KR20220091126A - Method and Apparatus for Determining Impulse Response Using Wave Field Synthesis - Google Patents

Abstract

A method and apparatus for determining an impulse response using sound field synthesis are disclosed. A method for determining an impulse response using sound field synthesis according to an embodiment of the present invention includes: identifying an impulse response for a first position of a listener in a space including a sound source; generating a gain and delay of sound field synthesis for a second position compared to the first position; and determining an impulse response for the second position by using the impulse response for the first position and the determined gain and delay.

Description

Method and Apparatus for Determining Impulse Response Using Wave Field Synthesis

The present invention relates to a method and apparatus for generating a room impulse response, which is an impulse response, using sound field synthesis, and more particularly, a technique for determining an impulse response based on a gain and delay of a sound field synthesis is about

As the VR (Virtual Reality) environment continues to spread, in order to provide 6DoF in a virtual three-dimensional space, the user's location and direction must be reflected in real time not only in the image but also in the sound. In order to reproduce the 3D sound in a 3D space, the 3D sound may be reproduced by convolving an impulse response (IR) of the space and an audio signal.

Among the prior art for obtaining an impulse response, a ray tracing method requires a complicated operation, and thus the operation time is long, which is not suitable for real-time operation. In addition, the image source method, which has relatively low complexity among the prior art for obtaining the impulse response, requires an operation every time to the listener position based on information on the structure of the dimensional space.

Therefore, there is a need for a method of calculating impulse information for each position in space to provide effective spatial sound to listeners without information on the three-dimensional spatial structure while maintaining the amount of computation not high.

The present invention can provide a method and apparatus for determining the impulse response of an adjacent point without a mathematical approach that requires a lot of computational power in determining the impulse response in an environment such as VR in which the listener's position freely changes.

In addition, the present invention may provide a method and apparatus for efficiently determining a room impulse response of an adjacent point in space using sound field synthesis.

A method of determining an impulse response using sound field synthesis according to an embodiment of the present invention includes: identifying an impulse response for a first position of a listener in a space; generating a gain and delay of sound field synthesis for a second position compared to the first position; and determining an impulse response for the second position by using the impulse response for the first position and the determined gain and delay.

The impulse response to the first position may be determined based on information on the position of the sound source and information on the first position.

Determining the impulse response for the second location may include: extracting a direct sound and a reflective sound of the impulse response for the first location; applying the determined gain and delay to the extracted directional sound and reflected sound; and generating an impulse response for the second location by combining the applied directional sound and the reflected sound.

The gain and delay of sound field synthesis for the second position are determined so that, when the second position is shorter than the first position from the virtual sound source, the gain of the second position is greater than the gain of the first position, The delay of the second position may be determined to be shorter than the delay of the first position.

The gain and delay of sound field synthesis for the second position are determined such that when the second position is longer than the first position from the virtual sound source, the gain of the second position is smaller than the gain of the first position, The delay of the second position may be determined to be longer than the delay of the first position.

In an apparatus for determining an impulse response for performing a method for determining an impulse response according to an embodiment of the present invention, the apparatus for determining an impulse response comprises a processor, the processor identifying an impulse response for a first position of a listener in a space, , generate a gain and delay of sound field synthesis for the second position compared to the first position, and determine the impulse response for the second position by using the impulse response for the first position and the determined gain and delay have.

The impulse response to the first position may be determined based on information on the position of the sound source and information on the first position.

The processor extracts a direct sound and a reflective sound of an impulse response for the first position, and applies the determined gain and delay to the extracted directional sound and the reflective sound; Combining the applied directional sound and reflective sound may produce an impulse response for the second location.

The gain and delay of sound field synthesis for the second position are determined so that, when the second position is shorter than the first position from the virtual sound source, the gain of the second position is greater than the gain of the first position, The delay of the second position may be determined to be shorter than the delay of the first position.

The gain and delay of sound field synthesis for the second position are determined such that when the second position is longer than the first position from the virtual sound source, the gain of the second position is smaller than the gain of the first position, The delay of the second position may be determined to be longer than the delay of the first position.

According to an embodiment of the present invention, in determining the impulse response in an environment such as VR in which the listener position freely changes, the impulse response of the adjacent point may be obtained without a mathematical approach that requires a lot of computational power.

