KR20090058224A - Method and apparatus for focusing the sound through the array speaker - Google Patents

Abstract

A method and an apparatus for accurately focusing a sound signal are provided to recognize a focusing signal of a low frequency band positioned in a specific direction and distance from an array speaker by focusing a harmonic wave signal corresponding to a low frequency signal in the array speaker. A filtering part(310) filters a high frequency signal having higher frequency than a reference frequency and a low frequency signal having lower frequency than a reference frequency. A high frequency focusing signal generating part(321) obtains a high frequency focusing signal for focusing the filtered high frequency signal to a predetermined position. A harmonic wave focusing signal generating part(322) generates a harmonic wave signal from the filtered low frequency signal. The harmonic wave focusing signal generating part obtains a harmonic wave focusing signal by controlling the harmonic wave signal at less than a threshold frequency. An output signal generating part(330) generates an output signal by synthesizing the obtained high frequency focusing signal and the obtained harmonic wave focusing signal.

Description

Method and apparatus for focusing the sound through the array speaker

The present invention relates to a focusing method and apparatus for concentrating a sound to be output to a specific position, wherein the sound is adjusted to a point located at a specific distance and direction from the array speaker by adjusting the sound signal through the array speaker composed of a plurality of speakers. A method and apparatus for focusing are provided.

Array speakers are used to combine multiple speakers to adjust the direction of the sound to be played or to send a sound to a specific area. In this regard, the principle of sound transfer, commonly referred to as directivity, utilizes the phase difference of a plurality of sound source signals to superimpose the signals so that the signal strength increases in a particular direction, thereby transmitting the signal in a specific direction. Therefore, this directivity is realized by arranging a plurality of speakers according to a specific position and adjusting a sound source signal output through the respective speakers constituting the array.

Recently, as various portable digital devices are commercialized, demand for speakers capable of reproducing sound signals is increasing. Accordingly, the expectations and desires of users for the sound reproduction function implemented in portable digital devices are gradually increasing. For example, there is a demand for progressively advanced speaker technology from simple mono speakers to stereo speakers and from stereo speakers to multichannel array speakers. In particular, array speakers are also used for listening to sound as devices such as digital multimedia broadcasting (DMB) devices, portable multimedia players (PMPs), and digital telephony devices, such as miniaturized digital devices, have become popular. There is a need for a focusing technique for focusing sound to a specific location desired by a user.

The technical problem to be solved by the present invention overcomes the limitation that the sound signal in the low frequency region is not properly focused due to the physically fixed size of the array speaker, and due to this problem, the user is acoustically located at a specific distance from the array speaker The present invention provides a method and apparatus for acoustic focusing of an array speaker, which solves a problem in that a signal in a low frequency region cannot be clearly heard when listening to the audio signal.

In order to achieve the above technical problem, the acoustic focusing method of an array speaker according to the present invention comprises the steps of filtering a high frequency signal higher in frequency than the reference frequency and a low frequency signal lower in frequency than the reference frequency from the input signal, respectively; Obtaining a high frequency focusing signal for focusing the filtered high frequency signal to a predetermined position; Acquiring a harmonic focusing signal by generating a harmonic signal replacing the low frequency signal from the filtered low frequency signal and controlling the harmonic signal below a threshold frequency capable of focusing to the predetermined position; And synthesizing the obtained high frequency focusing signal with the obtained harmonic focusing signal to generate an output signal.

In order to solve the above other technical problem, the present invention provides a computer-readable recording medium that records a program for executing the acoustic focusing method of the array speaker described above on a computer.

In order to achieve the above technical problem, the acoustic focusing apparatus of the array speaker according to the present invention includes a filtering unit for filtering a high frequency signal with a frequency higher than the reference frequency and a low frequency signal lower than the reference frequency from the input signal, respectively; A high frequency focusing signal generator for acquiring a high frequency focusing signal for focusing the filtered high frequency signal to a predetermined position; A harmonic focusing signal generation unit generating a harmonic focusing signal by generating a harmonic signal replacing the low frequency signal from the filtered low frequency signal and controlling the harmonic focusing signal below a threshold frequency capable of focusing to the predetermined position; And an output signal generator for synthesizing the obtained high frequency focusing signal and the obtained harmonic focusing signal to generate an output signal.

