JP2769448B2 - Standing wave or specific wave reduction device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a standing wave which can be mounted on an inner wall of a loudspeaker enclosure or a wall in a room, or can be independently installed to reduce standing waves and specific waves to improve sound quality. Alternatively, the present invention relates to an apparatus for reducing a specific wave (hereinafter, simply referred to as a standing wave).

[0002]

2. Description of the Related Art As a device for reducing standing waves and the like which has been conventionally used, there is a device in which a cube such as a kamaboko shape or a triangular prism is attached to a wall surface. As a method for reducing the standing wave, a soft porous sound-absorbing material such as glass wool or felt is put in a cabinet in a speaker, and the shape of the enclosure itself is a box made of a truncated pyramid or a curved surface And the like are publicly known and used.

[0003] A device for reducing standing waves or the like is used for the purpose of improving the sound quality by reducing the adverse effects of standing waves and flutter echoes generated in a speaker cabinet or between two parallel walls within a range that does not cause excessive sound absorption. . In the speaker cabinet, a standing wave is generated which depends on the shape and size of the cabinet and the installation position of the speaker unit. In a bass reflex baffle loudspeaker, a passing frequency that is radiated to the outside through a higher frequency than the tuning frequency fb of the duct is generated for an acoustic device in which the cabinet and the duct are coupled. At the frequency of the standing wave, the driving point impedance on the diaphragm of the speaker unit increases, and the load of air increases, so that a sound wave of that frequency is generated in the cabinet at an extremely large sound pressure compared to other frequencies. .

[0004] In the case of a standing wave generated between two parallel walls, the acoustic impedance at the node becomes theoretically infinite because the phases of the standing waves are perfectly aligned, and a strong standing wave is generated. Since the frequency of the standing wave is the fundamental vibration and a frequency that is an integral multiple of the fundamental vibration, a monotonous tone is generated, and each time music is reproduced by the speaker, there is a tendency that only the tone component is emphasized.

[0005]

Among the conventional examples described above, in the case of using a cube such as a kamaboko shape or a triangular prism, the sound waves are diffused only by the undulations created by these surfaces on the wall. The target sound wave is incident on the wall surface at a right angle, and the height from the wall surface is important in the form of a diffuser, and the higher the height, the lower the sound wave frequency can be improved. However, when the height is increased, the occupied area in the room increases, and it is difficult to install the speaker in a limited space such as a speaker cabinet, and it is difficult to efficiently reduce standing waves and the like.

In order to reduce a standing wave, if a soft porous sound absorbing material such as glass wool or felt is placed in a cabinet of a speaker, these do not selectively absorb a standing wave or a specific wave. However, it is not reasonable to suppress a standing wave generated by peaking at a specific frequency. Further, in order to absorb a sound wave of a specific frequency, a large number of sound absorbing materials must be inserted, and there is a problem that the cabinet needs to be enlarged and the sound quality is reduced. Further, since the bass reflex type speaker emits sound waves in the cabinet to enhance bass sound, using a large amount of sound absorbing material contradicts its purpose.

Further, a box having a speaker enclosure of a truncated quadrangular pyramid or a curved surface is an attempt to change the acoustic impedance condition of the cabinet so that strong standing waves are not fundamentally generated, and a sound absorbing material is used. It has the effect of selectively suppressing standing waves as compared with the case, and contributes to improvement in sound quality. However, compared to a normal rectangular parallelepiped enclosure, there are considerable difficulties in manufacturing, and there are drawbacks such as an increase in the occupied area as compared with the case where a rectangular parallelepiped having the same volume is installed.

An object of the present invention is to solve the above-mentioned problems and difficulties, to efficiently reduce a standing wave or a specific wave generated between two parallel walls in a speaker or a room, and to achieve excellent sound quality. It can reproduce rich bass, has a reduction effect exceeding the height of the aggregate from the wall side, is easy to manufacture, occupies a small area for installation, and is a standing wave that does not depend on sound absorption especially in bass reflex speakers It is an object of the present invention to provide a device for reducing a standing wave or the like which can realize a countermeasure, is easily mounted on a wall surface, and can be used as a portable independent body.

