JP4899090B2 - Sound absorption structure - Google Patents

Description

The present invention relates to a sound absorbing structure, in particular, it relates to a sound absorbing structure suitable for absorption and diffusion of the sound from the surface source in the closed space of the building.

  In a closed space separated by walls, the sound emitted from the sound source is reflected between the opposing wall surfaces, resulting in long-path echoes and flutter echoes, which may cause an acoustic disturbance that sounds can be heard separately. Since it is not preferable that such an acoustic disturbance occurs in an important room (a room where clarity of voice / musical sound is required), for example, an interior sound absorber as shown in Patent Document 1 is attached to a wall surface. The acoustic disturbance is suppressed.

This interior sound absorber has a space on the back surface side, and includes an elongated diffuser plate having a convex surface and / or a concave surface on the front surface side, and a sound absorbing material attached to the back surface of the diffuser plate. By forming a notch that communicates the outside with the space, the sound directed toward the wall surface in the room is diffused and reflected by the surface of the elongated diffuser plate having a convex part and / or a concave part, while the notch part of the diffuser plate The sound that has entered the space on the back side from the sound is absorbed by a resonance-type sound absorber made up of the space and the notch formed by the diffusion plate, and is simultaneously absorbed by the sound absorbing material attached to the back surface of the diffusion plate.
JP-A-8-177142

  In such a sound absorbing structure using a sound absorber for interior, for example, it is considered that an effective sound absorbing effect can be obtained for a sound having a spread that is emitted from a cone speaker of a point sound source. It is difficult to obtain an effective sound-absorbing effect for sound that has a sharp directivity and does not theoretically cause distance attenuation, such as that emitted from a flat speaker of a surface sound source that has been adopted.

  A plane sound wave, which is a special sound wave radiated from a flat speaker, theoretically does not decay with distance, and the plane sound wave is also reflected by the smooth opposite surface parallel to the sound source. Since they have equal characteristics, distance attenuation cannot be expected even for reflected sound waves.

  Therefore, in the case of the above-described interior sound absorber, in the case of a plane sound wave, generation of long path echoes and flutter echoes in the building space cannot be suppressed.

An object of the present invention is to provide a sound absorbing structure that can reliably suppress the generation of long-path echoes and flutter echoes when using plane sound waves in an architectural space.

In order to achieve the above object, a sound absorbing structure of the present invention is disposed in front of an indoor wall surface, and a sound absorbing layer made of a porous material that absorbs indoor sound;
An uneven diffusion layer that is disposed on the wall surface on the back side of the sound absorption layer and diffuses the sound that has passed through the sound absorption layer;
The sound absorbing layer is characterized in that the indoor side surface and the back surface are formed in an uneven diffusion shape for diffusing sound.

  According to the present invention, first, a sound wave traveling perpendicularly to a wall surface from a sound source enters a sound absorbing layer made of a porous material disposed in front of the indoor wall surface.

  In this sound absorbing layer, since the surface is formed in an uneven diffusion shape for diffusing sound, a part of the incident sound wave is diffusely reflected.

  The sound that is diffusely reflected by this sound absorbing layer is not diffusely reflected directly by the incident sound, but cannot be completely absorbed by the surface of the sound absorbing layer, and is reflected, and only the sound of a very small level is diffusely reflected. Will be lost.

  The sound that has entered the sound absorbing layer without being diffusely reflected by the sound absorbing layer is absorbed into the sound when passing through the sound absorbing layer, and the sound that cannot be absorbed proceeds to the diffusion layer.

  The sound wave incident on the diffusion layer is diffusely reflected by the diffusion layer, and the sound wave reflected by the diffusion layer loses the characteristic of a plane sound wave that travels only forward.

  Furthermore, the sound wave diffusely reflected by the diffusion layer is again absorbed by the sound absorption layer made of a porous material.

