Audio device

Abstract

Provided is an audio device (100) which comprises a plurality of reflection members (110) that reflect sound output from a speaker unit (200), and forms a reflection space surrounded by the reflection members (110), the audio device (100) comprising: a cylindrical sound tube (120) which has a one-end opening section (127) connected to a communication hole (117) provided in the reflection member (110) and has a closing section (129) on the other end thereof; and a sound absorption material (130) disposed at a central section (128) of a sound path formed by the sound tube (120).

Description

Technical Field

[0001] The present invention relates to an acoustic device that suppresses disturbances in the sound pressure frequency characteristics caused by standing waves generated in a space.

Background Art

[0002] It is known that the sound pressure frequency characteristics of the sound output from a speaker unit are disturbed by the internal shape of a speaker cabinet or the internal shape of a listening room. In order to correct such disturbances in the sound pressure frequency characteristics, Patent Document 1 describes a technique of providing an acoustic tube communicating with a reflection space inside a speaker cabinet to suppress the influence of standing waves generated in the reflection space.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, although the technique described in Patent Document 1 can suppress the peak of the sound pressure at the resonance frequency due to the resonance between the acoustic tube and the reflection space of the cabinet, it does not directly suppress the dips in the sound pressure frequency characteristics.

[0005] The present invention has been made in view of the above problems, and an object thereof is to provide an acoustic device capable of obtaining characteristics that are as flat as possible with few dips in the sound pressure frequency characteristics.

Means for Solving the Problems

[0006] In order to achieve the above object, an acoustic device according to one aspect of the present invention includes a plurality of reflecting members that reflect sound output from a speaker unit, and forms a reflecting space surrounded by the reflecting members, and is an acoustic device, including: a cylindrical acoustic tube having one end opening connected to a communication hole provided in the reflecting member and a closing portion at the other end; and a sound absorbing material disposed at a central portion of a sound path formed by the acoustic tube.

Advantages of the Invention

[0007] According to the present invention, the amplitude of the standing wave generated in the reflection space can be effectively suppressed by the sound absorbing material disposed at the central portion of the acoustic tube, and it is possible to flatten the sound pressure frequency characteristics.

Brief Description of the Drawings

[0008]

Figure 1

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Embodiments for Carrying Out the Invention

[0009] Hereinafter, embodiments of the acoustic device according to the present invention will be described with reference to the drawings. Note that the following embodiments are examples for explaining the present invention and are not intended to limit the present invention. For example, the shapes, structures, materials, components, relative positional relationships, connection states, numerical values, mathematical formulas, contents of each step in the method, the order of each step, etc. shown in the following embodiments are examples, and may include contents not described below. In addition, although geometric expressions such as parallel and orthogonal may be used, these expressions do not indicate mathematical precision and include substantially allowable errors, deviations, etc. Also, expressions such as simultaneous and identical also include a substantially allowable range.

[0010] Also, the drawings are schematic diagrams that are appropriately emphasized, omitted, or adjusted in ratio for explaining the present invention, and are different from the actual shapes, positional relationships, and ratios.

[0011] Also, in the following, a plurality of inventions may be comprehensively described as one embodiment. In addition, a part of the content described below is explained as an arbitrary component related to the present invention.

[0012] FIG. 1 is a perspective view showing the appearance of the acoustic device according to the embodiment. FIG. 2 is a perspective view showing a part of the reflection member of the acoustic device according to the embodiment with omission.

[0013] The acoustic device 100 according to the embodiment is a speaker cabinet in a so-called speaker system, and is a device to which the speaker unit 200 is attached. The acoustic device 100 includes a reflection member 110, an acoustic tube 120, and a sound-absorbing material 130.

[0014] The speaker unit 200 is an electroacoustic conversion device that converts an electrical signal such as an audio signal into vibration of a diaphragm. The sizes, shapes, and structures of the diaphragm, magnetic circuit, frame, etc. constituting the speaker unit 200 are not particularly limited. In the case of this embodiment, the speaker unit 200 employs a moving-coil type speaker including a cone-shaped diaphragm.

