Generating an audio signal associated with a virtual sound source.

Abstract

A method for generating an audio signal associated with a virtual sound source is disclosed. The method comprises the steps of obtaining an input audio signal x(t) and modifying the input audio signal x(t) to obtain a modified audio signal. The latter step comprises performing a signal delay operation. Optionally, modifying the input audio signal comprises a signal inversion operation and / or a signal amplification or attenuation and / or a signal feedback operation. The method further comprises generating an audio signal y(t) based on a combination, e.g., a summation, of the input audio signal x(t) and the modified audio signal.

Description

Technical Field

[0001] The present disclosure relates to a method and a system for generating an audio signal associated with a virtual sound source. In particular, the present disclosure relates to a method and a system in which an input audio signal x(t) is modified to obtain a modified audio signal, and the modification includes performing a signal delay operation. An audio signal y(t) is generated based on a combination, for example, a sum, of the input audio signal x(t) and the modified audio signal.

Background Art

[0002] In sound reproduction through a voice transmitter, i.e., a speaker, much of the essential spatial information of the (recorded) sound is lost. Therefore, the experience of sound through a speaker often feels lacking in depth (sounding "flat") and lacking in dimensionality (sounding "inside a box"). The active perception of height is completely lost from the sound experience across the speakers. These conditions create an essential separation between the listener and the sound in the environment. This creates an obstacle to the observer being fully physically and emotionally integrated with the sound environment, and generally this makes the sound experience more passive and less appealing.

[0003] A classical demonstration of this problem has been described by Von Bekesy (Experiments in Hearing, 1960), and the "inside a box" acoustic effect seems to increase with a decrease in the dimensions of the speaker. In experimental studies on the relationship between acoustic power, spectral balance, and the perceived spatial dimension and volume, Von Bekesy's subjects were unable to correctly indicate the relative dimensional shape of the sound source as soon as the dimension of the playback sound source exceeded the actual shape of the playback speaker box. It can be concluded that the spatial spectral characteristics of the speaker result in a message-media collision when transmitting sound information. We cannot recognize the spatial dimension of the sound source in the reproduced sound. Instead, we are listening to the characteristics of the speaker.

[0004] In the prior art, there is no satisfactory method for recording or calculating the dimensional information of a sound source. The near-field information of the sound-emitting object cannot be accurately obtained by a microphone, or theoretically, an infinite lattice of pressure and particle velocity transducers would be required to obtain the dimensional information of the object.

[0005] Regarding the calculation simulation of dimensional information, the solution of the wave equation is only applicable to a limited amount of basic geometric shapes and within a limited frequency range. Considering the lack of an analytical solution to the above problem, in order to attempt to reproduce the desired data, the simulation model has to resort to finite calculation methods. The data thus collected and reproduced using techniques involving FFT (Fast Fourier Transform), such as convolution or additive synthesis, requires complex calculations and a very large amount of data processing, and is therefore essentially very intensive for computer processing. This poses a problem for a voice reproduction system that limits the application of such methods and can accurately reproduce information.

[0006] Therefore, there is a need for a method for generating an audio signal associated with a virtual sound source that is not computationally expensive in the art.

Summary of the Invention

Means for Solving the Problems

[0007] For that purpose, a method for generating an audio signal associated with a virtual sound source is disclosed. The method includes (i) obtaining an input audio signal x(t), modifying the input audio signal x(t) using a signal delay operation that introduces a time delay to obtain a modified audio signal, and generating an audio signal y(t) based on the combination, e.g., summation, of the input audio signal x(t), or an inverted and / or attenuated or amplified version of the input audio signal x(t), with the modified audio signal. Alternatively, (ii) the method includes obtaining an input audio signal x(t), and generating an audio signal y(t) based on a signal feedback operation that recursively adds the modified version of the input audio signal x(t) to itself, wherein the signal feedback operation includes a signal delay operation that introduces a time delay and optionally, a signal inversion operation.

[0008] When a virtual sound source is said to have a specific size and shape and / or be located at a specific distance and / or at a specific height or depth, it can be understood that when an observer hears a generated sound signal, they perceive that the sound signal is emanating from a sound source having that specific size and shape and / or being located at the aforementioned specific distance and / or at the aforementioned specific height or depth. Human hearing is highly sensitive to spectral information correlated with the dimensions of a sound-producing object, as exemplified by the Von Bekesy experiment described above. Human hearing perceives the characteristics of a sound-producing object primarily through its resonance, i.e., the amplification of one or more fundamental frequencies and their correlated harmonics, such amplification resulting from standing waves generated by the object or space due to its specific size and shape. By adding or subtracting spectral information from a sound signal, the spatial spectral characteristics of a speaker can be at least partially neutralized, and a coherent spatial projection of the sound signal can be produced using its size and shape, such that the resulting spectrum closely resembles the resonance of the intended object or space. The applicant realized that such spatial information, relating to the dimensions of the sound source and its virtual distance, height, and depth relative to the observer, can be added to an input audio signal by performing relatively simple operations on the input audio signal. In particular, the applicant found that these simple operations are sufficient to generate an audio signal that, due to the physiology of the human auditory organ, causes the observer to perceive the audio signal as originating from a sound source having a certain location and dimensions other than the location and dimensions of the speaker producing the sound. The above method does not require filtering or combining individual (band) frequencies and amplitudes to add this spatial information to the input audio signal. The above method therefore avoids the need for FFT synthesis techniques for such purposes, thus simplifying the process and considerably reducing the required processing power.

[0009] Optionally, the above method includes the step of reproducing the generated audio signal by, for example, providing the generated audio signal to one or more speakers in order to reproduce the generated audio signal by one or more speakers.

[0010] Once the generated audio signal is reproduced by the speaker system, it produces the desired perception by the observer, regardless of how many speakers are used and regardless of the observer's position relative to the speakers.

[0011] A signal said to be generated based on the combination of two or more signals may simply be the sum of these two or more signals.

[0012] In one example, the generated audio signal is stored in a computer-readable medium so that it can be later reproduced by a speaker system.

[0013] Audio signals can be generated in real time, which may be understood as the audio signal being generated immediately upon arrival of an input audio signal, and / or as any change in the input audio signal at a given time being reflected in the generated audio signal within 3 seconds, preferably within 0.5 seconds, more preferably within 50 ms, and most preferably within 10 ms. Relatively simple operation for generating audio signals allows for such real-time processing. Optionally, the generated audio signal can be played back in real time, which may be understood as the audio signal being played back with virtually no delay once it has been generated.

[0014] In one embodiment, the virtual sound source has a shape. Such an embodiment includes the step of generating an audio signal component associated with each virtual point in the shape of the virtual sound source. This step includes generating a first audio signal component associated with a first virtual point in the shape of the virtual sound source and a second audio signal component associated with a second virtual point in the shape of the virtual sound source, (i) Generating a first audio signal component includes the step of modifying the input audio signal using a first signal delay operation that introduces a first time delay to obtain a modified first audio signal component, and the step of generating a first audio signal component based on the combination, e.g., summation, of the input audio signal, or the inverted and / or attenuated or amplified version of the input audio signal x(t), with the modified first audio signal component, or (ii) Generating a first audio signal component involves using a feedback loop that recursively adds a modified version of the input audio signal x(t) to itself, wherein the feedback loop includes a signal delay operation and a signal inversion operation that introduce a first time delay. Furthermore, in this embodiment, (i) Generating a second audio signal component includes the step of modifying the input audio signal using a second signal delay operation that introduces a second time delay different from the first time delay to obtain a modified second audio signal component, and the step of generating a second audio signal component based on the combination, e.g., summation, of the input audio signal, or the inverted and / or attenuated or amplified version of the input audio signal x(t), with the modified second audio signal component, or (ii) Generating a second audio signal component involves using a feedback loop that recursively adds a modified version of the input audio signal x(t) to itself, wherein the feedback loop includes a signal delay operation and a signal inversion operation that introduce a second time delay.

[0015] The applicant has found that this embodiment allows for the addition of dimensional information of a virtual sound source to an input audio signal x(t) in a simple manner, without requiring complex algorithms such as FFT algorithms, summation of individual frequency bands, or numerous bandpass filters to obtain the desired result, as in the prior art.

[0016] Preferably, many three or more virtual points may be defined in the shape of the virtual sound source. Any number of virtual points may be defined in the shape of the virtual sound source. For each of these virtual points, an audio signal component may be determined. Each determination of an audio signal component may then include determining a modified audio signal component using a signal delay operation that introduces a time delay for each component. Each audio signal component may then be determined based on the combination, e.g., sum, of its modified audio signal component and the input audio signal.

[0017] Each determination of a modified audio signal component may further include signal inversion and / or signal amplification or attenuation and / or signal feedback. In this specification, preferably, the signal feedback operation is performed last. In principle, the signal inversion, amplification / attenuation, and signal delay operations may be performed in any order.

[0018] The virtual points may be arranged at equal distances from each other in the shape of the virtual sound source. Furthermore, the virtual sound source may have any shape, such as a one-dimensional shape, e.g., a 1D string; a two-dimensional shape, e.g., a 2D plate; or a three-dimensional shape, e.g., a 3D cube.

[0019] The time delay in the audio signal can be zero for some audio signal components. For example, if the virtual sound source is a string, the time delay for the two virtual points at each end of the string where its vibration is restricted can be zero. This will be illustrated below with reference to the figure.

[0020] In one embodiment, the method includes the steps of obtaining shape data representing the virtual position of each virtual point in the shape of a virtual sound source, and determining a first or second time delay based on the virtual position of the first or second virtual point. Therefore, the respective time delays for determining each audio signal component for different virtual points may be determined based on the respective virtual positions of these virtual points.