Hereinafter, various embodiments of the present invention will be described in detail with reference to the accompanying drawings. In describing the embodiments, sound pressure refers to a force exerted by acoustic energy using a physical quantity of pressure, and a sound field conceptually represents a region of sound pressure around a sound source.

FIG. 1 is a beam pattern illustrating a sound field that appears when focusing sound through an array speaker according to a frequency to explain a problem situation to be solved by the present invention. Here, the beam pattern refers to a pattern representing a sound field formed by sound emitted through signal output devices such as speakers and antennas. Such a beam pattern is obtained by receiving a sound signal radiated according to a distance from an array speaker using a measuring device measuring an output signal, and visually showing the intensity of the received sound signal for each measurement distance on a graph.

In FIG. 1, the horizontal axis of each graph represents the front distance from the array speaker, and the vertical axis of the graph represents the distance around the array speaker. Each graph assumes that the array speaker is located on the left center of the vertical axis. That is, assume a situation in which sound is emitted in the right direction from the array speaker located on the vertical axis. The beam pattern 110 illustrates a case where the frequency of the acoustic signal radiated through the array speaker is 630 Hz, and the beam pattern 120 and the beam pattern 130 illustrate 1.6 kHz and 4 kHz, respectively.

Comparing the beam patterns, it can be seen that the higher the frequency of the emitted acoustic signal, the better the sound field is formed in the center of the beam pattern. In FIG. 1, the sound field is clearly formed in a dark color in the center of the beam pattern 130, whereas the light pattern is more blurred in the beam pattern 120, and more blurred in the beam pattern 110. In particular, when referring to the A portion of the beam pattern 110, it can be seen that the acoustic signal emitted from the edge of the array speaker hardly forms a sound field.

In general, in the case of using an array speaker, the sound control performance changes according to the frequency. In the low frequency region, when the wavelength is larger than the size of the array speaker, it is known that the beam width becomes larger, which makes it difficult to focus the sound to a specific position. 1, it can be seen that the lower the frequency of the acoustic signal emitted through the array speaker, the more difficult the sound field is to be formed. As a result, acoustic focusing focuses the sound to a point away from the array speaker. You can see that this is not done properly. The above problems are remarkable because the sound control is not easy when the size of the array speaker is too small, especially in a small acoustic device. Therefore, hereinafter, a detailed means for solving the problem of poorly focused acoustics in the low frequency region in outputting an acoustic signal through the array speaker will be described.

FIG. 2 is a view for explaining a principle of perceiving low frequency sound using psychological sound, and illustrates a basic principle used in an acoustic focusing apparatus and method according to various embodiments of the present disclosure. In the graph of FIG. 2, the horizontal axis represents frequency and the vertical axis represents loudness.

When classifying sound academically, the study of the nature of sound in the psychological aspect of human is called psychoacoustics, and the object of sound is called psychoacoustic. These psychoacoustic sounds are based on the characteristics that the listener perceives the sound perceived differently from the physically measured sound due to the characteristics or limitations of human hearing. Here, the principle of human perception of low frequency sound among various properties of psychoacoustic sound will be explained mainly on harmonics.

Harmonic waves are acoustic signals having a frequency that is an integer multiple of the fundamental frequency from the fundamental signal that becomes the fundamental frequency. In FIG. 2, when the fundamental frequency is f, the harmonic wave refers to an acoustic signal having frequencies such as 2f, 3f, and 4f. Harmonic waves are also called harmonics or over tone. On the other hand, the harmonic wave does not have the same magnitude as the basic signal 210 but becomes a signal attenuated according to the attenuation function 230. In addition, the harmonic may be a signal in which at least one harmonic wave whose amplitude of the signal is attenuated with increasing frequency is mixed. Here, the attenuation function may be a function in which the magnitude of the signal decreases as the frequency increases, such as exponential decay or natural attenuation, and various methods for defining such attenuation function may be used in the art. It will be easily understood by those skilled in the art.

Research in the field of psychoacoustics has generally shown humans a harmonic wave corresponding to an integer multiple of the fundamental frequency f, or harmonic waves corresponding to the frequency of their integral multiples except for the negative f component of the fundamental frequency f. Even if only the listener is told, the listener will feel the fundamental sound 210 corresponding to the existing frequency f from these harmonics. Although the actual physical frequency is an acoustic signal corresponding to a high frequency, the virtual pitch or the missing fundamental frequency recognizes the effect that the listener perceives as a low frequency acoustic signal that is a fundamental signal of harmonic waves. It is called).