[0009]

In order to achieve the above object, according to a first aspect of the present invention, a standing wave or a specific wave generated between two parallel wall surfaces is provided on one of the two wall surfaces facing a sound source. A plurality of hollow sound conducting paths having openings at one end or both ends in a single row or a plurality of rows and stacked in a plurality of stages near the wall surface (W) of the above, and the height of the opening of the hollow sound conducting path is provided. The length (h) is not more than 、, preferably not more than １０ of the wavelength of the target standing wave or specific wave, and the sound path length (l) of each hollow sound guide is on the wall (W) side. From the opening of each hollow sound guide path constituting the assembly is provided sequentially or intermittently short from
Total area is occupied by the wall (W) due to the size of the reduction device
A device for reducing a standing wave or a specific wave approximated to a product .

[0010] In the second aspect of the present invention, the assembly is provided so that it can be mounted on the inner wall of a speaker enclosure or a wall (W) in a room, or can be installed as an independent portable cube. A device for reducing a standing wave or a specific wave was used.

[0011]

According to the first aspect of the present invention, since a large number of hollow sound guide paths having openings at one end or both ends are provided on the wall (W) facing the sound source, the sound travels from the sound source to the wall (W) . The sound wave is guided from the opening at one end into the hollow sound guide path and is reflected at the closed portion (reflected wave), or enters through the opening at one end, passes through the hollow sound guide path, and passes through the other opening. Re-emitted (radiated wave). When considering the sound wave (T) in a box having two parallel wall surfaces, the smaller the cross-sectional area is, the higher the density of standing waves that appear at every integral multiple is, the more the ratio is destroyed, The peak of one standing wave is lowered, so that the sound diffusion action is improved and the sound quality is improved. When this is captured in terms of sound pressure change, the wall surface (W) facing the sound source is deformed to have the same effect as when the wall surface is extended by the sound path length (l) of the hollow sound guide, and the phase of the sound pressure is changed. And the occurrence of a standing wave or a specific wave can be effectively reduced.

Since a large number of hollow sound guide paths are arranged in a single row (when the opening width is large) or in a plurality of rows and stacked in a plurality of stages to form an aggregate, the conventional diffuser uses the reduction effect due to the outer shape protruding from the wall surface. Compared to that, it became a sound diffuser that exceeded this, and it became possible to exert sufficient damping action. Further, since the height (h) of the opening of each hollow sound guide path is set to 以下 or less, and preferably 1/10 or less, of the wavelength of the target sound wave, reflection after passing through the hollow sound guide path. Waves or radiation waves have no directivity and are stable. If the size exceeds one-fourth, the reflected wave is unstable, and the reduction effect is not reliable.
Even if it is one-tenth or less, it is effective as long as the airflow resistance is small and a sound wave (T) enters and can be reflected or re-emitted.

Further, since the sound path length of the hollow sound guide path is provided so as to be sequentially or intermittently shortened from the wall surface side, the sound wave (T)
Collides with the outer wall of the reduction device and is introduced into each hollow sound guide path from the opening. An aggregate formed by stacking a large number of hollow sound guide paths has a mountain shape as a whole and has a stable shape, and can be easily attached to the inner wall of a speaker or a wall surface in a room. When the sound path length is intermittently shortened from the wall surface (W) side, it is possible to obtain an effective reduction effect on a specific wave . Also, hollow sound guide
The area of the wall occupied by the aggregate of a plurality of rows stacked in one row or a plurality of rows is similar to the total area of the openings of the hollow sound guides, so that it is only comparable to the openings of many hollow sound guides. As in the case of deforming the wall surface, an effect of attenuating the generation of a standing wave or a specific wave can be obtained.

According to the second aspect of the present invention, since the assembly can be made small and compact, it can be used by attaching it to the inner wall surface of a speaker or a wall surface in a room, or can be installed as an independent cube at an arbitrary position in a room or the like.