[0021] The applicant has found that this embodiment makes it possible to take into account how sound waves propagate through a dimensional shape, thereby making it possible to precisely generate an audio signal that is perceived by an observer as originating from a sound source having a particular shape. When the generated audio signal components associated with a virtual point are reproduced through a speaker or dispersed across multiple speakers, the result is perceived as a single coherent sound source in space, as the signal components enhance their coherence at the corresponding wavelengths of harmonic ratios following the fundamental resonant frequencies of the virtual shape. This at least partially disables the mechanism of the ear that detects its actual output component, i.e., the speaker.

[0022] Preferably, the time delay for each time-delayed audio input signal is determined according to the relationship between spatial dimensions and time, an example of which is given below in the graphical description.

[0023] In one embodiment, the audio signal y(t) to be generated is associated with a virtual sound source having distance from the observer. This embodiment includes the steps of (i) modifying an input audio signal using a time delay operation and a signal feedback operation that introduce a time delay to obtain a first modified audio signal; (ii) generating a second modified audio signal based on a combination of an input audio signal x(t) and the first modified audio signal; and (iii) generating an audio signal y(t) based on the second modified audio signal, the steps of which include attenuating the second modified audio signal and optionally including a time delay operation that introduces a second time delay.

[0024] Human hearing perceives the distance to a sound source primarily by detecting changes in the overall intensity of auditory stimuli and the energy dissipation, which is proportional to the rate of change from high to low frequencies. The applicant has found that this embodiment allows for the addition of such distance information to an input audio signal in a very simple and computationally inexpensive manner.

[0025] A second introduced time delay may be used to produce a Doppler effect for the observer. This embodiment further allows for controlling the Q coefficient to narrow or widen the bandwidth of the resonant frequency in the signal. In this case, since the perceived resonant frequency is infinitely low at the farthest possible virtual distance, the Q coefficient affects the steepness of the curve across the entire audible frequency range from high to low frequencies, resulting in an intended gradual increase in high-frequency dissipation in the signal.

[0026] Preferably, the time delay introduced by the time delay operation performed to obtain the first corrected audio signal is less than 0.00007 seconds, preferably less than 0.00005 seconds, more preferably less than 0.00002 seconds, and most preferably about 0.00001 seconds.

[0027] The second modified audio signal may be attenuated depending on the distance to the virtual sound source. With respect to the signal feedback operation performed to determine the first modified audio signal, to which the attenuated signal is recursively added, the distance-dependent signal attenuation is also preferably performed. Optionally, such embodiments include the step of obtaining distance data representing the distance to the virtual sound source so that the attenuation can be automatically and appropriately controlled. This embodiment allows the virtual sound source to be "moved" toward and away from the observer simply by adjusting a few values.

[0028] In the above embodiment, the signal feedback operation includes attenuating a signal, such as a signal obtained after performing a time delay operation that introduces the time delay, and then recursively adding the attenuated signal to the signal itself. Such an embodiment may further include the step of controlling the attenuation in the signal feedback operation and the attenuation of the second modified audio signal in a distance-dependent manner, such that the greater the distance, the lower the attenuation in the signal feedback operation and the higher the attenuation of the second modified audio signal.

[0029] In one embodiment, the virtual sound source is at a distance from the observer. This embodiment includes the steps of: obtaining a first modified audio signal by modifying an input audio signal using a signal feedback operation that recursively adds a modified version of the input audio signal to itself, wherein the feedback operation includes a signal delay operation that introduces a time delay; and generating an audio signal y(t) based on the first modified audio signal, wherein the feedback operation includes signal attenuation and optionally a time delay operation that introduces a second time delay, and optionally this embodiment further includes generating a second modified audio signal based on a combination of the first modified audio signal and a time-delayed version of the first modified audio signal, and generating an audio signal y(t) based on the second modified audio signal and therefore on the first modified audio signal.

[0030] The above considerations regarding the introduced time delay also apply to attenuation in this embodiment.

[0031] In one embodiment, a virtual sound source is positioned at a distance from the observer, and a second modified audio signal is attenuated in a distance-dependent manner, and the step of modifying the input audio signal to obtain a first modified audio signal includes specific signal attenuation. This embodiment includes the step of controlling the attenuation of the specific signal attenuation and the attenuation of the second modified audio signal in a distance-dependent manner, such that the greater the distance, the lower the attenuation of the specific signal attenuation and the higher the attenuation of the second modified audio signal.

[0032] In one embodiment, the audio signal y(t) to be generated, associated with a virtual sound source, is positioned at a virtual height above the observer. In such an embodiment, the method includes (i) modifying an input audio signal x(t) using signal inversion, signal attenuation, and time delay operations to obtain a third modified audio signal, and (ii) generating an audio signal based on a combination, e.g., sum, of the input audio signal and the third modified audio signal.

[0033] The applicant has found that this embodiment allows for the generation of an audio signal arriving from a virtual sound source positioned at a certain height in a simple manner.

[0034] In this embodiment, the introduced time delay is preferably less than 0.00007 seconds, preferably less than 0.00005 seconds, more preferably less than 0.00002 seconds, and most preferably about 0.00001 seconds.

[0035] In the above embodiment, the step of modifying the input audio signal to obtain a third modified audio signal optionally includes a step of performing a signal feedback operation. In a particular example, this step includes recursively adding to itself the attenuated signal resulting from a time delay operation, a signal attenuation operation and a signal inversion operation performed to ultimately obtain the third modified audio signal.

[0036] In one embodiment, the audio signal to be generated is associated with a virtual sound source located at a virtual depth below the observer. Such an embodiment includes the step of modifying an input audio signal x(t) using a time delay operation, a signal attenuation operation, and a signal feedback operation to obtain a sixth modified audio signal. The step of performing a signal feedback operation includes, for example, the step of recursively adding to itself the attenuated signal resulting from the time delay operation and signal attenuation operation performed to finally obtain a signal such as the sixth modified audio signal. This embodiment further includes the step of generating an audio signal based on a combination of the input audio signal and the sixth modified audio signal.

[0037] In one embodiment, the virtual sound source is located at a virtual depth below the observer. This embodiment includes the step of generating an audio signal y(t) using a signal feedback operation that recursively adds a modified version of an input audio signal to itself, wherein the feedback operation includes a signal delay operation that introduces a time delay and a first signal attenuation operation.

[0038] In one embodiment, the virtual sound source is located at a virtual depth below the observer. This embodiment includes the steps of: modifying an input audio signal to obtain a sixth modified audio signal using a signal feedback operation that recursively adds a modified version of the input audio signal to itself, wherein the feedback operation includes a signal delay operation that introduces a time delay and a first signal attenuation; and generating an audio signal based on a combination of the sixth modified audio signal and the time-delayed and attenuated version of the sixth modified audio signal.

[0039] In the above embodiment in which the virtual sound source is placed in the virtual depth, the introduced time delay is preferably shorter than 0.00007 seconds, preferably shorter than 0.00005 seconds, more preferably shorter than 0.00002 seconds, and most preferably about 0.00001 seconds.

[0040] In one embodiment, the method includes receiving user input indicating the shape of a virtual sound source and / or the virtual position of each virtual point in the shape of the virtual sound source and / or the distance between the virtual sound source and the observer and / or the height at which the virtual sound source is positioned above the observer and / or the depth at which the virtual sound source is positioned below the observer. This embodiment allows the user to input parameters relating to the virtual sound source, thereby allowing the generation of an audio signal according to these parameters. This embodiment may include the steps of determining values ​​for the parameters described herein and generating an audio signal using these determined parameters.

[0041] In one embodiment, the above method is - The shape of the virtual sound source, - The virtual position of each virtual point in the shape of the virtual sound source, - Distance between the virtual sound source and the observer, - The height at which the virtual sound source is positioned above the observer, - Depth at which the virtual sound source is positioned below the observer The process includes generating a user interface that allows the user to input at least one of the following: This allows the user to easily input parameters related to the virtual sound source and thus allow the user to easily control the virtual sound source.

[0042] The methods described herein may be computer implementation methods.

[0043] One aspect of the present disclosure relates to a computer comprising a computer-readable storage medium in which computer-readable program code is embodied, and a processor coupled to the computer-readable storage medium, preferably a microprocessor, configured to perform one or more steps of the method described herein for generating audio signals associated with a virtual sound source in response to the execution of the computer-readable program code.

[0044] One aspect of the present disclosure relates to a computer program or a set of computer programs or a computer program product storing at least one software code portion, wherein the software code portion, when executed in a computer system, is configured to perform one or more steps of a method described herein for generating an audio signal associated with a virtual sound source.

[0045] One aspect of the present disclosure relates to a non-temporary computer-readable storage medium storing at least one software code portion, wherein the software code portion, when executed or processed by a computer, is configured to perform one or more steps of a method described herein for generating an audio signal associated with a virtual sound source.

[0046] One aspect of this disclosure relates to a user interface described herein.

[0047] As will be recognized by those skilled in the art, aspects of the present invention may be embodied as systems, methods, or computer program products. Accordingly, aspects of the present invention may take the form of entirely hardware embodiments, entirely software embodiments (including firmware, resident software, microcode, etc.), or embodiments combining software and hardware embodiments, all of which may be generally referred to herein as “circuits,” “modules,” or “systems.” The functions described herein may be implemented as algorithms executed by a computer microprocessor. Furthermore, aspects of the present invention may take the form of computer program products embodied in computer-readable program code, for example, in one or more stored computer-readable media.

[0048] Any combination of one or more computer-readable media may be used. The computer-readable media may be computer-readable signal media or computer-readable storage media. The computer-readable storage media may be, but are not limited to, electronic, magnetic, optical, electromagnetic, infrared, or semiconductor systems, apparatus, or devices, or any suitable combination thereof. More specific examples (non-exclusive enumeration) of computer-readable storage media may include: electrical connections with one or more wires, portable computer diskettes, hard disks, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), optical fibers, portable compact disk read-only memory (CD-ROM), optical storage devices, magnetic storage devices, or any suitable combination thereof. In the context of this document, the computer-readable storage medium may be any tangible medium that contains or can store programs for use by, or relating to, an instruction execution system, apparatus, or device.

