker on the other hand, can be chosen.

[0022] In another example, the loudspeaker can be positioned less than 15 cm, or less than 20 cm, or less than 30 cm, or less than 40 cm from the center of the head area to create a good near-field sound impression. The first and second seat loudspeakers can be positioned in a rear or front hemisphere of the first head area. The seat loudspeakers can be headrest loudspeakers arranged in a headrest of the first vehicle seat. The same applies to the seat loudspeakers of the second vehicle seat. The seat loudspeakers can be arranged centrally relative to the ideal head area of ​​the respective vehicle seat.

[0023] The first and second central loudspeakers can be arranged in a compact spatial configuration. The distance between the loudspeakers can be less than, for example, 100%, or <75%, or <50%, or <25%, or <10%, or <5% of the diameter of one of the loudspeakers, or for example <5 mm, or <10 mm, or <20 mm, or <30 mm, or <5 cm, or <10 cm. In other words, the distance between the centers of the first and second loudspeakers can be chosen such that it is less than half the loudspeaker diameter of the first loudspeaker plus half the loudspeaker diameter of the second loudspeaker plus 5 mm, or 10 mm, or 20 mm, or 30 mm, or 5 cm, or 10 cm. Alternatively, the central loudspeakers can be arranged directly adjacent to one another. This allows the position of the nulls in the radiation pattern of the central loudspeaker array to be efficiently controlled.

[0024] In the audio system, the first and second central loudspeakers can each comprise a broadband loudspeaker or a mid-high-frequency loudspeaker. The first and second loudspeakers can be configured to emit sound signals with the same frequency range and / or the same radiation characteristics. The first and second central loudspeakers can be identical loudspeakers. For example, it would also be possible for each central loudspeaker to consist of a loudspeaker pair, i.e., a mid-range speaker and a tweeter. In this case, the loudspeaker pair, i.e., the mid-range speaker and the tweeter, would each have to be arranged longitudinally one behind the other. The central loudspeakers can be arranged in a vehicle dashboard or in the vehicle headliner. The audio system can comprise at least two central loudspeakers, and both can be designed as mid-high-frequency loudspeakers, for example, as identically constructed loudspeakers.These two main speakers are positioned so that they are embedded, for example, in the vehicle's dashboard or in its roof lining, and thus centrally in front of the vehicle seats.

[0025] The orientation of the central loudspeaker array can be defined by the connecting line, i.e. the axis on which the centers of the first and second loudspeakers lie. This axis can also be referred to as the loudspeaker axis. The loudspeaker axis can be aligned along, i.e. parallel to, the longitudinal axis of the vehicle. To visualize this spatial alignment, one can imagine the position and orientation of the loudspeakers in a three-dimensional projection onto the vehicle floor or the X / Y plane. This means that when viewing the vehicle from above (top view), one can see the orientation of the loudspeaker axis in relation to the vehicle axes.

[0026] In some examples, the speaker axis could be positioned at an angle greater than 5°, 10°, 20°, 30°, 45°, or 60° to the longitudinal axis. Rotating the speaker axis allows the audio output to be optimally adapted to the vehicle seat positions and the lateral and longitudinal position relative to the seat positions.

[0027] The signal processing unit generates and uses specific audio signals for the respective loudspeakers for control. The first and / or second central audio signal can comprise an audio signal correlated with the input audio signal.

[0028] For example, a correlated audio signal may include a signal that bears a significant similarity or relationship to an original input audio signal, particularly with respect to its waveform or pattern. This means that changes or patterns in one signal often replicate or reflect similar changes or patterns in the other signal. "A correlated audio signal" in a patent claim excludes decorrelated signals, such as those resulting from reverberation effects.

[0029] In some examples, correlation may include both signals having similar waveform patterns, meaning that the peaks and valleys of the correlated signal correspond to those of the input audio signal. Another indication of correlation could be a coherent phase relationship between the two signals, such that despite possible temporal shifts, the phase structures of both signals remain constant relative to each other. Furthermore, frequency domain analysis may show that both signals have similar spectral content, indicating a correlation of their frequency patterns. Finally, the correlated signal might have a certain energy or amplitude relationship to the original input audio signal, suggesting that it was derived from the original signal through certain amplification or attenuation processes.

[0030] The audio system may be configured such that the seat speaker audio signals comprise decorrelated audio signals with respect to the input audio signal and / or the central audio signals.

[0031] To achieve enhanced spatial audio perception in a vehicle, the seat speaker audio signals do not directly reflect the input signal. This can be referred to as decorrelation. A decorrelated audio signal has little or no discernible relationship to the original input audio signal. Decorrelated signals often include spatial effects, such as multiple reflections, diffuse-field effects, or reverberation effects, where many reflected sound waves combine to create a complex combination of signals that are significantly different from the original signal.