Using this principle, when it is difficult to output a fundamental low frequency signal, the listener can achieve the same effect as listening to a low frequency fundamental signal by outputting a harmonic wave having an integer multiple of the fundamental signal. have. Accordingly, various embodiments of the present invention, which will be described below, replace and substitute a low frequency signal with a harmonic for an acoustic signal in a low frequency region in which focusing that concentrates the acoustic signal at a specific position through directivity is difficult to be implemented based on this principle. We will implement focusing through the harmonics. In implementing such focusing, since harmonics do not need to be used for signals in the high frequency region, the following embodiments consider the frequency bands of the input signals, and divide the input signals into the high frequency band and the low frequency band, and then, An apparatus and method for focusing by replacing harmonic waves with respect to input signals only are provided.

3 is a block diagram illustrating an apparatus for focusing sound in an array speaker according to an exemplary embodiment of the present invention, wherein a high pass filter (HPF) 311 and a low pass filter (LPF) are shown. An array speaker including a filtering unit 310 including a filter 312, a high frequency focusing signal generator 321, a harmonic focusing signal generator 322, an output signal generator 330, and a plurality of individual speakers. 340).

The filtering unit 310 filters the high frequency signal having a higher frequency than the reference frequency and the low frequency signal having a lower frequency than the reference frequency from the input signal, respectively. Here, the reference frequency refers to a frequency used as a reference for filtering input signals into high frequency signals and low frequency signals, respectively, and is also referred to as a cut-off frequency. The expression high frequency or low frequency is a very relative concept, and it is necessary to determine which frequency of the entire input sound source signal is to be separated from the high frequency and low frequency.

As described above, in the embodiments of the present invention, the separation of the input signal according to the frequency band is because the input signal is not properly focused in the low frequency band. Thus, determining the reference frequency should be at least above or equal to this starting point in search of the starting point of the frequency at which the input signal is not focused properly. In addition, in the low frequency region, when the wavelength is larger than the size of the array speaker, the beam width is increased, so that the sound does not focus well at a specific position. Therefore, the above reference frequency should be set higher or at least equal to the frequency at which the input signal is not focused to a specific position in consideration of the size of the array.

Such a reference frequency may be adjusted to an appropriate value according to the actual product or environment in which the embodiments of the present invention are implemented, and may be pre-calculated to a specific value through experiments. Alternatively, the reference frequency may be set through a separate device in consideration of the size of the array speaker without setting the reference frequency to a fixed value in advance.

Referring to FIG. 2 described above, the reference frequency is shown by the dashed line 220 between the frequency f and the frequency 2f. In FIG. 2, it can be seen that the frequency f of the fundamental wave 210 is smaller than the reference frequency. Accordingly, in the embodiment of FIG. 3, focusing is implemented using harmonics having a frequency greater than the reference frequency for low frequency signals smaller than the reference frequency.

In FIG. 3, the input signal is filtered through the high pass filter 311 and the low pass filter 312, and both filters 311 and 312 are a high frequency signal having a higher frequency than the reference frequency and a low frequency signal having a lower frequency than the reference frequency, respectively. Will pass. Next, a focusing process of focusing the sound source signal from the filtered high frequency signal and the low frequency signal to a target position of the user will be described in sequence.

The high frequency focusing signal generator 321 generates a high frequency focusing signal for focusing the high frequency signal filtered through the high pass filter 311 to a specific position. To this end, the high frequency focusing signal generator 321 adjusts the gain value or delay value of the filtered high frequency signal so as to indicate directivity from the array speaker in a specific direction. That is, the high frequency focusing signal generator 321 specifies the sound signal by overlapping the sound signal so that the strength of the signal increases in a specific direction by using the phase difference of the sound signals to be output through the plurality of individual speakers constituting the array speaker. Direction. The above process will be described in more detail with reference to FIG. 4.

FIG. 4 is a detailed block diagram illustrating a high frequency focusing signal generator 400 in an acoustic focusing apparatus according to an exemplary embodiment of the present invention, and includes a replica unit 410, a gain control unit 420, and a delay unit 430. It includes.

When one sound source signal is input, the copy unit 410 replicates the number of individual speakers constituting the array speaker (or the number of channels to be output). Next, the gain adjusting unit 420 adjusts a gain using a filter for each of the signals copied through the copying unit 410. That is, the gain of the sound source signals to be applied to the individual speakers is adjusted in consideration of the direction to be focused. Subsequently, the delay unit 430 delays the respective sound source signals according to the direction or distance to be focused. The directivity control of the acoustic signal output through the array speaker is calculated according to Equation 1 below.

