KR100636251B1 - Method and apparatus for spatial stereo sound - Google Patents

Abstract

A method and an apparatus for generating 3-dimensional sound are provided to obtain an efficient spaciousness with a small amount of calculation by patterning a reflection sound and to obtain a 3-dimensional sound by positioning reflection sounds. A apparatus for generating 3-dimensional sound comprises a delay filter(901), a gain adjusting unit(903), a feedback comb filter(905), a positioning filter(911) and a mixing unit(950). The delay filter(901) generates reflection sounds by delaying a signal of one channel according to different delay values. The gain adjusting unit(903) multiplies predetermined different gain values to the respective reflection sounds generated from the delay filter(901). The feedback comb filter(905) generates continuous reflection sound patterns to the respective reflection sounds through a feedback loop having delay values and gain values. The positioning filter(911) considers an incident interaural time differences(ITD) and an incident interaural level difference(ILD) between two ears to the respective reflection sound and separates a first channel signal with a second channel signal. The mixing unit(950) adds the first channel to the first channel, and the second channel to the second channel to the respective reflection sound signals separated at the positioning filter(911).

Description

Method and apparatus for generating stereo sound {Method and apparatus for spatial stereo sound}

1 is an echogram diagram for explaining a conventional method for generating a reflection sound.

2 is a block diagram of a conventional stereoscopic sound generating apparatus.

3 is a conceptual diagram showing a time difference between two ears.

4 is a conceptual diagram illustrating reflection sound generation in a virtual space.

5 is a basic unit block diagram used in the 3D sound generating apparatus according to the present invention.

FIG. 6 illustrates a reflection sound pattern generated in the operation of the block diagram of FIG. 5.

Figure 7 is a block diagram of a three-dimensional sound generating apparatus according to an embodiment of the present invention.

FIG. 8 is a signal pattern diagram illustrating a method for generating reflection sound in the stereoscopic sound generating apparatus of FIG. 7.

9 is a block diagram of a stereophonic sound generating apparatus according to another embodiment of the present invention.

10A to 10F are various other examples of the localization filter unit of FIG. 9.

11 is a flowchart showing a three-dimensional sound generating method according to the present invention.

The present invention relates to a three-dimensional sound system, and more particularly, to a three-dimensional sound generating method and apparatus for generating reflected sounds for the input sound signal, and generating a stereo sound using the reflected sounds.

Typically, the stereophonic sound generating apparatus forms a virtual sound source at a specific position in a virtual space through headphones or a speaker placed at a specific position, so that the sound heard by the listener is actually heard from where the virtual sound source is located. It creates a sense of space. For example, the 3D sound generating device generates a 3D sound signal using the reflected sound so that the listener can feel a 3D feeling and a spatial feeling when playing through 2 channels of headphones, earphones, or speakers.

1 is an echogram diagram for explaining a conventional method for generating a reflection sound.

Referring to FIG. 1, the echogram is composed of a direct sound (no reflection sound), an early reflection sound, and a late reflection sound (reverberation sound).

Early reflections typically use the Tapped delay line method, which consists of a delay filter and multipliers. The Tapped Delay Line method performs a kind of FIR filtering and requires tens to hundreds of delay filters, multipliers, adders, etc. to generate tens to hundreds of early reflections.

Late reflection is also artificially generated using a Schroeder reverberator, as shown in FIG. Schroeder reverberators are mentioned as prior art in US 5,491,754 (filed Feb. 19, 1993 titled Method and system for artificial spatialization of digital audio signals).

This shredder reverberator includes four feedback comb filters and two all-pass filters. The input acoustic signals x (z) pass through four feedback comb filters connected in parallel with different time delay values and gain values, and are summed and output. The summation output of the four feedback comb filters passes through two all-pass filters in series with different time delays and gains to produce reflections. Finally, the signal passing through the all-pass filter is output as a spatial sound signal y (z).

However, since the shredder reverberator is not located in the reflection sounds, there is no consideration in the direction that plays an important role in the listener's perception of the direction of the sound source.

Therefore, the conventional stereo sound generation method using the reflected sound has a large amount of calculation using the tap delay line and the artificial reverberator separately, and the reflection sound sources are not located.

In addition to the above-described prior art, there are methods using a head related transfer function (HRTF) to generate more sophisticated stereo sound, but methods using the head transfer function require a large amount of computation. There is a disadvantage.