[0032] When the seat loudspeaker audio signals are decorrelated to the input audio signal, they do not share the same characteristic features or patterns of the input signal. This may mean that, despite both signals originating from the same audio source, the waveforms of the signal reproduced by the seat loudspeakers are significantly altered compared to the input audio signal. The phase relationship between the two signals may be inconsistent or variable, disrupting the coherent structure of the original signal. In the frequency domain, the spectral contents of the decorrelated signal may differ from the input audio signal by more than a predetermined threshold. The energy or amplitude relationship may also be inconsistent or predictable, indicating independent amplification or attenuation processing of the seat loudspeaker signal.The aim of this decorrelation is to ensure an enveloping and spatial sound experience in the vehicle interior.

[0033] The audio system may be configured so that the seat speaker audio signals include reverberated audio signals based on the input audio signal and / or the central audio signals. The audio system may be designed so that the sound signals emitted by the speakers in the seats are processed with an echo or reverberation. The reverberation may be based on the original audio input and / or the audio signals from the central speakers.

[0034] The audio system may include at least a third and a fourth seat loudspeaker positioned in a second head region associated with a position of a second vehicle seat. For example, the first head region may be arranged in a left hemisphere of the listening environment and the second head region may be arranged in a right hemisphere of the listening environment. The center of the compact loudspeaker array may be arranged transversely between the first and second listening areas. The center of the compact loudspeaker array may be positioned on a longitudinal axis, in particular a central axis or axis of symmetry, between the first and second head regions.The signal processing unit of the system may be further configured to, based on the processing of the input audio signal, drive the third seat loudspeaker by means of a third seat loudspeaker audio signal and the fourth seat loudspeaker by means of a fourth seat loudspeaker audio signal to generate a spatial sound envelopment of the virtual soundstage around the second head region.

[0035] In some examples, the first and second seat speaker audio signals may be generated based on or using the position of the first head region in the listening environment. In some examples, the third and fourth seat speaker audio signals may be generated based on or using the position of the second head region in the listening environment. This may create an interactive, immersive listening environment for two listeners.

[0036] In these examples, an improved and spatial sound envelopment for two occupants of a vehicle can be generated by placing an additional pair of seat speakers near the second head area, usually the passenger side. By positioning the compact speaker array and the additional seat speakers near the respective listening positions, an immersive sound experience can be created with a soundstage in front of the listener and also around the listener, with enveloping surround sound for both respective occupants of the vehicle, each perceived in a longitudinal position centered in front of the respective occupant.

[0037] The first and second central loudspeakers, particularly the centers of the loudspeakers, can be arranged on an axis through a center between the first and second head areas. This can help ensure that both the driver and the front passenger experience a harmonious and centered sound experience in a vehicle.

[0038] A first zero point of the compact loudspeaker array can be shifted toward the head region of the first vehicle seat. A second zero point of the compact loudspeaker array, which is symmetrical to the first zero point with respect to a longitudinal axis through the centers of the first and second central loudspeakers, can be shifted toward the head region of the second vehicle seat.

[0039] The first and second central loudspeakers, in particular their centers or midpoints, can be arranged on a longitudinal axis of symmetry or plane of symmetry of the first and second head regions, in other words, positioned longitudinally one after the other. In other words, the connecting line or loudspeaker connection axis between the centers of the loudspeakers can run in the longitudinal direction.

[0040] The speaker that is closer to the vehicle seats or listening positions / head areas can receive the delayed signal.

[0041] However, it is also possible for the connecting line to run at an angle of less than 5°, or less than 10°, or less than 20°, or less than 45°, or less than 60°, or less than 90° to the longitudinal direction. In particularly preferred examples, the angle can be 90° or 0°.

[0042] The position of the center of the loudspeaker array may deviate from a central position in the transverse direction and be adjusted accordingly in the longitudinal direction so that the first zero point and the second zero point extend in the direction of the first head region and the second head region, respectively. The compact loudspeaker array generates a zero point on both sides of the loudspeaker axis, or in both half-spaces relative to the loudspeaker axis, which can be referred to as the first and second zero points. In other words, the loudspeaker array can form zero points on both sides of the connecting axis, or connecting plane, between the first and second central loudspeakers.

[0043] In particularly preferred examples, the central loudspeakers can be arranged in a longitudinal arrangement, i.e., along a longitudinal axis of the vehicle interior, in particular a central axis between the head regions in the longitudinal direction. Due to the symmetry of the array's directional characteristic, two seats, or their head regions, can each be treated with a zero point, or overlapped.

