Speaker system

Abstract

A speaker system (10) comprises: a first speaker array (12) configured by arranging a plurality of first speakers (16) on a straight line; and a second speaker array (14) configured by arranging a plurality of second speakers (18) on a straight line. A first phase setting unit (20) sets, for the plurality of first speakers (16), a phase of a drive signal on the basis of a tangent method so as to output a sound beam in the shape of a circular arc C1. A second phase setting unit (22) sets, for the plurality of second speakers (18), the phase of the drive signal on the basis of the tangent method so as to output a sound beam in the shape of a circular arc C2. Thus, a listening point is set at the point of intersection LP1 between the two circular arcs C1 and C2.

Description

[Technical Field]

[0001] The present disclosure relates to a speaker system. [Background Art]

[0002] Research has been conducted on techniques for generating a so-called localized sound field that allows sound output from a speaker to be audible only within a specific area. Japanese Unexamined Patent Application Publication No. 2016-136656 discloses a speaker system including a speaker array configured by dispersively arranging a plurality of sub-speakers on an array surface, and a mechanism that independently controls the volume and amplitude phase of each sub-speaker. This speaker system describes a technique for generating a localized sound field by focusing on the sound cancellation phenomenon occurring in a rectangular flat plate and simulating the vibration mode of the rectangular flat plate with the speaker array. Furthermore, a technique for generating an arc-shaped sound beam using the principle of the tangential method (also referred to as the stationary phase method) is known in the art (Zhao, et al., J. Acoust. Soc. Am. 137(2), 1036-1039, 2015, Zhao, et al., ICSV22, Florence, Italy, 12-16 July 2015) [Summary of the Invention] [Problem to be Solved by the Invention]

[0003] All of the above techniques relate to generation of a localized sound field, but there remains room for improvement in order to enable a listening point to be set at an arbitrary position.

[0004] The present disclosure provides a speaker system capable of generating a localized sound field, in which a listening point can be set at an arbitrary position. [Means for Solving the Problem]

[0005] A speaker system according to the first embodiment includes: a first speaker array configured by arranging a plurality of first speakers in a straight line; a second speaker array configured by arranging a plurality of second speakers in the straight line; a first phase setting unit that sets the phase of a drive signal based on the tangential method so that a beam of sound is output in an arc shape to the plurality of first speakers constituting the first speaker array; and a second phase setting unit that sets the phase of a drive signal based on the tangential method so that a beam of sound is output in an arc shape that intersects with the beam output from the first speaker array to the plurality of second speakers constituting the second speaker array.

[0006] In the speaker system according to the first embodiment, the first speaker array comprises a plurality of first speakers arranged in a straight line. The second speaker array comprises a plurality of second speakers arranged in a straight line.

[0007] The first phase setting unit sets the phase of the drive signal based on the tangential method so that a sound beam is output in an arc shape to multiple first speakers. The second phase setting unit also sets the phase of the drive signal based on the tangential method so that a sound beam is output in an arc shape to multiple second speakers. Here, the second phase setting unit sets the phase of the drive signal so that a sound beam intersects with the beam output from the first speaker array. By adjusting the amplitude and phase of the sound beams output from the first speaker array and the sound beams output from the second speaker array, the sound pressure can be increased by approximately double at the beam intersection. As a result, a local sound field can be generated with the intersection of the sound beams as the listening point. Furthermore, since the intersection point changes if the size or position of the sound beam is changed, the listening point can be set at any arbitrary position. Note that the term "arc shape" here is not limited to a perfect circle, but broadly includes convex curve shapes.

[0008] In the speaker system according to the second embodiment, the beam output from the first speaker array and the beam output from the second speaker array have symmetrical shapes.

[0009] In the speaker system according to the second embodiment, sound beams with symmetrical shapes are output from the first speaker array and the second speaker array, making it easy to set the listening point at the intersection. The term "symmetrical shape" here broadly includes shapes that are inverted horizontally and shapes that are inverted vertically.

[0010] In the speaker system according to the third embodiment, in the first embodiment or the second embodiment, the number of first speakers constituting the first speaker array and the number of second speakers constituting the second speaker array are the same.

[0011] In the speaker system according to the third embodiment, by making the number of first speaker arrays and second speaker arrays the same, the arcs of the sound beams have similar shapes. This makes it easier to set the listening point.

[0012] In the speaker system according to the fourth embodiment, in any one of the first to third embodiments, the distance between adjacent first speakers and the distance between adjacent second speakers are set to be the same.