[0015]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. FIG. 1 shows a basic configuration of a device for reducing a standing wave or the like. Reference numeral 1 denotes a device for reducing a standing wave or the like. It is an aggregate that is stacked in multiple stages. Reference numeral 3 denotes an opening, which is opened at one end of the hollow sound guide 2 and has a height (h) of 1/10 or less of the wavelength of the target sound wave (T). If the purpose of a sound wave is 1000H _Z,
3.4 cm 2 was used (λ = c / f). The sound path length (l) of the hollow sound guide path 2 is an aggregate that is successively shortened to l ₁ , l ₂ --- l _{4 in} the height (H) direction from the wall surface (W).
Opening width (w) of hollow sound guide 2-width in the depth direction in the figure-
If it is large, it may be in a row, and this is stacked in multiple stages,
When the opening width (w) is small, a plurality of rows are stacked in a plurality of rows. A porous sound-absorbing material having a small airflow resistance in the hollow sound-conducting path 2;
For example, a material such as glass wool may be filled.

In FIG. 1, a sound wave (T) enters from the opening 3 of each hollow sound guide path 2, travels through the hollow sound guide path 2, is reflected by the closing part, and is reflected from the opening 3. Figure 2 is a reference diagram for explaining the operation of the reduction device 1 of the standing waves and the like, the wall surface (W) of each hollow sound guide path 2 each sound path lengths as shown in FIG. 2 (l ₁ -
According to-), it has the same effect as extending the depth or projecting over the entire surface. In FIG. 2, since the opening height (h) in the height (H) direction from the wall surface (W) is sufficiently smaller than the wavelength of the target sound wave (T), the sound wave The directivity is very little and stable.

In the case of a plane wave reciprocating between two walls facing each other in parallel with each other, the standing wave is acoustically called an axial wave, and the axial wave has a particularly long reverberation time, so that the standing wave has a serious adverse effect on acoustics. Becomes In the present invention, a countermeasure is considered mainly by taking up this axial wave. In the reduction device according to the present embodiment, the same operation as when the wall surface (W) is deformed as described above is performed.
The phase of the sound pressure is shifted by the reflection surface, and the generation of the standing wave can be reduced.

FIG. 3 shows the box length (x) on the horizontal axis and the cross-sectional area (S) on the vertical axis, showing the reduction of the cross-sectional area by the reduction device of the present invention, where A is the surrounding space, and B is the reduction device. Indicates that a large inclination (4) has occurred on the wall surface (W) in the space defined by the sound path length. In addition, the shape of the above-described standing wave reduction device, sound path length,
The number, arrangement, assembly, and the like of the hollow sound guide paths can be variously changed as described later.

FIG. 4 shows an apparatus for demonstrating the operation of the apparatus for reducing standing waves and the like. In this device, the acoustic impedance of the surrounding space was calculated by installing a device for reducing standing waves and the like on a wall (W) facing in parallel with a wall having a speaker. The length (x) of the sealed enclosure 5 is 60 cm, the wall (W) is 29 cm, and the depth is 25 cm. The speakers and microphones are installed on a central axis of 29 x 25 cm, and the sound waves generated by the upper and lower walls and the depth walls are set. To reduce the effect.
The sound path length (l) of the standing wave reducing device is 10 to 25 cm, the height of the opening (h) is 4.4 cm, and the opening width (w) in the depth direction in the drawing is 4.8 cm. Was.

A speaker was installed and driven on a flat side wall serving as a node of a standing wave, the sound pressure generated there was measured, and the acoustic impedance at the driving point was indirectly measured. 1
Is a device for reducing standing waves and the like, and is installed in a rectangular parallelepiped closed enclosure 5 having a sound path length (l). This sealed enclosure 5 is subjected to reinforcement and processing for suppressing plate vibration. Reference numeral 6 denotes a speaker which enables a sine wave of an arbitrary frequency to be oscillated from an FM sound source of a personal computer, and a closed enclosure 7 is filled with glass wool 8 to absorb sound. Reference numeral 9 denotes a microphone, which picks up sound pressure from the speaker 6, amplifies the sound pressure with the amplifier 10, and measures the sound pressure with the tester 11.

