WO2002071820A1

WO2002071820A1 - Soundproofing cabinet with muffler for the noise reduction

Info

Publication number: WO2002071820A1
Application number: PCT/KR2002/000238
Authority: WO
Inventors: Heeseob Park
Original assignee: Heeseob Park
Priority date: 2001-03-05
Filing date: 2002-02-16
Publication date: 2002-09-12

Abstract

The field of the present invention is the acoustic noise control. The air flow from a fan produces much noise especially when they are finally coming out of the computer case. The noise from computer(5) can be reduced effectively with efficient air cooling by complete enclosure of the computer within the soundproofing cabinet(1) which this invention discloses. The said cabinet(1) consists of three main parts (air intake part(2), soundproofing box(3) and muffler part(4)). All of these parts are made of sound-reflecting material such as wood plate and inside of them are lined with sound-absorbing material such as polyurethane foam. The air coming from the air outlet hole of soundproofing box passes through the sinusoidal path of muffler part but the noise is reduced by reflection and destructive interference between the sound reflecting walls(403, 404). The distance between the two sound reflecting walls can be adjusted manually to find the optimal distance for the noise reduction. At the optimal distance, the noise is reduced most by the maximum reflection and destructive interference. The present invention can be applied for the total acoustic noise reduction of any noisy device, for example a computer, which uses the air discharging fan for cooling. Moreover the total space of the soundproofing cabinet can be reduced by locating the air intake part and muffler part together on one side of the soundproofing box or by using the front or rear door as the air intake part or the muffler part respectively.

Description

[Description] [Title of Invention]

Soundproofing Cabinet with Muffler for the Noise Reduction

[Technical Field]

The present invention relates to the cabinet for the total acoustic noise reduction of any noisy device, for example a computer, which uses the air discharging fan. The field of the present invention is the acoustic noise control.

[Background Art]

Most computer use the air cooling fan to cool the inner components and CPU(Central Processing Unit) and use the air discharging fan to discharge the hot air thus made. The air flow from a fan produces much noise especially when they are finally coming out of the computer case. Besides the air cooling fan, the hard disk and CD-ROM drive uses electric motors which produce much noise. The noise thus produced annoys the human and reduces the attention for work.

The individual component which produces the noise is improved to reduce the noise level as technologies developed but the improvement is not satisfactory up to now. To solve the noise problem of the devices with air discharging fan, a cabinet is invented which encloses the noisy devices completely but through which the air flow can pass efficiently with reduced noise.

It is well known in the noise control field that to reduce the noise the outer or inner part of the noisy machine is lined with the sound-absorbing or sound-reflecting material ( from now on lets call this soundproofing material ) (US Patent 3,951,228 5,056,331 6,005,768 6,062,033 ). But if the noisy machine uses air as the cooling media, there must be inlet and outlet of air flow through which the noise can pass. Furthermore the air flow from the air discharging fan may produce noise if the air is discharged at high rate. Generally muffler ( or silencer ) is used to reduce the noise from the air flow of high flow rate. But this kind of muffler ( US Patent 6,102,154 ) is designed to be used when the air pressure is high, for example the exhaust gas from car engine. So it is not suitable for the noise reduction from air flow of low pressure. The devices using air discharging fan , for example computer, produces air flow of low pressure. The pressure of the air flow from air discharging fan is not high and produces low frequency noise. When the traditional muffler is applied for this kind of low pressure air flow, the air flow is obstructed and the cooling cannot be done efficiently. Though the sinusoidal tunnel method for noise reduction (US Patent 5,526,226 ) is invented, this method uses only one passage of sinusoidal path resulting in the insufficient noise reduction. The several passage of sinusoidal path is invented for the noise reduction of micron filtering system (US Patent 4,810,269). But this method uses narrow air inlets and outlets between the sinusoidal path. Therefore if this method is applied for the air flow of low pressure, then the air flow is obstructed resulting in poor cooling effect. More sophisticated method for the noise reduction of air flow of low pressure is invented using Helmholtz resonance theory (US Patent 5,508,477). But this method uses complex electric and electronic circuit. The present invention is soundproofing cabinet with muffler to reduce noise from air flow

The device using air discharging fan may be enclosed in the soundproofing box to reduce, the noise from the device. But the noise should not escape through the air inlet and outlet hole while the air flow of low pressure is not obstructed to make sure the efficient cooling effect.

Moreover the whole space that the soundproofing cabinet occupies should be reduced without any performance reduction by locating the air intake part and muffler part on the one side, on the front or on the rear part of the soundproofing box.