The technical problem to be achieved by the present invention is to provide a three-dimensional sound generating method and apparatus for providing a three-dimensional effect by providing a sense of space with a small amount of calculation by reflecting the patterned reflection sound and positioning a plurality of reflection sounds.

In order to solve the above technical problem, the present invention is a stereo sound generating method,

Delaying an input signal according to a plurality of different delay values to generate a plurality of reflection sounds;

Multiplying the delayed reflections by predetermined gains;

Generating continuous reflections through a feedback loop reflecting a different delay value and a gain value for each reflected sound multiplied in the above process, wherein the different delay values are determined based on a size of a predetermined virtual space. The different gain values may be determined based on the degree of sound absorption of the virtual space.

In order to solve the above other technical problem, the present invention provides a stereo sound generating apparatus,

A delay filter unit delaying a signal of one channel according to a plurality of delay values and generating a plurality of reflection sounds;

A gain adjusting unit multiplying predetermined reflection values different from each of the reflection sounds generated by the delay filter unit;

A feedback comb filter unit generating continuous reflection sound patterns through a feedback loop by reflecting a plurality of different delay values and gain values for each reflection sound multiplied by the gain adjusting unit;

A localization filter unit for splitting the reflected sound generated by the feedback comb filter unit into signals of the first and second channels by reflecting an incident time difference between two ears and a sound pressure difference;

And a mixer unit for adding the first channel and the second channel to each of the reflected sound signals separated by the channel from the localization filter unit, wherein the localization filter unit generates an IDL filter reflecting a level difference between two ears and a time difference between the two ears. It has a reflected ITD filter, and outputs the signal of one channel as it is, and outputs the signal of the other channel through the ITD filter and the ILD filter.

Hereinafter, exemplary embodiments of the present invention will be described with reference to the accompanying drawings.

The present invention basically generates a two-channel stereo sound signal reflecting a three-dimensional feeling and a sense of space with respect to the input signal of one channel for each channel, when the listener reproduces the signal using two-channel headphones, earphones, speakers, etc. Make you feel The method of obtaining a three-dimensional feeling and a sense of space is to arrange a plurality of virtual sound sources around the listener to give a three-dimensional surround effect that makes the listener feel surrounded by the sound. It avoids in head localization and makes the listener feel as if the image is out of head. To this end, the present invention design a virtual room to generate a plurality of reflections, so that the listener can feel the sound field effect as if listening in the virtual space.

With regard to stereophonic sound generation, the relative perception of the sound source from the listener can be obtained from the difference in sound pressure of the signal incident on both ears. The typical perception of the direction of the sound source is the time difference between two ears (ITD) and the level difference between two ears (ILD). The time difference between two ears (ITD) refers to the time difference of a signal transmitted between two ears resulting from the difference in the length of the path from the source to the two ears of the listener as shown in FIG. ITD may be represented as in Equation 1.

ITD = r (θ + sinθ) / C ₀

Where C ₀ is the speed of sound, about 344 m / s in air.

The ITD can effectively perceive in the low frequency range below approximately 700 Hz.

On the other hand, ILD means the amplitude difference or the level difference of the signal transmitted between the two ears of the listener. ILD is mainly caused by negative scattering in the head and ears.

Therefore, location of sound source can be realized by using ITD and ILD. That is, ITD is a delay value and ILD can be implemented by gain adjustment.

In general, when listening to a stereo sound signal through headphones or earphones, the sound image is often formed in the head or both ears. If the sound image is moved like listening through two speakers, the listener may feel a 3D effect.

On the other hand, the headphone playback system is susceptible to the so-called "In-head localization" phenomenon in which the sound image forms in the head of the listener when stereo sound is not reproduced or provided correctly. Therefore, by adding the reflections generated in the virtual space to the headphone playback sound, the "in-head localization" phenomenon can be eliminated and the image can be formed at a desired position outside the head.