[0013] In the speaker system according to the fourth embodiment, by making the number of first speaker arrays and second speaker arrays the same, the arcs of the sound beams have similar shapes. This makes it easier to set the listening point.

[0014] In the speaker system according to the fifth embodiment, in any one of the first to first embodiments, the first speaker and the second speaker are arranged at an interval of less than half the upper limit wavelength in the frequency band of the sound to be output.

[0015] In the speaker system according to the fifth embodiment, spatial aliasing (spatial errors and spectral errors occurring in the sound field) can be suppressed by setting the distance between adjacent first speakers and the distance between adjacent second speakers to less than half the wavelength.

[0016] The speaker system according to the sixth embodiment includes a moving mechanism for moving the position of at least one of the first speaker array and the second speaker array, in any one of the first to fifth embodiments.

[0017] In the speaker system according to the sixth embodiment, the listening point can be changed at any time by moving the first speaker array and the second speaker array using a moving mechanism.

[0018] In the speaker system according to the seventh embodiment, the shape of the beam output from at least one of the first speaker array and the second speaker array can be changed in any one of the first to sixth embodiments.

[0019] In the speaker system according to the seventh embodiment, the position of the listening point can be changed without moving the speaker array itself by changing the shape of the beam. Various methods can be employed to change the shape of the beam, such as stopping the output of some of the speakers constituting the speaker array, or changing the phase of each speaker to correspond to the tangent of the modified arc-shaped beam. [Effects of the Invention]

[0020] As explained above, the speaker system according to this disclosure allows a listening point to be set at any position in a speaker system capable of generating a local sound field. [Brief explanation of the drawing]

[0021] [Figure 1] This is a schematic model diagram showing the sound beam generated by the speaker system according to the embodiment. [Figure 2] This is a graph showing the sound pressure distribution generated by the sound beam shown in Figure 1, illustrating the sound pressure distribution on a two-dimensional plane. [Figure 3] This is a graph showing the sound pressure distribution generated by the sound beam shown in Figure 1, illustrating the sound pressure distribution in a three-dimensional space. [Figure 4] This is a graph showing the sound pressure distribution corresponding to Figure 2 when a rigid sphere with a diameter of 0.1 m is arranged at the listening point. [Figure 5] This is a graph showing the sound pressure distribution corresponding to Figure 2 when a rigid sphere with a diameter of 0.2 m is arranged at the listening point. [Figure 6] This is a graph showing the sound pressure distribution corresponding to Figure 2 when a rigid sphere with a diameter of 0.4 m is arranged at the listening point. [Figure 7] This is a graph showing the sound pressure distribution corresponding to Figure 3 when a rigid sphere with a diameter of 0.4 m is arranged at the listening point. [Figure 8] This is a schematic diagram schematically showing the first speaker array and the second speaker array in the embodiment. [Figure 9] This is a model diagram schematically showing a sound beam generated by a speaker system according to a modified example. [Figure 10] This is a model diagram schematically showing a sound beam generated by the tangent method. [Figure 11] This is a model diagram schematically showing a sound beam generated by a method according to a comparative example. [Figure 12] This is a graph showing the sound pressure distribution generated by the sound beam shown in Figure 11, illustrating the distribution on a two-dimensional plane. DETAILED DESCRIPTION OF EMBODIMENTS

[0022] A speaker system according to an embodiment will be described with reference to the drawings. The speaker system of the present embodiment uses the principle of generating sound beams by the tangent method. Hereinafter, the principle of the tangent method will be described with reference to Figure 10.

[0023] (Tangent Method) As shown in Figure 10, the curved trajectory of the sound beam generated by the tangent method is considered to be a semicircle C centered at coordinate (0,a). Consider the tangent line L at a point on the semicircle C. Let θ be the angle between the tangent line L and the y-axis, and let x be the intersection point of the tangent line L and the x-axis. Then the relationship in equation (1) can be obtained.

[0024]

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[0025] Furthermore, if the phase of a point sound source at coordinate (x,0) is denoted by φ(x), the relationship between the distance along the x-axis and the phase shift is expressed by equation (2).

[0026]

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[0027] Equation (3) can be derived from equation (2) above.

[0028]

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[0029] In equation (3) above, dφ is the phase shift between adjacent point sources, dx is the distance between adjacent point sources, and k is the wavenumber. Substituting equation (1) into equation (3) and integrating, we obtain equation (4).

