JP2000295682A - Acoustic casing and sound absorptive panel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress stationary waves generated inside a casing such as a room or an enclosure for a speaker system and to improve the quality of acoustic reproduction by constructing at least one part with a planar structure having a hollow part formed by partitioning with bulkheads arranged parallel in one direction. SOLUTION: A planar structure 10 has a hollow structure in which plural hollow parts 12 that communicate in the longitudinal direction (Y direction) while separated by bulkheads 11 in the lateral direction (X direction) of plate material are arranged with an equal interval. That is, the structure 10 has a structure which forms the parts 12 surrounded by a top wall plate 13, a bottom wall plate 14, the bulkheads 11 and side plates 15 by providing a box with a hollow structure formed by the plate 13 and 14 and the two side plates 15 with plural bulkheads 11 with equal interval. The parts 12 constituting the structure 10 operates as an open acoustic tube in the case both edge parts are opened and operates as a closed acoustic tube in the case one end is closed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of an acoustic housing (for example, a frame constituting a room, an enclosure for a speaker system, etc.) and a sound absorbing panel in the field of architectural acoustics and acoustic equipment.

[0002]

2. Description of the Related Art Conventionally, when sound is reproduced in a rectangular parallelepiped room or a rectangular parallelepiped speaker system enclosure, at a specific frequency determined by the dimensions of the room and the dimensions of the enclosure due to the reflection of internally generated sound waves. It is known that a so-called standing wave that resonates is generated, and the quality of sound reproduction is significantly impaired, and the sound pressure frequency characteristic of the speaker system is disturbed.

[0003]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned drawbacks of the related art, and suppresses a standing wave generated in an acoustic housing such as a room or an enclosure for a loudspeaker system. It is an object of the present invention to provide a novel acoustic housing and a sound absorbing panel capable of significantly improving quality.

[0004]

According to the first aspect of the present invention, there is provided an acoustic housing having a planar structure having a hollow portion formed by partitioning at least a part of a partition arranged in parallel in one direction. It is characterized by comprising.

According to a second aspect of the present invention, there is provided the acoustic housing according to the first aspect, wherein the hollow portion has an opening, and is located at a predetermined length from the opening. It is characterized in that a closing part is formed.

According to a third aspect of the present invention, there is provided an acoustic casing according to the second aspect, wherein the planar structure comprises:
It is characterized by being constituted by an aggregate of a plurality of hollow portions having different lengths.

According to a fourth aspect of the present invention, there is provided an acoustic casing according to the second or third aspect, wherein the acoustic casing is a speaker system enclosure.

According to a fifth aspect of the present invention, there is provided an acoustic housing according to the fourth aspect, wherein the opening is provided on an inner surface of the speaker system enclosure. .

According to a sixth aspect of the present invention, there is provided an acoustic casing according to any one of the first to third aspects, wherein the acoustic casing is a frame forming a room. .

According to a seventh aspect of the present invention, in the sound absorbing panel, at least a part thereof is formed of a planar structure having a hollow portion defined by partition walls arranged in parallel in one direction. Features.

The sound absorbing panel according to the invention according to claim 8 is the sound absorbing panel according to claim 7, wherein the hollow portion has an opening, and the closing portion is located at a predetermined length from the opening. It is characterized by being formed.

A sound absorbing panel according to a ninth aspect of the present invention is the sound absorbing panel according to the eighth aspect, wherein the planar structure is formed of an aggregate of a plurality of hollow portions having different lengths. It is characterized by the following.

A sound absorbing panel according to a tenth aspect of the present invention is the sound absorbing panel according to any one of the seventh to ninth aspects, wherein the sound absorbing panel is formed of a plurality of planar structures and has a hollow portion. Are connected internally.