As shown in FIG. 4, the reflected sound can be implemented from a simple structural model of the room. 4 shows one of the mirror image sources for one sound source 403 in a given virtual room. The mirror image sound source 405 is a virtual sound source in which the sound source 403 is reflected from the wall on a symmetrical plane of the virtual wall. The reflected sound can be modeled using a mirror image sound reflected on the virtual wall. That is, the delay time of the reflected sound reaching the sound of the listener 400 from the sound source 403 may be replaced by the delay time of the linear distance from the corresponding mirror image sound source 405 to the listener 400. The intensity of the reflected sound can also be calculated from the strength of the mirror image sound source depending on the degree of sound absorption of the wall. In addition to the original sound source, the virtual sound sources are regenerated as infinite sound sources due to the reflection sound from the wall of the virtual space. Set finite virtual sound sources at an appropriate level among infinite virtual sound sources. The delay time and the sound source strength for each virtual sound source are calculated. For each virtual sound source, each ITD and ILD are calculated according to the incident angle to the listener. Each calculated parameter depends on the type and boundary conditions of the given room and the location of the listener and sound source. Therefore, it is necessary to properly design the virtual space in order to generate the effective reflection sound.

5 is a basic unit block diagram used in the 3D sound generating apparatus according to the present invention.

Referring to FIG. 5, the unit block performs patterning of reflection sounds reflected on a wall in a virtual space, and generates a first reflection sound using the first delay unit 501 and the first gain adjuster 503. And a feedback comb filter composed of an adder 505, a second delay unit 507, and a second gain adjuster 509 to generate a reflection pattern related to the first reflection sound.

The first delay unit 501 and the first gain adjuster 503 generate the first reflection sound signal for the input signal as shown in FIG. That is, the input signal is delayed by the delay value of the first delay unit 501, and then the gain is adjusted to the gain value of the first gain adjuster 503. At this time, if the delay value of the first delay unit 501 and the gain value of the first gain adjuster 503 are properly adjusted, the same signal as the reflection sound for the input signal can be generated in space.

The feedback comb filter composed of the adder 505, the second delayer 507, and the second gain adjuster 509 continuously generates additional reflection sound patterns related to the first reflection sound as shown in FIG. 6. The feedback comb filter generates the second reflection sound, the third reflection sound, and the n th reflection sound as shown in FIG. 6. The pattern of the reflected sounds is gradually reduced in level according to the gain value set in the second gain adjuster 509 at intervals of the delay value set in the second delay unit 507. Accordingly, by properly adjusting the delay value of the second delay unit 507 and the gain value of the second gain adjuster 509, a signal pattern that is almost similar to the reflection sounds in space may be generated in terms of psychoacoustics.

The gain value of the second gain adjuster 509 may be adjusted to adjust the magnitude (strength) of the reflected sound fed back to the adder 505. This corresponds to changing the average sound absorption in the real space. In addition, the delay value of the second retarder 507 may be changed in order to change the feeling of space, that is, the feeling of space. In other words, if the delay value of the second retarder 507 is varied, it is heard that the reflection sound density is changed on the time axis acoustically, and the sense of space is acoustically changed.

Accordingly, the apparatus for generating stereo sound according to the present invention can be configured by connecting unit blocks having the configuration as shown in FIG. 5 in parallel.

Figure 7 is a block diagram of a three-dimensional sound generating apparatus according to an embodiment of the present invention.

The stereoscopic sound generating apparatus of FIG. 7 implements the patterning of the reflected sounds reflected on the n walls of the virtual space, and includes a delay unit 701, a gain adjusting unit 703, a feedback comb filter unit 705, and an adder unit 750. ). The stereoscopic sound generating apparatus according to the present embodiment basically arranges the unit blocks described in FIG. 5 in parallel, and adds outputs of these unit blocks through the adder 750.

In the 3D sound generating apparatus, the delay unit 701 includes eleventh through n1 delays 7011 through 701n, and the eleventh through n1 delayers 7011 through 701n respectively output the input signal IN. , t21,, tn1 Delayed by the time and outputs. The gain adjusting unit 703 includes eleventh through n1 gain adjusters 7031 through 703n, and the eleventh through n1 gain adjusters 7031 through 703n respectively output the eleventh through n1 retarders 7011 through 701n. A signal obtained by multiplying each of the gain values g11, g21, and gn1 is output.

Delay values of each of the eleventh to n1 delayers 7011 to 701n may be set from delay times reaching the listeners from the n mirror image sources generated from the virtual sound sources located in the virtual room, respectively. This depends on the size of the virtual space.

The gain values g11, g21, and gn1 of the eleventh to n1 gain adjusters 7031 to 703n are proportional to the relative sound pressure levels of the n mirror image sources generated from the virtual sound source, which is the boundary of the virtual room. It depends on the condition.