[0030]

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[0031] Equation (4) above represents the spatial phase profile of an array of point sources for generating a local sound field along a semicircle C, i.e., the phase φ of the sound source at location x. Therefore, when the speaker array has N point sources, it is expressed as in equation (5).

[0032]

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[0033] Here, x n =nd indicates the position of the nth point source, and n=0,1,2...d indicates the distance between adjacent point sources. This method of setting the spatial phase profile of a speaker array is called the tangent method.

[0034] In the tangent method, only point sound sources on tangent lines extending from a single point on the circle affect the sound pressure at the point of contact. That is, in Figure 10, when considering a tangent line L that touches a single point on semicircle C, only a point sound source placed at the point where this tangent line L intersects with the x-axis contributes to the sound pressure at that single point. On the other hand, point sound sources placed at positions far from the point where the tangent line L intersects with the x-axis cancel each other out. As a result, in the tangent method, sound pressure is maintained only on semicircle C in Figure 10, and an arc-shaped beam of sound is generated.

[0035] (Configuration of speaker system 10) Next, a speaker system 10 according to this embodiment, which applies the tangent method, will be described. As shown in Figure 8, the speaker system 10 is composed of a first speaker array 12 and a second speaker array 14.

[0036] The first speaker array 12 is a linear array, consisting of multiple first speakers 16 arranged at equal intervals along a straight line. The size of the first speaker array 12, the number of first speakers 16, and their spacing are changed according to the position of the listening point and the frequency band of the sound to be output, as will be described later.

[0037] In this embodiment, as an example, the audio frequency band is set to 300Hz to 3400Hz. The spacing between the first speakers 16, which act as point sound sources, is set to 0.05m, and there are 21 first speakers 16 in total. In other words, the spacing between adjacent first speakers 16 is set to a value less than half the wavelength of a 3400Hz sound wave.

[0038] The second speaker array 14 is a linear array, and is composed of multiple second speakers 18 arranged at equal intervals along a straight line. The size of the second speaker array 14, the number of second speakers 18, and the spacing between them are changed according to the position of the listening point and the frequency band of the sound to be output, as will be described later. In this embodiment, as an example, the second speaker array 14 is configured in the same way as the first speaker array 12. That is, the spacing between adjacent second speakers 18 is set to 0.05m, and the number of second speakers 18 is 21.

[0039] The first speaker array 12 is electrically connected to the first phase setting unit 20, and the second speaker array 14 is electrically connected to the second phase setting unit 22. The first phase setting unit 20 sets the phase of the drive signal for each of the multiple first speakers 16. The second phase setting unit 22 sets the phase of the drive signal for each of the multiple second speakers 18. Although not shown in the diagram, multiple wires extend from the first phase setting unit 20, and each wire is connected to the first speaker 16. Similarly, multiple wires extend from the second phase setting unit 22, and each wire is connected to the second speaker 18.

[0040] The arrangement of the first speaker array 12 and the second speaker array 14 will be described with reference to Figure 1. With respect to the xy coordinate system shown in Figure 1, the first speaker array 12 is positioned in the range AR1 from coordinate (0,0) to coordinate (a,0) on the x axis. In this embodiment, as an example, the length of the first speaker array 12 is set to 1.0m, so the length from coordinate (0,0) to coordinate (a,0) is 1.0m.

[0041] Based on the tangential method, the spatial phase profile of the first speaker array 12, set by the first phase setting unit 20, generates a quadrant arc C1 centered at coordinate (a,0). In other words, the first phase setting unit 20 sets the phase of the drive signal based on the tangential method for the multiple first speakers 16 constituting the first speaker array 12 so that a beam of sound is output in the shape of a quadrant arc.

[0042] On the other hand, the second speaker array 14 is positioned in the range AR2 from coordinate (b,0) to coordinate (a+b,0) on the x-axis. Here, since coordinate (b,0) is closer to the origin (0,0) than coordinate (a,0), the second speaker array 14 is set on a straight line such that a portion of it overlaps with the positioning area of ​​the first speaker 16.

[0043] Furthermore, a quadrant arc C2 centered at coordinate (a+b,a) is generated by the spatial phase profile of the second speaker array 14 set by the second phase setting unit 22 based on the tangent method. Here, arc C2 is symmetrical to arc C1, specifically, it is a horizontally inverted shape. For this reason, the second phase setting unit 22 sets the phase of the drive signal based on the tangent method for the multiple second speakers 18 constituting the second speaker array 14 so that a sound beam is output in the shape of a quadrant arc that is horizontally inverted from arc C1.