The acoustic housing of the present invention is an acoustic housing at least partially constituted by a planar structure, wherein the planar structure is at least partially defined by partitions arranged in parallel in one direction. The hollow portion has an opening, a closing portion is formed at a position of a predetermined length from the opening, the opening formed in the planar structure. By providing the acoustic wave on the inner side surface, the standing wave inside the acoustic case can be suppressed, and the quality of sound reproduction can be significantly improved. Further, the acoustic housing of the present invention is a body constituting a speaker system enclosure or room,
The standing wave in the speaker system enclosure or the room can be suppressed, and the quality of sound reproduction can be significantly improved. Further, the sound absorbing panel of the present invention is formed of a plurality of planar structures, and the hollow portions of each other are connected internally, so that a sound absorbing panel having a long hollow portion corresponding to the size of the room is formed. By installing the sound absorbing panel close to and parallel to the wall surface of the room, standing waves inside the room can be suppressed, and the quality of sound reproduction can be significantly improved.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION The acoustic housing of the present invention is constituted by using a planar structure having a plurality of hollow portions formed by partitioning at least a part of partitions arranged in parallel in one direction. FIGS. 1 to 3 show the structure of this planar structure.
This will be described with reference to FIG. 1 and 2 are perspective views of a main part of the planar structure. The planar structure 10 shown in FIG. 1A has, for example, a hollow structure in which a plurality of hollow portions 12 communicating with each other in a vertical direction (Y direction) across a partition 11 in a horizontal direction (X direction) of a plate material are arranged at equal intervals. have. In other words, the planar structure 10
A plurality of partitions 11 are provided at equal intervals in a box having a hollow structure formed by an upper plate 13 above the paper, a lower plate 14 below the paper, and two side plates 15, so that the upper plate 13 and the lower plate 14 are provided. , Partition 1
It has a structure in which a plurality of hollow portions 12 surrounded by one and a side plate 15 are formed.

The hollow portion 12 constituting the planar structure 10 is
If both ends are open, it acts as an open acoustic tube, and if one end is closed, it acts as a closed acoustic tube. The planar structure 10 shown in FIG.
In this example, a part of the upper plate 13 is formed at a position of a predetermined length (L) in the vertical direction (Y direction) from (a hatched portion in the drawing), for example, a V-shaped or concave opening 17. In addition, an open acoustic tube in which the entire planar structure 10 is formed by the hollow portion 12 having the length L can be provided.

Next, FIG. 2 shows a planar structure 10 acting as a closed acoustic tube. The planar structure 10 shown in FIG.
Is an example in which one end is opened and a closing plate 18 is formed at a position of a length L in a vertical direction (Y direction), and the entire planar structure 10 is formed by a hollow portion 12 having the same length L. It can be a closed acoustic tube. The planar structure 10 shown in FIG. 2B has, for example, an opening surface 16 on the left side of the planar structure 10 in the drawing.
From the opening surface 16 to the position of the length L1 on the right side in the drawing of the planar structure 10, and the position where the closing plate 18 is sequentially formed for each adjacent hollow portion 12 is changed. This is a configuration example. With such a configuration, the planar structure 10 can be an aggregate of closed acoustic tubes including a plurality of hollow portions 12 having different lengths.

As described above, the planar structure 10 acting as an open acoustic tube need only form the hollow portion 12 communicating in the vertical direction (Y direction) as shown in FIG.
For example, a so-called hollow extrusion molding using a resin material such as PVC (polyvinyl chloride) or PP (polypropylene) or a metal material such as aluminum, or two side plates 15 and a plurality of partition walls 11 on a lower plate 14 are used. Is bonded by an adhesive or the like, and then the upper plate 13 is attached.
In the planar structure 10 acting as a closing acoustic tube, it is necessary to form a closing plate 18 at a predetermined position as shown in FIG. Therefore, for example, as shown in FIG. 3 (a), two uneven plate members each having convex portions corresponding to the side plate 15 and the plurality of partition walls 11 of the planar structure 10 are prepared in parallel, Can be easily formed by arranging the closing plate 18 and then bonding the other uneven plate material with an adhesive or the like. The above is the description of the structure of the planar structure 10.

Next, a speaker system enclosure 20 which is an acoustic housing of the present invention will be described below with reference to FIGS. 4 and 5 are views showing an embodiment in which a part of the speaker system enclosure 20 is constituted by the planar structure 10, and FIG. 4 shows that the mounting position of the speaker unit 21 is located at the center in the longitudinal direction of the enclosure. FIG. 5 shows the case where the speaker unit 21 is not installed, and the mounting position of the speaker unit 21 is at the center of the speaker system enclosure 20. FIG. 4A is a perspective view of the speaker system enclosure 20, in which a part of the horizontal plate 22 of the speaker system enclosure 20 is temporarily opened for the purpose of illustrating the configuration of the planar structure 10. ing.
FIG. 4B is a plan view of a case where the planar structure 10 having the opening 17a and the closing part 18 is provided on the left and right horizontal plates 22 constituting a part of the speaker system enclosure 20, and FIG. c) is a plan view of the case where the planar structure 10 in which the closing portions 18 are formed in the left and right horizontal plates 22 constituting the speaker system enclosure 20 and the openings 17b are formed in the top plate 23 and the bottom plate 24 is formed. is there.