[0044] The first and / or second loudspeaker may have symmetrical dispersion patterns. In this case, the zeros or axes of the zeros may also be symmetrical to the connecting axis or plane.

[0045] A first zero point can be aligned with the first head area, in particular with a central side area where one of the listeners' ears is positioned, and the second zero point can be aligned with the second head area, in particular with a central side area where another listener's ear is positioned. Thus, the impression of a seat-centered virtual soundstage can be created for one or two listeners.

[0046] One of the first or second central loudspeakers can be located longitudinally closer to the center of the listening environment or closer to the vehicle seats, or closer to at least one of the head regions. This central loudspeaker can be driven with the central audio signal delayed by the time duration.

[0047] The central audio signal of the loudspeaker closer to the center of the listening environment can have a time delay compared to the other central audio signal. Those skilled in the art are familiar with various signal processing techniques for manipulating the phase and time offset of audio signals. These include, for example, delay filters, all-pass filters, phase rotators or time offset blocks in digital signal processors. These could be used to shift the second central audio signal in time relative to the first central audio signal. Methods for inverting audio signals are also state of the art in audio technology. Phase inverters or digital signal processing, for example, can be used for this. The loudspeakers of the central loudspeaker array and the seats are placed with high spatial accuracy, e.g. at defined mounting points.Thus, sound field simulations can be used to predict and optimize the resulting directional characteristic or the position of the zero points for a given loudspeaker arrangement, for example, through optimizations. The simulation can then be used to optimize the temporal offset. The radiation characteristics of the loudspeaker system can be measured using measurement methods such as near-field scanning.

[0048] Thus, techniques are known to the person skilled in the art, in particular all necessary simulation, measurement and optimization techniques, both for loudspeaker positioning, signal inversion and for setting the time offset between the channels, in order to implement the control of the loudspeaker signals and positioning of the loudspeakers for the desired directional characteristic and control of the zero points to the head areas as claimed in the invention.

[0049] A corresponding method for generating a virtual sound stage in a vehicle interior is provided.

[0050] The method for generating a virtual soundstage in a vehicle interior is based on an audio system having the following components: A loudspeaker array with at least a first and second central loudspeaker, which is centrally arranged in the vehicle interior. At least one first and second seat loudspeaker, which are positioned near a first head region associated with the laterally offset position of a first vehicle seat. A signal processing unit connected to the loudspeaker array and the seat loudspeakers and receiving an input audio signal to generate corresponding audio signals for the loudspeakers.

[0051] The process is carried out by the signal processing unit and comprises the following steps.

[0052] In one step, an input audio signal is received by the signal processing unit. In a further step, based on the processing of the input signal, the first central loudspeaker is driven with a first and the second central loudspeaker with an inverted and delayed second central audio signal. This shifts a zero point of the radiation characteristic towards the head area of ​​the first seat and produces a reduced sound pressure, whereby the center of the virtual stage is located centrally in front of the head area. In a further step, also based on the processing of the input signal, the first seat loudspeaker is driven with a first and the second seat loudspeaker is driven with a second seat loudspeaker audio signal, whereby a spatial sound envelope around the head area is created.

[0053] The method may also include one or more or any combination of features or steps described in connection with the audio systems disclosed herein.

[0054] The method may be a computer-implemented method, for example, executed by at least one computing device.

[0055] A computing device, for example a computing device or computer or signal processing unit, for generating a virtual sound stage in a vehicle interior comprises a computing unit (processor), a storage unit (memory), optionally an interface for receiving and providing audio signals, wherein the storage unit comprises instructions executable by the computing unit which, when executed by the computing unit, cause it to carry out the steps of any method or any combination of methods according to the present disclosure.

[0056] A computer program, or computer program product, comprises instructions that, when executed by a processor, cause the processor to perform the steps of any method or combination of methods according to the present disclosure.

[0057] For example, a computer program can comprise software that can be loaded into the memory of a programmable control device or a computing unit of a medical imaging system. The described methods can be carried out using this computer program product when the computer program product is running in the control device. The computer program product may require program resources, e.g. libraries and auxiliary functions, in order to implement the described methods. In other words, the claim directed to the computer program product is intended to protect software with which the described methods can be carried out. The software can be source code (e.g. C++), which still needs to be compiled and linked, or which only needs to be interpreted, or it can be executable software code that only needs to be imported into the corresponding computing unit orcontrol device is to be loaded.

[0058] A computer-readable data carrier comprises instructions that, when executed by a processor, cause the processor to perform the steps of any method or any combination of methods according to the present disclosure. For example, the data and instructions for executing the method according to the invention can be stored in a distributed database, in particular a cloud.