Δ is a delay value, λ is a wavelength of a sound source signal to be output, d is an interval between individual speakers constituting the array speaker, and θ is an angle formed by the radiation direction of the array speaker and the sound source signal. That is, the delay unit 430 delays each channel in consideration of the physical characteristics of the array speaker such as the distance d between the individual speakers, the nature of the sound source to be output such as the wavelength λ, and various variables such as the direction or focusing position to be output. The value will be determined. This gain to delay value is a value calculated to form a sound field such as a desired focusing position and beam width.

The process of generating the high frequency focusing signal by the high frequency focusing signal generator 321 of FIG. 3 has been described above with reference to FIG. 4. In the above-described embodiment, the sound source signal may be adjusted by performing various signal processing, such as adjusting the gain according to the sound source characteristics, delaying a signal applied to a specific channel, or filtering through a FIR type filter. have. In addition, the process of focusing the high frequency signal as described above may be implemented by appropriately modifying some of the configurations within the limits to which a functional equivalent is recognized by those skilled in the art.

3, the harmonic focusing signal generator 322 will be described.

The harmonic focusing signal generator 322 generates a harmonic signal that replaces the low frequency signal from the low frequency signal filtered through the low pass filter 312, and controls the harmonic wave by controlling the frequency below a threshold frequency that enables focusing to a specific position. Generate a signal. Here, the limit frequency refers to the maximum frequency that can be focused to a specific position when the sound signal is output through the array speaker. This limit frequency is known to be determined by the spacing between the individual speakers that make up the array speaker.

Hereinafter, a process of generating a harmonic focusing signal in the harmonic focusing signal generator 322 will be described in more detail with reference to FIGS. 5A and 5B.

FIG. 5A is a block diagram illustrating in detail a harmonic focusing signal generator in an acoustic focusing apparatus according to an embodiment of the present invention. FIG. 5A illustrates a harmonic signal generator 510, a distortion controller 520, and a focusing processor 530. Include.

The harmonic signal generator 510 replaces the low frequency signal by generating a harmonic signal corresponding to a multiple of the frequency of the low frequency signal and having a frequency higher than or equal to the reference frequency from the low frequency signal filtered through the low pass filter (not shown). The harmonic signal may be composed of a sum of at least one harmonic signal whose magnitude decreases as the frequency increases. Further, since the acoustic signal is not properly focused below the reference frequency, it is natural that the harmonic signal should be above the reference frequency. As described above, the harmonic signal generated by the harmonic signal generator 510 makes the listener feel as if he is listening to a low frequency signal even though the harmonic signal generated by the harmonic signal generator 510 is physically a high frequency signal of more than a reference frequency.

The distortion controller 520 controls the distortion of the harmonic signal by limiting the harmonic signal generated by the harmonic signal generator 510 to a threshold frequency or less. Hereinafter, a detailed process of controlling the distortion of the harmonic signal by the distortion controller 520 will be described with reference to FIG. 5B.

FIG. 5B is a block diagram illustrating in detail a distortion controller 520 included in a harmonic focusing signal generator in an acoustic focusing apparatus according to an exemplary embodiment of the present invention. 523 and a frequency limiter 524.

First, the distortion control unit 522 sets the limit frequency in consideration of the distance between the individual speakers constituting the array speaker. Next, the comparator 523 receives the highest frequency 521 and the limit frequency of the harmonic signal and compares the two. The highest order frequency represents the highest frequency among the frequencies of the plurality of signals included in the harmonic wave. Finally, the frequency limiting unit 524 outputs the harmonic signal 525 of which the highest order frequency is adjusted by limiting the frequency of the harmonic signal so that the frequency of the generated harmonic signal does not exceed the set limit frequency.

Through the above process, if the highest order frequency 521 of the harmonic signal is smaller than the limit frequency, the harmonic signal corresponding to the input highest order frequency 521 may be used for focusing. On the other hand, if the input highest-order frequency 521 is larger than the limit frequency, it may not be used for focusing. This is because, when the harmonic wave containing the frequency components of such order is used for focusing, there is a fear that the sound quality deteriorates due to the addition of the harmonic wave. Therefore, the harmonic signal output through the distortion controller 520 may be defined as in Equation 2 below.