Here, when an acoustic housing such as a speaker system enclosure is constructed using the planar structure 10, the top plate and the horizontal plate, or the bottom plate and the horizontal plate of the acoustic housing are independent surfaces. In the case where the closed acoustic tube has a length (L) from the top plate to the horizontal plate or from the bottom plate to the horizontal plate, it is not a problem in the case where the closed acoustic tube is constituted by the like-shaped structure 10, as shown in FIG. As described above, the cut edge at the end of the planar structure 10 is 4 ° with respect to the plane of each plate.
The opening is formed at an angle of 5 degrees, and the ends of the bottom plate and the horizontal plate, or the ends of the top plate and the horizontal plate are bonded to each other, so that the hollow portion 12 of the planar structure 10 is moved from the top plate side to the horizontal plate It is possible to form a closed acoustic tube of a length (L) to the side or from the bottom plate side to the horizontal plate side.

In the speaker system enclosure 20 shown in FIG. 4A, the top plate 23 and the bottom plate 24 are made of a solid plate (a solid plate) or the opening surfaces 16 on both sides.
Is constituted by the planar structure 10 closed by the closing plate 18. The left and right horizontal plates 22 have openings 17a formed in the inner space side of the speaker system enclosure 20, that is, a part of the inner surface of the speaker system enclosure 20, and the closing plate 18 is provided at a predetermined length. It is composed of a planar structure 10. Opening 17a of planar structure 10
Are provided at the upper and lower ends of the horizontal plate 22 (positions in contact with the top plate 23 or the bottom plate 24), and the length (L) forming the closing plate 18 when the longitudinal dimension of the enclosure is H
Is located approximately at H / 2 from the opening 17a.

The acoustic housing 20 shown in FIG.
The opening 17b of the planar structure 10 is connected to the top plate 23 and the bottom plate 24.
The position where the closing plate 18 is formed is substantially the length of H / 2 from the opening 17b in the same manner as described above. The speaker system enclosure 20 shown in FIG. 4C shows a case where the position where the closing plate 18 of the planar structure 10 is formed is not in the top plate 23 or the bottom plate 24. In such a case, as described in FIG.
Opening such that the cutouts at the ends of the planar structure 10 constituting the top plate 23, the bottom plate 24, and the left and right horizontal plates 22 are each 45 degrees with respect to the plane of each plate, and the opening portions are bonded together. The top plate 23 and the bottom plate 24 communicate with the hollow portions 12 of the left and right horizontal plates 22 to form the closing plate 18 at a position of a predetermined length.

Next, when the mounting position of the speaker unit 21 is at the center of the speaker system enclosure, as shown in FIG. 5, the position where the closing plate 18 is formed is substantially H / 4 from the opening. Is set to FIG.
(A) The speaker system enclosure 20 shown in FIG.
Are the openings 1 in the planar structure 10 constituting the left and right horizontal plates 22.
FIG. 5B shows an example of a speaker system enclosure 20 in which an opening 17 d and a closing plate 18 are provided in a planar structure 10 constituting a top plate 23 and a bottom plate 24. This is an example.

As described with reference to FIGS. 4 and 5, openings 17a, 17b, 17c, and 17d are formed by opening the inner space side of the speaker system enclosure 20, that is, a part of the inner surface of the speaker system enclosure. In addition, by providing a closing plate 18 for closing the hollow portion 12 at a position of a predetermined length from the opening, a closed acoustic tube having a predetermined length can be configured. The closed acoustic tube configured as described above operates as a tube-resonant sound absorber having a frequency that matches the frequency of a standing wave generated inside the speaker system enclosure. Further, if the porous sound absorber is slightly inserted into the hollow portion 12, the sound absorbing effect can be further enhanced.