[Disclosure of Invention]

The disclosed invent ion(l) consists of three main parts (Fig 1) ( the air intake part(2), the soundproofing box(3) and the muffler part(4). The air intake part is the lower part of the soundproofing cabinet. The soundproofing box is the middle part of the soundproofing cabinet. The muffler part is the upper part of the soundproofing cabinet. These three parts can be made separately and assembled later or these three parts can be manufactured as one unit.

All of the three part is made of sound-reflecting material such as wood plate, plastic plate or metal plate and inside of them are lined with sound-absorbing material such as soundsorber(Trade Mark) polyether foam, polyurethane foam, plastic foam, glass wool or rock wool. The said soundsorber(Trade Mark) is sheet of rubber layer and polyurethane layer. These materials and method is well known in the noise control field ("Acoustics and Noise Control" B. J .Smith 1996)

The soundproofing box(3) is a hexahedron box which encloses the computer(5) inside of it. Its shape is not important only if it completely encloses the noisy computer. It has two doors(6, 7) to access the computer, one of which is at the front of the soundproofing box to access the computer from the front side and the other is at the rear of the soundproofing box to access the computer from the rear side. The door is connected to the box by way of some kind of hinge and there is a door knob (these are not shown in the figure). Air inlet hole (8) is at the front part of the bottom of the box(3) and the air out let (9) is at the rear part of the ceiling of the box. In order for the noise not to escape from the soundproofing box, all the conjunctions are tightly closed. When the noisy device is installed in the soundproofing box there must be the some kind of air duct (901) which connects the air-discharging fan(lθ) of the device to the air outlet(9) of the soundproofing box. This can be any flexible tubing. It is convenient to use the rubber tubing with spring in it. The electric wire(302) from computer can be arranged at the ramp(303) at the air intake part(206) running out of the soundproofing box to the outside. Any crack occurring between wires can be packed with sound-absorbing material like sponge.

The muffler part (4) of the cabinet has special structure as described in detail below. The muffler part consists of two long hexahedron tunnels ( the inner tunnel(401) and the outer tunnel (402)). Each tunnel has long hexahedron shape and has one planar vertical sound-reflecting wal 1(403, 404) and one open end(405) opposite to the said sound-reflecting wall, though which the air flow can pass without any obstruction. The outer tunnel covers the inner tunnel so that the said walls face each other in opposite direction. With this structure there must be one sinusoidal air path(406) between the two tunnels. The distance between the two planar vertical walls can be adjusted manually to find the optimal distance for the noise reduction in the air flowCFig 23).

And there is a gap (407) between the side walls of the said two tunnels. The gap is parallel and laminar through which the air flow can come out of the muffler part.

There occur many processes to reduce the noise in the air flow in this structured muffler part.

Firstly the air enters the muffler part and flows parallel to the inner tunnel. The noise is absorbed by the sound-absorbing material while passing the long tunnel. High frequency of noise is especially absorbed by the foam layer. The sound wave of the noise becomes a parallel wave (lets call this a parallel wave) while passing the long tunnel as well known in this acoustic field. Secondly the air bends while passing through the serpentine path of the tunnel. Mid frequency of noise is reduced when the air bends. Thirdly the non-absorbed sound is reflected from planar vertical sound-reflecting wall of the outer tunnel made of the sound-reflecting material and they are going back to the open end of the inner tunnel from which they come. At optimum distance, maximum of the reflected sound is going back to the open end of the inner tunnel. So for the efficient reflection of the sound the parabolic line sound-reflecting wall (Fig 27, 404) or parabolic surface sound-reflecting wall (Fig 24, 404) can be used instead of the planar vertical sound-reflecting wall. Fourthly the sound coming from the inner tunnel interferes with the sound wave reflected from the said planar vertical wall of the outer tunnel destructively at the optimum distance. The high frequency of the noise is reduced by the sound-absorbing material and the remaining frequency of the noise is reduced by the reflection and destructive interference as said above. Therefore total noise reduction is achieved.

The optimum distance varies depending on the sound-reflecting material, sound-absorbing material, the tunnel length and the noise source. By moving the outer tunnel over the inner tunnel backward and forward manually, the noise level increases or decreases. The outer tunnel is fixed by means of some kind of screw when the minimum noise is achieved.