Here, G (n) represents a harmonic signal, x (n) represents the highest order frequency, n represents an order that is an integer multiple of the fundamental frequency, and F_h represents a limit frequency. That is, Equation 2 means that the harmonic signal whose highest order frequency is smaller than the limit frequency is used for focusing.

Referring to FIG. 2 described above, the limit frequency is shown by dashed line 240 between frequencies 3f and 4f. According to FIG. 2, the highest order frequency will be 3f, and the frequency 4f is a value exceeding the limit frequency 240 and will be limited by the distortion control unit 522. Thus, the harmonic signal will consist only of frequency 2f and frequency 3f.

The focusing processor 530 of FIG. 5A focuses the limited harmonic signal to a specific position through the distortion controller 520. This process is the same as the high frequency focusing signal generation process described above with reference to the embodiment of FIG. 4. First, the harmonic signal generated by the harmonic signal generator 510 and the distortion controller 520 is no longer a low frequency signal below the reference frequency, and substantially corresponds to a high frequency signal. Therefore, the harmonic signal is focused in a specific direction and distance by performing various signal processing such as adjusting a gain, delaying a signal applied to a specific channel, or filtering through a filter as in the above-described high frequency focusing signal generation process. . In the above, the process of generating the harmonic focusing signal in the harmonic focusing signal generator 322 of FIG. 3 has been described with reference to FIGS. 5A and 5B.

Subsequently, the output signal generator 330 synthesizes the high frequency focusing signal and the harmonic focusing signal acquired through the high frequency focusing signal generator 321 and the harmonic focusing signal generator 322 to generate an output signal. . The generated output signal is applied to the array speaker 340 and output. The output signal is composed of high frequency signals above the reference frequency that can be focused in the array speaker 340, and will be accurately radiated to a specific position desired by the user through the focusing process.

The output signal generator 330 will be described in more detail with reference to FIG. 6 as follows. 6 is a block diagram illustrating in detail an output signal generator in an acoustic focusing apparatus according to an exemplary embodiment of the present invention, which includes a signal synthesizer 610 and an amplifier 620. The signal synthesizing unit 610 synthesizes the high frequency focusing signal and the harmonic wave focusing signal for each speaker constituting the array speaker. Subsequently, the amplifier 620 amplifies the synthesized signals for each speaker in consideration of the positions of the individual speakers constituting the array speaker and the frequency of the output signal. The amplified output signal is applied to the array speaker 640 and output.

In the above, the apparatus for focusing sound in the array speaker according to an embodiment of the present invention has been described in detail. According to the present exemplary embodiment, the harmonic signal corresponding to the low frequency signal can be focused in the array speaker by separating the high frequency signal and the low frequency signal according to the reference frequency, generating a harmonic signal replacing the low frequency signal, and generating a focusing signal. As a result, it is possible for a listener located in a specific direction and distance from the array speaker to clearly perceive the focusing signal in the low frequency region.

7A to 7C are block diagrams illustrating various methods of applying an output signal to an array speaker in an acoustic focusing apparatus according to another exemplary embodiment of the present invention.

FIG. 7A illustrates a harmonic focusing signal generated by the harmonic focusing signal generator 722 and a high frequency focusing signal generated by the high frequency focusing signal generator 721 in the acoustic focusing apparatus according to the exemplary embodiment described above. A process of synthesizing through one output signal generator 730 and then amplifying and applying it to the array speaker 740 is illustrated.

In contrast, the output signal generator 730 of FIG. 7B includes a plurality of signal synthesizers and amplifiers. In addition, the output signals amplified through each amplifier are differentially applied to the plurality of individual speakers constituting the array speaker 740. It is assumed that the array speaker 740 of FIG. 7B is composed of N individual speakers, and a differentiated output signal is supplied from the output signal generator 730 for each of them.

Differentiating the output signal may be designed in consideration of the positions of the individual speakers constituting the array speaker 740. For example, in the case of a high frequency signal, since the straightness is strong and the focusing is well performed, it may be effective to output through the speakers located in the center of the array speaker among the individual speakers constituting the array speaker. On the other hand, in the case of low frequency signals, since the linearity is relatively weak compared to the high frequency signals, and focusing is poor, it may be effective to output through the end of the array speaker (means both edges of the array speaker). .