[0044] As described above, when arcs C1 and C2 are generated, the sound pressure becomes high at the intersection point LP1 of arcs C1 and C2. In other words, the intersection point LP becomes the listening point. The x-coordinate of the intersection point LP1 is expressed by equation (6).

[0045]

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[0046] Furthermore, the y-coordinate of intersection point LP1 is given by the equation of arc C1: y = a - (a 2 -x 2 ) -1By substituting equation (6) into the equation, we can obtain the result shown in equation (7).

[0047]

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[0048] Here, the y-coordinate of the intersection point LP1 is equal to the distance from the array planes of the first speaker array 12 and the second speaker array 14 to the listening point. Therefore, the distance to the listening point can be adjusted by changing the coordinates of a and b in Figure 1. In other words, by changing the placement range of the first speaker array 12 and the placement range of the second speaker array 14, the shape (size) of the arc of the sound beam changes, and thus the listening point changes.

[0049] Furthermore, although Figure 1 uses an xy coordinate system for explanation, the local sound field generated by the speaker system 10 is axially symmetric with respect to the x-axis. Therefore, it is possible to confine the local sound field to three-dimensional space.

[0050] (action) Next, the operation of this embodiment will be described.

[0051] In the speaker system 10 of this embodiment, the second phase setting unit 22 sets the phase of the drive signal so that the sound beam is output in an arc shape (symmetrical shape) that is horizontally inverted from the beam output from the first speaker array 12. As a result, the sound beam output from the first speaker array 12 and the sound beam output from the second speaker array 14 become symmetrical in a plan view, and the sound pressure can be increased at the intersection point LP1. As a result, a local sound field can be generated with the intersection point LP1 of the sound beams as the listening point.

[0052] Furthermore, by changing the arrangement range of the first speaker array 12 and the second speaker array 14, the position of the sound beam changes and the intersection point LP1 changes, so that the listening point can be set at any position. In other words, in a speaker system capable of generating a local sound field, the listening point can be set at any position.

[0053] Furthermore, in this embodiment, by making the configuration of the first speaker array 12 and the second speaker array 14 identical, the arcs C1 and C2 of the sound beams have similar shapes. This makes it easier to set the intersection point LP1.

[0054] Furthermore, in this embodiment, spatial aliasing can be suppressed by setting the distance between adjacent first speakers 16 and the distance between adjacent second speakers 18 to less than half the wavelength.

[0055] The above effects will be explained with reference to the sound pressure distribution.

[0056] (Sound pressure distribution) The sound pressure distributions shown in Figures 2 and 3 represent the sound pressure distribution when the first speaker array 12 and the second speaker array 14 are placed at the positions shown in Figure 1, and a sound is played at 2000 Hz. Specifically, the radius of the curved trajectory of the sound beam is 1.0 m, and the y-coordinate of the listening point LP1 is 0.5 m. In other words, the listening point is set at a distance of 0.5 m from the array surface. The sound pressure distributions are based on simulation results using the finite element method and the boundary element method. In Figure 2, the darker colored areas, such as the roughly triangular region at the bottom, indicate high sound pressure. Outside of this region, the color is lighter, indicating low sound pressure. The streaky areas extending in the y-direction to the left and right of the roughly triangular region are shown in a darker color to differentiate them from other regions, but these areas have lower sound pressure than the lighter colored areas in the figure.

[0057] As shown in Figure 2, at the intersection (listening point) LP1, the beams of the first speaker array 12 and the second speaker array 14 overlap with the same amplitude and phase, resulting in an improvement in sound pressure. Furthermore, the increased sound pressure in the region from the listening point to the array surface is due to the side lobes.

[0058] In other words, in the region from the listening point to the array surface, the sound pressure is high because the side lobes from the first speaker array 12 and the side lobes from the second speaker array 14 overlap. In contrast, in other regions, the sound pressure is low because the side lobes do not overlap. As a result, the local sound field is confined in the region from the listening point to the array surface. Note that when only the first speaker array 12 is output, side lobes appear outside the arc C1. Similarly, when only the second speaker array 14 is output, side lobes appear outside the arc C2.

[0059] Furthermore, looking at the sound pressure distribution shown in Figure 3, it can be confirmed that, similar to Figure 2, the local sound field is confined in the region between the listening point and the array surface.