[0059] For example, the data carrier may comprise a DVD, a magnetic tape, a hard disk, or a USB stick on which electronically readable control information, in particular the described software, is stored. If this control information (software) is read from the data carrier and stored in a control device or processing unit of a magnetic resonance system, the described methods can be carried out.

[0060] The audio system, the computing device, the computer program or computer program product, and the computer-readable data storage are configured to perform any method or combination of methods according to the present disclosure.

[0061] For such devices, computer programs, cloud solutions and electronically readable data carriers, technical effects can be achieved which correspond to the technical effects for the device according to the present disclosure.

[0062] A vehicle includes any audio system according to the present disclosure.

[0063] Although the features described in the summary above and the detailed description below are described in connection with specific examples, it is to be understood that the features may not only be used in the respective combinations, but may also be used in isolation or in any combination, and features from different examples of the systems, devices, and methods may be combined with each other and thus correlate with each other, unless expressly stated otherwise.

[0064] The above summary is intended only to provide a brief overview of some features of some embodiments and implementations and is not intended to be limiting. Other embodiments may include additional features than those described above. Short description of the drawings

[0065] The invention is explained in more detail below using preferred embodiments with reference to the accompanying drawings.

[0066] In the figures, identical reference numerals designate identical or similar elements. The figures are schematic representations of various embodiments of the claimed solution, with the elements shown in the figures not necessarily being drawn to scale. Rather, the various elements shown in the figures are depicted in such a way that their function and general purpose are understandable to those skilled in the art. Fig. 1 shows a dipole radiation pattern of the first and second central loudspeakers without signal delay, according to a non-claimed example. Fig. 2 shows a dipole radiation pattern of the central loudspeakers of the Fig. 1 with signal delay, according to various embodiments. Fig. 3 illustrates the localizations of virtual seat-centered sound stages based on shifting the symmetric zeros of the dipole radiation characteristics of the central loudspeakers, according to various embodiments. Fig. 4 illustrates virtual enveloping sound stages for the occupants of a vehicle, according to various embodiments. Fig. 5 shows a flowchart with steps for carrying out a method for generating virtual sound stages, according to various embodiments. Fig. 6 shows a schematic drawing of an audio system configured to generate virtual sound stages according to various embodiments. Detailed description of implementation examples

[0067] In the following, concepts of exemplary embodiments of the invention are explained in more detail with reference to the accompanying drawings.

[0068] The above-described properties, features, and advantages of this invention, as well as the manner in which they are achieved, will become clearer and more readily understood in conjunction with the following description of exemplary embodiments. It should be noted that the description of the exemplary embodiments is not to be understood in a limiting sense. The scope of the claimed solution is not intended to be limited by the exemplary embodiments described below or by the figures, which serve only for illustrative purposes.

[0069] The drawings are to be considered schematic representations, and the elements depicted in the drawings are not necessarily drawn to scale. Rather, the various elements are illustrated in such a way that their function and general purpose will be apparent to one skilled in the art. Any connection or coupling between functional blocks, devices, components, modules, or other physical or functional entities depicted in the drawings or described herein may also be achieved through a direct or indirect connection or coupling. Coupling between the components may also be established via a wireless connection. Functional blocks may be implemented in hardware, firmware, software, or a combination thereof.

[0070] Below, various techniques for creating a seat-position-centered, enveloping virtual soundstage are described in more detail. The disclosed techniques are described in the context of a vehicle interior, but it should be understood that the techniques are not limited in this regard and can be used in any scenario, exterior or interior, in which a central compact loudspeaker array and individual near-field loudspeakers for a listener are arranged. For example, in an interior for video projection, conference room, movie theater, any other vehicle such as an aircraft or ship, and other situations in which a loudspeaker array is not centrally located in front of one or more listeners, and a mechanical structure such as a seat is present near the listeners.

[0071] Fig. 1 shows a dipole radiation characteristic of a loudspeaker array comprising a first central loudspeaker 1 and a second central loudspeaker 2, without signal delay, according to a non-claimed example.

[0072] In the example of Fig. 1, the central loudspeakers are arranged symmetrically with respect to a central axis. One loudspeaker is located in the left hemisphere and the other in the right hemisphere of the radiation pattern. The two loudspeakers are operated without signal delay, but with an inverted second central audio signal, with reference numerals 11 and 12 indicating a first and a second zero point in the dipole radiation pattern, which run along the central axis.

