Speaker device

Abstract

A speaker device (1) comprises: a speaker unit (10); a housing (20) in which the speaker unit (10) is stored and which forms an internal space surrounded by wall surfaces; and a porous plate (30) which is plate-shaped and in which a plurality of pores are provided in a direction intersecting the plate surface of said porous plate (30), wherein the porous plate (30) is disposed, at a position where two locations in the wall surfaces face each other, separately from both of said two locations such that the plate surface intersects a direction connecting the wall surfaces at said two locations, and a surface facing at least one of said two locations is exposed.

Description

Speaker device

[0001] The present disclosure relates to a speaker device.

[0002] Patent Document 1 discloses a standing wave suppression technology in which sound-absorbing materials are attached to both sides of a plate material with many through holes, and the sound-absorbing materials are inserted at the antinode positions of the particle velocity distribution of standing waves inside a speaker cabinet. With this technology, the sound-absorbing materials attached to both sides of the plate material suppress standing waves inside the speaker cabinet.

[0003] Japanese Patent Application Laid-Open No. 2019-186879

[0004] However, in the conventional configuration, the sound absorbing effect of the sound absorbing material extends over a wider range than standing waves, which causes interference with frequency components other than standing waves and impairs sound quality. The present disclosure aims to solve the conventional problems and to provide a speaker device that more appropriately suppresses standing waves within a speaker cabinet and improves sound quality.

[0005] A speaker device according to one aspect of the present disclosure comprises a speaker unit, a housing in which the speaker unit is housed and which forms an internal space surrounded by walls, and a plate-shaped pore plate having a plurality of pores arranged in a direction intersecting the plate surface of the pore plate, the pore plate being positioned at a position where two of the wall surfaces face each other, spaced apart from both of the two surfaces, so that the plate surface intersects in a direction connecting the two wall surfaces, and the surface facing at least one of the two surfaces is exposed.

[0006] According to the present disclosure, it is possible to provide a speaker device with more appropriately improved sound quality.

[0007] FIG. 1 is a perspective view showing an example of the appearance of a speaker device according to an embodiment of the present invention. FIG. 2 is a front view showing an example of the appearance of a speaker device according to an embodiment. FIG. 3 is a side view showing an example of the appearance of a speaker device according to an embodiment. FIG. 4 is a graph showing the sound absorption characteristics of a perforated plate and a sound-absorbing material. FIG. 5 is a graph of a simulation result showing the relationship between the plate thickness of a perforated plate and the sound absorption characteristics. FIG. 6 is a graph of a simulation result showing the relationship between the aperture ratio of a perforated plate and the sound absorption characteristics. FIG. 7 is a graph of a simulation result showing the relationship between the length of an air space behind a perforated plate and the sound absorption characteristics. FIG. 8 is a graph of a simulation result showing the relationship between the hole diameter of a perforated plate and the sound absorption characteristics. FIG. 9 is a diagram showing an example of a perforated plate according to an embodiment. FIG. 10A is a graph showing the output sound pressure characteristics of a speaker device according to an embodiment. FIG. 10B is a graph showing an enlarged view of the output sound pressure characteristics of a speaker device according to an embodiment. FIG. 11 is a side view showing an example of the appearance of a speaker device according to another embodiment. FIG. 12 is a front view showing an example of the appearance of a speaker device according to another embodiment. Fig. 13 is a front view showing an example of the appearance of a speaker device according to another embodiment. Fig. 14 is a view showing an example of how to attach a porous plate according to another embodiment. Fig. 15 is a view showing an example of the configuration of a porous plate according to another embodiment. Fig. 16 is a side view showing an example of the appearance of a speaker device according to another embodiment.

[0008] (Knowledge forming the basis of the disclosure) It has been known that standing waves occur within a speaker cabinet. Standing waves have a negative impact on the sound quality of a speaker cabinet. For example, Patent Document 1 describes a configuration in which sound-absorbing material for absorbing standing waves is inserted at the antinode position of the particle velocity distribution of the standing waves to suppress the effects of standing waves. However, adopting the configuration described in Patent Document 1 requires the use of sound-absorbing material, which makes it difficult to generate a sound-absorbing effect tailored to the frequency of the standing waves. Furthermore, other necessary sound frequencies are also attenuated, leaving room for improvement in terms of sound quality. Furthermore, the sound-absorbing material described in Patent Document 1 must be inserted at the antinode position, and a relatively thick plate-like member with the sound-absorbing material attached is provided at a predetermined position within the speaker cabinet, potentially reducing the degree of freedom in designing the speaker cabinet.