[0049] A computer-readable signal medium may include propagated data signals in which computer-readable program code is embodied, for example, in the baseband or as part of a carrier wave. Such propagated signals may take any of various forms, including but not limited to electromagnetic, optical, or any suitable combination thereof. A computer-readable signal medium may be any computer-readable medium, not a computer-readable storage medium, that can communicate, propagate, or transfer programs for use by or relating to an instruction execution system, apparatus, or device.

[0050] The program code embodied in a computer-readable medium may be transmitted using any suitable medium, including but not limited to wireless, wireline, optical fiber, cable, RF, or any suitable combination thereof. The computer program code for performing the operations for aspects of the present invention may be written in any combination of one or more programming languages, including functional or object-oriented programming languages ​​such as Java®, Scala, C++, Python, and conventional procedural programming languages ​​such as the C programming language or similar programming languages. The program code may run entirely on the user's computer, partially on the user's computer, as a standalone software package, partially on the user's computer and partially on a remote computer, or entirely on a remote computer, server, or virtualization server. In the latter scenario, the remote computer may be connected to the user's computer through any type of network, including a local area network (LAN) or wide area network (WAN), or may be connected to an external computer (for example, via the Internet using an Internet service provider).

[0051] Aspects of the present invention are described below with reference to example flowcharts and / or block diagrams of methods, apparatus (systems) and computer program products according to embodiments of the present invention. It will be understood that each block in the example flowcharts and / or block diagrams, and combinations of blocks in the example flowcharts and / or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general-purpose computer, a dedicated computer or other programmable data processing device, in particular a microprocessor or central processing unit (CPU) or graphics processing unit (GPU), such that the instructions are executed via the processor of a computer, another programmable data processing device or other device, and produce means for implementing the functions / operations specified in one or more blocks of the flowcharts and / or block diagrams, thereby generating a machine.

[0052] These computer program instructions may be stored on a computer-readable medium that can instruct a computer, other programmable data processing device, or other device to function in a particular manner, so as to generate a product that includes instructions that implement functions / operations specified in one or more blocks of a flowchart and / or block diagram.

[0053] Computer program instructions may be loaded into a computer, other programmable data processing device, or other device such that instructions executed in the computer or other programmable device provide a process for implementing functions / operations specified in one or more blocks of a flowchart and / or block diagram, and a series of operational steps may be performed in the computer, other programmable device, or other device to generate a computer implementation process.

[0054] The flowcharts and block diagrams in the figures illustrate the architecture, functionality, and operation of possible implementations of systems, methods, and computer program products according to various embodiments of the present invention. In this regard, each block in the flowchart or block diagram may represent a module, segment, or portion of code, comprising one or more executable instructions for implementing a specified logical function. It should be noted that in some alternative implementations, the functions shown in the blocks may occur in a different order than shown in the figures. For example, two blocks shown consecutively may actually be executed substantially in parallel, or blocks may sometimes be executed in reverse order, depending on the functions involved. It should also be noted that each block in the block diagrams and / or flowchart examples, as well as combinations of blocks in the block diagrams and / or flowchart examples, can be implemented by a dedicated hardware-based system or a combination of dedicated hardware and computer instructions that performs the specified function or operation.

[0055] The present invention will be further illustrated with reference to the accompanying drawings which schematically illustrate embodiments thereof. It will be understood that the present invention is not limited in any way to these specific embodiments.

[0056] Aspects of the present invention will be described in more detail by reference to the illustrative embodiments shown in the drawings. [Brief explanation of the drawing]

[0057] [Figure 1A] A method and system according to one embodiment are illustrated below. [Figure 1B] A method and system according to one embodiment are illustrated below. [Figure 1C] A method and system according to one embodiment are illustrated below. [Figure 1D] A method and system according to one embodiment are illustrated below. [Figure 1E] A method and system according to one embodiment are illustrated below. [Figure 1F] A method and system according to one embodiment are illustrated below. [Figure 1G] A method and system according to one embodiment are illustrated below. [Figure 1H] A method and system according to one embodiment are illustrated below. [Figure 1I] A method and system according to one embodiment are illustrated below. [Figure 1J] A method and system according to one embodiment are illustrated below. [Figure 2] The spectrogram of an audio signal generated using a method and / or system according to one embodiment is shown. [Figure 3A] A virtual sound source according to one embodiment, particularly the shape of a virtual sound source as a string, is illustrated. [Figure 3B] The input audio signal and the signal-inverted and time-delayed versions of the input audio signal that may be involved in the embodiment are schematically shown. [Figure 4] This example illustrates a method for adding dimensional information to an audio signal, where the dimensional information relates to the shape of a virtual sound source. [Figure 5] An example of a panning system that may be used in one embodiment is provided. [Figure 6A] Examples of 2D and 3D virtual sound sources are provided. [Figure 6B] The input signals that may be involved in the embodiment and the time-delayed versions of these signals are shown. [Figure 7A] This document provides examples of methods for generating audio signals associated with a two-dimensional virtual sound source, such as a board. [Figure 7B] A schematic diagram illustrates how several parameters used in one embodiment can be determined. [Figure 7C] An alternative embodiment to the one shown in Figure 7A is presented as an example. [Figure 7D] An alternative embodiment to the one shown in Figure 7A is presented as an example. [Figure 8A] This shows the spectrogram of each audio signal component associated with each virtual point on the virtual sound source. [Figure 8B] This shows the spectrogram of each audio signal component associated with each virtual point on the virtual sound source. [Figure 9A] An example of the generation of a virtual sound source positioned at a distance from the observer according to one embodiment is provided. [Figure 9B] An example of the generation of a virtual sound source positioned at a distance from the observer according to one embodiment is provided. [Figure 9C] An alternative embodiment of the embodiment shown in Figure 9A is illustrated. [Figure 9D] An alternative embodiment of the embodiment shown in Figure 9A is illustrated. [Figure 9E] An alternative embodiment of the embodiment shown in Figure 9A is illustrated. [Figure 10] The spectrograms are shown, associated with virtual sound sources placed at different distances. [Figure 11A] An example of generating a virtual sound source positioned above the observer's height according to one embodiment is provided. [Figure 11B] An example of generating a virtual sound source positioned above the observer's height according to one embodiment is provided. [Figure 12] The spectrograms are shown, associated with virtual sound sources positioned at each height. [Figure 13A] An example of generating a virtual sound source located at a depth below the observer's level according to one embodiment is provided. [Figure 13B] An example of generating a virtual sound source located at a depth below the observer's level according to one embodiment is provided. [Figure 13C] An alternative embodiment of the embodiment shown in Figure 13A is illustrated. [Figure 13D] An alternative embodiment of the embodiment shown in Figure 13A is illustrated. [Figure 13E] An alternative embodiment of the embodiment shown in Figure 13A is illustrated. [Figure 13F] An alternative embodiment of the embodiment shown in Figure 13A is illustrated. [Figure 14] This example illustrates the generation of an audio signal associated with a virtual sound source having a certain shape and positioned at a certain location. [Figure 15]An example of a user interface according to one embodiment is shown. [Figure 16] An example of a data processing system according to one embodiment is provided. [Modes for carrying out the invention]

[0058] Sound waves inherently carry detailed information about the environment and about the observer of the sound within the environment. This disclosure describes a method for generating a sound wave transformer (spatial wave transformer or SWT), an audio signal, which is perceived to have spatially coherent properties with respect to the dimensional size and shape of the reproduced sound source, its relative distance to the observer, its height or depth above or below the observer, and its directionality if the sound source is moving toward or away from the observer.

[0059] Generally, spatial wave conversion is an algorithm performed by a computer that takes a digital audio signal (e.g., a digital recording) as input and outputs one or more modified audio signals that can be reproduced by a conventional audio playback system. Alternatively, the above conversion can also apply to analog (non-digital) means that generate and / or process the audio signal. By reproducing the modified audio signal, the observer is given an improved perception of the magnitude and shape of the dimensions of the reproduced sound source (e.g., a recording of a violin sounds as if the violin were physically present) and the spatial distance, height, and depth of the sound source relative to the observer (e.g., the violin sounds at a specific distance from the listener and at a higher height or lower depth), while masking the physical characteristics of the sound output medium, i.e., the speaker (i.e., the violin does not sound as if it were coming from the speaker).

[0060] Figure 1A is a flowchart illustrating a method and / or system according to one embodiment. An input audio signal x(t) is obtained. The input audio signal x(t) may be analog or digital. Thus, each of the operations illustrated in Figure 1, namely operations 4, 6, 8, 10, 12, and 14, may be performed by analog or digital circuit components. The flowchart in Figure 1 may be understood as illustrating the steps of a method that can be performed by a computer running appropriate software code.

[0061] The input audio signal x(t) may have been output by a recording process in which sound was recorded and optionally converted into a digital signal. In one example, an instrument such as a violin was recorded in a studio to obtain an audio signal to be input for the method for generating the audio signal described herein.

[0062] The input audio signal x(t) is then modified to obtain a modified audio signal. Signal modification includes signal delay operation 4 and / or signal inversion operation 6 and / or signal amplification or attenuation operation 8 and / or signal feedback operation 10, 12.

[0063] The signal delay operation 4 may be performed using well-known components such as delay lines. The signal inversion operation 6 may be understood as inverting the signal so that the input signal x(t) is converted to -x(t). The amplification or attenuation 8 may be linear amplification or attenuation, and may be understood as amplifying or attenuating the signal by a constant coefficient a so that the signal x(t) is converted to a*x(t).