[0060] (Comparative example) Here, the sound pressure distribution of the comparative example speaker system is illustrated and explained. The model diagram shown in Figure 11 schematically shows the sound beam generated by the principle of delayed sum beamformer instead of the tangent method. The shape of the speaker array and the listening point are set in the same way as in the embodiment.

[0061] As shown in Figure 11, in the comparative example, a beam is generated linearly from the center point of the first speaker array, coordinate (a / 2,0), toward the listening point, intersection LP2, with a linear inclination angle of θ2. The spatial profile of the first speaker array is expressed by equation (8).

[0062]

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[0063] The spatial phase profile of the second speaker array is inverted horizontally with respect to the first speaker array. Here, the principle of delayed-sum beamformers allows control over the propagation direction of sound waves, but not over the beam length.

[0064] Figure 12 shows the sound pressure distribution based on the principle of delayed-sum beamformers. This distribution reveals that the sound field is not confined to the region between the listening point (LP2) and the array surface, but is widely diffused. This is presumably because the beam length cannot be controlled in the delayed-sum beamformer method.

[0065] (Evaluation of robustness) Next, the results of the robustness evaluation of the speaker system 10 according to this embodiment will be described. Here, assuming a listener's head, the sound pressure distribution when a rigid ball, which is an obstacle, is placed near the listening point will be described with reference to the drawings.

[0066] Figure 4 illustrates the sound pressure distribution when a rigid sphere with a diameter of 0.1 m is placed near the listening point. Figure 5 illustrates the sound pressure distribution when a rigid sphere with a diameter of 0.2 m is placed near the listening point. Figures 6 and 7 illustrate the sound pressure distribution when a rigid sphere with a diameter of 0.4 m is placed near the listening point. The rigid sphere with a diameter of 0.2 m is about the same size as the listener's head and close to the size of the acoustic wavelength (0.17 m). The rigid sphere with a diameter of 0.1 m is smaller than the acoustic wavelength.

[0067] As shown in Figures 4, 5, and 6, it can be seen that the sound pressure behind the rigid sphere decreases as its size increases. However, as shown in Figure 6, even when the diameter of the rigid sphere is increased to about twice the size of the listener's head, it can be confirmed that the local sound field is properly confined between the listening point and the array surface. Furthermore, as shown in Figure 7, it can be confirmed that the local sound field is properly confined in the sound pressure distribution in three-dimensional space as well. Thus, the robustness of the speaker system 10 according to this embodiment has been confirmed.

[0068] Although the speaker system 10 according to the embodiment has been described above, it goes without saying that it can be implemented in various forms without departing from the gist of this disclosure. For example, in the above embodiment, as shown in Figure 1, a quadrant arc C1 is generated by the spatial phase profile of the first speaker array 12 and a quadrant arc C2 is generated by the spatial phase profile of the second speaker array 14, but it is not limited to this. That is, a beam in the shape of an arc shorter than a quadrant may be generated, as shown in the modified example in Figure 9.

[0069] (modified version) As shown in Figure 9, in this modified example, the first speaker array 12 is positioned in range AR1 on the x-axis, which is a shorter range than in Figure 1. The second speaker array 14 is positioned in range AR2 on the x-axis, which is also a shorter range than in Figure 1.

[0070] An arc-shaped beam is generated by the spatial phase profile of the first speaker array 12, which is set by the first phase setting unit 20 based on the tangent method. In Figure 9, an arc-shaped beam slightly longer than the intersection point LP1 is generated, and the point where the tangent of the arc at intersection point LP1 intersects with the x-axis is one end of range AR1. The other end of range AR1 is the point at coordinate (0,0).

[0071] An arc-shaped beam is generated by the spatial phase profile of the second speaker array 14, which is set by the second phase setting unit 22 based on the tangent method. In Figure 9, an arc-shaped beam slightly longer than the intersection point LP1 is generated, and the point where the tangent to the arc at intersection point LP1 intersects with the x-axis is one end of range AR2. The other end of range AR2 is set at the point where the arc intersects with the x-axis.

[0072] As described above, in the modified configuration, the installation range AR1 of the first speaker array 12 and the installation range AR2 of the second speaker array 14 are arranged so as not to overlap. Even in this case, the local sound field can be confined between the intersection point LP1 and the array surface, similar to the embodiment.