[0009] In view of the above, the present disclosure provides a speaker device having steep sound absorption characteristics at the frequency of a standing wave by providing a perforated plate in a speaker cabinet that generates Helmholtz resonance. This perforated plate only requires a single plate to be provided along the intersecting plane of the standing wave, and can achieve a high sound quality improvement effect even without being provided at the antinode of the particle velocity distribution of the standing wave. The present disclosure aims to provide a speaker device with improved sound quality by suppressing standing waves using a perforated plate, thereby generating a steep sound absorption effect at the frequency of the standing wave while minimizing a reduction in the design freedom of the speaker device.

[0010] A more specific outline of the present disclosure is as follows.

[0011] A speaker device according to a first aspect of the present disclosure comprises a speaker unit, a housing in which the speaker unit is housed and which forms an internal space surrounded by walls, and a plate-shaped pore plate having a plurality of pores arranged in a direction intersecting the plate surface of the pore plate, the pore plate being positioned at a position where two of the wall surfaces face each other, spaced apart from both of the two surfaces, so that the plate surface intersects in a direction connecting the two wall surfaces, and the surface facing at least one of the two surfaces is exposed.

[0012] According to this speaker device, a space is provided behind the perforated plate (between the perforated plate and the wall surface), and the space and the perforations in the perforated plate can simulate a Helmholtz resonator. A Helmholtz resonator has a steep sound absorption characteristic with respect to frequency, and can effectively suppress sounds of specific frequencies. In other words, compared to conventional sound-absorbing materials that have sound absorption characteristics over a wide frequency range, it can specifically suppress targeted sounds. Therefore, standing waves generated in the speaker device can be effectively suppressed by a perforated plate tuned to the frequency. Moreover, since the wall surface of the housing is used to form the Helmholtz resonator, it is only necessary to place the perforated plate at an appropriate position within the space. In other words, standing waves can be suppressed with a simple configuration. Therefore, the speaker device can improve sound quality by suppressing standing waves, and more appropriately improve sound quality in terms of sound absorption characteristics in the frequency domain with a simple configuration.

[0013] A speaker device according to a second aspect is the speaker device according to the first aspect, wherein the porous plate is fixed to an internal component housed in the housing.

[0014] According to this, when the perforated plate is placed in the space, the perforated plate can be fixed by utilizing the built-in components already present in the space of the speaker device.

[0015] Furthermore, the speaker device according to the third aspect is the speaker device according to the first or second aspect, in which the pore plates are provided at two or more positions where two of the wall surfaces face each other, and the two or more pore plates are connected so as to intersect with each other.

[0016] According to this, two or more pore plates are individually provided for each of the standing waves occurring in two or more locations (two or more directions), and these two or more pore plates are connected so as to cross each other, thereby reducing the volume occupied by the pore plates in space.

[0017] Furthermore, a speaker device according to a fourth aspect is a speaker device according to any one of the first to third aspects, in which the porous plate has exposed surfaces facing both of two opposing portions of the wall surface.

[0018] This allows the porous plate, which has exposed surfaces on both sides, to more appropriately improve the sound quality.

[0019] In addition, a speaker device according to a fifth aspect is a speaker device according to any one of the first to fourth aspects, in which the thickness of the porous plate is greater as the frequency of standing waves generated by two opposing points on the wall surface is lower.

[0020] This allows the thickness of the porous plate to be adjusted to the frequency of the standing waves that are generated.

[0021] Furthermore, a speaker device according to a sixth aspect is a speaker device according to any one of the first to fifth aspects, in which the diameter of the pores provided in the pore plate is smaller as the frequency of the standing wave generated by two opposing points on the wall surface is higher, and the sound absorption coefficient for the standing wave is larger as the diameter of the pores provided in the pore plate is smaller.

[0022] This allows the perforations to be provided in the perforated plate with a diameter that is in accordance with the frequency of the standing waves to be generated and the required sound absorption coefficient.

[0023] In addition, the speaker device according to the seventh aspect is a speaker device according to any one of the first to sixth aspects, and the aperture ratio, which is the ratio of the total area of ​​the pores provided in the pore plate to the area of ​​the pore plate, is larger the higher the frequency of the standing wave generated by two opposing points on the wall surface.