After passing the sinusoidal air path, the air flow passes the gap(407) between the inner tunnel and the outer tunnel. Since the gap is parallel and laminar, air flow is not disturbed anymore and shallow air flow can contact with much sound-absorbing material, producing no more noise. By making the area of the cross section of the gap larger than that of the air-discharging fan(501), the blocking of the air flow and the increase of the air pressure is prevented. The cross section of two tunnels need not be the square shape. Any long tunnels with the cross section of triangular shape(Fig 34) or circular shape(Fig 35) with sound-reflecting walls facing each other (403, 404) and with a gap between said two tunnels can be used as muffler with the same noise reduction mechanism described in this invention. The key point is that the sound-reflecting walls(403, 404) should face each other to reflect the noise back to the entrance of the inner tunnel.

In the vertical type muffler(Fig 21), the outer tunnel covers the inner tunnel from above realizing the noise reduction mechanism described above. The gap (407) is formed at the upper part of the inner tunnel. In the horizontal type muffler(Fig 30) the inner tunnel(401) is placed at the center of the outer tunnel(402) and the gap(408) is formed at the both sides of the inner tunnel symmetrically. If the gap is not symmetric, some of the noise is not reflected back to the open end of the inner tunnel resulting in the less reduction of the noise. By making the gap at the both side of the inner tunnel, the horizontal type has advantage of reducing the height of the muffler part. But the small noise escapes and interferes again horizontally.

In the parabolic line type muffler(Fig 27) and the parabolic surface type muffler(Fig 24), the shape of the sound-reflecting wall (404) is parabolic line 2-dimensionally and the parabolic surface 3-dimensionally and is good for focusing the sound wave. If the focus is in the inner tunnel by adjusting the distance between the said two walls, then the maximum reflection of the noise can be achieved. In the parabolic line type muffler, the sound-reflecting wall is the 2-dimensional parabolic. In the parabolic surface type muffler, the sound-reflecting wall is the 3-dimensional parabolic.

The air intake part(2) is same structure as the muffler part(4) and operates based on the same principle as that of the muffler part. But as the air intake part is placed at the lower part of the sound-proofing cabinet, the outer tunnel of the air intake part cannot be moved backward or forward to adjust the distance between the said walls. Therefore the inner tunnel (201) is made to move backward or forward instead of the outer tunnel.

The vertical type air intake part(Figl2) has basically the same structure as the vertical type muffler(Fig 21) except that the inner tunnel has a supporting wall in order not to fall down from the ceiling of the air intake part. The horizontal type air intake part(Fig 15)is same as the horizontal muffler(Fig 30). If the noise from the device itself is relatively smaller than that from the air-discharging fan , for example a computer, the air intake part can be made simple (simple type air intake) (Fig 18) in order to reduce the manufacturing cost of this invention as the noise escaping from the air inlet at the front bottom part of the soundproofing box is small. In this case the bottom can be removed from the air intake part and the floor of the building where the soundproofing cabinet is placed can be the bottom of the air intake part to reduce the manufacturing cost. Though the noise reduction is not efficient as there is no sound-absorbing material at the bottom of the outer tunnel, satisfactory result can be achieved with this simple type air intake.

If the specification of the air discharging fan is same, then the noise is of same property among the devices. In this case the distance between the two sound-reflecting wall can be optimized, and fixed when the soundproofing cabinet is manufactured and there is no need to use the moving structure of the inner or outer tunnel, which results in reduction of the manufacturing cost.

In the air cooling system, the air (205) coming from the air inlet hole becomes hot as it absorbs heat from the hot device(5). Since the hot air naturally rises upward due to its lower density, the air flows efficiently if the air inlet hole (8 of Fig 1) is at the bottom and the air outlet hole (9 of Fig 1) is at the ceiling of the cabinet.

The vertical type muffler(Fig 21), the horizontal type muffler (Fig 30), the parabolic line type muffler (Fig 27) or the parabolic surface type muffler (Fig 27) can be combined with the vertical type air intake part (Fig 12), the horizontal type air intake part (Fig 15), or the simple type air intake part (Fig 18), which results in various kinds of soundproofing cabinet

For example a soundproofing cabinet(Fig 1) with the vertical type air intake and vertical type muffler can be constructed or a soundproofing cabinet(Fig 5) with the horizontal type air intake and vertical type muffler can be constructed or soundproofing cabinet (Fig 6) with the simple type air intake and vertical type muffler or soundproofing cabinet (Fig 7) with the simple type air intake part and parabolic surface type muffler or soundproofing cabinet (Fig 8) with the simple type air intake part and the horizontal type muffler can be constructed

The muffler part can be attached at the rear part of the soundproofing box instead of the upper part to reduce the total height of the soundproofing cabinet (Fig9). In this case it is apparent that the air outlet hole should be placed at the rear part of the soundproofing box.