In addition, according to an embodiment of the present invention, it is possible to efficiently determine an impulse response of an adjacent point in space using sound field synthesis.

1 is a diagram illustrating an apparatus for determining an impulse response according to an embodiment of the present invention.
2 is a diagram illustrating an example of gain and delay of sound field synthesis according to an embodiment of the present invention.
3 is a diagram illustrating an impulse response actually measured in a great hole according to an embodiment of the present invention.
4 is a diagram illustrating microphones for measuring an impulse response in a great hall according to an embodiment of the present invention.
5 is a diagram illustrating a process of determining an impulse response according to an embodiment of the present invention.
6 is a diagram illustrating a process of determining an impulse response using sound field synthesis according to an embodiment of the present invention.
7 is a diagram illustrating an example of determining an impulse response of a second position using sound field synthesis based on an impulse response of a first position according to an embodiment of the present invention.
8 is a flowchart illustrating a method of determining an impulse response using sound field synthesis according to an embodiment of the present invention.

Hereinafter, embodiments will be described in detail with reference to the accompanying drawings. However, since various changes may be made to the embodiments, the scope of the patent application is not limited or limited by these embodiments. It should be understood that all modifications, equivalents and substitutes for the embodiments are included in the scope of the rights.

The terms used in the examples are used for the purpose of description only, and should not be construed as limiting. The singular expression includes the plural expression unless the context clearly dictates otherwise. In this specification, terms such as "comprise" or "have" are intended to designate that a feature, number, step, operation, component, part, or a combination thereof described in the specification exists, but one or more other features It should be understood that this does not preclude the existence or addition of numbers, steps, operations, components, parts, or combinations thereof.

Unless defined otherwise, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which the embodiment belongs. Terms such as those defined in commonly used dictionaries should be interpreted as having a meaning consistent with the meaning in the context of the related art, and should not be interpreted in an ideal or excessively formal meaning unless explicitly defined in the present application. does not

In addition, in the description with reference to the accompanying drawings, the same components are given the same reference numerals regardless of the reference numerals, and the overlapping description thereof will be omitted. In describing the embodiment, if it is determined that a detailed description of a related known technology may unnecessarily obscure the gist of the embodiment, the detailed description thereof will be omitted.

1 is a diagram illustrating an apparatus for determining an impulse response according to an embodiment of the present invention.

FIELD OF THE INVENTION The present invention relates to techniques for determining the impulse response for generating stereophonic sound in a space. The present invention can determine the impulse response of the current position from the impulse response of the previous position through an efficient operation using Wave Field Synthesis. The method for determining an impulse response according to an embodiment of the present invention is performed by an apparatus for determining an impulse response. The determining device may include a processor.

Referring to FIG. 1 , the determination apparatus according to an embodiment of the present invention may determine an impulse response of an audio signal based on a location of a sound source and a location of a listener. The determining device may determine the impulse response for the changed position of the listener from the impulse response using sound field synthesis.

Sound field synthesis is a theory based on Huygens' principle that every point on a wavefront generated by a sound source acts as a point source of a spherical secondary wavefront. Sound field synthesis may be implemented with a loudspeaker arranged in a line array.

Through the sum of the sound waves produced by each loudspeaker, it creates a sound field close to the real world. A plane wave having a characteristic of recognizing the same sound source direction to a plurality of listeners in a listening space may be generated through sound field synthesis. The virtual sound source can be located anywhere in the room, such as behind a loudspeaker or inside the listening room.

In this case, as the distance from the sound source increases with respect to the loudspeaker closest to the sound source, the sound pressure of the waveform generated by the loudspeaker may decrease and time may be delayed.

2 is a diagram illustrating an example of gain and delay of sound field synthesis according to an embodiment of the present invention.

FIG. 2A is a diagram illustrating an impulse response of a loudspeaker arranged in a line array. In the graph for the impulse response of each loudspeaker shown in (a) of FIG. 2, each vertical axis represents sound pressure, and the horizontal axis represents time.