[0024] This allows the perforated plate to be provided with perforations having an aperture ratio that matches the frequency of the standing waves that are generated.

[0025] Hereinafter, embodiments will be described in detail with reference to the drawings. Note that the embodiments described below are all comprehensive or specific examples. The numerical values, shapes, materials, components, component placement and connection configurations, steps, and step order shown in the following embodiments are merely examples and are not intended to limit the present disclosure. Furthermore, among the components in the following embodiments, components that are not recited in independent claims will be described as optional components. Note that each figure is a schematic diagram and is not necessarily an exact illustration. Furthermore, in each figure, substantially identical components are assigned the same reference numerals, and duplicated descriptions may be omitted or simplified.

[0026] Furthermore, in this specification, terms indicating the relationship between elements, such as parallelism, terms indicating the shape of elements, such as rectangular parallelepiped, and numerical ranges are not expressions that only express a strict meaning, but are expressions that also include a substantially equivalent range, for example, a difference of a few percent (less than 10%).

[0027] In addition, each drawing is a schematic diagram in which emphasis, omission, or adjustment of proportions has been appropriately made to illustrate the present disclosure, and is not necessarily an exact illustration, and may differ from the actual shape, positional relationship, and proportion. In each drawing, substantially the same configuration is assigned the same reference numeral, and duplicated explanations may be omitted or simplified.

[0028] Each figure also shows an X-axis, a Y-axis, and a Z-axis, which represent three mutually orthogonal directions, and these axes and the axial directions along these axes are used as necessary for explanation. Note that each axis is added for explanation purposes only and does not limit the direction or posture in which the speaker device is used.

[0029] (Embodiment) Hereinafter, a speaker device according to the present embodiment will be described with reference to Figs. 1 to 10B.

[0030] [1. Configuration of the speaker device] First, the configuration of the speaker device according to this embodiment will be described with reference to Figs. 1 to 3. Fig. 1 is a perspective view showing an example of the appearance of the speaker device 1 according to this embodiment. Fig. 2 is a front view showing an example of the appearance of the speaker device 1 according to this embodiment. Fig. 3 is a side view showing an example of the appearance of the speaker device 1 according to this embodiment. In the figures, the configuration that can be seen through the housing 20 is indicated by dashed lines.

[0031] As shown in FIGS. 1 to 3, the speaker device 1 includes a speaker unit 10, a housing 20, a porous plate 30, and a rod 31 for attaching the porous plate 30.

[0032] The speaker unit 10 is attached to a housing 20, with one surface of the diaphragm exposed outside the housing 20 and the other surface exposed to the internal space of the housing 20. The speaker unit 10 is composed of the above-mentioned diaphragm (not shown), a magnetic circuit 11 (see FIG. 11 described later), and a voice coil (not shown).

[0033] The housing 20 has, for example, a hexahedron shape and an internal space in which at least a portion of the speaker unit 10 (e.g., the magnetic circuit 11) and the perforated plate 30 are housed. The internal space is surrounded by the walls of the housing 20 (the inner surfaces of the housing 20 facing the internal space). When the housing 20 is hexahedron-shaped, the internal space also has an approximately hexahedron shape. In this case, the top and bottom surfaces of the internal space face each other, the front and rear surfaces corresponding to the housing front surface 20a face each other, and the right and left surfaces corresponding to the housing side surface 20c face each other. In other words, the speaker device shown in the figure generates standing waves in three directions. Standing waves are generated where two inner walls face each other, depending on the shape of the housing 20. In this embodiment, a perforated plate 30 is provided in the area where the standing waves are generated, and Helmholtz resonance is generated in the air layer between the perforated plate 30 and the inner wall, absorbing the standing waves. Therefore, the position where the porous plate 30 is provided must be such that the plate surface is aligned in a direction intersecting (preferably perpendicular to) the standing waves. The housing 20 is also called a speaker cabinet or a speaker box.

[0034] For example, the speaker unit 10 is inserted from an opening on the positive side of the X axis of the housing 20 and stored in the internal space of the housing 20. Furthermore, by providing a rod 31 fixed to a wall surface inside the housing 20, the perforated plate 30 is attached to the rod 31 and stored in the internal space. The perforated plate 30 is disposed so as to face the inner wall of the housing 20 so as to provide an air layer between the perforated plate 30 and the inner wall of the housing 20. The material of the housing 20 is not particularly limited, and hard materials capable of maintaining a three-dimensional shape, such as wood, metal, and resins such as plastic, are used.