FIG. 6 is a diagram showing a frequency characteristic of a sound absorbing effect of the above-described enclosure for a speaker system.
The vertical axis indicates the sound absorption coefficient, and the horizontal axis indicates the frequency. The characteristics shown in FIG. 6 are obtained by generating a sound of a predetermined level from the speaker unit 21 by continuously changing the frequency, and measuring the sound pressure of a microphone provided in the enclosure. It shows that the sound absorbing effect is high at f1 and frequency f2. In other words, two frequencies f1,
At f2, a standing wave unique to the enclosure has been generated. Therefore, the speaker system enclosure 20 is constituted by the planar structure 10 provided with the opening 17 and the closing plate 18 at positions corresponding to the standing waves of the two frequencies f1 and f2, so that the frequency of the standing wave is increased. The length of the tube-resonant sound-absorbing body conforming to the above is formed, and the generation of standing waves can be suppressed over the entire frequency.

Next, the principle of the operation of the speaker system enclosure of the present embodiment as a tube resonance type sound absorber will be described. Generally, the acoustic impedance Zi per unit area of an acoustic tube in which one end is opened and the other end is closed is viewed from the open end by the following equation (1). Zi = -jρ0Ccot (kL) (1) where ρ0: density of air C: sound velocity k: wavelength constant (= 2πf / C, f: frequency) L: length of acoustic tube Therefore, kL = ( Tube resonance occurs at a frequency of (n + 1/2) π, and Zi = 0, that is, a state of sucking sound, and kL
= Nπ indicates that Zi = ∞ (infinity), that is, the same state as the sound-reflecting wall (where n = 0, 1, 2,...). On the other hand, the inside of the speaker system enclosure is exactly the same as this acoustic tube. For example, when viewed in the longitudinal direction, the length of the closed acoustic tube from the center of the speaker system enclosure to one end is connected to both sides in the longitudinal direction. Since it is considered as a closed acoustic tube of H (= 2L), the sound wave in the enclosure for the speaker system is reflected at the closed end, and a standing wave is generated at a frequency fs where kH (= 2 kL) = π. Therefore, a portion having an acoustic impedance of 0 (or a minimum) is provided in the vicinity of the closed end, and the generation of standing waves can be prevented by absorbing the sound waves to prevent reflection. FIG. 4 of the present invention shows an example in which this principle is applied. That is, the openings 17a and 17b are provided near the top plate 23 and the bottom plate 24 of the speaker system enclosure corresponding to the closed end.
And a closed acoustic tube whose length (L) is approximately H / 2,
The acoustic impedance seen from the openings 17a and 17b becomes 0 at the frequency where kL = π / 2, that is, kH = π from the equation (1), and this frequency matches the frequency fs of the standing wave.

When the mounting position of the speaker unit 21 is at the center of the speaker system enclosure (FIG. 5), even if a standing wave is generated at the frequency fs,
At the position of the speaker unit 21, the acoustic impedance is zero or minimal at the node of the standing wave, so that the operation of the speaker is not affected at all. However, at a frequency of 2 fs, a secondary standing wave is generated, and at the position of the speaker unit, the antinode of the standing wave, that is, the acoustic impedance becomes infinite, which greatly affects the operation of the speaker. In order to improve this, as shown in FIG. 5, the length (L) of the above-mentioned acoustic tube is set to approximately H corresponding to 2 fs.
By setting / 4, it is possible to operate as a sound absorber. The above is the description of the principle on which the speaker system enclosure operates as the tube resonance type sound absorber.

According to the acoustic housing such as the speaker system enclosure of the present embodiment, the tube resonance type absorber is
In the band equal to or lower than the fundamental frequency, the sound tube operates as a mere sound volume, so that the volume inside the enclosure for the speaker system is a volume obtained by adding the sound volume of the sound tube.
In particular, when the speaker system enclosure is small and has a substantially small internal volume, this substantial internal volume expansion effect greatly contributes to expansion of the low-frequency reproduction band of the speaker system. As an example, the external dimensions are 200 mm x 200
When compared with a cubic enclosure having a size of 200 mm × 200 mm and a thickness of 20 mm, the sheet-like structure 10 of the hollow plate has an effective thickness converted into the thickness of the solid plate having the same cross-sectional area of 1 mm of the solid thickness. / 2, it is possible to increase the substantial internal volume to about 1.4 times that of the solid plate. This means that there is an effect of lowering the low-frequency reproduction lower limit frequency (or the lowest resonance frequency) to about 85%.