[0064] The signal feedback operation can be understood as consisting of recursively coupling a signal with its own attenuated state. This is schematically illustrated by the attenuation operation 12 and coupling operation 10 located in the feedback loop. Attenuation, i.e., by decreasing the expansion constant b in Figure 1A, can increase the peak intensity and narrow the bandwidth of the resonant frequency in the sound spectrum, the so-called Q coefficient. Along with this, the response of different materials to vibration can be simulated based on their density and stiffness. For example, the response of a metallic object will result in a higher Q coefficient than that of an object of the same size and shape made from wood.

[0065] The coupling operations 10 and 14 involve two or more signals {x1(t), ..., x n It can be understood that (t) is being combined. The input signal can be converted to the signal y(t) as follows.

[0066] In Figure 1A, the audio signal y(t) is generated based on the combination, e.g., summation, of the input audio signal x(t) and the modified audio signal. In one example, the audio signal y(t) is the result of combining, e.g., summing, the input audio signal x(t) and the modified audio signal.

[0067] The conversion of an input audio signal x(t) to an audio signal y(t) may henceforth be referred to as spatial wave conversion (SWT).

[0068] The method for generating the audio signal y(t) does not require finite computational methods, such as methods involving the Fast Fourier Transform, which can limit the achievable resolution of the generated audio signal. Therefore, the method disclosed herein makes it possible to form a high-resolution audio signal. In this specification, high resolution may be understood as a signal spectrally corrected for an infinite number of frequency components. Since the desired spectral correction of frequency components arises from a simple summation, i.e., from the wave interference of two identical audio signals with specific time delays, amplitudes, and / or phase differences, rather than the need to compute and correct the desired spectral information for each individual frequency component, as in convolution or simulation models, virtually infinite resolution is achieved. This operation results in phase and amplitude differences for each frequency component of the harmonic ratio, i.e., corresponding to the spectral pattern brought about by resonance. A reasonable time delay for this method is typically between 0.00001 and 0.02 seconds, but longer times are not excluded.

[0069] The generated audio signal y(t) may be presented to the observer through a conventional audio output medium, such as one or more speakers. The generated audio signal may be delayed and / or attenuated before being output to the audio output medium.

[0070] Figures 1B to 1G illustrate flowcharts depicting methods and / or systems according to other embodiments. Here, Figure 1B differs from Figure 1A in that the signal inversion and signal attenuation operations occur after the feedback coupling 10.

[0071] Furthermore, Figures 1C and 1D illustrate respective embodiments in which an audio signal y(t) is generated based on a signal feedback operation that recursively adds a modified version of the input audio signal x(t) to itself. The signal feedback operation includes a signal delay operation and a signal inversion operation that introduce a time delay.

[0072] Here, Figure 1C illustrates an embodiment in which an input audio signal is modified using signal feedback operation to obtain a modified audio signal indicated by 11. In this embodiment, the audio signal y(t) is generated based on the combination of this modified audio signal and a time-delayed, inverted version of this modified audio signal, indicated by 13. As illustrated in Figure 1C, this may be achieved by also sending the signal that is fed back to coupler 9 to coupler 10.

[0073] In Figures 1C and 1D, the attenuation function resulting from the signal feedback operation is frequency-independent, and therefore these embodiments can be understood as constituting an all-pass filter.

[0074] The embodiment in Figure 1E differs from that illustrated in Figure 1A in that the signal delay operation, signal inversion operation, and attenuation are performed as part of the signal feedback operation. The embodiment in Figure 1E is particularly advantageous in that it produces a harmonic pattern consisting of a frequency-dependent attenuation function. Due to this attenuation function, the higher the frequency in the signal, the faster it attenuates than the lower the frequency.

[0075] Embodiments in Figure 1F or Figure 1G illustrate each embodiment in which signal attenuation occurs after or before the signal feedback operation. It should be noted that signal attenuation may be placed at any position in the flowchart, and several signal attenuations may exist at each position in the flowchart.

[0076] Figures 1H to 1J illustrate respective embodiments in which the audio signal y(t) is generated based on the combination 10 of the input audio signal x(t) which has been inverted and / or attenuated or amplified, and the modified audio signal, and the modified audio signal is obtained using signal delay operation and signal feedback operation.

[0077] Figure 1H illustrates an embodiment in which the modified audio signal is combined with an attenuated version of the input audio signal, Figure 1I illustrates an embodiment in which the modified audio signal is combined with an inverted version of the input audio signal, and Figure 1J illustrates an embodiment in which the modified audio signal is combined with an inverted and attenuated version of the input audio signal.

[0078] It should be recognized that the embodiment in Figure 1 can be used as a building block to construct more complex embodiments, for example, those illustrated in Figures 4, 7, and 14. Thus, while these more complex embodiments use the embodiment in Figure 1A as a building block, any of the embodiments in Figures 1B to 1J may be used as a building block. In these complex embodiments, these building blocks may be any of the embodiments in Figures 1B to 1J, as indicated by 21.

[0079] Figure 2 (top) shows the spectrogram of the generated audio signal when the input audio signal x(t) is white noise, the time delay introduced by time delay operation 4 is approximately 0.00001 sec, the signal inversion operation 6 is performed, and the signal feedback operations 10 and 12 are not performed.

[0080] Figure 2 (center) shows the spectrogram of the generated audio signal when the input audio signal x(t) is white noise, the time delay introduced by time delay operation 4 is approximately 0.00036 sec, the signal inversion operation 6 is performed, and the signal feedback operations 10 and 12 are not performed.

[0081] Figure 2 (below) shows the spectrogram of the generated audio signal when the input audio signal x(t) is white noise, the time delay introduced by time delay operation 4 is approximately 0.00073 sec, the signal inversion operation 6 is performed, and the signal feedback operations 10 and 12 are not performed.

[0082] These figures demonstrate that the spectrum of an audio signal can be precisely modified according to its harmonic ratio using a very simple operation.

[0083] Figure 3A illustrates a virtual sound source in the form of a string. Several virtual points n are defined in the shape of the string; in this example, there are 17 virtual points. The points may be equidistant from each other, as shown in the figure. A certain distance selected between each pair of particles determines the resolution at which the virtual sound source is defined.

[0084] Figures 4 and 7 illustrate embodiments of methods and / or systems that may be used to generate an audio signal perceived to originate from a sound source having a specific shape, for example, the string shape illustrated in Figure 3A, the plate-shaped source or cubic source exemplified in Figure 6. In these embodiments, the method associates the audio signal component y with each virtual point in the shape of the virtual sound source. n The step includes generating (t). Each audio signal component y n The step that generates (t) is a time delay Δt n The process includes the step of modifying the input audio signal using a signal delay operation that introduces a modified audio signal component. Then, each audio signal component y n (t) is generated based on the combination, for example, the sum, of the input audio signal and its modified audio signal components. Preferably, the amplitude of each signal component resulting from the above combination is controlled by signal attenuation elements 191-19 n This results in, for example, a -6dB attenuation. At least two of the introduced time delays are different from each other. Audio signal component y n (t) can be understood as together constituting the generated audio signal y(t). In one example, the audio signal components are combined to generate an audio signal. However, in another example, these audio signal components are individually sent to a panning system that distributes each component to multiple speakers individually. When the audio signal components are reproduced simultaneously through an audio output medium, for example, through one or more speakers, the resulting audio signal will be perceived by the observer as originating from a sound source having a specific shape.

[0085] Figure 4 illustrates an embodiment for generating an audio signal that is perceived as being emitted from a sound source shaped as a string, for example the string illustrated in Figure 3A. Thus, referring to Figure 3A, the generated audio signal component y1(t) is associated with point n = 1, and the audio signal component y2(t) is associated with point n = 2, etc. In this embodiment, each modification to the input audio signal involves, in order to obtain a modified audio signal component, the introduction of a time delay Δt n not only, but also the inversion of the audio input signal as indicated by signal inversion operations 161 to 16 n . The modified audio signal components are inverted with respect to the input audio signal in the case of a sounding body whose edges cannot vibrate freely, such as in the case of a string under tension or the skin of a drum. In the case of all sounding bodies whose edges vibrate freely, none of the modified audio signal components are inverted, and preferably, a high-pass filter is applied to the resulting signal component y n (t) to attenuate the low frequencies of the audio signal.

[0086] Optionally, the above modification also includes signal feedback operations 181 to 18 n , although this is not necessary for adding the dimensional information of the virtual sound source to the audio signal. The illustrated embodiment shows that each audio signal component y n (t) may be the result of the sum of the input audio signal x(t) and the inverted and time-delayed input audio signal. Figure 4 shows that the time delay operation is performed before the signal inversion operation 16, although this may be the opposite.

[0087] For a virtual sound source in the shape of a 1-meter-long string, the time differences for 17 equally spaced virtual points on the string may be as follows:[[ID=佃]]

[0088]

Table 1

[0089] These values for the introduced time delay are Δt n = Lx nIt follows / v, where L represents the length of the string, x n The multiplication coefficient is given by the virtual point n, and v is the speed of sound in the medium. For the values ​​in the table, a value of 343 m / s is used, which is the speed of a sound wave traveling through air at 20 degrees Celsius. The virtual point may be understood as being located on a line segment running from the center of the virtual sound source, e.g., a string, plate, or cube, to the edge of the virtual sound source. Thus, the virtual point may be understood as dividing the line segment into two parts: a first part running between the edge of the virtual sound source and the virtual point, and a second part running between the virtual point and the center of the virtual sound source. The multiplication coefficient may be equal to the ratio between the length of the first part of the line segment and the length of the second part of the line segment. Therefore, if the virtual point is located at the edge of the sound source, the multiplication coefficient is zero, and if the virtual point is located at the center of the virtual sound source, the multiplication coefficient is 1. Therefore, these values ​​would lead the user to perceive the generated audio signal as originating from a string-shaped sound source that is 1 meter long, while the speaker does not need to be spatially positioned in a specific manner.