In FIG. 2 , when the loudspeaker outputs stereophonic sound in the positive direction on the horizontal axis on the graph, the virtual sound source 200 may be located in the center of the back of the loudspeaker. Referring to FIG. 2 , the loudspeaker 201 closest to the virtual sound source outputs the audio signal so that the gain of sound field synthesis is determined to be the highest, and outputs the audio signal so that the delay of the sound field synthesis is determined to be the shortest.

Referring to FIG. 2 , with respect to the loudspeaker 201 closest to the virtual sound source, the waveforms of the other loudspeakers and the gain or delay value of sound field synthesis may be symmetrical. That is, as the listener's position is closer to the virtual sound source, the gain of sound field synthesis may be determined to be high, and the delay of the sound field synthesis may be determined to be the shortest. Conversely, as the listener's position is farther from the virtual sound source, the gain of sound field synthesis may be determined to be low, and the delay of sound field synthesis may be determined to be longest.

A method of calculating the audio signal output from the loudspeaker in sound field synthesis may be according to Equation 1 below.

은 라우드스피커 중 n번째 라우드스피커가 방사하는 오디오 신호를 나타낼 수 있다.

는 가상 음원의 오디오 신호를 의미할 수 있다.

는 출력되는 오디오 신호의 크기에 대한 가중치이며,

는 라우드 스피커의 지향성으로 음압에 적용되는 웨이팅(weighting)을 의미할 수 있다.

may represent an audio signal emitted by the nth loudspeaker among the loudspeakers.

may mean an audio signal of a virtual sound source.

is the weight for the size of the output audio signal,

is the directivity of the loudspeaker and may mean weighting applied to sound pressure.

는 수직거리에 대한 가상음원과 n번째 라우드스피커 사이의 거리의 비율을 의미하고,

는 고주파 증폭 이퀄라이징을 나타내며,

는 가상 음원과 n번째 라우드 스피커 사이의 거리에 의해 발생하는 전달 시간을 의미할 수 있다. 그리고, 라우드 스피커가 라인 어레이로 배열되므로 가상 음원이 선 음원인 경우,

는 하나의 원통파(cylindrical wave)의 확산을 의미한다.

is the ratio of the distance between the virtual sound source and the nth loudspeaker to the vertical distance,

represents the high-frequency amplification equalization,

may mean a transmission time caused by the distance between the virtual sound source and the nth loudspeaker. And, since the loudspeakers are arranged in a line array, if the virtual sound source is a line sound source,

is the spread of one cylindrical wave.

According to Equation 1, the gain or delay of the other loudspeakers may be symmetric with respect to the loudspeaker 201 closest to the virtual sound source. In fact, as a result of measurement in the great hall of FIG. 4 , the waveform output from each loudspeaker as shown in FIG. 3 is similar to that of FIG. 2 .

3 is a diagram illustrating an impulse response actually measured in a great hole according to an embodiment of the present invention. 3 is a diagram illustrating an impulse response actually collected through microphones arranged in a line array in a great hall. The internal structure of the great hole will be described later with reference to FIG. 4 .

Referring to FIG. 3 , in the graph for the impulse response of each microphone shown in FIG. 3A , each vertical axis represents sound pressure, and the horizontal axis represents time. The impulse response of the microphone shown in FIG. 3 may have a waveform similar to that of FIG. 2 . The sound source 300 of FIG. 3 may correspond to the speaker 400 of FIG. 4 .

4 is a diagram illustrating microphones for measuring an impulse response in a great hall according to an embodiment of the present invention. 4 is a view showing the structure of the great hole. When the audio signal generated from the actual sound source 400 is collected through the microphone 401 arranged in a line array, a waveform as shown in FIG. 3 may be obtained. In FIG. 4 , when a waveform is connected to the delay of sound field synthesis, it may appear as the line segment 402 of FIG. 4 .

5 is a diagram illustrating a process of determining an impulse response according to an embodiment of the present invention.

In order to determine the impulse response according to an embodiment of the present invention, the impulse response 504 for the listener's first position must be determined. The first location may mean an initial location of the listener. A method for determining an impulse response according to an embodiment of the present invention may be used when the location of another listener is identified or when an altered location of the listener is identified.