Approximate calculations by a computer were performed on the closed space of FIGS. 5A and 5B for the absolute value | Z | of the complex acoustic impedance on the wall surface when the wall surface (C) was forcibly driven. The length (x) of the closed box is 60cm,
(X ') is 50 cm and the same volume. FIG. 6 shows the result. The horizontal axis represents the frequency f ( _HZ ), and the vertical axis represents the absolute value | Z | of the acoustic impedance. The frequency at which the peak of the acoustic impedance occurs in (A) is shown by equation (1), where a standing wave is generated. _{f n = nC 0 / 2l (} H Z) ---- (1) where, n is a natural _{number, C 0 = 34000 (cm /} s), l = 60cm
The changes between (a) and (b) in FIG. 5 are as follows.

A (840) --- B (630) A ₁ (560) --- B ₁ (430) A ₂ (280) --- B ₂ (270) (B) Comparison with (A) , Each peak moves to a lower frequency, and the rate of the movement increases as the frequency increases. This means that each standing wave will be relatively weak, the ratio between their frequencies will be disturbed from simple integer multiples, and will be relatively random,
Further, it is considered that the existence density of the standing wave was increased, and as a result, it was considered that the habit of the timbre was weakened, and a change in the direction of improving the sound diffusion as a whole was caused.

As described above, it has been found that the difference in the shape of the wall surface (W) causes an important difference in the acoustic conditions inside, and in the present invention, by providing a special ordered reduction device, FIG. In the case of the box-type experimental device, the acoustic conditions are converted as if the wall surface (W) was changed to obtain the effect shown in FIG. FIG. 7 shows the data of the experimental apparatus in FIG. 4 and the calculation results by the computer according to FIGS. 5 and 6. If the experimental apparatus does not use the reduction device (1) such as a standing wave, the standing wave A ₃ is 570H
Although appearing to _Z, it has become a standing wave B ₃ in 440H _Z in the case of using the reduction device (1) such as a standing wave. This movement of the standing wave coincides with the calculation result and the experimental result. The movement of the standing wave A ₃ to the lower-frequency standing wave B ₃ means an increase in the sound path length (l), It is considered that a condition corresponding to the deformation of the wall (W) shape occurred.

In FIG. 4, the standing wave reducing device has an outer shape in the height direction from the wall surface (W) of about 25 cm on the long side and is almost triangular, and the opening height (h) of the sound guide path is Up to 4.8cm
Thick and less affected by airflow resistance, etc., and agrees well with the approximate calculation. It is also clear from the above experiment that the standing wave reducing device (1) has an outer shape in the height direction from the wall surface (W) of 25 cm on the long side. Therefore, it can be said that the present invention has an effect that exceeds the outer shape of a device for reducing standing waves or the like.

The opening of each hollow sound guide (2) constituting the device (1) for reducing standing waves or the like has a wavelength of less than one-fourth, particularly 10 minutes, of the wavelength of the sound wave to be reduced. About 1 is appropriate. If the size exceeds one-fourth, the reflected wave is unstable, and the reduction effect is not reliable. In the case of 1/10 or less, it is effective as long as the airflow resistance is small and a sound wave (T) can enter and reflect or radiate.

A comparison between the case where the hollow sound guide path (2) is open at one end and the other end is closed as shown in FIG. 1 and the case where both ends are open is shown in FIG. The same effect can be considered as if there was a change in the wall surface corresponding to the sound path length (l), but if both ends were opened, they would be introduced and transmitted from the openings, respectively, so two with one end opened Works the same as used.

Regarding the bending of the hollow sound guide path (2), there is no influence on the sound wave transmitted through the inside of the duct since the transmission loss at the bent portion is almost zero when the diameter of the duct is sufficiently small with respect to the wavelength. it is conceivable that. The cross-sectional area of the hollow sound guide path (2), when it becomes smaller from the open end to the inner side, has little effect other than the point where a reflected wave is generated there (see FIG. 20). When the inside spreads greatly from the opening end, a phenomenon close to Helmholtz resonance occurs, and there is a possibility that sound absorption may occur, and therefore, it is not included in the present invention.