As described above, in synthesizing both signals generated by the high frequency focusing signal generator 721 and the harmonic focusing signal generator 722, the synthesized signals are considered in consideration of the frequency characteristics of the respective signals and the use position of the array speaker. It can be distributed to individual speakers. In addition, it is possible to amplify the magnitude of the signal differentially for each of the synthesized output signals. For example, the output signal to be applied to a specific speaker may be amplified according to the direction to focus. Such a method of signal synthesis, signal amplification, and application to an individual speaker can be appropriately configured according to various implementation environments of the present embodiment by those skilled in the art.

FIG. 7C is a diagram illustrating a method of differentially supplying an output signal to the array speaker 740 in the output signal generator 730 of FIG. 7B, and applied to each position of the array speaker 740 including N individual speakers. The output signal to be displayed is displayed according to the frequency. In FIG. 7C, a signal having a frequency lower than a signal output through the center portion is output from the center portion to the end portion of the array speaker.

According to the present embodiment, the focusing performance of the array speaker can be improved by synthesizing, amplifying, and applying the output signal differentially according to the position of the array speaker.

8 is a flowchart illustrating a method of focusing sound in an array speaker according to still another embodiment of the present invention, which includes the following steps.

In operation 810, a high frequency signal having a higher frequency than the reference frequency and a low frequency signal having a lower frequency than the reference frequency are respectively filtered from the input signal. This reference frequency may be set to a frequency higher than or equal to the frequency at which the input signal is not focused in consideration of the size of the array speaker.

In operation 820, a high frequency focusing signal for focusing the filtered high frequency signal to a specific position is obtained. This process is accomplished by adjusting the gain or delay of the high frequency signal.

In step 830, a harmonic focusing signal is generated from the low frequency signal filtered in step 810 to replace the low frequency signal and controlled below a threshold frequency capable of focusing to a specific position. First, a harmonic signal corresponding to a multiple of the frequency of the low frequency signal and having a frequency equal to or greater than a reference frequency is generated from the low frequency signal filtered through step 810 to replace the low frequency signal. Next, the distortion of the harmonic signal is controlled by limiting the generated harmonic signal to a threshold frequency or less, and then the limited harmonic signal is focused.

In step 840, the high frequency focusing signal and the harmonic focusing signal acquired through steps 820 and 830 are synthesized to generate an output signal. In generating the output signal, the high frequency focusing signal and the harmonic focusing signal generated through the above steps are synthesized for each individual speaker constituting the array speaker, and synthesized for each individual speaker in consideration of the positions of the individual speakers and the frequency of the output signal. You can also amplify the signals.

According to this embodiment, the harmonic signal corresponding to the low frequency signal can be focused in the array speaker, and as a result, it is possible for a listener located in a specific direction and distance from the array speaker to clearly perceive the focusing signal in the low frequency region.

Meanwhile, the present invention can be embodied as computer readable codes on a computer readable recording medium. Computer-readable recording media include all types of recording devices that store data that can be read by a computer system.

Examples of computer-readable recording media include ROM, RAM, CD-ROM, magnetic tape, floppy disks, optical data storage devices, and the like, which may also be implemented in the form of carrier waves (for example, transmission over the Internet). Include. 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. And functional programs, codes and code segments for implementing the present invention can be easily inferred by programmers in the art to which the present invention belongs.

The present invention has been described above with reference to various embodiments thereof. Those skilled in the art will understand that the present invention can be implemented in a modified form without departing from the essential features of the present invention. Therefore, the disclosed embodiments should be considered in descriptive sense only and not for purposes of limitation. The scope of the present invention is shown in the claims rather than the foregoing description, and all differences within the scope will be construed as being included in the present invention.

FIG. 1 is a beam pattern illustrating a sound field according to a frequency when a sound is focused through an array speaker to explain a problem situation to be solved by the present invention.

2 is a view for explaining the principle of perceiving low frequency sound using psychological sound.

3 is a block diagram illustrating an apparatus for focusing sound in an array speaker according to an exemplary embodiment of the present invention.

4 is a detailed block diagram illustrating a high frequency focusing signal generator in an acoustic focusing apparatus according to an exemplary embodiment of the present invention.

5A and 5B are detailed block diagrams of a harmonic focusing signal generator in an acoustic focusing apparatus according to an exemplary embodiment of the present invention.

6 is a block diagram illustrating in detail an output signal generator in an acoustic focusing apparatus according to an exemplary embodiment of the present invention.