In order to determine the impulse response 504 for the first position, the information 501 about the first position of the listener, the information 502 about the position of the sound source, and the audio signal of the sound source may be used in the operation 503 . have. The impulse response 504 for the first position may be determined in a variety of ways and may not be limited to a specific example. Whenever the listener's position is changed, when the impulse response is determined in the above manner, the amount of computation can be large. Therefore, in the present invention, the impulse response 504 for the initial position is determined, and the gain of the sound field synthesis 505 and Delay can be used.

When the impulse response 504 for the first position is determined, and a second position distinct from the first position is identified, the determining device determines the gain of the sound field synthesis 505 for the second position relative to the first position and It can create delays. The determining device may determine the impulse response 506 for the second position by using the impulse response for the first position and the determined gain and delay.

When the second location is shorter than the first location from the virtual sound source, the gain of the second location may be determined to be greater than the gain of the first location, and the delay of the second location may be determined to be shorter than the delay of the first location.

The gain and delay of sound field synthesis for the second position are determined such that, when the second position is longer than the first position from the virtual sound source, the gain of the second position is smaller than the gain of the first position, and the delay of the second position may be determined to be longer than the delay of the first position.

6 is a diagram illustrating a process of determining an impulse response using sound field synthesis according to an embodiment of the present invention.

When the impulse response 601 for the first position is determined and a second position distinct from the first position is identified, the determining device generates a gain and delay of sound field synthesis for the second position relative to the first position. can do.

Referring to FIG. 6 , the determination device may extract a direct sound 602 and a reflective sound 603 of an impulse response 601 for a first position. The determining device may apply the determined gain and delay to the extracted directional sound 602 and reflected sound 603 .

In one embodiment, when the second position is shorter than the distance from the virtual sound source than the first position, the determining device determines the impulse response 601 for the first position by the gain of sound field synthesis for the second position compared to the first position. It is possible to increase the sound pressure of the directional sound 602 and decrease the sound pressure of the reflective sound 603 .

In one embodiment, when the second position is shorter than the distance from the virtual sound source than the first position, the determining device determines the impulse response 601 for the first position by the delay of sound field synthesis for the second position compared to the first position. It is possible to reduce the delay of the directional sound 602 and increase the delay of the reflective sound 603 .

In one embodiment, when the second position is longer than the first position from the virtual sound source, the determining device determines the impulse response 601 for the first position by the gain of sound field synthesis for the first position compared to the second position. It is possible to decrease the sound pressure of the directional sound 602 and increase the sound pressure of the reflective sound 603 .

In one embodiment, when the second position is longer from the virtual sound source than the first position, the determining device determines the impulse response 601 for the first position by a delay of sound field synthesis for the first position compared to the second position. It is possible to increase the delay of the directional sound 602 and decrease the delay of the reflective sound 603 .

The determining device may generate an impulse response for the second position by combining the directional sound 605 and the reflected sound 606 with gain and delay applied.

7 is a diagram illustrating an example of determining an impulse response of a second position using sound field synthesis based on an impulse response of a first position according to an embodiment of the present invention.

FIG. 7A is a diagram illustrating an impulse response to a first position as a graph, and FIG. 7B is a diagram illustrating an impulse response to a second position as a graph. 7 illustrates a case in which the distance from the virtual sound source is increased when the listener is changed from the first position to the second position.

In one embodiment, when changing from the first position to the second position, when the distance from the virtual sound source is increased, the sound pressure of the impulse response directional sound 701 in FIG. is reduced by the gain of sound field synthesis for the first position compared to the second position, and may appear as a directional sound 703 .

In one embodiment, when changing from the first position to the second position, when the distance from the virtual sound source increases, the delay of the directional sound 701 of the impulse response in FIG. is increased by the delay of sound field synthesis for the first position compared to the second position in , and may appear as a directional sound 703 .

In one embodiment, when changing from the first position to the second position, when the distance from the virtual sound source increases, the sound pressure of the impulse response reflective sound 702 in FIG. ) is increased by the gain of sound field synthesis for the first position compared to the second position, and may appear as a reflective sound 704 .

In one embodiment, when changing from the first position to the second position, when the distance from the virtual sound source increases, the delay of the reflective sound 702 of the impulse response in FIG. ) is reduced by the delay of sound field synthesis for the first position compared to the second position, and may appear as a reflective sound 704 .