  Thus, first, diffuse reflection of sound waves on the surface of the sound absorption layer, second, sound absorption at the sound absorption layer, third, diffuse reflection at the diffusion layer, and fourth, sound absorption again at the sound absorption layer, By losing the characteristics of the sound wave, it is possible to reliably suppress the generation of long path echo and flutter echo when using the plane sound wave.

In particular, the generation of long-pass echoes and flutter echoes is reliably suppressed in rooms with flat floors where long-path echoes and flutter echoes are more likely to occur when using plane sound waves than in rooms where the floor is stepped. be able to.
In addition, a more reliable sound absorbing effect can be obtained by further diffusely reflecting the sound wave diffusely reflected by the diffuser by the uneven diffusion shape provided on the back surface of the sound absorbing layer.

  In the present invention, an air layer can be formed between the sound absorbing layer and the diffusion layer.

  By adopting such a configuration, it is possible to more reliably perform sound absorption in the low frequency range.

  In the present invention, a plurality of the sound absorbing layers may be disposed.

  With such a configuration, sound can be diffused and absorbed by a plurality of sound absorbing layers, and a more reliable sound absorbing effect can be obtained.

  Embodiments of the present invention will be described below with reference to the drawings.

  1 to 4 are views showing a sound absorbing structure according to an embodiment of the present invention.

  FIG. 1 (1) is a plan view showing a state of the room using the sound absorbing structure according to the present embodiment, FIG. 1 (2) is a cross-sectional view thereof, and the room 10 is in a state where the floor 12 is flat. A planar speaker 16 that is a surface sound source is disposed on one wall surface 14 side, and a planar sound wave 18 is emitted from the planar speaker 16.

  Since the plane sound wave 18 has a sharp directivity and a small distance attenuation, it can provide a uniform and clear sound level regardless of the size of the space. If the light is reflected on the opposite surface parallel to the surface, it has almost the same characteristics as the plane sound wave. Therefore, the distance attenuation of the reflected sound cannot be expected. If the wall surface 20 on the opposite surface is flat, the floor 12 is flat and an obstacle is present. Therefore, the long-path echo and the flutter echo are generated by the reflected sound on the wall surface 20.

  For this reason, the sound absorbing structure 22 for the plane sound wave 18 is provided on the wall surface 20 to perform sound absorption, thereby suppressing the generation of long-path echo and flutter echo when using the plane sound wave, and providing a good environment for listening to sound. .

  As shown in FIG. 2, the sound absorbing structure 22 includes a sound absorbing layer 24, an air layer 26, and a diffusion layer 28. For example, the sound absorbing structure 22 mainly performs sound absorption in a frequency band position of 250 to 500 Hz. Yes.

  The sound absorbing layer 24 is disposed in front of the indoor wall surface 20 (inside the room) and absorbs indoor sound, and is formed by disposing a plurality of sound absorbing materials 30.

  Each sound absorbing material 30 is made of a porous material such as glass wool, rock wool, or urethane foam, and is formed in a convex diffusion shape in which the indoor surface 32 is convex toward the indoor side where the plane sound wave 18 is diffusely reflected. ing.

  As the diffusion shape of the surface 32, various shapes such as a semicircular bar shape, a square bar shape, a semicircular shape, a conical shape, and a pyramid shape can be adopted.

  Thus, by making the surface of the sound absorbing material 30 into a diffusing shape, the incident sound is not diffusely reflected as in the case of using a hard diffusing material, but as a very small sound at a certain level. The sound that can be reflected and the remaining sound that has not been reflected can be absorbed by the sound absorbing material 30.

  Further, the back surface 34 of the sound absorbing material 30 is formed in a concave diffusion shape that is concave on the indoor side where sound is diffused.

  As the diffusion shape of the back surface 34, various shapes such as a semicircular bar shape, a square bar shape, a semicircular shape, a conical shape, and a pyramid shape can be adopted.

  Thus, by making the back surface 34 of the sound absorbing material into a diffusing shape, a part of the sound diffused and reflected by the diffusion layer 28 can be further diffused and reflected, and the remaining sound can be absorbed by the sound absorbing material 30.