The sound-absorbing material is also a heat insulator. Therefore it prevent the direct heat flow from the device surface to the outside of the device. Thus the cooling effect by the direct heat flow becomes reduced and the existing air discharging fan (501 of Fig 33) of the device may not be sufficient to cool the device fully. In this case an additional air outlet hole(902 of Fig 33) can be made beside the existing air outlet hole (9 of Fig 33) and the additional air discharging fan(904) can be attached to resolve this problem. The power for the additional fan can be obtained from the device or from the outside.

The additional air discharging fan (904) can be attached at the end of the air duct and hung without any fixing to the wall of the cabinet or it can be fixed to the wall (301) of the cabinet.

It is apparent that this cabinet can also be applied to any noisy device which uses air discharging fan(501) as well as computer.

Moreover Fig 36 shows the soundproofing cabinet (1) with the air intake part(2) and the muffler part(4) located together on the front and rear top of the soundproofing box(3). With this structure, the total length of the tunnel is shortened but the width of the tunnel can be maintained as before. Therefore the intake and discharging rate of the air can be maintained as before while the total space of the said cabinet is reduced.

This kind of structure can be made on any part of the soundproofing box, for example on the bottom, side, front or rear part of the soundproofing part to reduce the total space that the soundproofing cabinet occupies.

Fig 38 shows the soundproofing cabinet (1) with the air intake part(2) and muffler part (4) located together parallel on the side of the soundproofing box(3). With this structure the total height of the soundproofing cabinet can be reduced while the length and the width of the tunnel are maintained as before hence maintaining same performance as before. This kind of structure can be made on any side of the soundproofing box, for example on the right or left side of the soundproofing box.

The front (6) or rear (7) door can have the tunnel structure to be the air intake part or muffler part resulting in the reduction of space and cost. Fig 41 shows the soundproofing cabinet with the air intake part (2) at front door (6) and the muffler part (4) at the rear door (7). With this structure the total height of the soundproofing cabinet can be reduced.

The air intake part and the muffler part can be located on either side of soundproofing box covering the whole side to become a large air intake or muffler part. With this structure the air intake or the muffler part can be made very large with the small tunnel gap maintaining the same cross section area of tunnel as before. With this structure the total space of the soundproofing cabinet can be reduced while more material for the larger air intake or muffler part are used. Since the air intake part and the muffler part have the same structure basically, they can be located in place of the other one very easily.

[Brief Description of Drawings]

Fig 1 shows a side view of the cabinet(l) which encloses a computer(5). The arrow(205) shows the air flow.

Fig 2 is a side sectional view of the cabinet of Fig 1. Fig 3 is the front view of the cabinet of Fig 1. Fig 4 is the rear view of the cabinet of Fig 1.

Fig 5 shows a side view of the cabinet(l) which consists of the horizontal type air intake part (2), soundproofing box(3) and vertical type muffler(4)

Fig 6 shows a side view of the cabinet(l) which consists of the simple type air intake part (2), soundproofing box(3) and vertical type muffler(4) .

Fig 7 shows a side view of the cabinet(l) which consists of the simple type air intake part (2), soundproofing box(3) and parabolic surface type muffler(4) .

Fig 8 shows a side view of the cabinet(l) which consists of the simple type air intake part (2), soundproofing box(3) and horizontal type muffler(4) .

Fig 9 shows a side view of the cabinet(l) which consists of the simple type air intake part (2), soundproofing box(3) and rear vertical type muffler(4) .

Fig 10 is the side sectional view of the cabinet of Fig 9.

Fig 11 is the rear view of the cabinet of Fig 9. The arrow(205) shows the air flow.

Fig 12 shows the side view of the vertical type air intake part. The arrow(205) shows the air flow.

Fig 13 is the disassembly view of the air intake part of Fig 12.

Fig 14 is the side view showing the movement of the inner tunnel of the air intake part of Fig 12. The inner tunnel moves back and forth in the direction of the arrow(200).

Fig 15 shows the side view of horizontal type air intake part. The arrow(205) shows the air flow.

Fig 16 is the disassembly view of the air intake part of Fig 15.

Fig 17 is the side view showing the movement of the inner tunnel of the air intake part of Fig 15. The arrow(205) shows the air flow.