[0090] In one embodiment, the method includes the steps of obtaining shape data representing the virtual position of each virtual point in the shape of a virtual sound source, and preferably determining the time delay to be introduced by each time delay operation based on the virtual position of each virtual point, according to the above formula.

[0091] Figure 3B schematically illustrates the modified audio signal components 222, 223, and 224 for points n=1, 2, and 3, respectively. These audio signal components are inverted with respect to the audio input signal 20 and time-delayed by Δt2, Δt3, and Δt4, respectively.

[0092] Figure 4 shows that the embodiment shown in Figure 1A is used as building block 21, but any of the embodiments shown in Figures 1A to 1J may be used.

[0093] Figure 5 illustrates that the generated audio signal, or generated audio signal components that together form the generated audio signal, can be panned to one or more speakers. This panning step may be performed using methods known in the art. In principle, the methods disclosed herein can add spatial information relating to the dimensions, distance, height, and depth of a virtual sound source to the audio signal, regardless of the panning method and regardless of how many speakers are used to reproduce the audio signal.

[0094] In one embodiment, each of the generated audio signal components may, in principle, be sent to all present speakers. However, depending on the panning method used, some of the audio signal components may be sent to speakers with zero amplification. In practice, such speakers will not receive such audio signal components. This is illustrated in Figure 5 for speakers C and D with respect to y1, for speakers A and D with respect to y2, and for speaker A with respect to y3. Typically, the panning system will provide the speakers with audio signal components through discrete amplification of each audio signal component to each speaker between 0 and 1.

[0095] Figure 6A depicts a further example of a virtual sound source to illustrate that the method can be used for virtual sound sources with more complex shapes. The generated audio signal y(t) may be perceived as originating from, for example, a plate-shaped sound source 24 or a cube-shaped sound source 26. Virtual points are defined in the shape of the virtual sound source. A total of 25 virtual points are defined on the plate-shaped sound source 24 in the example shown.

[0096] The virtual sound source may be formed as a set of regular polygons, or it may be an asymmetrical, irregular, or organically formed shape.

[0097] Figure 6B illustrates several modified audio signal components that can be used when the virtual sound source has a two-dimensional or three-dimensional shape. The figure shows that all modified audio signal components may be time-delayed, and that none of the modified audio signal components are inverted with respect to the input audio signal, according to the virtual sound source whose edges all oscillate freely.

[0098] Figure 7A is a flowchart illustrating an embodiment in which the observed person perceives the generated audio signal y(t) as emanating from a sound source formed as a plate. Again, multiple audio signal components y are associated with virtual points defined in the shape. n (t) is determined. In this embodiment, the audio signal component y n Each decision in (t) has a time delay Δt in order to obtain the corrected audio signal component. n.1 This includes modifying the input audio signal using a signal delay operation that introduces a second time delay, and optionally using a signal feedback operation 30. Subsequently, a second modified audio signal component is generated based on the combination 32 of the input audio signal and the modified audio signal component. The second modified audio signal component may be attenuated by, for example, about -6 dB (see attenuation element 34). The second modified audio signal component is then subjected to a signal delay operation Δt that introduces a second time delay. n.2 And optionally, a third modified audio signal component may be obtained by modifying it using a signal feedback operation 36. Then, based on the combination 38 of the second and third modified audio signal components, an audio signal component y n (t) may occur. Optionally, audio signal component y n This step of generating (t) may be understood as, for example, a -6dB attenuation action 40 and / or attenuation of frequencies below the lowest fundamental frequency occurring in the board, f n This includes the step of performing a high-pass filter operation 42 that applies a cutoff frequency.

[0099] In this embodiment, the step of determining the audio signal components includes the step of determining a first modified audio signal component and a third modified audio signal component. The step of determining the first or third modified audio signal component may include using a first or second time delay operation and a signal inversion operation, and optionally a first or second signal feedback operation, respectively.

[0100] In this example, two coupling operations 32 and 38 are performed per audio signal component. However, for virtual sound sources with more complex shapes, such as three-dimensional sound sources, three or more coupling operations are performed per audio signal component. An example of this is illustrated in Figure 14.

[0101] In Figure 7A, each y x (t) The diagram shows that two building blocks 21 are arranged in series to generate the signal, but each y x (t) It should be acknowledged that three or more building blocks 21, such as three, four, five, six or more, can also be arranged in series in order to generate a signal.

[0102] Figure 7B illustrates how the associated time delay and cutoff frequency can be calculated for each virtual point in a virtual sound source 50 formed as a square plate. As an example, Figure 7B illustrates how the time delay and cutoff frequency are calculated for point n=7 in the virtual sound source 50 formed as a plate.

[0103] The first step is to determine the three values ​​for the multiplication coefficient x mentioned above, namely x, for each virtual point, according to the following formula. A , x B , x C This consists of determining:

[0104]

number

[0105] Here, R represents the radius of the circle 52 that passes through the vertices where two or more edges of the virtual sound source 50 intersect. In this example, R is the radius of the circumscribed circle 52 of the square plate 50.

[0106] Furthermore, r n.A (See the example on the left in Figure 7B) represents the radius of the circle 56 passing through the vertices of square 54, where square 54 is a square whose midpoint coincides with the midpoint of the virtual sound source 50 and has point n, in this example point 7, on one of its sides. The sides of square 54 are parallel to the edge of board 50.

[0107] r n.B (See the central example in Figure 7B) represents the radius of the circle 60 passing through the vertices of the square 58, where the square 58 has a midpoint that coincides with the vertex closest to point n and has sides that are parallel to the edges of the virtual board sound source 50.

[0108] r n.C (See the example on the right side in Figure 7B) represents the minimum distance between the midpoint of board 50 and the edge of square 62, where square 62 has a midpoint that coincides with the midpoint of the virtual sound source 50 and has point n on one of its sides. Furthermore, square 62 has sides that are perpendicular to at least one diagonal of board A. In this example, since the virtual sound source is a square, square 62 is tilted 45 degrees with respect to board 50.

[0109] In the next step, the associated time delay Δt A Δt B Δt C Δt is determined according to Δt = Ax / v, but Δt B is, x B It is determined only when is 0.25 or less. Therefore, as shown in Figures 6A and 7B, a square plate with a 25 cm long edge and 25 virtual points, and for v = 500 m / s, x A , x B , x C and Δt A Δt B Δt C The values ​​for this are as follows:

[0110] [Table 2]

[0111] As shown, Δt A Δt B Δt C Some of the values ​​are zero, or x B The value >0.25 is not determined. As a result, for each virtual point n, Δt A Δt B Δt C There exist one or two distinct non-zero values ​​for . These values ​​are then determined to be Δt1 and Δt2. (See the table below.)

[0112] The cutoff frequency for the high-pass filter for each virtual point n may be determined.

[0113]

number

[0114] Therefore, its edge vibrates freely and its material structure is homogeneous, 625 cm 2 For a virtual sound source having a plate shape with a total surface area A, Δt and f c The following values ​​may be used for this.

[0115] [Table 3]

[0116] Therefore, these values ​​will lead the user to perceive that the generated audio signal originates from a homogeneous, plate-shaped sound source of a specific size, while the speaker does not need to be spatially positioned in a particular manner.

[0117] In one embodiment, the method includes the steps of obtaining shape data representing the virtual position of each virtual point in the shape of a virtual sound source, and determining the time delay to be introduced by each time delay operation based on the virtual position of each virtual point. If the virtual sound source is formed as a square plate, the time delay may be determined using the formula described above.

[0118] Similar to the case of 2D shapes, for 3D shapes, the generated audio signal component y is associated with a virtual point defined in the shape. n Two or more modified audio signal components are determined for part or each of (t). The value for the time delay to be introduced for each virtual point follows Δt = Vx / v, where V is the volume of the shape and x is the radial length r from the center and / or edge of the shape to point n with respect to the virtual point n. n This represents a multiplication coefficient that follows a certain rule, where v is related to the speed of sound in the medium.

[0119] For each geometric shape and / or heterogeneous material or material with different material conditions, various modifications to the algorithm may be applied according to the relationship between the spatial dimension of the shape and the time difference value at each virtual point.

[0120] If the shape is not a regular polygon and / or is irregularly shaped, the resulting audio signal component y n Three or more modified audio signal components may be obtained for part or each of (t).

[0121] Figure 7C illustrates an alternative embodiment to the embodiment in Figure 7A. While the embodiment in Figure 7A shows two building blocks 21 arranged in series, the embodiment in Figure 7C shows that the two building blocks 21 can be arranged in parallel. Value a in the embodiment of Figure 7C x,x This is the value a in the embodiment shown in Figure 7A. x,x It is the same as b x,x The value of is the value b in the embodiment shown in Figure 7A. x,x It is the same as this.

[0122] In the embodiment shown in Figure 7C, for each signal component y1(t), b n.1 and b n.2 This is particularly advantageous because the values ​​of each can be controlled independently of each other.

[0123] Figure 7C shows each y x (t) The diagram shows that two building blocks 21 are arranged in parallel for the generation of the signal, but each y x (t) It should be acknowledged that three or more building blocks 21, such as three, four, five, six or more, can be arranged in parallel in order to generate a signal.

[0124] Figure 7D illustrates an alternative embodiment to the embodiment in Figure 7C. While the embodiment in Figure 7C shows that two building blocks 21 can be arranged in parallel, Figure 7D shows that instead of two complete building blocks, two or more modified audio signals, for example three, four, five, six or more, are generated in parallel from the audio input signal, then summed, and optionally each signal y x The diagram illustrates that the audio input signal can be further modified by attenuation before being summed with (t) to generate the value a in the embodiment shown in Figure 7D. x,x This is the value a in the embodiments of Figures 7A and 7C. x,x It is the same as Figure 7D. Figure 7D is advantageous in that it allows for more efficient processing by reducing the amount of signal paths in the building block arrangement.