  The thickness of the sound absorbing layer 24 is set so as to perform sound absorption in the frequency band.

  The air layer 26 is formed between the sound absorbing layer 24 and the diffuser 28 to ensure sound absorption in the low frequency range, and is set to absorb sound in the frequency band.

  The diffusion layer 28 is provided on the wall surface 20 with the air layer 26 behind the sound absorbing layer 24, and has a concavo-convex shape for diffusing sound that has passed through the sound absorbing layer 24. The diffusion layer 28 includes a plurality of diffusers 36. Is formed.

  Each diffuser 36 includes a diffuser 36a having a semicircular rod-like convex shape as shown in FIG. 3 (1), a curved diffuser 36b having a convex shape of a curved quadrangular pyramid as shown in FIG. In addition to the diffuser 36c having a quadrangular pyramid shape as shown in FIG. 3 (3), various other shapes such as a pyramid shape, a square bar shape, a semicircular shape, and a conical shape can be employed.

  When the vertical and horizontal shapes are different, such as the semicircular rod-shaped convex diffuser 36a shown in FIG. 3A, the diffusers 36a are arranged in a staggered manner as shown in FIG. Then, the sound can be diffusely reflected in various directions.

  Each diffuser 36 is set so as to absorb sound in the frequency band.

  A net-like finishing material 38 is attached to the front surface of the sound absorbing structure 22 (front surface of the sound absorbing layer 24) so that the internal state cannot be seen.

  According to such a sound absorbing structure 22, first, the plane sound wave 18 traveling perpendicularly to the opposing wall surface 20 from the planar speaker 16 that is a surface sound source is a sound absorbing layer made of a porous material disposed in front of the opposing wall surface 20. 24 is incident.

  In the sound absorbing layer 24, since the surface 32 is formed in an uneven diffusion shape for diffusing sound, a part of the incident sound wave is diffusely reflected.

  Since the sound absorbing layer 24 is made of a porous material, the sound diffused and reflected by the sound absorbing layer 24 is not directly diffused and reflected, and only a small level of reflected sound is diffusely reflected and the plane sound wave 18 is reflected. The characteristics of will be lost.

  The sound that is not diffusely reflected by the sound absorbing layer 24 is absorbed into energy when passing through the sound absorbing layer 24, becomes a low level sound, and proceeds to the diffusion layer 28 through the air layer 26.

  In the air layer 26, low-temperature sound is absorbed and reaches the diffusion layer 28.

  The sound wave incident on the diffusion layer 28 is diffusely reflected by the diffusion layer 28, and the sound wave reflected by the diffusion layer 28 loses the characteristic of a plane sound wave that travels only forward, and has a distance attenuation characteristic.

  Furthermore, the sound wave diffusely reflected by the diffusion layer 28 passes through the air layer 26 again and is absorbed by the sound absorbing layer made of a porous material.

  In this way, first, diffuse reflection of sound waves on the surface of the sound absorbing layer, second, sound absorption at the sound absorbing layer, third, sound absorption at the air layer 26, fourth, diffuse reflection at the diffusion layer 28, fifth By reabsorbing the sound in the air layer 26 and sixthly reabsorbing the sound in the sound absorbing layer, the plane sound wave is surely absorbed, and the generation of long path echo and flutter echo when using the plane sound wave is surely suppressed. be able to.

  In particular, as in the present embodiment, it is possible to reliably suppress the generation of long path echoes and flutter echoes in a room on a flat floor 12 where long path echoes and flutter echoes are likely to occur when using plane sound waves.

  FIG. 5 is a view showing a sound absorbing structure according to another embodiment of the present invention.

  In this embodiment, in addition to the sound absorbing layer 24, the air layer 26 and the diffusion layer 28 in the above embodiment, another layer, a sound absorbing layer 24, is added to the back side of the sound absorbing layer 24.

  The added sound absorbing layer 24 is the same as the sound absorbing layer 24 in the above embodiment.