FIG. 8 shows an example in which a number of hollow sound guides 12 made of synthetic resin or metal pipes are provided on the wall surface as a set of five rows and four stages. doing. FIG. 9 similarly shows an apparatus for reducing standing waves or the like as an aggregate in which a plurality of hollow sound guides 14 are provided in four rows in one row using a synthetic resin or metal plate. In FIG. 10, a plurality of hollow sound guide paths 16 are stacked in many rows to constitute a device 17 for reducing standing waves and the like. FIG. 11 shows a hollow sound guide 1
8 shows a reduction device 19 in which a plurality of rows 8 are stacked in a plurality of rows, but the steps are provided intermittently to shorten the sound path length (l).

FIG. 12 shows a reduction device 20 mounted near the ceiling of a small room to reduce booming and the like. FIG. 13 shows a case where the speaker is mounted on a wall behind the speaker system, and is an independent reduction device 21. In addition, the present invention can be applied to a reduction device that reduces flutter echo. In order to improve the sound quality by improving the acoustic conditions of the speaker system, shapes shown in FIGS. 14 to 17 are used. In FIG. 14, 22 is a reduction device that acts on sound waves traveling in the horizontal direction, and 23 is a reduction device that acts on sound waves traveling in the vertical direction, both of which are provided. Although not shown, it can also be provided for sound waves in the depth direction. FIG. 15 shows a reduction device 24 in which a sound path length is increased by using a bent sound guide path in a speaker cabinet. FIG. 16 shows a case where the camera is mounted on a super woofer cabinet.
Reference numeral 5 denotes a reduction device for reducing standing waves and improving acoustic conditions.

FIG. 17 shows a reduction device 26 used in a cabinet of a bass reflex type speaker. FIG. 18 shows a reduction device 27 having an outer shape of approximately a truncated cone. The sound path length 28 is such that each disk is rotatable about a central axis, and is easily adapted to the sound wave (T) direction. FIG. 19 shows a reduction device 29 acting in two directions of the XY axes.
FIG. 20 shows an example in which the cross-sectional area of the sound path length 30 is reduced from the opening end.

By mounting the apparatus for reducing standing waves of the present invention on the inner wall of a rectangular parallelepiped enclosure, it is possible to generate acoustic conditions corresponding to a large inclination of the wall, which is difficult to realize with the modified enclosure. In addition, a device for reducing standing waves and the like also has the effect of reinforcing the enclosure and saving the plate thickness. In addition, by installing a sound absorbing material such as glass wool near the opening of the hollow sound guide path of the standing wave reducing device, the structure of the sound absorbing material having an air layer behind can be easily obtained, and the sound absorbing material such as glass wool for low frequencies can be obtained. Rate can be increased.

[0032]

According to the first invention, the wavelength of the target sound wave is 4
Since a hollow sound guide having an opening having a height of 1/10 or less (h), particularly, a height of 1/10 or less, is provided, a stable reflected wave or radiated wave can be obtained. Are arranged in a single row or a plurality of rows and are stacked in a plurality of stages, so that the same effect can be obtained as if the phases of the sound pressure were shifted to deform the cabinet or the wall surface in the room. Therefore, a standing wave or a specific wave generated in the speaker, in the room, or between two parallel wall surfaces is converted to a direction in which the timbre of the timbre is small, and is efficiently reduced, so that a rich low tone with excellent sound quality can be reproduced. Moreover, while standing waves and the like are reduced, there is no sound loss due to sound absorption.

[0033] In contrast to the conventional diffuser, which can only provide the effect of the size of the outer shape, in the present invention, the internal volume of the hollow sound guide path is open in the cabinet or the room.
It can be used without waste, has a large volume, and can exhibit a reduction effect exceeding the size of the external shape, which is extremely advantageous for bass reproduction. The standing wave reduction device as an aggregate has a single block shape, is easy to manufacture, and occupies a small area for installation. Good, clarity, high efficiency,
Provide a device that reduces standing waves, etc. that realizes tough sound quality, has crisp sound, is rich in inflection, has rich bass and high resolution, can be mounted on a wall, and can be used as a portable independent body. I was able to. Furthermore, since the total area of the openings is close to the area occupied by the wall surface or the back surface of the aggregate, the effect as a sound diffuser is enhanced.