7A to 7C are block diagrams illustrating various methods of applying an output signal to an array speaker in an acoustic focusing apparatus according to another exemplary embodiment of the present invention.

8 is a flowchart illustrating a method of focusing sound in an array speaker according to another embodiment of the present invention.

Claims (14)

Filtering a high frequency signal having a frequency higher than a reference frequency and a low frequency signal having a frequency lower than the reference frequency from an input signal, respectively; Obtaining a high frequency focusing signal for focusing the filtered high frequency signal to a predetermined position; Acquiring a harmonic focusing signal by generating a harmonic signal replacing the low frequency signal from the filtered low frequency signal and controlling the harmonic signal below a threshold frequency capable of focusing to the predetermined position; And And synthesizing the obtained high frequency focusing signal and the obtained harmonic focusing signal to generate an output signal. The method of claim 1, Acquiring the harmonic focusing signal Generating a harmonic signal corresponding to a multiple of the frequency of the low frequency signal and having a frequency above the reference frequency from the filtered low frequency signal to replace the low frequency signal; Controlling the distortion of the harmonic signal by limiting the generated harmonic signal below the threshold frequency; And Focusing the limited harmonic signal to the predetermined position. The method of claim 2, Controlling the distortion of the harmonic signal Setting the threshold frequency in consideration of the distance between individual speakers constituting the array speaker; And And limiting the frequency of the harmonic signal so that the frequency of the generated harmonic signal does not exceed the set threshold frequency. The method of claim 1, Generating the output signal Synthesizing the high frequency focusing signal and the harmonic focusing signal for each speaker constituting the array speaker; And And amplifying the synthesized signals for each speaker in consideration of the positions of the speakers and the frequency of the output signal. The method of claim 1, Setting a frequency higher or equal to a frequency at which the input signal is not focused in consideration of the size of the array speaker as the reference frequency, Filtering each of the high frequency signal and the low frequency signal according to the set reference frequency. The method of claim 1, The acquiring of the high frequency focusing signal may focus on the predetermined position by adjusting a gain value or a delay value of the filtered high frequency signal. A non-transitory computer-readable recording medium having recorded thereon a program for executing the method of claim 1. A filtering unit for filtering a high frequency signal having a higher frequency than a reference frequency and a low frequency signal having a frequency lower than the reference frequency from an input signal, respectively; A high frequency focusing signal generator for acquiring a high frequency focusing signal for focusing the filtered high frequency signal to a predetermined position; A harmonic focusing signal generation unit generating a harmonic focusing signal by generating a harmonic signal replacing the low frequency signal from the filtered low frequency signal and controlling the harmonic focusing signal below a threshold frequency capable of focusing to the predetermined position; And And an output signal generator for synthesizing the obtained high frequency focusing signal and the acquired harmonic focusing signal to generate an output signal. The method of claim 8, The harmonic focusing signal generator A harmonic signal generator for generating a harmonic signal having a frequency equal to or greater than the frequency of the low frequency signal from the filtered low frequency signal and replacing the low frequency signal; A distortion controller configured to control the distortion of the harmonic signal by limiting the generated harmonic signal below the threshold frequency; And And a focusing processor for focusing the limited harmonic signal to the predetermined position. The method of claim 9, The distortion control unit A limit frequency setting unit for setting the limit frequency in consideration of an interval between individual speakers constituting the array speaker; And And a frequency limiter for limiting the frequency of the harmonic signal so that the frequency of the generated harmonic signal does not exceed the set limit frequency. The method of claim 8, The output signal generator A signal synthesizing unit for synthesizing the high frequency focusing signal and the harmonic wave focusing signal for each speaker constituting the array speaker; And And an amplifier for amplifying the synthesized signals for each speaker in consideration of the positions of the speakers and the frequency of the output signal. The method of claim 8, A reference frequency setting unit configured to set a frequency higher or equal to a frequency at which the input signal is not focused in consideration of the size of the array speaker as the reference frequency, The filtering unit acoustic focusing apparatus of the array speaker, characterized in that for filtering according to the set reference frequency. The method of claim 8, And the high frequency focusing signal obtaining unit focuses to the predetermined position by adjusting a gain value or a delay value of the filtered high frequency signal. The method of claim 8, And a signal having a frequency lower than a signal output through the center portion from the center portion to the end portion of the array speaker.

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