  By adding the sound absorbing layer 24 in this way, diffusion and sound absorbing effect by the added sound absorbing layer 24 are doubled.

  The sound absorbing layer 24 is not limited to two layers, and may be three or more layers.

  Other configurations and operations are the same as those in the above embodiment, and the description thereof is omitted.

  6 and 7 are views showing a sound absorbing and diffusing member according to one embodiment of the present invention.

  In the sound absorbing and diffusing member 40 shown in FIG. 6, as shown in (1), a diffuser 46 is integrally formed on the back side of the porous sound absorbing material 42 with an air layer 44 therebetween.

  The sound absorbing material 42 has a semi-cylindrical shape, and is formed in a convex diffusion shape where the front surface 48 diffuses sound and a concave diffusion shape where the back surface 50 diffuses sound.

  The diffuser 46 has a semicircular bar shape, and has a convex diffusion shape whose surface diffuses sound that has passed through the sound absorbing material 42.

  The air layer 44 is formed between the end portions of the sound absorbing material 42 attached to the side portions of the diffuser 46.

  In addition, as shown in (2), the sound absorbing and diffusing member 40 has a substantially square shape in a plan view so that no gap is formed between the sound absorbing and diffusing member 40 attached adjacently.

  Thus, diffuse reflection by the surface 48 of the sound absorbing material 42, sound absorption by the sound absorbing material 42, sound absorption by the air layer 44, diffuse reflection by the diffuser 46, sound absorption by the air layer 44 again, diffuse reflection by the back surface of the sound absorbing material 42, By forming the integral sound-absorbing / diffusing member 40 that absorbs sound by the sound-absorbing material 42 again, if the sound-absorbing / diffusing material 40 is attached to a plurality of wall surfaces, a sound-absorbing structure that can effectively absorb plane sound waves can be easily formed. Can do.

  In the sound absorbing and diffusing member 52 shown in FIG. 7, as shown in (1), a diffuser 58 is integrally formed on the back side of the porous sound absorbing material 54 with an air layer 56 therebetween.

  The sound absorbing material 54 has a hollow conical shape, and the front surface 60 is formed in a conical convex diffusion shape for diffusing sound, and the back surface 62 is formed in a shape for diffusing sound.

  The diffuser 58 has a conical shape, and has a conical convex diffusion shape in which the surface diffuses the sound that has passed through the sound absorbing material 54.

  And the air layer 56 is formed between the edge part of the sound-absorbing material 54, and the edge part of the diffuser 58 with the connection member 64 between them.

  In addition, as shown in (2), the sound-absorbing diffusion member 52 is formed in a substantially square shape in plan view by cutting a conical skirt, and there is a gap between the sound-absorbing diffusion member 52 attached adjacently. It is made not to occur.

  Other configurations and operations are the same as in the case of FIG.

  8 to 11 show experimental examples.

  In this experiment, as shown in the plan view of FIG. 8, a rear wall 72 of 1800 mm wide was installed at a distance of 2700 mm from three 300 mm square flat speakers 70, and an acoustic measuring device was installed at the center position 74. .

  The rear wall 72 was formed of five types of test bodies 1 to 5 shown in FIGS. 9 (1) to (5), and each was tested.

  Only the urethane 76 having a thickness of 20 mm is used for the test body 1, only the rigid plate 78 having a thickness of 12 mm is used for the test body 2, and the rigid plate 78 having a thickness of 12 mm and the urethane 76 having a thickness of 20 mm are used for the test body 3. A combination of these was used.

  The test body 4 is a combination of a rigid plate 78, a semi-cylindrical diffuser 80 having a diameter of 200 mm, and a semi-cylindrical diffusion urethane 82 having a thickness of 20 mm. 4 was used in which an air layer 84 having a spacing of 20 mm was formed between a semicircular diffuser 80 and a semicircular diffused urethane 82.

  FIG. 10 (1) shows the test result of the test body 1 when the test was performed with a frequency source of 2 kHz, FIG. 10 (2) shows the test result of the test body 2, and FIG. 3).