Reflected sounds output in parallel from the gain adjusting unit 703 are transmitted to the feedback comb filter unit 705. The feedback comb filter unit 705 continuously generates a plurality of reflections whose time is delayed and the gain is adjusted for each of the reflection sounds input from the gain adjusting unit 703 through a feedback loop. That is, the feedback comb filter unit 705 continuously generates additional reflection sounds for each of the reflection sounds output from the gain adjusting unit 703. If the delay values of the feedback comb filter unit 705 are t12, t22, and tn1 and the gain values are g12, g22 and gn2, each of these values can be set based on the reflection pattern in the virtual space. In this case, the gain values g11, g22, and gn2 are values whose absolute value is smaller than one.

The adder 750 generates one output signal by summing respective reflection sounds output from the feedback comb filter 705.

FIG. 8 is a signal pattern diagram illustrating a method for generating reflection sound in the stereoscopic sound generating apparatus of FIG. 7.

FIG. 8A illustrates the first reflection sound generated by the eleventh delayer 7011 and the eleventh gain adjuster 7031 and the reflection pattern continuously generated by the first feedback comb filters 7071, 7091, and 7071. .

FIG. 8B illustrates the reflection sound delayed through the twenty-first delay unit 7022 and the twenty-first gain adjuster 7082 and the reflection sound patterns continuously generated through the second feedback comb filters 7092, 7092, and 7072.

FIG. 8C illustrates the reflection sound delayed through the n th delay unit 701 n and the n th gain adjuster 703 n and the reflection sound pattern continuously generated through the n th feedback comb filters 705 n, 709 n, and 707 n.

FIG. 8D is a reflection sound finally output by adding each reflection sound generated in each basic block in FIGS. 8A to 8B.

9 is a block diagram of a stereophonic sound generating apparatus according to another embodiment of the present invention.

The stereoscopic sound generating apparatus of FIG. 9 differs from the above-described embodiment in that it further includes a positioning filter unit 911 and a mixer unit 950.

In other words, the functions and configurations of the delay unit 901, the gain adjusting unit 903, and the feedback comb filter unit 905 are the same as those described with reference to FIG. However, the present exemplary embodiment further includes a positioning filter unit 911 and an adder 950 to separate the signal output from the feedback bag comb filter unit 905 into left and right channels, thereby providing a more three-dimensional sound signal. To create. Here, the positioning filter unit 911 locates the reflected sound by reflecting characteristics such as a time difference between two ears, a level difference between two ears, or a level difference between two ears for each frequency. In FIG. 9, the positioning filter unit 911 includes a delay filter and a gain adjuster, but according to embodiments, various characteristics are reflected by reflecting characteristics such as a time difference between two ears, a level difference between two ears, or a level difference between two ears for each frequency. Can be combined.

In this regard, each of the reflection sounds passing through the feedback comb filter unit 905 is transferred to the positioning filter unit 911 which moves the sound image. Each reflection sound input to the positioning filter unit 911 for moving the sound image is divided into left and right channels, respectively, and a delay filter, a gain adjuster, or a bilateral level difference filter for reflection sounds belonging to either of the left and right channels. Will go through. For example, assuming that the sound image of the reflection sound passing through the first feedback comb filters 9051, 9071, and 9091 of the feedback comb filter unit 905 is on the left side, the reflection sound belongs to the signal of the left channel, and the thirteenth delay The reflected sound after the unit 9111 and gain adjuster 9131 or the bilateral level filter belongs to the signal of the right channel.

Delay values of the thirteenth to n3 retarders 9111 to 911n of the positioning filter unit 911 are t13, t23, and tn3, and gain values of the thirteenth to n3 gain adjusters 9131 to 913n are g13. Let, g23,, gn3. Delay values t13, t23, tn3 and gain values g13, g23, gn3 implement the time difference and the sound pressure difference at which each of the reflected sounds reach the two ears of the listener, and depend on the negative angle of incidence. Therefore, when each reflected sound has different angles of incidence, it can produce a three-dimensional sound effect.

The reflection sounds of the left channel or the right channel output from the positioning filter unit 911 are transmitted to the mixer unit 950.

The mixer unit 950 adds left channels or right channels of the respective reflection sounds output from the positioning filter unit 911. That is, the first adder 951 adds the left channels of the respective reflection sounds separated by the positioning filter unit 911 to output the left channel signal Lo, and the second adder 952 supplies the positioning filter unit. The right channels of each of the reflection sounds separated at 911 are added and output as the signal Ro of the right channel.