[0015] The reflecting member 110 is a member that reflects the sound output from the speaker unit 200. The space surrounded by the reflecting member 110 becomes a reflecting space that reflects the sound output from the speaker unit 200. In the case of the present embodiment, the reflecting member 110 is composed of a plurality of plate-like members 110 including a top plate 111, a bottom plate 112, a front plate 113, a back plate 114, and two side plates 115, and is assembled in a rectangular parallelepiped shape to form a rectangular parallelepiped-shaped reflecting space 101. The speaker unit 200 is attached to a mounting hole 116 provided in a penetrating manner on the front plate 113, which is one of the reflecting members 110, in a state where it is inserted. A penetrating communication hole 117 for communicating the sound path 121 with the reflecting space 101 is provided in the bottom plate 112, which is one of the reflecting members 110. Specifically, the bottom plate 112 is shorter than the top plate 111 in the depth direction (X-axis direction in the figure), and the space surrounded by the bottom plate 112, the back plate 114, and both side plates 115 serves as the communication hole 117.

[0016] The material constituting the reflecting member 110 is not particularly limited, and examples thereof include wood, resin, building materials, ceramics, etc., and a combination of a plurality of materials may be used.

[0017] The acoustic tube 120 is a cylindrical member having an opening 127 at one end and a closing portion 129 at the other end, and is a member that forms a sound path 121 communicating with the reflecting space 101 formed by the reflecting member 110. The length of the sound path 121 formed by the acoustic tube 120 is not particularly limited, and may be determined, for example, by the position of a dip in the sound pressure frequency characteristics disturbed by the influence of the reflecting space 101 formed by the reflecting member 110. For example, when a dip occurs in the sound pressure frequency characteristics due to a standing wave caused by the length from the reflecting member 110 disposed opposite to the communication hole 117 to the communication hole 117, and in the case of the present embodiment, due to the length from the top plate 111 to the bottom plate 112, an acoustic tube 120 is set to form a sound path 121 having a length of 50% or more of the length from the reflecting member 110 disposed opposite to the communication hole 117 to the communication hole 117. In the case of the present embodiment, the length of the sound path 121 is set to be the same as the length from the top plate 111 to the bottom plate 112.

[0018] The sound-absorbing material 130 is a member disposed at the central portion 128 of the sound path 121 formed by the sound pipe 120. The sound-absorbing material 130 is not particularly limited as long as it is a material capable of suppressing the vibration of air, and examples thereof include a sound-absorbing material 130 such as a sponge with continuous air bubbles, and a wool-type sound-absorbing material 130 in which glass fibers, rock fibers, etc. are aggregated. The arrangement of the sound-absorbing material 130 is not particularly limited as long as it is at the central portion of the sound path 121. For example, the sound-absorbing material 130 may be arranged so as to block the sound pipe 120, or the sound-absorbing material 130 may be attached to the inner surface of the sound pipe 120 without blocking the sound pipe 120. Note that arranging the sound-absorbing material 130 near the opening 127 of the sound pipe 120 has little effect on improving the dip in the sound pressure frequency characteristics. Also, arranging the sound-absorbing material 130 near the closing portion 129 of the sound pipe 120 is not preferable because it has little effect on improving the dip in the sound pressure frequency characteristics and may generate a new dip.

[0019] The arrangement position of the sound-absorbing material 130 inside the sound pipe 120 can be said to be, in other words, a region including a portion where the particle velocity is high inside the sound pipe 120. That is, the sound pipe 120 forms a sound path 121 having a length equal to or near half the wavelength of the standing wave generated in the reflection space 101 and serving as the source of the dip. Thereby, a standing wave vibrating at the same frequency as the standing wave in the reflection space 101 can be generated inside the sound pipe 120. When the sound-absorbing material 130 is arranged at the central portion of the sound path 121, the vibration of the portion where the particle velocity of the standing wave inside the sound pipe 120 is maximum is suppressed, and the standing wave is effectively suppressed. Therefore, it is possible to selectively suppress the target dip without affecting the sound pressure frequency characteristics of other frequencies, particularly low frequencies.