  As shown in FIG. 2A, it can be seen that even in the case of the test body 1 made only of urethane, flutter echo is generated due to reflection on the surface.

  In the case of the test body 2 having only the hard plate and the test body 3 having urethane and the hard plate, as shown in FIGS. 2 (2) and 3 (3), flutter echo is clearly generated.

  Further, the test result of the test body 4 in which the rigid plate 78, the semi-cylindrical diffuser 80, and the semi-cylindrical diffused urethane 82 are combined is shown in FIG. The test result is shown in FIG.

  This test result has shown the result of having tested with each frequency sound source of 1 kHz, 2 kHz, 4 kHz, and 8 kHz from the upper stage about each of the test body 4 and the test body 5. FIG.

  Comparing under the condition of 2 kHz similar to the case of FIG. 10, it can be seen that in the case of the test body 4 and the test body 5, the reflected sound is greatly reduced.

  Moreover, when the test body 4 and the test body 5 are compared, it can be seen that the reflected sound becomes smaller in the test body 5 having the air layer 84 as the sound range becomes lower.

  Thus, it has been found that the semi-cylindrical diffuser 80 and the semi-cylindrical diffused urethane 82 are effective in reducing the reflected sound.

  The present invention is not limited to the above-described embodiment, and can be modified into various forms within the scope of the gist of the present invention.

  In the above-described embodiment, the sound absorbing structure and the sound absorbing and diffusing member with respect to the plane sound wave have been described.

  Moreover, although the case where the sound absorbing structure is provided only on the wall surface facing the sound source has been described in the above embodiment, the sound absorbing structure may be provided on the ceiling or other wall surface.

  Furthermore, although the sound-absorbing and diffusing member has been described with respect to a semicircular bar shape and a conical shape, it can also be a pyramid shape, a hemispherical shape, or the like.

(1) is a top view which shows the state of the room | chamber interior using the sound absorption structure concerning one embodiment of this invention, (2) is the sectional drawing. It is the elements on larger scale of the sound absorption structure of FIG. (1) is a semicircular rod-shaped diffuser, (2) is a curved quadrangular pyramid diffuser, and (3) is a perspective view showing a quadrangular pyramid diffuser. It is a top view which shows the state which has arrange | positioned the semicircular rod-shaped diffuser in the zigzag form changing the vertical and horizontal directions. It is the elements on larger scale similar to FIG. 2 which shows the sound-absorbing structure concerning other embodiment of this invention. BRIEF DESCRIPTION OF THE DRAWINGS The sound-absorbing diffusion member concerning one embodiment of this invention is shown, (1) is sectional drawing, (2) is a top view. The other sound-absorbing diffusion member is shown, (1) is sectional drawing, (2) is a top view. It is a top view which shows the condition of an experiment site. (1)-(5) is sectional drawing which shows the test bodies 1-5, respectively. (1)-(3) is a chart which shows the test result of each of the test bodies 1-3. (1) And (2) is a chart which shows the test result of the test bodies 4 and 5, respectively.

Explanation of symbols

10 chamber 16 plane speaker 18 plane sound wave 22 sound absorbing structure 24 sound absorbing layer 26, 44, 56 air layer 28 diffusion layer 30, 42, 54 sound absorbing material 32, 48, 60 surface 34, 50, 62 back surface 36, 46, 58 diffuser 40, 52 Sound-absorbing diffusion member

Claims (3)

A sound-absorbing layer disposed in front of the indoor wall surface and made of a porous material that absorbs indoor sound;
An uneven diffusion layer that is disposed on the wall surface on the back side of the sound absorption layer and diffuses the sound that has passed through the sound absorption layer;
The sound absorbing layer is characterized in that the indoor front surface and back surface are formed in an uneven diffusion shape for diffusing sound. In claim 1,
A sound absorbing structure, wherein an air layer is formed between the sound absorbing layer and the diffusion layer. In claim 1 or 2,
The sound absorbing layer is provided with a plurality of sound absorbing layers.