[0125] Figure 8 shows the spectrogram of (top) audio signal component y1(t) shown in Figure 6A, the spectrogram of (second from the top) audio signal component y6(t), the spectrogram of (middle) audio signal component y7(t), and (second from the bottom) audio signal component y 11 Spectrogram of (t) and (below) audio signal component y 13 The spectrogram of (t) is shown. The value of the time delay and the frequency cutoff f are shown. c The value can be found in the table above.

[0126] Figure 9A illustrates a flowchart of one embodiment of this method in which the generated audio signal is perceived by the observer as originating from a sound source S located at a distance, such as a horizontal distance away from the observer O. The horizontal distance can be understood as the distance between the perceived virtual sound source and the observer, where the virtual sound source is located in front of the observer.

[0127] In this embodiment, the input audio signal x(t) is modified using a time delay operation and a signal feedback operation that introduce a time delay to obtain a first modified audio signal. A second modified audio signal is then generated based on the combination of the input audio signal x(t) and the first modified audio signal. The audio signal y(t) is generated by attenuating the second modified audio signal and by performing the time delay operation as optionally illustrated.

[0128] Preferably, the time delay introduced by the time delay operation performed to obtain the first modified audio signal is as short as possible, for example, shorter than 0.00007 seconds, preferably shorter than 0.00005 seconds, and more preferably shorter than 0.00002 seconds. Most preferably, it is about 0.00001 seconds. For a digital sample rate of 96 kHz, the time delay may be 0.00001 seconds.

[0129] Depending on the value of c along with the value of d, the observer will perceive various distances between themselves and the virtual sound source. In this specification, the values ​​within the triangle, i.e., within the attenuation or amplification operation, may be understood to represent constants to which the signal is multiplied. Thus, if such a value is greater than 1, signal amplification occurs. If such a value is less than 1, signal attenuation occurs. When c=0 and d=1, no distance is perceived, and when c=1 and d=0, the maximum distance corresponding to the relative distance is perceived, the sound source becomes unperceptible, and therefore the resulting total audio signal output will be 0 (-inf dB). To perform a signal feedback operation to determine the first modified audio signal, the value for d may be related to the value for c as d=1-cx, where the value for x is a multiplication coefficient of 1 or less applied to the amount of signal feedback that affects the steepness of the high-frequency dissipation curve.

[0130] In one example, the method includes the step of obtaining distance data representing the distance of a virtual sound source. Then, in order to obtain a modified audio signal, the input audio signal is attenuated depending on the distance of the virtual sound source.

[0131] An arbitrarily chosen time delay, denoted by Δt², can produce a Doppler effect associated with the movement of a virtual sound source. Δt² can be determined as Δt² = L / v, where L is the distance between the sound source S and the observer O, and v is the speed of sound in the medium.

[0132] Figures 9C, 9D, and 9E illustrate alternative embodiments of the embodiment shown in Figure 9A. In this specification, the values ​​for c, d, and the introduced time delay are the same as those shown in Figure 9B.

[0133] Figure 9C differs from the embodiment illustrated in Figure 9A in that the signal delay operation is performed in the signal feedback operation.

[0134] Figure 9D illustrates an embodiment in which the input audio signal is modified to obtain a first modified audio signal 11 by using a signal feedback operation that recursively adds a modified version 13 of the input audio signal to itself, wherein the feedback operation includes a signal delay operation that introduces a time delay. In this embodiment, the audio signal y(t) is generated based on the first modified audio signal 11, and this step includes a signal attenuation 15 and, optionally, a time delay operation that introduces a second time delay.

[0135] Figure 9E illustrates an embodiment that includes the steps of generating a second modified audio signal 17 based on a combination 10 of a first modified audio signal 11 and a time-delayed version 13 of the first modified audio signal, and generating an audio signal y(t) based on the second modified audio signal and therefore on the first modified audio signal.

[0136] Figure 10 (top) shows the spectrogram of the total audio signal after applying c=0. The input audio signal is white noise. Here, when c=0, no correction is seen in the total audio signal.

[0137] Figure 10 (middle) shows the spectrogram of the total audio signal after applying c=0.5. The input audio signal is white noise. Observable results are a -12 dB decrease in volume and a gradual attenuation of high frequencies as the perceived distance between the observer and the sound over length L increases, i.e., higher frequencies of the sound dissipate more quickly and proportionally than lower frequencies. The curvature of high-frequency dissipation will increase or decrease by changing the value x, which is less than 1 and multiplied by the signal feedback amplitude.

[0138] Figure 10 (below) shows the spectrogram of the total audio signal after applying c=0.99. The input audio signal is white noise. The overall volume decreased by -32 dB, and the steepness of the high-frequency dissipation curve increased, making the output audio signal almost inaudible. The perceived effect was that the sound seemed to have dissipated almost completely in the distance.

[0139] Figure 11A illustrates a flowchart illustrating an embodiment of the method in which a virtual sound source S is positioned at a virtual height H above the observer O (see also Figure 11B). Here, in order to obtain a third modified audio signal, the input audio signal x(t) is modified using signal inversion, signal attenuation, and a time delay operation that introduces a time delay. The audio signal is then generated based on the combination, e.g., summation, of the input audio signal and the third modified audio signal.

[0140] It should be acknowledged that the signal delay operation, signal inversion operation, and signal attenuation operation may be performed in any order.

[0141] The input audio signal x(t) may be attenuated in a height-dependent manner, preferably such that the attenuation is lower as the virtual sound source is positioned higher than the observer, to obtain a third modified audio signal. This is illustrated in Figure 11 in that the value for e increases as the height of the sound source S increases.

[0142] The introduced time delay, as shown in Figure 11A, is preferably as short as possible, for example, shorter than 0.00007 seconds, preferably shorter than 0.00005 seconds, and more preferably shorter than 0.00002 seconds. Most preferably, for a digital sample rate of 96 kHz, the time delay may be 0.00001 seconds.

[0143] When the virtual sound source is positioned above the listener, modifying the input audio signal to obtain a third modified audio signal optionally includes performing a signal feedback operation. In certain examples, this step includes recursively adding to itself the attenuated signal resulting from time delay, signal attenuation, and signal inversion operations performed to ultimately obtain the third modified audio signal, for example. When a signal feedback operation is performed, the value f may be equal to f = e * x, where the value for x is a multiplier less than 1 applied to the amount of signal feedback that affects the steepness of the low-frequency dissipation curve. By varying the value e, preferably between 0 and 1, a sense of height can be optionally added to the audio signal simultaneously with the value f, where e = 0 and f = 0 correspond to no perceived height, and e = 1 and f < 1 correspond to the maximum perceived height, i.e., a distance above the observer where the sound source is almost imperceptible.

[0144] Figure 12 shows the spectrum of an audio signal according to one embodiment of the present invention.

[0145] Figure 12 (top) shows the spectrogram of the total audio signal after applying e=0. The input audio signal is white noise. Here, when e=0, no correction is seen in the total audio signal.

[0146] Figure 12 (middle) shows the spectrogram of the total audio signal after applying e=0.5. The input audio signal is white noise. The observable result is a gradual attenuation of low frequencies as the perceived height H of the sound source S above the observer O increases; that is, the lower the frequency of the sound, the more it dissipates with a proportional increase in the value e. The steepness of the low-frequency dissipation curve can be increased or decreased by changing the value x, which is less than 1 and multiplied by the signal feedback amplitude f.

[0147] Figure 12 (below) shows the spectrogram of the total audio signal after applying e=0.99. The input audio signal is white noise. The steepness of the high-frequency dissipation curve increased, making the output audio signal almost inaudible over f<12kHz, and the perceived effect was that the sound was far above the listener's head.

[0148] Figure 13A illustrates a flowchart illustrating an embodiment of the method in which a virtual sound source S is located at a virtual depth D below the observer O. (See also Figure 13B). This embodiment includes the steps of modifying an input audio signal x(t) using a time delay operation, signal attenuation, and signal feedback operation to obtain a sixth modified audio signal. In the depicted embodiment, the step of performing the signal feedback operation includes the step of recursively adding to itself the attenuated signal, e.g., the signal resulting from the time delay operation performed to ultimately obtain the sixth modified audio signal. In the depicted embodiment, this means that the value for h is non-zero. Preferably, the recursively added signal is attenuated depending on the depth below the observer, for example, the lower the virtual sound source is located below the observer (corresponding to a high value for h in Figure 13). The attenuation of the input audio signal before the feedback operation may be performed such that the lower the virtual sound source is located below the observer (corresponding to a high value for g in Figure 13), the lower the attenuation. Next, the audio signal y(t) is generated based on the combination of the input audio signal and the sixth modified audio signal.

[0149] The introduced time delay, as shown in Figure 13A, is preferably as short as possible, for example, shorter than 0.00007 seconds, preferably shorter than 0.00005 seconds, and more preferably shorter than 0.00002 seconds. Most preferably, for a digital sample rate of 96 kHz, the time delay may be 0.00001 seconds.

[0150] When g=0 and h=0, no depth is perceived, while when g=1 and h=1, the maximum depth is perceived between the sound source S and the observer O. To perform signal feedback operation to determine a third modified audio signal, the value for h may be related to the value for g, as h=g*x, where the value for x is a multiplication coefficient of 1 or less applied to the amount of signal feedback, which affects the steepness of the high-frequency dissipation curve.

[0151] Figures 13C to 13F illustrate alternative embodiments of the embodiment in Figure 13A, in which the virtual sound source is located at a virtual depth below the observer. The value of q and the time delay introduced by the signal delay operation may be the same as in Figure 13A.