[0073] The two loudspeakers 1, 2 are operated in a dipole configuration. This means that the loudspeaker signal from one of the loudspeakers is inverted relative to the signal from the other loudspeaker, but without a temporal shift. Such a configuration leads to destructive interference in the center plane between the loudspeakers, creating nulls 11, 12 in the dispersion pattern. These nulls, at which the perceived sound pressure is greatly reduced or essentially zero, can run along the null axes. In other words, a null can be characterized by an axis or direction and run along this axis or direction.

[0074] As in Fig. As can be seen in Figure 1, the zero points run along the center plane between the loudspeakers, i.e. in the middle between them.

[0075] For example, a processor such as a DSP (Digital Signal Processor) can be used to generate and control the null in the dispersion pattern. This can be achieved by feeding an inverted signal to one of the speakers and / or by adding a time delay to the signal from one of the speakers to direct the null to a specific position or direction, as explained in more detail below.

[0076] Fig. 2 shows a dipole radiation characteristic of the central loudspeakers 1, 2 of the Fig. 1 with signal delay by a predetermined time period Δt, according to various embodiments.

[0077] As in Fig. 2, a dipole radiation pattern is generated by a first central loudspeaker 1 and a second central loudspeaker 2, similar to Fig. 1. In the middle, a dashed central axis 13 can be seen.

[0078] As opposed to Fig. 1 are in Fig. 2, the zero points 11 and 12 are not arranged along the central axis, but along an axis that is rotated by a certain angle relative to the central axis. This rotation of the zero point axis occurs because the second central audio signal of the second central loudspeaker 2 is inverted and additionally delayed by a time period Δt relative to the first central audio signal of the first central loudspeaker 1.

[0079] Due to this time delay of the inverted signal at the second central loudspeaker 2, the resulting zero axis in the dipole radiation pattern shifts and rotates accordingly by the angle relative to the central axis between the two central loudspeakers 1 and 2.

[0080] A dashed loudspeaker axis 14 can be seen between the centers of the two central loudspeakers 1 and 2. The dipole radiation characteristic is determined by the signal delay, unlike in Fig. 1, no longer symmetrical with respect to the central axis 13. However, the zero points 11 and 12 are arranged symmetrically with respect to the loudspeaker axis 14 between the centers of the central loudspeakers 1 and 2, since the central loudspeakers 1, 2 individually have a radiation characteristic symmetrical with respect to the central axis 13.

[0081] Fig. 3 illustrates the localizations of virtual seat-centered sound stages based on shifting the symmetrical zero points 11, 12 of the dipole radiation characteristics of the central loudspeakers 1, 2, according to various embodiments.

[0082] In Fig. 3 shows the two central loudspeakers 1 and 2, which are also shown in Fig. 1 and Fig. 2. A dashed central axis runs between the centers of the central loudspeakers 1 and 2.

[0083] Furthermore, head regions 21, 22 are shown, representing typical or ideal head positions of people positioned offset in vehicle seats to the left and right of the central loudspeaker array. Delays Δt are shown at the zero points 11, 12, indicating that the audio signals from the central loudspeakers are offset in time.

[0084] Furthermore, zero points 11, 12 of the resulting dipole radiation pattern are shown. The zero points each lie on an axis that is rotated by a specific angle relative to the center axis between the central loudspeakers. The axes or directions of the zero points 11, 12 are symmetrical with respect to the loudspeaker axis, and thus they can each be directed to a different head region associated with a different one of the first and second vehicle seats.

[0085] The locations of the virtual soundstage to the left and right of the central loudspeakers indicate that by positioning the zero points 11 and 12 based on the signal delay, the virtual soundstages are shifted laterally from the center due to the reduced sound pressure at one of the two ears and are perceived as centered for the people in the seats.

[0086] In Fig. 3, the central loudspeakers 1 and 2 are positioned so that their centers are located on a longitudinal axis between the two head positions 21 and 22. The head positions 21 and 22 represent ideal or typical head areas of persons positioned on seats in the vehicle and looking straight ahead in the direction of travel.

[0087] The zero points 11 and 12 of the resulting dipole radiation pattern are each directed towards the lateral head areas, in particular towards the side areas of the head areas 21 and 22 facing the center. This means that the zero points at least partially overlap the area of ​​the head area in which one ear of the listener is located.

[0088] Through this targeted alignment of the zero points 11 and 12 to the lateral head areas where the ears are positioned, the perception of the sound source center of the virtual sound stage is centered in front of his respective head area for each listener in seats 21 and 22.

[0089] The longitudinal positioning of the central loudspeakers 1, 2 between the head areas in combination with the lateral orientation of the zero points to the ear areas of the head areas enables an individual, seat position-centered perception of the virtual sound stage for each listener in the vehicle.