Further, as described with reference to FIG. 2B, by providing the closing plate 18 at a different position for each of the adjacent partition walls 11, it is possible to form an aggregate of many acoustic tubes having different lengths. In this case, even if the frequency of the standing wave varies, each acoustic tube can function as a tube-resonant sound absorber having a frequency that matches each frequency. In addition, standing waves are generated in the width direction and the depth direction in addition to the longitudinal direction of the enclosure. If the dimensions in the respective directions are not in an integer proportional relationship, it is not possible to cope with only one type of dimension in which the length of the acoustic tube is adjusted to the frequency of the standing wave in the longitudinal direction. Therefore, this case can be solved at the same time by using a set of acoustic tubes having different dimensions according to the standing waves of the width and the depth.

FIG. 7 is a cross-sectional view of a main part when a speaker system enclosure and a sound tube are combined to form a phase inversion type speaker system enclosure 30 having a Helmholtz resonance type acoustic structure. In the case of the phase inversion type, an acoustic tube having one end having an opening inside the speaker system enclosure and the other end having an opening outside the speaker system enclosure is required. Therefore, as a plate material constituting the speaker system enclosure, for example, the bottom plate 24 is constituted by the planar structure 10 having the opening 17 formed at a predetermined position inside the speaker system enclosure. Is arranged so as to be exposed to the outside of the acoustic casing, a phase inversion type acoustic casing can be configured. Therefore, since the hollow portion 12 of the planar structure 10 can be used as a sound tube for Helmholtz resonance, there is no need to provide a separate sound tube.

FIG. 8 shows the characteristics of the speaker system using the speaker system enclosure 20 of the present embodiment (FIG. 8B) and the characteristics of the speaker system using the conventional enclosure (FIG. 8A). ing. In the figure, the symbol (a) indicates the electrical admittance (reciprocal of the input impedance) of the speaker, and (b) indicates the output sound pressure level. In the characteristic of (a), the minimum frequency seen near 100 Hz is proportional to the low-frequency reproduction limit frequency of the speaker system, and is compared with the characteristic (a) of the conventional enclosure and the characteristic (b) of the enclosure of the present embodiment. In ()), it can be seen that the frequency shifts to a lower frequency, and thus the low-frequency reproduction limit frequency is lowered. Also,
In the characteristic (b), the characteristic around 500 to 1000 Hz shows a sharp change (Ta portion) in the characteristic (a) of the conventional enclosure, and the influence of the standing wave in the enclosure appears. On the other hand, in the characteristic (b) by the enclosure of the present invention, the change is smooth (Tb portion), and it can be seen that the generation of the standing wave is suppressed.

As described above, in the speaker system enclosure 20 of the present embodiment, the opening 17 and the closing plate 18 of the planar structure 10 are positioned at predetermined positions based on the sound pressure frequency characteristics of the conventional speaker system enclosure. Thus, standing waves can be suppressed and the quality of sound reproduction can be significantly improved.

Although the speaker system enclosure has been described as an example, the above-described speaker can also be used when the frame or wall of the room is formed using the planar structure 10, that is, when the room is formed as an acoustic housing. It is possible to configure in the same way as the system enclosure,
For example, it can be dealt with only by increasing the plate thickness of the planar structure 10 by the larger dimension and increasing the cross-sectional area of the acoustic tube. Also in this case, based on the sound pressure frequency characteristics of the room,
By forming the opening 17 and the closing plate 18 of the planar structure 10 at predetermined positions, standing waves can be suppressed, and the quality of sound reproduction can be significantly improved.

When an acoustic tube is to be formed later in an existing room, the independent sound absorbing panel 40 having the structure shown in FIG. 9 can be installed close to and parallel to the wall surface of the room.
The independent sound absorbing panel 40 shown in FIG. 9A has the same configuration as the above-described speaker system enclosure 20. However, in this case, since the standing wave in the room has a large size, it is necessary to considerably lengthen the length L of the acoustic tube. Therefore, the independent sound absorbing panel 40 is shown in FIG.
As shown in (b), a planar structure 10a provided with an opening 17 in the vicinity of a surface opposite to the opening surface 16 exposed to the outside.
And the planar structure 10b provided with an opening 17 near the surface opposite to the surface closed by the closing plate 18 and the opening 17
They are arranged so as to face each other and are in agreement with each other. With this configuration, the two planar structures 10a and 10b
The hollow portion 12 is connected via an opening 17 to form an independent sound-absorbing panel 40 in which one closed acoustic tube having a length approximately twice the height of the planar structure 10 is formed. it can.
Also in this case, as shown in FIG. 2, by providing the closing plate 18 at a predetermined position, the closing acoustic tube can be configured to have a desired length.