[0152] Figures 13C and 13D are other embodiments that include, respectively, the steps of modifying an input audio signal x(t) using a time delay operation 23, a first signal attenuation operation 25, and a signal feedback operation to obtain a modified audio signal, and generating an audio signal based on the combination of the input audio signal and this modified audio signal. As can be readily seen, the embodiments of Figures 13C and 13D differ from the embodiment of Figure 13A in that the signal delay operation and signal attenuation may or may not occur in the signal feedback operation.

[0153] Figure 13E illustrates an embodiment that includes steps to generate an audio signal y(t) using a signal feedback operation that recursively adds a modified version of the input audio signal to itself, wherein the feedback operation includes a signal delay operation 23 that introduces a time delay and a first signal attenuation operation 25.

[0154] Figure 13F illustrates an embodiment in which a modified audio signal 11 is determined using signal feedback operation, and the audio signal y(t) is determined based on a combination 10 of the modified audio signal and the time-delayed and attenuated version of this modified audio signal.

[0155] Figure 14 illustrates a method and system for generating an audio signal according to one embodiment of the present invention. In particular, Figure 14 depicts a complex flowchart of spatial wave conversion. Based on the input signal x(t), several audio signal components y n (t) is determined, for example, for each virtual point in the shape of the virtual sound source. Each audio signal component y n (t) is Box 70 n The audio signal component y1(t) is determined by performing the steps shown inside. Each box 70 n In this case, although similar steps may be performed, parameters with different values ​​are used.

[0156] Figure 14 illustrates some combinations of several embodiments described herein. Box 72 consists of the embodiment shown in Figure 7A, however it may also consist of the embodiment shown in Figure 7C or Figure 7D. Box 74 consists of the embodiment illustrated in Figure 9A, however it should be acknowledged that any of embodiments 9C, 9D, and 9E may be implemented in box 74. Box 76 consists of the embodiment illustrated in Figure 11A. Box 78 consists of the embodiment illustrated in Figure 13A, however any of embodiments 13C, 13D, 13E, and 13F may be implemented in box 78. Therefore, the time delay introduced by the time delay operation of box 72 may be determined according to the method described herein with reference to Figures 7A to 7D. As described above, the signal inversion operation in box 72 only needs to be performed when the virtual sound source cannot vibrate freely at its edge. In such cases, the high-pass filter 73 does not operate. If the virtual sound source can vibrate freely at its edge, the signal inversion operation in box 72 does not occur. In such cases, preferably, the high-pass filter is activated. The value for the cutoff frequency may be determined according to the method described with reference to Figures 7A to 7D. Furthermore, parameters c and d in box 74 and the time delay may be valued and / or modified and / or determined as described with reference to Figures 9A to 9E. Parameters e and f may be valued and / or modified and / or determined as described with reference to Figures 11A and 11B. Parameters g and h may be valued and / or modified and / or determined as described with reference to Figures 13A to 13F.

[0157] Furthermore, it should be acknowledged that building block 21 may be any of the building blocks depicted in Figures 1B to 1J.

[0158] In the depicted embodiment, the steps for generating audio signal components thus include adding dimensional information to the input audio signal, which may be done by the step shown in box 72; adding distance information, which may be done by the step shown in box 74; and adding height information, which may be done by the step shown in box 76; or adding depth information, which may be done by the step shown in box 78. Furthermore, a Doppler effect may be added to the input audio signal, for example, by adding an additional time delay as illustrated in box 80.

[0159] Preferably, the virtual sound source is positioned above or below the observer, so only one of module 76 or 78 is performed. Module 76 can be deactivated by setting e=0, and module 78 can be deactivated by setting g=0.

[0160] Figure 15 shows a user interface 90 according to one embodiment of the present invention. One embodiment of the present method includes the step of generating the user interface 90 described herein. This user interface 90 allows the user to control the shape of a virtual sound source. - The virtual position of each virtual point in the shape of the virtual sound source, - Distance between the virtual sound source and the observer, - The height at which the virtual sound source is positioned above the observer, - Depth at which the virtual sound source is positioned below the observer This allows input.

[0161] All functional operations of spatial wave conversion are translated into front-end user characteristics, i.e., audible manipulation of sound in virtual space. The applications of the present invention are by no means limited to the layout of this particular interface example, and are subject to numerous system design techniques and can involve numerous levels of control for shaping and positioning sound sources in virtual space, and are not limited to any particular platform, medium, or visual design and layout.

[0162] The depicted user interface 90 includes an input module that allows the user to control the input audio signals of the chain using an input receiver. The input receiver may consist of multiple audio channels received from other chains or external audio sources, which together form the audio input signals of the chain. The user interface allows the user to control the amplification of each input channel, for example, by using a gain knob 92.

[0163] The user interface 90 may further include an output module that allows the user to route the combined audio output signals of a chain as audio input signals to other chains.

[0164] The user interface 90 may further include a virtual sound source definition section that allows the user to input parameters related to the virtual sound source, such as its shape, using, for example, a drop-down menu 96, and / or whether the virtual sound source is hollow or solid, and / or its scale and / or dimensions, such as its Cartesian dimension and / or rotation and / or resolution. The latter indicates how many virtual points are determined per unit of virtual surface area. This allows the user to control the amount of computation required.

[0165] The input means for inputting rotation parameters may be presented as an endless rotation knob for dimensions x, y, and z.

[0166] The user interface 90 may further include a position sector that allows the user to input parameters related to the position of the virtual sound source. The position of the shape in three-dimensional space may be represented by rectangular coordinates + / -x, y, z, with the virtual center of the space indicated as 0,0,0, and may be presented as a visible three-dimensional field in which virtual objects can be placed and moved. This three-dimensional control field may be expanded or contracted by adjusting the radius of the field.

[0167] The user interface 90 may further include an attribute section 100 that allows the user to control various parameters such as the bandwidth and peak level of resonance, perceived distance, perceived altitude, and Doppler effect.

[0168] The user interface 90 may further include an output section 102 that allows the user to control the output. For example, discrete amplification of each audio signal component distributed to a set amount of audio output channels may be controlled. The gain of each speaker may be automatically controlled by i) modeling the shape of the virtual sound source, ii) rotation of the shape in three-dimensional space, and iii) position of the shape in three-dimensional space. The method for distributing the audio signal components to the audio output channels may depend on the type of speaker configuration and may be achieved by any such method known in the art.

[0169] The output section 102 may include a master level fader 104.

[0170] User input received through the user interface may be used to determine appropriate values ​​for parameters in accordance with the methods described herein.

[0171] Figure 16 illustrates a block diagram illustrating a data processing system according to one embodiment. As shown in Figure 16, the data processing system 1100 may include at least one processor 1102 coupled to a memory element 1104 via a system bus 1106. Thus, the data processing system may store program code in the memory element 1104. Furthermore, the processor 1102 may execute program code accessed from the memory element 1104 via the system bus 1106. In one embodiment, the data processing system may be implemented as a computer suitable for storing and / or executing program code. However, it should be acknowledged that the data processing system 1100 may be implemented in the form of any system including a processor and memory capable of performing the functions described herein.

[0172] The memory element 1104 may include one or more physical memory devices, such as local memory 1108, and one or more mass storage devices 1110. Local memory may generally refer to random access memory or other non-persistent memory devices used during the actual execution of program code. Mass storage devices may be implemented as hard drives or other persistent data storage devices. The processing system 1100 may also include one or more cache memories (not shown) that provide temporary storage for at least some of the program code in order to reduce the number of times the program code must be retrieved from the mass storage devices 1110 during execution.

[0173] Input / output (I / O) devices, described as input device 1112 and output device 1114, can be optionally connected to the data processing system. Examples of input devices may include, but are not limited to, keyboards, pointing devices such as mice, etc. Examples of output devices may include, but are not limited to, monitors or displays, speakers, etc. Input and / or output devices may be connected to the data processing system directly or through an intermediary I / O controller.

[0174] In one embodiment, the input and output devices may be implemented as a composite input / output device (illustrated in Figure 16 by dashed lines surrounding input device 1112 and output device 1114). An example of such a composite device is a touch-sensitive display, sometimes referred to as a “touchscreen display” or simply a “touchscreen.” In such embodiments, input to the device may be provided by the movement of a physical object, such as a stylus or a user’s finger, on or near the touchscreen display.

[0175] The network adapter 1116 may also be coupled to the data processing system, enabling it to be coupled to other systems, computer systems, remote network devices, and / or remote storage devices through an intervening private or public network. The network adapter may include a data receiver for receiving data transmitted to the data processing system 1100 by the aforementioned systems, devices, and / or networks, and a data transmitter for transmitting data from the data processing system 1100 to the aforementioned systems, devices, and / or networks. Modems, cable modems, and Ethernet cards are examples of different types of network adapters that may be used with the data processing system 1100.

[0176] As shown in Figure 16, the memory element 1104 may store the application 1118. In various embodiments, the application 1118 may be stored in local memory 1108, in one or more mass storage devices 1110, or separately from local memory and mass storage devices. It should be acknowledged that the data processing system 1100 may further run an operating system (not shown in Figure 16) that facilitates the execution of the application 1118. The application 1118 is implemented in the form of executable program code and can be executed by the data processing system 1100, for example, by the processor 1102. Depending on the execution of the application, the data processing system 1100 may be configured to perform one or more steps of operation or method described herein.

[0177] In one embodiment of the present invention, the data processing system 1100 may represent an audio signal processing system.

[0178] Various embodiments of the present invention may be implemented as program products for use in computer systems, and the program of the program product defines the function of the embodiments (including the methods described herein). In one embodiment, the program may be housed in various non-temporary computer-readable storage media, but as used herein, the expression “non-temporary computer-readable storage media” includes all computer-readable media, with the sole exception being temporary, propagating signals. In another embodiment, the program may be housed in various temporary computer-readable storage media. Exemplary computer-readable storage media include, but are not limited to, (i) non-writable storage media on which information is persistently stored (e.g., read-only memory devices in a computer, such as CD-ROM disks, ROM chips, or any type of solid-state non-volatile semiconductor memory, readable by a CD-ROM drive), and (ii) writable storage media on which modifiable information is stored (e.g., flash memory, floppy disks or hard disk drives in a diskette drive, or any type of solid-state random-access semiconductor memory). The computer program may be executed in the processor 1102 described herein.