[0090] Overall visualized Fig. 3, how the localization of the virtual sound stage can be individually adjusted for each listener in seats 21 and 22 by shifting the zero points in the dipole radiation characteristic by means of signal delay.

[0091] Fig. 4 illustrates virtual enveloping sound stages for the occupants of a vehicle, according to various embodiments.

[0092] Fig. 4 schematically shows an audio system 100 for generating virtual sound stages in a vehicle interior according to various embodiments of the invention.

[0093] In the central area of ​​the vehicle is a loudspeaker array, as in Fig. 4, with a first central loudspeaker 1 and a second central loudspeaker 2 arranged, for example, in a dashboard or vehicle headliner. The central loudspeakers 1 and 2 are arranged in a compact spatial configuration.

[0094] Central speakers 1 and 2 each comprise a mid-high-frequency speaker and are configured with the same frequency range and dispersion characteristics. The central audio signals driving the central speaker array are correlated with the audio input signal.

[0095] The central loudspeakers 1 and 2 are positioned longitudinally one behind the other so that their centers are located on an axis of symmetry in the longitudinal direction between the two head positions 21 and 22.

[0096] These head positions 21 and 22 represent ideal head areas for people positioned in the left and right seats of the vehicle, respectively. The people are facing straight ahead in the direction of travel. Their head areas are offset laterally from the center speakers 1 and 2.

[0097] Each seat has a pair of seat speakers surrounding the head area. The seat speakers can be integrated into the headrests. The first seat has a first pair of seat speakers with seat speakers 3 and 4. The second seat has a second pair of seat speakers with seat speakers 5 and 6.

[0098] The seat speaker pairs are positioned centrally around the respective head area and spatially surround it. Their audio signals are decorrelated to the input signal and may, for example, exhibit reverberation effects.

[0099] Between the two central loudspeakers 1 and 2, two zero points 11 and 12 are shown. These zero points are located along symmetrical axes (to the loudspeaker axis), each of which is rotated relative to the longitudinal axis through the loudspeaker centers. These zero points result from the dipole radiation pattern of the central loudspeakers, with the audio signal of the second central loudspeaker 2 being inverted and delayed in time compared to the first central loudspeaker 1.

[0100] The zero points 11 and 12 are directed toward the lateral head areas 21 and 22, respectively, more precisely toward the side areas facing the center, where the people's ears are located. Thus, the zero points partially overlap the ear areas in the heads, producing reduced sound pressure there.

[0101] This allows each listener to perceive the sound source center of the virtual soundstage in front of their head area. The virtual soundstages are represented by thick arrows positioned in front of the head areas.

[0102] All speakers are connected to a signal processing unit (not shown) that receives an input audio signal and generates the central and seat speaker signals accordingly, as well as controlling the speakers individually.

[0103] This audio system with a central speaker array and side seat speakers can create personalized, virtual sound spaces for each listener in the vehicle, creating an impressive, enveloping sound experience.

[0104] Fig. 5 shows a flowchart with steps for carrying out a method for generating virtual sound stages, according to various embodiments.

[0105] The method can be carried out, for example, by a signal processing unit of a (vehicle) audio system and begins in step S10. In step S20, an input audio signal is received. In step S30, based on processing the input audio signal, the first central loudspeaker is controlled by means of a first central audio signal, and the second central loudspeaker is controlled by means of a second central audio signal that is inverted and delayed relative to the first central audio signal. In step S40, based on processing the input audio signal, the seat loudspeakers of one seat loudspeaker pair, or of both seat loudspeaker pairs, are controlled by means of respective seat loudspeaker audio signals.The seat loudspeaker audio signals contain audio signals that are decorrelated to the input audio signal and / or the central audio signals, creating the effect of an enveloping virtual soundstage that is perceived for each vehicle seat with an individually different center.

[0106] Fig. 6 shows a schematic drawing of an audio system 100 configured to generate virtual sound stages according to various embodiments.

[0107] Fig. 6 schematically shows an audio system 100 for generating a virtual sound stage in a vehicle interior, comprising a signal processing unit 7 connected to central loudspeakers 1, 2, and seat loudspeakers 3, 4, 5, 6.

[0108] The signal processing unit 7 contains at least one processor and memory for processing audio signals, as well as an interface for receiving and providing audio signals. The memory unit comprises instructions executable by the computing unit, which, when executed by the computing unit, cause the computing unit to perform the steps of any method or any combination of methods according to the present disclosure. The central loudspeakers 1 and 2 form the central loudspeaker array. The seat loudspeakers 3, 4 and 5, 6 represent seat loudspeaker pairs, each surrounding the head areas of the occupants in the seats.