[0020] An example of the operation of the acoustic device 100 configured as described above will be described using the sound pressure frequency characteristics of FIG. 3. The (a) stage of FIG. 3 shows the sound pressure frequency characteristics of the acoustic device 100 in which the communication hole 117 is not provided in the reflection member 110 without providing the acoustic tube 120. The (b) stage of FIG. 3 shows the sound pressure frequency characteristics of the acoustic device 100 in which the acoustic tube 120 is connected to the communication hole 117 of the reflection member 110 and the sound absorption material 130 is not provided. The (c) stage of FIG. 3 shows the sound pressure frequency characteristics of the acoustic device 100 according to the present embodiment.

[0021] In the case of the sound pressure frequency characteristics of the conventional sealed acoustic device without the acoustic tube 120 shown in the (a) stage of FIG. 3, there is a dip 301 in the sound pressure near 350 Hz. This is considered to be due to the standing wave of 350 Hz generated in the reflection space 101.

[0022] Next, in the case shown in the (b) stage of FIG. 3, when the acoustic tube 120 is attached to the communication hole 117 of the reflection member 110 and the sound absorption material 130 is not provided, dips are generated in addition to the dip 301 because the acoustic tube 120 is connected to the rectangular parallelepiped reflection space 101. The disturbance of the sound pressure frequency characteristics is more disturbed than in the case where the acoustic tube 120 is not provided.

[0023] In the case of the present embodiment shown in the (c) stage of FIG. 3, the dip 301 generated when the acoustic tube 120 is not provided (FIG. 3(a)) is greatly improved, and the sound pressure frequency characteristics are smooth. Also, the peak generated near the high-frequency side of the dip 301 is suppressed. Further, the dips other than the dip 301 generated due to the presence of the acoustic tube 120 disappear, and almost no influence appears on the sound pressure frequency characteristics on the low-frequency side of the dip 301.

[0024] Next, the influence of the opening area of the communication hole 117 on the sound pressure frequency characteristics will be described. The opening area of the communication hole 117 portion is preferably an area included in the range of 5% or more and 50% or less of the area of the reflection member 110 provided with the communication hole 117 portion (specifically, the area of the reflection member 110 when the communication hole 117 is not provided) (see FIG. 4). The graph shown in the (a) stage of FIG. 4 shows the sound pressure frequency characteristics when the opening area of the communication hole 117 is less than 5% (specifically, 1%). It is shown that it is difficult to suppress the dip 301 with such an opening area of the communication hole 117. The graph shown in the (b) stage of FIG. 4 shows the sound pressure frequency characteristics when the opening area of the communication hole 117 is 5%. When the opening area of the communication hole 117 becomes such, the dip 301 of the sound pressure frequency characteristics can be suppressed. The graph shown in the (c) stage of FIG. 4 shows the sound pressure frequency characteristics when the opening area of the communication hole 117 is 10%. When the opening area of the communication hole 117 becomes such, the dip 301 of the sound pressure frequency characteristics can be further suppressed. The graph shown in the (d) stage of FIG. 4 shows the sound pressure frequency characteristics when the opening area of the communication hole 117 is 50%. When the opening area of the communication hole 117 becomes such, the vicinity of the dip 301 to be suppressed becomes almost flat. Note that when the opening area of the communication hole 117 is larger than 50%, the volume of the box including the acoustic tube 120 becomes large, so it becomes impractical.