[0179] The technical terms used herein are for the sole purpose of describing specific embodiments and are not intended to limit the invention. Where used herein, the singular forms “a,” “an,” and “the” are intended to include the plural form unless otherwise specified by the context. Where used herein, the terms “comprises” and / or “comprising” identify the presence of a stated feature, integer, step, operation, element, and / or part, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, parts, and / or groups thereof.

[0180] In addition to all means or steps in the following claims, corresponding structures, materials, actions and equivalents of functional elements are intended to include any structures, materials or actions for performing a function in combination with other claimed elements which are claimed in detail. The description of embodiments of the present invention is presented for illustrative purposes only and is not intended to be exhaustive or to be limited to the implementations of the disclosed forms. Many changes and modifications will be apparent to those skilled in the art without departing from the scope and spirit of the invention. The embodiments have been selected and described to best illustrate the principles and some practical applications of the present invention and to enable those skilled in the art to understand the invention in relation to various embodiments with various modifications suitable for the particular use intended. [Explanation of Symbols]

[0181] 4. Signal delay operation 6. Signal Inversion Operation 8. Signal amplification or attenuation 10. Coupling operation 11. Corrected audio signal 12 Damping operation 10, 12 Signal Feedback Operation 13 Revised 14. Coupling operation 15. Signal attenuation 161~16 n Signal inversion operation 17. Second corrected audio signal 181~18 n Signal feedback operation 191~19 n Signal attenuation element 20 Audio input signals 21 Building Blocks 222, 223, and 224 Modified Audio Signal Components 23-hour delayed operation 24. Sound source in the shape of a plate 25. First signal attenuation operation 26. Cube-shaped sound sources 30. Signal Feedback Operation 32 Combine 34 Attenuation elements 36. Signal Feedback Operation 38 Combine 40 Damping operation 42. High-pass filter operation 50 Virtual Sound Sources 52 yen 54 squares 56 yen 58 squares 60 yen 62 squares 70 n box 72 boxes 73 High-pass filter 74 Boxes 76 boxes 78 boxes 80 boxes 90 User Interface 92 Gain knob 96 Drop-down menu 100 Attribute Sections 102 Output Section 104 Master Level Fader 1100 Data Processing System 1102 Processor 1104 memory elements 1106 System Bus 1108 Local memory 1110 Mass Storage Devices 1112 Input Devices 1114 Output Device 1116 Network Adapter 1118 applications x(t) Input audio signal y(t) Generated audio signal y n (t) Audio signal component

Claims

1. A method for generating an audio signal y(t) which is perceived by an observer as originating from a virtual sound source and the virtual sound source has a shape, wherein the method is The steps include obtaining an input audio signal x(t), The steps include determining a plurality of virtual points in the shape of the virtual sound source, For each of the aforementioned virtual points n, each audio signal component y is associated with that virtual point. n The step of generating (t) includes, The above method is (i) Each time delay Δt n The input audio signal x(t) is modified using a signal delay operation that introduces a corresponding modified audio signal component x'. n The steps to obtain (t), The modified audio signal component x' of the input audio signal x(t), or the inverted and / or attenuated or amplified version of the input audio signal x(t). n Based on the combination with (t), each of the aforementioned audio signal components y n The step includes generating (t), or (ii) Based on a signal feedback operation that recursively adds the modified input audio signal x(t) back to itself, each of the audio signal components y n (t) is a step in which the signal feedback operation generates the respective time delay Δt n Steps including a signal delay operation that introduces, The audio signal y(t) is divided into its respective audio signal components y n A method including the step of determining based on (t).

2. The steps include obtaining shape data that represents the respective virtual positions of each of the virtual points in the shape of the virtual sound source, A step of determining the respective time delay based on the respective virtual position of each of the aforementioned virtual points. The method according to claim 1, including the method described in claim 1.

3. The virtual sound source is at a distance from the observer, and the method is A step of obtaining a first modified audio signal by modifying the input audio signal using a time delay operation and a signal feedback operation that introduce a time delay, The steps include generating a second modified audio signal based on the combination of the input audio signal x(t) and the first modified audio signal, A step of generating the audio signal y(t) based on the second modified audio signal, comprising attenuating the second modified audio signal depending on the distance of the virtual sound source from the observer, and / or The method according to claim 1 or 2, further comprising the step of performing a time delay operation that introduces an additional time delay.

4. The virtual sound source is at a distance from the observer, and the method is A step of obtaining a first modified audio signal by modifying the input audio signal using a signal feedback operation that recursively adds the modified version of the input audio signal to itself, wherein the feedback operation includes a signal delay operation that introduces a time delay. The method includes the step of generating the audio signal y(t) based on the first modified audio signal, the step of including a time delay operation that introduces signal attenuation and / or an additional time delay, A step of generating a second modified audio signal based on a combination of the first modified audio signal and a time-delayed version of the first modified audio signal, The steps include attenuating the second modified audio signal depending on the distance of the virtual sound source from the observer, A step of generating the audio signal y(t) based on the attenuated second modified audio signal, and therefore based on the first modified audio signal, The method according to claim 1 or 2, further comprising:

5. The method according to claim 3 or 4, wherein the introduced time delay is shorter than 0.00007 seconds.

6. The method according to any one of claims 3 to 5, comprising the step of attenuating the second modified audio signal depending on the distance of the virtual sound source from the observer.

7. The signal feedback operation includes attenuating the signal and recursively adding the attenuated signal to the signal itself, and the method is The method according to claim 6, further comprising the step of controlling the first attenuation in the signal feedback operation and the second attenuation of the second modified audio signal in a distance-dependent manner, such that the greater the distance, the lower the first attenuation in the signal feedback operation and the higher the second attenuation of the second modified audio signal.

8. The virtual sound source is positioned at a virtual height above the observer, and the method is The steps include modifying the input audio signal x(t) using a signal inversion operation, a signal attenuation operation, and a time delay operation to introduce a time delay in order to obtain a third modified audio signal, The method according to any one of claims 1 to 7, comprising the step of generating the audio signal based on the combination of the input audio signal and the third modified audio signal.

9. The method according to claim 8, wherein the step of modifying the input audio signal to obtain the third modified audio signal includes the step of performing a signal feedback operation.

10. The method according to claim 8 or 9, wherein the signal attenuation operation for obtaining the third modified audio signal is performed depending on the height of the virtual sound source.

11. The method according to claim 10, wherein the signal attenuation operation is performed such that the degree of attenuation of the third modified audio signal decreases as the virtual sound source is positioned higher above the observer.

12. The method according to any one of claims 8 to 11, wherein the time delay introduced to obtain the third modified audio signal is shorter than 0.00007 seconds.

13. The virtual sound source is located at a virtual depth below the observer, and the method is The steps include modifying the input audio signal x(t) using a time delay operation, a first signal attenuation operation, and a signal feedback operation to obtain a sixth modified audio signal, The method according to any one of claims 1 to 7, further comprising the step of generating the audio signal based on the combination of the input audio signal and the sixth modified audio signal.

14. The virtual sound source is located at a virtual depth below the observer, and the method is The method according to any one of claims 1 to 7, comprising the step of generating the audio signal y(t) using a signal feedback operation that recursively adds a modified version of the input audio signal to itself, wherein the feedback operation includes a signal delay operation that introduces a time delay and a first signal attenuation operation.

15. The virtual sound source is located at a virtual depth below the observer, and the method is A step of obtaining a sixth modified audio signal by modifying the input audio signal using a signal feedback operation that recursively adds the modified input audio signal to itself, wherein the feedback operation includes a signal delay operation that introduces a time delay and a first signal attenuation operation. The method according to any one of claims 1 to 7, comprising the step of generating the audio signal based on a combination of the sixth modified audio signal and a time-delayed and attenuated version of the sixth modified audio signal.

16. The method according to any one of claims 13 to 15, wherein the introduced time delay for obtaining a sixth modified audio signal is less than 0.00007 seconds.

17. The method according to any one of claims 14 to 16, wherein the step of performing the signal feedback operation includes the step of recursively adding the attenuated signal to itself.

18. The method according to any one of claims 13 to 17, wherein the first signal attenuation operation is performed depending on the depth of the virtual sound source below the observer.

19. - Indicates the shape of the virtual sound source, and / or - Indicates the virtual position of each virtual point in the shape of the virtual sound source, and / or - Indicates the distance between the virtual sound source and the observer, and / or - The virtual sound source is positioned at a height above the observer, and / or - Indicates the depth at which the virtual sound source is positioned below the observer. The method according to any one of claims 1 to 18, further comprising the step of receiving user input.

20. - The shape of the virtual sound source, - The virtual position of each virtual point in the shape of the virtual sound source, - The distance between the virtual sound source and the observer, - The virtual sound source is positioned at a height above the observer, - Depth at which the virtual sound source is positioned below the observer The method according to any one of claims 1 to 19, further comprising the step of generating a user interface that allows the user to input at least one of the following.

21. A computer-readable storage medium in which computer-readable program code is embodied, A processor coupled to the computer-readable storage medium, configured to perform the method described in any one of claims 1 to 20 in response to the execution of the computer-readable program code, and A computer equipped with [a specific feature / equipment].

22. A computer program comprising at least one software code portion, wherein the software code portion, when executed in a computer system, is configured to perform the method according to any one of claims 1 to 20.

23. A non-temporary computer-readable storage medium storing at least one software code portion, wherein the software code portion is configured to perform the method described in any one of claims 1 to 20 when executed or processed by a computer.

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