Fig 18 shows side view of the simple type air intake part. The arrow(205) shows the air flow.

Fig 19 is the disassembled view of air intake part of Fig 18.

Fig 20 is the side view showing the movement of the inner tunnel of the air intake part of Fig 118. The inner tunnel moves back and forth in the direction of the arrow(200).

Fig 21 shows side view of the vertical type muffler part. The arrow(205) shows the air flow. Fig 22 is the disassembly view of the muffler part of Fig 21. Fig 23 is the side view showing the movement of the outer tunnel of the air intake part of Fig 21. The outer tunnel moves back and forth in the direction of the arrow(200).

Fig 24 shows side view of the parabolic surface type muffler part. The arrow(205) shows the air flow.

Fig 25 is the disassembly view of the muffler part of Fig 24.

Fig 26 is the side view showing the movement of the outer tunnel of the air intake part of Fig 24. The outer tunnel moves back and forth in the direction of the arrow(200).

Fig 27 shows side view of the parabolic line type muffler part. The arrow(205) shows the air flow.

Fig 28 is the disassembly view of the muffler part of Fig 27.

Fig 29 is the side view showing the movement of the outer tunnel of the air intake part of Fig 27. The outer tunnel moves back and forth in the direction of the arrow(200).

Fig 30 shows side view of the parabolic line type muffler part. The arrow(205) shows the air flow.

Fig 31 is the disassembly view of the muffler part of Fig 27.

Fig 32 is the side view showing the movement of the outer tunnel of the air intake part of Fig 30. The outer tunnel moves back and forth in the direction of the arrow(200).

Fig 33 shows the soundproofing cabinet with additional air discharging fan(904)

Fig 34 shows the side view of the muffler which consists of the triangular type inner and outer tunnel. Fig 35 shews the side -view of -the muffler which consists of the round type inner and outer tunnel.

Fig 36 shows the soundproofing cabinet with the air intake part and muffler part located together front and rear on the top part of the soundproofing box.

Fig 37 shows the side section view of the said cabinet (Fig 36).

Fig 38 shows the soundproofing cabinet with the air intake part and the muffler part located together parallel on the side part of the soundproofing box.

Fig 39 shows the side view of only the air intake part and the muffler part of the said cabinet (Fig 38).

Fig 40 shows the front section view of the said cabinet (Fig 38).

Fig 41 shows the soundproofing cabinet with the air intake part located at front and the muffler part located at the rear part of the soundproofing box.

Fig 42 shows the side section view of the said cabinet (Fig 41).

[Best Mode for Carrying Out the Invention] embodiment 1-

When the computer is installed in the soundproofing cabinet which consists of the soundproofing box of a hexahedron shape and the vertical type air intake part (15*33*60 centimeter, height*width* length) and vertical type muffler (inner tunnel 10*26*47, outer tunnel 15*33*60 centimeter ) all of which are made of wood plate with thickness of 1.6 centimeter as sound-reflecting material and inside of which are lined with polyurethane foam with thickness of 2 centimeter as sound-absorbing material, the noise is reduced to the level of nearly silence at the distance of 56 centemeter between the sound-reflecting walls. If the distance is longer or shorter than this, then there is a slight increase of noise level. While the noise is hardly heard, the- temperature inside of computer does not rise after long operation due to the efficient air cooling.

embodiment 2 :

When the inner tunnel (6 * 11 * 17 centimeter, height * width * length ) and outer tunnel (10 *19* 30 centimeter) made of polypropelene of 0.15 centimeter thickness as sound-reflecting material and polyurethane of 2 centimeter thickness as sound-absorbing material is tested, the noise is reduced to the satisfactory level with the optimal distance of 30 centimeter between the sound-reflecting walls. Though there is some escaping noise directly through the side wall of muffler part, the noise is hardly heard at some distance. Since these material is cheap and the weight is light to carry, this has the cost merit when manufactured.

embodiment 3 ^'■

The ordinary tin plate is used as a sound-reflecting material and the polyurethane of 2 centimeter thickness is used as a sound-absorbing material for the vertical type muffler.

The dimension of the inner tunnel is 10*20*23 cm and the dimension of the outer tunnel is 13*25*33 cm. At the distance of 30 cm between the sound-ref ecting walls, the noise is reduced most. Some noise penetrates the muffler wall. But the total noise level is much lower than before the muffler is installed.

embodiment 4 :

The soundproofing box of a hexahedron shape with dimension of 65 * 33* 55 centimeter including the horizontal type air intake part is made of plastic plate of 0.4 centimeter thickness as sound-reflecting material and inside of it is lined with polyurethane foam of 2 centimeter thickness as sound-absorbing material.