[0109] The signal processing unit receives an input signal and controls the speakers based on this signal to create a personalized virtual enveloping soundstage for each listener in the vehicle. This allows the virtual seat-centered soundstage to envelop the listener (surround effect), extending all around the listener.

[0110] From the above, the following conclusions can be drawn: In general, the radiation pattern (directional pattern) resulting from the time shift can be simplified as a rotated dipole pattern. In detail, however, by shifting the zero point, the radiation pattern may not exhibit a complete dipole pattern (rotated dipole), but rather a different directional pattern (polar pattern) with a zero point located at a different spatial position. By controlling the spatial position of the zero point, the zero point remains at a new spatial position, but the pattern around the zero point can change. This can be referred to as a controlled dipole.

[0111] The volume level of the first and second central audio signals can be adjusted based on the time offset of the central audio signals to create a more realistic spatial listening effect.

[0112] In addition, in a minimum phase tuning, a frequency response of the first and / or second loudspeaker signal can be adjusted based on the time duration in order to further improve the spatial (ie enveloping) listening effect.

[0113] The audio signal can correspond to a left or right channel of a stereo audio signal. Using the method according to the invention, another stereo channel can be reproduced simultaneously for the listener through the same audio system.

[0114] The first central audio signal can be inverted to generate the second loudspeaker signal, resulting in a speaker radiation pattern that resembles a figure-eight dipole with a null (zero pole) at its center. The radiation pattern of a figure-eight dipole is highly directional, meaning the energy is radiated primarily in two main lobes perpendicular to the null axis (or zero plane). The main lobes are located in the directions of the two halves of the figure-eight, and the dipole pattern has a null in the direction of the "loop" of the figure-eight.

[0115] A temporal shift (by a predetermined amount of time) can be added to the first or second loudspeaker signal. The spatial position of the zero point is determined by the relative time duration of the loudspeaker signals based on interference effects of the sound (pressure) waves.

[0116] The zero point is directed toward one of the listener's ears by shifting the signal based on the duration. The virtual soundstage is created by all speakers emitting sound signals based on their respective audio signals, which can be perceived by the listener. For example, a virtual soundstage for one listener is shifted to the left side by shifting the zero point to the listener's right ear, and vice versa.

[0117] It will further be apparent to those skilled in the art that the disclosed techniques can be applied in a variety of applications where a compact central speaker arrangement in combination with seat-centered individual near-field speakers is intended to create a spatial auditory impression. It is also possible to further adjust the duration and the seat-speaker audio signal based on information from a head-tracking system that tracks and determines the listener's listening pose.

[0118] Using the techniques described, a seat-centered soundstage can be created in front of, to the left and right of the listener and around them. The dipole configuration of the loudspeaker array can provide a spatial listening experience with reduced computational effort and through combination with seat-mounted loudspeakers. For example, a phantom image can be created in the center in front of the listener (0°) and a soundstage that extends to the left and right in front of and surrounds the listener (+-180°). In other words, the soundstage can provide a sound envelopment for the listener, with the soundstage extending around the listener and the center of the soundstage perceived as centrally in front of the seating position.

[0119] The seat loudspeakers of a seat loudspeaker pair can be arranged both or each in the near field and / or in the diffuse field relative to the head position. The distance of one or both loudspeakers from a listener, or more generally from a position of a listener's typical listening posture, can be less than 1 m, preferably less than 0.5 m, or more preferably less than 0.3 m. It will be understood by those skilled in the art that other distances between the loudspeaker and the listener are also possible.

[0120] It is conceivable that the duration of the audio signal playback is varied (in steps or continuously), and the first and second seat loudspeakers are controlled using seat loudspeaker signals generated at the varying duration. For example, head-tracking information can be taken into account.

[0121] In summary, the inventive techniques are based on the following findings. The central, compact loudspeaker array, consisting of at least two central loudspeakers, generates a dipole radiation pattern with adjustable zero points by inverting and delaying the audio signals. These zero points can be specifically directed at the sides of the listener's head, where the ears are located. This creates a reduced sound pressure in this area. For each listener, the perception of the sound source center of the virtual soundstage is thus centered in front of their head. This creates the impression of a personalized, seating-position-centered soundstage. The pairs of seat loudspeakers, each arranged around the head areas, complement this effect by spatially enveloping the sound. Their decorrelated audio signals with reverberation effects create immersion.The combination of these two components - centered sound image through null superposition and spatial sound envelopment through near-field speakers - leads to an improved sound experience with a centered virtual stage and immersive sound environment.