[0035] The pore plate 30 is a plate-shaped member having pores extending in a direction intersecting the plate surface (thickness direction). The pore plate 30 is a member arranged in the internal space of the housing 20 so as not to interfere with the speaker unit 10, particularly the diaphragm. The pore plate 30 is formed by adjusting the pore diameter, plate thickness, and aperture ratio. As described above, the pore plate 30 has a large number of pores (through holes), which may be arranged at equal intervals or at unequal intervals. The configuration of the pores will be described later. The size and material of the pore plate 30 are not particularly limited, and a hard material capable of maintaining a three-dimensional shape, such as wood, metal, or resin such as plastic, of an appropriate size to fit into the housing 20, is used. The planar shape of the pore plate 30 is also not limited to the rectangular shape shown in the figure.

[0036] In this embodiment, the perforated plate 30 is attached to the rod 31 as described above to hold it at a predetermined position in the internal space. However, it may be fixed directly to the wall surface without using the rod 31 and maintained in the internal space, for example, by making the length equivalent to the width of the internal space. However, since completely dividing the internal space into two by the perforated plate 30 is undesirable in terms of acoustic characteristics, the spaces facing each of the two main surfaces of the perforated plate 30 are connected in a plane along the plate surface of the perforated plate, separately from the holes. The perforated plate 30 is a bare single plate, and both sides are exposed to the internal space. In other words, no other components such as sound-absorbing materials are provided on the surface of the perforated plate 30. Furthermore, both sides of the perforated plate 30 directly face the inner wall, which generates standing waves. Therefore, it is believed that most of the standing waves generated on the inner wall are directly incident on the perforated plate 30.

[0037] 2. Sound absorption characteristics of perforated plate The sound absorption characteristics of the perforated plate 30 will be described with reference to Fig. 4. Fig. 4 is a graph showing the sound absorption characteristics of a perforated plate and a sound-absorbing material. Fig. 4 shows the results of a comparison of the normal incidence sound absorption coefficient of the perforated plate 30 with the normal incidence sound absorption coefficient of a commercially available sound-absorbing material (Thinsulate (registered trademark)) when the plate thickness is 1 mm, the hole diameter is 1 mm, and the opening ratio is 1.6%.

[0038] As shown in Figure 4, the sound-absorbing material exhibits a sound absorption effect with a sound absorption coefficient of 0.8 or higher over a wide frequency range above 300 Hz, where the sound absorption coefficient peaks near 400 to 500 Hz. Even at higher frequencies, the sound absorption coefficient exceeds 0.5, demonstrating sound absorption. On the other hand, the perforated plate 30 exhibits a more localized (steeper) sound absorption effect than the sound-absorbing material near the peak of 400 Hz, demonstrating that the sound absorption effect at higher frequencies is also suppressed. Therefore, by inserting the perforated plate 30 into the speaker device 1, only standing waves perpendicular to the perforated plate 30 are suppressed, while no excessive sound absorption effect is produced at frequencies other than the standing waves. In other words, it is possible to realize a speaker device 1 that does not impair sound quality at frequencies other than the standing waves. It is also possible to confirm that a dip occurs near frequencies that are integer multiples of approximately 1.7 kHz. This is thought to be due to the effect of standing waves caused by the 10 cm air layer behind the speaker device when measuring with an acoustic tube.

[0039] The sound absorption characteristics of the above-mentioned perforated plate 30 when the design conditions are changed will be explained with reference to Figures 5 to 8. Figures 5 to 8 are graphs showing the sound absorption characteristics when simulations were performed with different design conditions for the perforated plate. Note that the back air space here refers to the distance from the perforated plate 30 to the inner wall of the housing 20.

[0040] 5 shows the results of determining the sound absorption coefficient characteristics when the plate thickness is changed to 5 mm, 2 mm, 1 mm, and 0.5 mm, with an open area ratio (the ratio of the total area of ​​the holes in the perforated plate 30 to the plate surface area of ​​the perforated plate 30) of 1%, a hole diameter of 1 mm, and a back air space of 100 mm. As shown in FIG. 5, by reducing the plate thickness of the perforated plate 30, the peak of the sound absorption coefficient shifts to the higher frequency side, and the magnitude of the sound absorption coefficient also changes. Therefore, the thickness of the perforated plate 30 should be increased as the frequency of the generated standing waves decreases.