[0035]

The acoustic housing or the sound absorbing panel of the present invention is constituted by a planar structure having a hollow portion, and the hollow portion can be used as an acoustic tube acting as a tube resonance type sound absorber. The standing wave generated inside the body can be removed or reduced. In addition, it is easy to design and process the hollow part as a set of acoustic tubes that change length approximately continuously by using a closing plate, and easily configure a tube resonance type sound absorber that supports a wide range of frequencies. can do. Further, since the hollow portion can be substantially used as the internal volume of the acoustic housing, the effective internal volume can be increased.
In addition, compared with an acoustic housing having the same external dimensions formed of the same solid plate material, the structural rigidity can be increased if the weight is the same, and the weight can be significantly reduced if the rigidity is the same.

[Brief description of the drawings]

FIG. 1 is a structural explanatory view of a planar structure constituting an acoustic housing or a sound absorbing panel of the present invention.

FIG. 2 is a structural explanatory view of a planar structure having a closing plate constituting an acoustic housing or a sound absorbing panel of the present invention.

FIG. 3 is an explanatory view of a method of assembling a planar structure having a closing plate constituting an acoustic housing or a sound absorbing panel of the present invention.

FIG. 4 is a configuration diagram of an acoustic housing according to the embodiment of the present invention.

FIG. 5 is another configuration diagram of the acoustic housing according to the embodiment of the present invention.

FIG. 6 is a diagram illustrating a relationship between a sound absorbing rate and a frequency of an acoustic housing or a sound absorbing panel.

FIG. 7 is an essential part cross-sectional view of a case where the acoustic housing and the acoustic tube are combined to form a phase inversion acoustic housing having a Helmholtz resonance type acoustic structure.

FIG. 8 is a diagram showing a sound pressure frequency characteristic of the acoustic housing according to the embodiment of the present invention.

FIG. 9 is a structural view of a stand-alone sound absorbing panel according to an embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Planar structure 11 ... Partition wall 12 ... Hollow part 13 ... Inner wall board 14 ... Outer wall board 15 ... Side plate 16 ... Opening surface 17 ... Opening 18 ..Closing part 20 ... Acoustic housing 21 ... Speaker unit 22 ... Horizontal plate 23 ... Top plate 24 ... Bottom plate

 ────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Yoshitomo Imanishi 4-2610 Hanazono, Tokorozawa-shi, Saitama F-term in Pioneer Corporation Tokorozawa Plant 5D017 AD22 5D061 AA06 AA16 BB07 BB37 CC12 DD02

Claims (10)

[Claims] 1. An acoustic housing comprising at least a part of a planar structure having a hollow portion defined by partition walls arranged in parallel in one direction. 2. The acoustic casing according to claim 1, wherein the hollow portion has an opening, and a closing portion is formed at a position at a predetermined length from the opening. 3. The acoustic housing according to claim 2, wherein the planar structure is constituted by an aggregate of the plurality of hollow portions having different lengths. 4. The speaker according to claim 2, wherein the acoustic housing is an enclosure for a speaker system.
The described acoustic enclosure. 5. The acoustic housing according to claim 4, wherein the opening is provided on an inner surface of the speaker system enclosure. 6. The acoustic housing according to claim 1, wherein the acoustic housing is a frame forming a room. 7. A sound-absorbing panel comprising at least a part of a planar structure having a hollow portion defined by partition walls arranged in parallel in one direction. 8. The sound absorbing panel according to claim 7, wherein the hollow portion has an opening, and a closing portion is formed at a position of a predetermined length from the opening. 9. The sound-absorbing panel according to claim 8, wherein the planar structure is constituted by an aggregate of the plurality of hollow portions having different lengths. 10. The sound absorbing panel according to claim 7, wherein the sound absorbing panel is formed of a plurality of the planar structures, and the hollow portions are connected to each other inside. Sound absorbing panel.