The vertical type muffler in the embodiment 2 is used. When a computer is installed inside this soundproofing cabinet, the noise is reduced to the satisfactory level. While the noise is reduced much, the temperature inside of the computer does not rise after long operation due to the efficient air cooling.

[Industrial Applicability]

This cabinet can be applied to reduce the noise from any device which uses air discharging fan(501) as well as computer.

Claims

[Claims] [Claim 1]

A soundproofing cabinet(l) for the acoustic noise reduction for a device(5) using air-discharging fan (501), which is made of wood plate as sound-reflecting material and polyurethane as sound-absorbing material. The air intake part(vertical type air intake part(2)) of the said cabinet is at the lower of the said cabinet and consists of two hexahedron tunnels (inner tunnel (202) and outer tunnel (201) between which there is parallel gap and at the end of which there are vertical planar sound-reflecting walls(206) the distance of which can be adjusted by moving the inner tunnel. The soundproofing box is at the middle part of the said cabinet and is of the hexahedron shape which has two doors(6, 7) at the front and the rear and has an air inlet hole(8) at the front of bottom and an air outlet hole at the rear of the ceiling. The muffler part is at the upper part of the said cabinet and consists of two hexahedron tunnels (inner tunnel(401), outer tunnel(402)) between which there is parallel gap and at the end of which there are vertical planar sound-reflecting walls(403, 404) facing each other the distance of which can be adjusted by moving the outer tunnel

[Claim 2]

A soundproofing cabinet (Fig 30) as recited in claim 1 having the horizontal type muffler part instead of the vertical type muffler part. In horizontal type muffler part, the inner tunnel is placed at the middle of the outer tunnel and the gap is formed at the both side of the inner tunnel symmetrically instead of at the upper part of the inner tunnel as in the vertical type muffler part.

[Claim 3] A soundproofing cabinet (Fig 27) as recited in claim 1 having the parabolic line type muffler part. In the parabolic line type muffler part, the sound reflecting wall is 2 dimensional ly parabolic instead of just planar vertical wall.

[Claim 4]

A soundproofing cabinet (Fig 24) as recited in claim 1 having the parabolic surface type muffler part. In the parabolic surface type muffler part, the sound reflecting wall is 3 dimensional ly parabolic instead of just planar vertical wall.

[Claim 5]

A soundproofing cabinet (Fig 15) as recited in claim 1, 2, 3, 4 having the horizontal type air intake part instead of the vertical type air intake part. In horizontal type air intake part, the inner tunnel is placed at the middle of the outer tunnel and the gap (206 of Fig 15) is formed at the both side of the inner tunnel symmetrically instead of at the upper part of the inner tunnel as in the vertical type air intake part .

[Claim 6]

A soundproofing cabinet (Fig 18) as recited in claim 1, 2, 3, 4 having the simple type air intake part instead of the vertical type air intake part. In the simple air intake part, the structure is same as the air intake recited in claim 5 but the bottom is removed for the cost reduction purpose.

[Claim 7] A soundproofing cabinet as recited in claim 1, 2, 3, 4 having that the shape of the cross section of the inner and outer tunnel of the air intake part or the muffler part is a triangular shape (Fig 34) or a round shape (Fig 35) instead of the rectangular shape so long as the sound reflecting wall is facing each other and parallel to each other.

[Claim 8] A soundproofing cabinet as recited in claim 1, 2, 3, 4 having that the muffler part (4) is attached at the rear part of the soundproofing box(2).

[Claim 9] A soundproofing cabinet as recited in claim 1 having that the sound-absorbing material is polyurethane foam, polyether foam, plastic foam, glass wool or rock wool.

[Claim 10] A soundproofing cabinet as recited in claim 1 having that the sound-reflecting material is wood plate, polypropane plate, plastic plate, rubber plate or metal plate.

[Claim 11] A soundproofing cabinet (Fig 36) with the air intake part and muffler part located together front and rear on the top, bottom, side, front or rear part of the soundproofing box.

[Claim 12] A soundproofing cabinet(Fig 38) with the air intake part and the muffler part located together parallel on the top, bottom, side, front or rear part of the soundproofing box.

[Claim 13] A the soundproofing cabinet (Fig 41) with the air intake part or muffler part located at front door , rear door or side part of the soundproofing box.