[0041] Figure 6 shows the results of determining the sound absorption coefficient characteristics when the aperture ratio is changed to 5%, 2%, 1%, and 0.5% with a plate thickness of 1 mm, a hole diameter of 1 mm, and a back air space of 100 mm. As shown in Figure 6, by reducing the aperture ratio of the perforated plate 30, the peak of the sound absorption coefficient shifts to the lower frequency side, and the magnitude of the sound absorption coefficient also changes. Therefore, the aperture ratio of the perforated plate 30 should be increased as the frequency of the generated standing waves increases.

[0042] Figure 7 shows the results of determining the sound absorption coefficient characteristics when the back air space is changed to 150 mm, 100 mm, 70 mm, and 50 mm with an open area ratio of 1%, a plate thickness of 1 mm, and a hole diameter of 1 mm. As shown in Figure 7, by reducing the distance between the perforated plate 30 and the back wall surface, the peak of the sound absorption coefficient shifts to the higher frequency side, and the magnitude of the sound absorption coefficient also changes. Therefore, the length of the back air space should be reduced as the frequency of the generated standing waves increases.

[0043] Figure 8 shows the results of determining the sound absorption coefficient characteristics when the hole diameter is changed to 2 mm, 1 mm, 0.8 mm, and 0.5 mm, with an open area ratio of 1%, a plate thickness of 1 mm, and a backing air space of 100 mm. As shown in Figure 8, by reducing the hole diameter of the perforated plate 30, the peak of the sound absorption coefficient shifts somewhat to the higher frequency side, but the sound absorption coefficient increases as the hole diameter becomes smaller. Therefore, since there is little frequency-dependent change in the sound absorption coefficient compared to when the plate thickness, the open area ratio of the perforated plate 30, and the length of the backing air space are changed, by setting each parameter, the sound absorption coefficient curve can be adjusted to the target standing wave frequency, and then by further reducing the hole diameter, a significant standing wave suppression effect can be achieved.

[0044] In this way, the sound absorption coefficient and the frequency at which the sound absorption effect is produced can be adjusted by adjusting the plate thickness, pore diameter, opening rate, etc. of the porous plate 30, so it can be flexibly designed according to the size of the housing 20 used and the frequency band of the standing waves to be absorbed.

[0045] [3. Output sound pressure frequency characteristics of the speaker device] The output sound pressure frequency characteristics of the speaker device 1 configured as above will be described with reference to Fig. 9, Fig. 10A and Fig. 10B. Fig. 9 is a diagram showing an example of a micro-pore plate according to the embodiment. Fig. 10A is a graph showing the output sound pressure characteristics of the speaker device according to the embodiment. Fig. 10B is a graph showing an enlarged view of the output sound pressure characteristics of the speaker device according to the embodiment.

[0046] The porous plate 30 used in the speaker device 1 has numerous holes (through holes 32) as shown in Figure 9, and here each through hole 32 has a hole diameter of 0.3 mm, and is designed to have a plate thickness of 0.5 mm and an aperture ratio of 1.2%.

[0047] The perforated plate 30 designed under the above conditions was placed in a speaker box with internal dimensions of 250 mm high x 165 mm wide x 220 mm deep, parallel to the front surface 20a of the housing, i.e., in a direction intersecting the X-axis direction, at a distance of 110 mm from the front surface 20a of the housing and 70 mm from the bottom surface of the housing. The output sound pressure frequency characteristics of the speaker device 1 in this case were compared between when the perforated plate 30 was not placed and when it was placed, as shown in Figures 10A and 10B. Note that Figure 10B is an enlarged view of the frequency band where standing waves occur in Figure 10A.

[0048] 10A and 10B, by using the porous plate 30, a suppression effect is observed for the standing wave around 700 Hz resulting from 220 mm in the X-axis direction, which is the depth direction of the housing interior dimension. Also, as shown in FIG. 10A, it is possible to suppress changes in characteristics in frequency bands other than the standing wave around 700 Hz.

[0049] In this way, the speaker device 1 can suppress only the standing waves resulting from the internal dimensions of the housing 20 through the sound-absorbing effect of the perforated plate 30 arranged within the housing 20, while preventing a deterioration in sound quality in frequency bands other than the target standing waves, thereby achieving a speaker device 1 with higher sound quality.