[0073] Furthermore, although the first speaker array 12 and the second speaker array 14 are fixed in the above embodiment, the invention is not limited to this, and at least one of the first speaker array 12 and the second speaker array 14 may be configured to be movable.

[0074] For example, the first speaker array 12 and the second speaker array 14 may be supported by support members (not shown), and a moving mechanism may be provided that allows the first speaker array 12 and the second speaker array 14 to be moved along the x and y axes, respectively, using a driving force such as a motor. In this case, the first speaker array 12 and the second speaker array 14 can be moved at any time according to the position of the listening point to be set.

[0075] Furthermore, in the above embodiment, as an example, the distance between the first speaker 16 and the second speaker 18 was set to 0.05m, and the number of first speakers 16 and second speakers 18 was set to 21, but the embodiment is not limited to this. For example, if the listening point is to be brought closer to the array surface, the number of first speakers 16 and second speakers 18 may be reduced to make the size of the arc smaller. Also, the number of first speakers 16 and the number of second speakers 18 may be different.

[0076] Furthermore, the spacing between the first speaker 16 and the second speaker 18 is not limited. For example, the spacing may be set without considering the wavelength of the frequency band of the sound to be output. Also, the spacing between the first speaker 16 and the second speaker 18 may not be equal, but rather at different intervals.

[0077] Furthermore, although the above embodiment described the first phase setting unit 20 and the second phase setting unit 22 as independent setting units, the system is not limited to this. For example, the function corresponding to the first phase setting unit for setting the phase of the first speaker 16 and the function corresponding to the second phase setting unit for setting the phase of the second speaker 18 may be performed by a single control unit.

[0078] Furthermore, in the above embodiment, as shown in Figure 1, the beam output from the first speaker array 12 and the beam output from the second speaker array 14 were inverted horizontally, but the invention is not limited to this. For example, in Figure 1, the arcs C1 and C2 may be designed to have different shapes. Alternatively, the two speaker arrays may each output sound beams that are inverted vertically.

[0079] Furthermore, although the above embodiment describes a structure in which the first speaker array 12 and the second speaker array 14 are physically separated, as shown in Figure 8, the invention is not limited to this. For example, a speaker system in which the first speaker array and the second speaker array are integrally formed may be employed. Even in this case, if the first phase setting unit 20 sets the phase of the drive signal based on the tangential method so that a sound beam is output in the shape of a quadrant arc C1 for the plurality of speakers constituting the first speaker array, and the second phase setting unit sets the phase of the drive signal based on the tangential method so that a sound beam is output in the shape of a quadrant arc C2 that is horizontally inverted from arc C1 for the plurality of speakers constituting the second speaker array, the same operation as in the above embodiment can be achieved. Alternatively, the functions of the first phase setting unit 20 and the second phase setting unit may be realized by a single phase setting unit. The disclosure of Japanese Patent Application No. 2021-106882 is incorporated herein by reference in its entirety. All documents, patent applications, and technical standards described herein are incorporated by reference to the same extent as if each individual document, patent application, and technical standard were specifically and individually described as being incorporated by reference.

Claims

1. A first speaker array is configured by arranging multiple first speakers in a straight line, A second speaker array is configured by arranging a plurality of second speakers on the aforementioned straight line, A first phase setting unit sets the phase of the drive signal based on the tangential method so that a beam of sound is output in an arc shape to a plurality of first speakers constituting the first speaker array, A second phase setting unit sets the phase of the drive signal based on the tangential method so that a beam of sound is output in an arc shape that intersects with the beam output from the first speaker array for a plurality of second speakers constituting the second speaker array, A speaker system having [a certain feature].

2. The speaker system according to claim 1, wherein the beam output from the first speaker array and the beam output from the second speaker array have symmetrical shapes.

3. The speaker system according to claim 1 or 2, wherein the number of first speakers constituting the first speaker array is the same as the number of second speakers constituting the second speaker array.

4. The speaker system according to any one of claims 1 to 3, wherein the distance between adjacent first speakers and the distance between adjacent second speakers are set to the same distance.

5. The speaker system according to any one of claims 1 to 4, wherein the first speaker and the second speaker are arranged at an interval of less than half the upper limit wavelength in the frequency band of the sound to be output.

6. A speaker system according to any one of claims 1 to 5, comprising a moving mechanism for moving the position of at least one of the first speaker array and the second speaker array.

7. A speaker system according to any one of claims 1 to 6, wherein the shape of the beam output from at least one of the first speaker array and the second speaker array can be changed.

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