8 is a flowchart illustrating a method of determining an impulse response using sound field synthesis according to an embodiment of the present invention.

In step 801 , the determining device may identify an impulse response for the first predetermined location. Also, the determining device may identify a second location that is distinct from the first location.

In step 802 , the determining device may generate a gain and delay of the sound field synthesis 505 for the second position relative to the first position. In step 803 , the determining device may determine the impulse response 506 for the second position by using the impulse response for the first position and the determined gain and delay.

Meanwhile, the method according to the present invention is written as a program that can be executed on a computer and can be implemented in various recording media such as magnetic storage media, optical reading media, and digital storage media.

Implementations of the various techniques described herein may be implemented in digital electronic circuitry, or in computer hardware, firmware, software, or combinations thereof. Implementations may be implemented for processing by, or for controlling the operation of, a data processing device, eg, a programmable processor, computer, or number of computers, a computer program product, ie an information carrier, eg, a machine readable storage It may be embodied as a computer program tangibly embodied in an apparatus (computer readable medium) or a radio signal. A computer program, such as the computer program(s) described above, may be written in any form of programming language, including compiled or interpreted languages, as a standalone program or in a module, component, subroutine, or computing environment. It can be deployed in any form, including as other units suitable for use in A computer program may be deployed to be processed on one computer or multiple computers at one site or distributed across multiple sites and interconnected by a communications network.

Processors suitable for processing a computer program include, by way of example, both general and special purpose microprocessors, and any one or more processors of any kind of digital computer. In general, a processor will receive instructions and data from either read-only memory or random access memory or both. Elements of a computer may include at least one processor that executes instructions and one or more memory devices that store instructions and data. In general, a computer may include one or more mass storage devices for storing data, for example magnetic, magneto-optical disks, or optical disks, receiving data from, sending data to, or both. may be combined to become Information carriers suitable for embodying computer program instructions and data are, for example, semiconductor memory devices, for example, magnetic media such as hard disks, floppy disks and magnetic tapes, Compact Disk Read Only Memory (CD-ROM). ), optical recording media such as DVD (Digital Video Disk), magneto-optical media such as optical disk, ROM (Read Only Memory), RAM (RAM) , Random Access Memory), flash memory, EPROM (Erasable Programmable ROM), EEPROM (Electrically Erasable Programmable ROM), and the like. Processors and memories may be supplemented by, or included in, special purpose logic circuitry.

In addition, the computer-readable medium may be any available medium that can be accessed by a computer, and may include both computer storage media and transmission media.

While this specification contains numerous specific implementation details, they should not be construed as limitations on the scope of any invention or claim, but rather as descriptions of features that may be specific to particular embodiments of particular inventions. should be understood Certain features that are described herein in the context of separate embodiments may be implemented in combination in a single embodiment. Conversely, various features that are described in the context of a single embodiment may also be implemented in multiple embodiments, either individually or in any suitable subcombination. Further, although features operate in a particular combination and may be initially depicted as claimed as such, one or more features from a claimed combination may in some cases be excluded from the combination, the claimed combination being a sub-combination. or a variant of a sub-combination.

Likewise, although acts are depicted in the drawings in a particular order, it should not be construed that all acts shown must be performed or that such acts must be performed in the specific order or sequential order shown to obtain desirable results. In certain cases, multitasking and parallel processing may be advantageous. Further, the separation of the various device components of the above-described embodiments should not be construed as requiring such separation in all embodiments, and the program components and devices described may generally be integrated together into a single software product or packaged into multiple software products. You have to understand that you can.

On the other hand, the embodiments of the present invention disclosed in the present specification and drawings are merely presented as specific examples to aid understanding, and are not intended to limit the scope of the present invention. It will be apparent to those of ordinary skill in the art to which the present invention pertains that other modifications based on the technical spirit of the present invention can be implemented in addition to the embodiments disclosed herein.

101: impulse response determining device
102: location information of the sound source
103: location information of the listener
104: impulse response

Claims (1)

A method for determining an impulse response using sound field synthesis, the method comprising:
identifying an impulse response for a first location of a listener in space;
generating a gain and delay of sound field synthesis for a second position compared to the first position; and
determining an impulse response for the second position by using the impulse response for the first position and the determined gain and delay;
A decision method comprising

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