Finally, the Lo and Ro signals output from the mixer 950 may be reproduced through headphones or the like to listen to stereoscopic sound.

10A to 10F are various other examples of the positioning filter unit 911 of FIG. 9.

Referring to FIG. 10A, the positioning filter unit 911 includes a delay filter (DL) and a low pass filter (LPF) reflecting the ITD and the ILD, and for a signal belonging to either of the left and right channels. A delay filter (DL) and a low pass filter (LPF) are passed through.

Referring to FIG. 10B, the positioning filter unit 911 includes a delay filter (DL) and an ILD filter reflecting the ITD and the ILD, and the delay filter and the ILD for signals belonging to either of the left and right channels. Going through the filter.

Referring to FIG. 10C, the positioning filter unit 911 includes first and second delay filters DL1 and DL2 and first and second gain adjusters g1 and g2 reflecting the ITD and the ILD. The first delay filter DL1, the first gain adjuster g1, the first delay filter DL2, and the first gain adjuster g2 are respectively passed to the right channel signal.

Referring to FIG. 10D, the positioning filter unit 911 includes first and second delay filters DL1 and DL2 and first and second low pass filters LPF1 and LPF2 reflecting ITD and ILD. The first delay filter DL1, the first low pass filter LPF1, the second delay filter DL2, and the second low pass filter LPF2 pass through the right channel signal.

Referring to FIG. 10E, the positioning filter unit 911 includes a first delay filter DL1, a first HRTF filter HRTF1, a second delay filter DL2, and a second HRTF filter HRTF2 for both channels, respectively. The first delay filter DL1, the first HRTF filter HRTF1, the second delay filter DL2, and the second HRTF filter HRTF2 are respectively passed to the left and right channel signals.

Referring to FIG. 10F, the positioning filter unit 911 includes first and second HRTF filters HRTF1 and HRTF2 for both channels, and the first HRTF filter HRTF1 and the first for the signals of the left and right channels, respectively. It is convolved with a 2HRTF filter (HRTF2).

11 is a flowchart showing a three-dimensional sound generating method according to the present invention.

First, n reflection sounds are generated through delay filters connected in parallel with respect to an input signal (S1210).

The n reflection sounds may be generated by delaying and gain adjusting the input signal using different time delay values determined according to the size of the virtual space and different gain values determined according to the boundary conditions of the virtual space.

A reflection sound is continuously generated through the feedback loop for each of the n reflected sounds generated (S1220). The generated reflection sounds perform the positioning of the sound source reflecting the difference in time and sound pressure incident between the left and right ears of the virtual listener (S1230).

Therefore, a reflection may be generated for the input signal to provide a sense of space, and a plurality of virtual reflections may be positioned to generate a three-dimensional effect.

The present invention is not limited to the above-described embodiment, and of course, modifications may be made by those skilled in the art within the spirit of the present invention.

The invention can also be embodied as computer readable code on a computer readable recording medium. The computer-readable recording medium includes all kinds of recording devices in which data that can be read by a computer system is stored. Examples of computer-readable recording media include ROM, RAM, CD-ROM, magnetic tape, hard disk, floppy disk, flash memory, optical data storage device, and also carrier waves (for example, transmission over the Internet). It also includes the implementation in the form of. The computer readable recording medium can also be distributed over network coupled computer systems so that the computer readable code is stored and executed in a distributed fashion.

As described above, according to the present invention, the stereophonic sound signal may be generated using the reflected sounds generated by time delay and gain adjustment of the input signal. In addition, a plurality of virtual sound sources are positioned to provide a three-dimensional effect. In addition, the present invention can implement a three-dimensional sound effectively in a virtual space without using a Head Related Transfer Function (HRTF), it is possible to significantly reduce the amount of calculation with little variation of the tone. Therefore, by easily applied to a portable device such as headphones, earphones, etc., the listener can listen to the sound signal having a three-dimensional sense and a spatial feeling with little change in the tone.