According to the second aspect of the present invention, the assembly can be mounted on the inner wall of a speaker enclosure or a wall in a room, or a portable cube, so that it can be installed at any position.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a basic configuration of a device for reducing standing waves and the like according to the present invention.

FIG. 2 is an explanatory diagram of the operation of the reduction device of the present invention.

FIG. 3 is an explanatory diagram showing a change in cross-sectional area by the reduction device of the present invention.

FIG. 4 is a cross-sectional view of an experimental apparatus for changing acoustic conditions.

FIG. 5 is an explanatory view of an experimental apparatus, in which (a) is a normal case,
(B) shows the effect when the reduction device is provided.

FIG. 6 is a comparative explanatory diagram of acoustic impedance when a reduction device is attached.

FIG. 7 is an explanatory diagram showing a change in sound pressure in the experimental apparatus of FIG.

FIG. 8 is a perspective view of a reduction device using a pipe.

FIG. 9 is a perspective view of a plate-shaped, single-row, multi-stage reduction device.

FIG. 10 is a perspective view of a reduction device having openings at both ends in a plurality of rows and a plurality of stages.

FIG. 11 is a perspective view of a reduction device provided with a hollow sound guide path intermittently.

FIG. 12 is a perspective view of a reduction device mounted on a ceiling.

FIG. 13 is a perspective view of an independent portability reduction device.

FIG. 14 is a cross-sectional view of a reduction device provided with a plurality of hollow sound guide paths.

FIG. 15 is a cross-sectional view of a reduction device having a bent hollow sound guide path.

FIG. 16 is a sectional view showing a case where the present invention is applied to a super woofer cabinet.

FIG. 17 is a cross-sectional view when provided in a bass reflex speaker.

FIG. 18 is a plan view of a reduction device formed as a truncated cone.

FIG. 19 is a perspective view of a reduction device used for sound waves in two directions.

FIG. 20 is a perspective view of an example in which the hollow sound guide path is reduced from the opening toward the back.

[Explanation of symbols]

1, 13, 15, 17, 19, 20, 21, 22, 23, 24, 25, 26, 27, 29, 31 Reduction device of the present invention 2, 12, 14, 16, 18, 28, 30 Hollow sound guide 3 opening 6 speaker

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-60-57798 (JP, A) JP-A-5-316584 (JP, A) Fully open 1984-38517 (JP, U) Really open 1979- 124533 (JP, U) JP-A 53-133627 (JP, U) JP-B-5-3594 (JP, B2) JP-B 55-47162 (JP, B2) JP-B 54-42728 (JP, B2) 57-4547 (JP, Y2) (58) Field surveyed (Int. Cl. ⁶ , DB name) H04R 1/28 310

Claims (2)

(57) [Claims] An opening is provided at one or both ends of a standing wave or a specific wave generated between two parallel wall surfaces in the vicinity of a wall surface (W) which is one of the two wall surfaces and faces a sound source. A plurality of hollow sound guides having a single row or a plurality of rows and having a plurality of stacked layers are provided, and the height (h) of the opening of the hollow sound guide is set to a wavelength of a desired standing wave or specific wave. A quarter of
Or less, preferably to 1/10 or less of the sound path length of each hollow sound conducting path (l) is successively or intermittently formed shorter from the wall (W) side, of the hollow sound guide paths constituting the aggregate Opening joint
The total area is reduced. The occupied area of the wall (W) by the size of the device
An apparatus for reducing a standing wave or a specific wave, wherein 2. An assembly comprising a speaker enclosure (e)
2. The standing wave or specific wave reducing device according to claim 1, wherein the device can be attached to an inner wall of the enclosure or a wall surface (W) of a room, or can be installed as an independent portable cube.