Claims

[1] An audio system for generating a virtual sound stage in a vehicle interior, comprising: - a loudspeaker array comprising at least a first and a second central loudspeaker, which is arranged laterally in the vehicle interior between a first and a second vehicle seat, - a pair of seat loudspeakers in each of the two vehicle seats, wherein for each of the two vehicle seats the corresponding pair of seat loudspeakers is arranged so that an ideal head area of ​​a person sitting on the respective vehicle seat is arranged between the corresponding pair of seat loudspeakers, - a signal processing unit connected to the loudspeaker array and the seat loudspeaker pairs and providing audio signals to the loudspeakers to generate sound signals, the signal processing unit being configured to: - Receiving an input audio signal; - Controlling, based on processing the input audio signal, the first central loudspeaker by means of a first central audio signal, and the second central loudspeaker by means of a second central audio signal inverted and delayed with respect to the first central audio signal, whereby a first zero point in the radiation characteristic of the sound signals of the loudspeaker array hits the ideal head area of ​​the first vehicle seat, not centrally but laterally shifted. [2] Audio system according to claim 1, wherein the zero point hits the ideal head area near the one ear of the person sitting on the vehicle seat, which ear faces the other vehicle seat when the two people on the two vehicle seats are looking in the same direction. [3] Audio system according to one of the preceding claims, wherein the seat speakers are headrest speakers arranged centrally relative to the ideal head area in a headrest of the first vehicle seat. [4] An audio system according to any one of the preceding claims, wherein the first and second central loudspeakers are arranged in a compact spatial configuration, wherein the distance between the loudspeakers is less than 50%, or 25%, or 10%, of the diameter of one of the central loudspeakers, or wherein the central loudspeakers are arranged immediately adjacent to one another. [5] Audio system according to one of the preceding claims, wherein the first and the second central loudspeaker each comprise a midrange / tweeter, in particular with the same frequency range and / or the same radiation characteristic, and are arranged in a dashboard of a vehicle or the vehicle headliner. [6] Audio system according to one of the preceding claims, wherein the first and / or second central audio signal comprises an audio signal correlated with the input audio signal. [7] Audio system according to one of the preceding claims, further comprising: - Controlling, based on processing the input audio signal, the seat loudspeakers of a seat loudspeaker pair by means of respective seat loudspeaker audio signals, wherein a first and a second seat loudspeaker of the seat loudspeaker pair are controlled without any time delay to one another. [8] The audio system of claim 7, wherein the seat speaker audio signals comprise decorrelated audio signals with respect to the input audio signal and / or the central audio signals. [9] An audio system according to any preceding claim, wherein the seat speaker audio signals comprise reverberated audio signals with respect to the input audio signal and / or the central audio signals. [10] An audio system according to any preceding claim, wherein the first head region is arranged in a left hemisphere of the loudspeaker array, and the second head region is arranged in a right hemisphere of the loudspeaker array, and the center of the compact loudspeaker array is arranged on a longitudinal axis between the first and second head regions. [11] Audio system according to one of the preceding claims, wherein the first zero point of the loudspeaker array is located at least partially in a side region of the first head region directed towards the center, and a second zero point of the loudspeaker array, which is symmetrical to the first zero point with respect to a loudspeaker axis passing through the centers of the first and second central loudspeakers, is located at least partially in a side region of the second head region directed towards the center. [12] The audio system of claim 11, wherein the speaker axis extends between the first and second vehicle seats. [13] An audio system according to any preceding claim, wherein the first and second central loudspeakers are arranged on a longitudinal axis of symmetry with respect to the centers of the first and second head regions. [14] Method for generating a virtual sound stage in a vehicle interior based on an audio system comprising the following components: - a loudspeaker array comprising at least a first and a second central loudspeaker, which is arranged centrally in the vehicle interior between a first and a second vehicle seat, - a pair of seat loudspeakers in each of the vehicle seats, wherein for each of the vehicle seats the corresponding pair of seat loudspeakers is arranged so that an ideal head area of ​​a person sitting on the vehicle seat is arranged between the corresponding pair of seat loudspeakers, - a signal processing unit connected to the compact loudspeaker array and the seat loudspeakers, and configured to receive an input audio signal and, based thereon, to provide respective audio signals to the loudspeakers for generating sound signals; wherein the method is carried out by the signal processing unit and comprises the following steps: - Receiving an input audio signal; - Controlling, based on processing the input audio signal, the first central loudspeaker by means of a first central audio signal, and the second central loudspeaker by means of a second central audio signal inverted and delayed with respect to the first central audio signal, whereby a first zero point in the radiation characteristic of the sound signals of the loudspeaker array hits the ideal head area of ​​the first vehicle seat, not centrally but laterally shifted. [15] A vehicle comprising an audio system according to any one of claims 1 to 13.

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