Claims (20)

In the stereo sound generating method, Delaying an input signal according to a plurality of different delay values to generate a plurality of reflection sounds; Multiplying the delayed reflections by predetermined gains; And generating continuous reflections through a feedback loop having a different delay value and a gain value for each reflection sound multiplied in the process. The method of claim 1, wherein the different delay values are determined based on a size of a predetermined virtual space. The method of claim 1, wherein the different gain values are determined based on the degree of sound absorption of the virtual space. The method of claim 1, wherein the continuous reflections through the feedback loop are generated according to a delay value and a gain value determined based on the pattern of each multiplied reflection sound. In the stereo sound generating method, Generating a plurality of reflection sounds by delaying a signal of one channel according to a plurality of different delay values; Multiplying each of the generated reflection sounds by predetermined gain values; Generating continuous reflections through a feedback loop having a plurality of delay and gain values different for each of the reflections multiplied in the process; Separating the reflected sound of the first and second channels by reflecting the time difference between the two ears and the sound pressure difference for each of the reflected sounds generated in the above process; And adding the first channel and the second channel to each of the reflected sound signals separated into the first and second channels. The method of claim 5, wherein the plurality of different delay values are determined according to the size of the virtual space. The method of claim 5, wherein the different gain values are determined according to the degree of sound absorption of the virtual space. The method of claim 5, wherein the channel separation process comprises positioning the reflection sound by reflecting a time difference between two ears and a level difference between the two ears. The method of claim 5, wherein the channel separation process comprises positioning the reflection sound by reflecting a time difference between two ears and a level difference between two ears which differ in frequency. The method of claim 5, wherein the channel separation process comprises assigning different delay values to one of the left and right channels to reflect a time difference between two ears according to different angles of incidence of each sound. . The method of claim 5, wherein the channel separation process comprises assigning different gain values reflecting the level difference between the two ears to one of the left and right channels according to different angles of incidence of each sound. . In the stereo sound generating method, Generating an input signal as a first reflection sound having a time delay and a gain adjusted according to a delay value and a predetermined gain value; And continuously generating reflected sound patterns related to the first reflected sound through a feedback loop having a delay value and a gain value with respect to the first reflected sound generated in the process. 13. The method of claim 12, wherein the gain value is calculated from an intensity of a mirror image sound source that depends on the degree of sound absorption of the virtual space. The method of claim 12, wherein the delay value is calculated from the size of the virtual space. In the stereo sound generating device, A delay filter unit delaying a signal of one channel according to a plurality of delay values and generating a plurality of reflection sounds; A gain adjusting unit multiplying predetermined reflection values different from each of the reflection sounds generated by the delay filter unit; A feedback comb filter unit generating continuous reflection sound patterns through a feedback loop having a plurality of different delay values and gain values for each of the reflection sounds multiplied by the gain adjusting unit; A localization filter unit for splitting the reflected sound generated by the feedback comb filter unit into signals of the first and second channels by reflecting an incident time difference between two ears and a sound pressure difference; And a mixer unit for adding the first channel and the second channel to respective reflection sound signals separated by the channel from the localization filter unit. The ITD filter of claim 15, wherein the positioning filter unit includes an ITD filter reflecting a time difference between two ears and an ILD filter reflecting a level difference between the two ears, and outputs a signal of one channel as it is and outputs an ITD filter of another channel. And output through the ILD filter. The method of claim 15, wherein the localization filter unit comprises an ITD filter reflecting the time difference between the two ears and the ILD filter reflecting the level difference between the two ears for each frequency, and outputs the signal of one channel as it is and the signal of another channel Stereo output device characterized in that for outputting through the ITD filter and the ILD filter. The method of claim 15, wherein the positioning filter unit comprises a delay and gain adjuster reflecting the level difference between the two ears and the time difference between the two ears, and outputs the signal of one channel as it is and delay the signal of the other channel and Stereo output device, characterized in that output through the gain adjuster. Delaying an input signal according to a plurality of different delay values to generate a plurality of reflection sounds; Multiplying the delayed reflections by predetermined gains; Generating continuous reflections through a feedback loop reflecting a different delay value and a gain value for each reflection sound multiplied in the above process; A computer-readable recording medium having recorded thereon a program for executing a stereo sound generating method on a computer, comprising the steps of adding each of the reflection sounds generated in the process. Generating a plurality of reflection sounds by delaying a signal of one channel according to a plurality of different delay values; Multiplying each of the generated reflection sounds by predetermined gain values; Generating continuous reflections through a feedback loop by reflecting a plurality of different delay values and gain values for each reflection sound multiplied in the above process; Separating the signals of the first and second channels by reflecting the time difference between the two ears and the sound pressure difference for each of the reflected sounds generated in the above process; The method may further include adding a first channel and a second channel to each of the reflected sound signals separated into the first and second channels. Recording media.

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