[0050] (Other Embodiments) While the speaker devices according to one or more aspects have been described above based on the respective embodiments, the present disclosure is not limited to these respective embodiments. As long as they do not deviate from the spirit of the present disclosure, various modifications conceivable by those skilled in the art to the present embodiments and configurations constructed by combining components of different embodiments may also be included in the present disclosure.

[0051] 1 to 3 of the above embodiment, if the position of the porous plate 30 is moved parallel (on the Y-Z plane) while keeping the distance between the porous plate 30 and the inner wall of the housing 20 constant, the standing wave suppression effect is maintained. As a result, the position of the porous plate 30 is not affected by the contents inside the speaker box, allowing for more flexible speaker design.

[0052] In addition, for example, in the above embodiment, the pore plate 30 is arranged in a direction parallel to the front surface 20a of the housing in Fig. 1, but it may be arranged in a direction parallel to the bottom surface or the side surface 20c of the housing as shown in the examples of Fig. 12 and Fig. 13. In this case, a sound absorbing effect is generated against standing waves resulting from the internal dimensions of the housing in a direction perpendicular to the pore plate 30.

[0053] Furthermore, for example, in the above embodiment, the perforated plate 30 is attached by attaching the rod 31 to the housing 20, but it may also be attached to the magnetic circuit 11 of the speaker unit 10 as shown in Fig. 14. In this way, the perforated plate 30 can be fixed to any of the built-in components housed in the internal space of the housing 20, such as the magnetic circuit 11 of the speaker unit 10.

[0054] Further, for example, in each of the above embodiments, the standing waves resulting from the dimension in the depth direction (X-axis direction) of the housing 20 were suppressed by aligning only one perforated plate 30 with the depth direction (X-axis direction) of the housing 20, but two perforated plates 30 connected in a cross shape as shown in FIG. 15 may also be used. The two cross-shaped perforated plates 30 shown in FIG. 15, when arranged as shown in FIG. 16, for example, can simultaneously suppress standing waves in the X-axis direction and the Z-axis direction in the speaker box. In this way, the shape of the perforated plate 30 is not particularly limited as long as the perforated plate 30 is oriented parallel to the inner wall of the housing 20 (in a direction intersecting the standing waves, more preferably perpendicular).

[0055] In addition, this disclosure also includes forms obtained by applying various modifications to each embodiment that a person skilled in the art would think of, or forms realized by arbitrarily combining the components and functions of each embodiment within the scope that does not deviate from the intent of this disclosure.

[0056] The present disclosure is useful as a speaker device or the like that produces a sound absorbing effect only at a specific frequency.

[0057] 1, 2, 3, 4, 5, 6 Speaker device 10 Speaker unit 11 Magnetic circuit 20 Housing 20a Housing front surface 20c Housing side surface 30 Perforated plate 31 Rod 32 Through hole

Claims

1. A speaker device comprising: a speaker unit; a housing in which the speaker unit is housed and which forms an internal space surrounded by walls; and a plate-shaped porous plate having a plurality of pores formed in a direction intersecting the plate surface of the porous plate, wherein the porous plate is positioned at a position where two of the wall surfaces face each other, is spaced apart from both of the two surfaces, and has a plate surface that intersects in a direction connecting the two wall surfaces, and the surface facing at least one of the two surfaces is exposed.

2. The speaker device according to claim 1, wherein the porous plate is fixed to an internal component housed in the housing.

3. The speaker device according to claim 1, wherein the porous plates are provided at two or more positions on the wall surface where two portions of the wall surface face each other, and the two or more porous plates are connected so as to intersect with each other.

4. The speaker device according to claim 1, wherein the porous plate has exposed surfaces facing both of two opposing portions of the wall surface.

5. The speaker device according to any one of claims 1 to 4, wherein the thickness of the porous plate is greater as the frequency of standing waves generated by two opposing portions of the wall surface is lower.

6. A speaker device according to any one of claims 1 to 4, wherein the diameter of the pores provided in the pore plate is smaller as the frequency of the standing wave generated by two opposing points on the wall surface is higher, and the sound absorption coefficient for the standing wave is greater as the diameter of the pores provided in the pore plate is smaller.

7. A speaker device according to any one of claims 1 to 4, wherein the aperture ratio, which is the ratio of the total area of ​​the pores provided in the pore plate to the area of ​​the pore plate, increases as the frequency of standing waves generated by two opposing points on the wall surface increases.

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