[0025] Next, the influence of the length of the sound path 121 formed by the acoustic tube 120 on the sound pressure frequency characteristics will be described. FIG. 5 is a graph showing the respective sound pressure frequency characteristics when the lengths of the sound paths are different. When the length of the sound path 121 is less than 50% of the half wavelength corresponding to the dip 301 to be suppressed in the sound pressure frequency characteristics (for example, the (a) stage in FIG. 5, 25% of the half wavelength), the dip 301 is hardly improved. As shown in the (b) stage of FIG. 5, when it reaches 50% of the half wavelength, the dip 301 to be suppressed becomes shallower and improvement can be seen. If the length is equal to the half wavelength as in the present embodiment (the (c) stage in FIG. 5), the dip 301 becomes shallower. On the other hand, even if the length of the sound path 121 is set longer than the half wavelength (for example, the (d) stage in FIG. 5, 125% of the half wavelength), the shallowness of the dip 301 does not change compared to the case where it is equal to the half wavelength. That is, it is preferable that the length of the sound path 121 is 50% or more of the half wavelength corresponding to the dip 301 to be suppressed. The specific length is set based on the disturbance of the sound pressure frequency characteristics in other frequency regions.

[0026] As described above, according to the present embodiment, by disposing the acoustic tube 120 forming the sound path 121 in which the sound absorption material 130 is disposed at the central portion 128 in the communication hole 117 provided in the reflection member 110, the standing wave generated by the relationship between the distance between the opposing reflection members 110 in the reflection space 101 and the wavelength of the sound radiated by the speaker unit 200 can be suppressed. Also, in the low frequency range lower than the frequency of the standing wave, the volume of the acoustic tube 120 in which the sound absorption material 130 is disposed at the central portion of the sound path 121 is added to the volume of the reflection space 101, and the influence on the sound pressure level in the low frequency range can be suppressed.

[0027] Note that the present invention is not limited to the above-described embodiment. For example, another embodiment realized by arbitrarily combining the components described in this specification and excluding some of the components may also be an embodiment of the present invention. Also, modification examples obtained by applying various modifications conceived by those skilled in the art without departing from the gist of the present invention, that is, the meaning indicated by the language described in the claims, with respect to the above-described embodiment are also included in the present invention.

[0028] In the above-described embodiment, the speaker cabinet in the speaker system was exemplified as the acoustic device 100, but the acoustic device 100 is not limited to the cabinet. For example, as shown in FIG. 6, the acoustic device 100 may be a listening room in which a stereo system 210 including a speaker system is arranged inside. In this case, building materials constituting walls, floors, ceilings, etc. function as the reflection member 110.

[0029] Also, the shape of the acoustic tube 120 is not particularly limited, and any shape such as a cylindrical shape or a rectangular tube shape can be adopted. Further, the shape of the sound path 121 formed by the acoustic tube 120 may be straight, curved, or bent. In the case of the present embodiment, the acoustic tube 120 is a rectangular tube shape, and the sound path 121 formed by the acoustic tube 120 is bent in a U shape. The material forming the acoustic tube 120 is not particularly limited, and it may be a material different from that of the reflection member 110. In the case of the present embodiment, the acoustic tube 120 is formed by a portion extending the front panel 113, the back panel 114, the both side panels 115, the acoustic tube plate 122, the partition plate 123, and the bottom panel 112 commonly used.

[0030] Also, in the above-described embodiment, the length of the sound path 121 formed by the acoustic tube 120 was determined based on the length from the reflection member 110 disposed opposite to the communication hole 117 to the communication hole 117. However, as shown in FIG. 7, an acoustic tube 120 that forms a sound path 121 having a length corresponding to a standing wave generated based on the distance between the top panel 111 and the bottom panel 112 may be connected to the communication hole 117 provided in the back panel 114.

[0031] Also, in the above-described embodiment, the bent sound path 121 was described, but the sound path 121 may be provided in a straight tube shape as shown in FIG. 8. Further, an acoustic tube 120 that forms the sound path 121 may be provided inside the cabinet formed by the reflection member 110 using the partition plate 123.

[0032] Also, a communication hole 117 may be provided in at least one of the side panel 115 and the top panel 111 to connect the acoustic tube 120.

[0033] Further, a plurality of acoustic tubes 120 that form sound paths 121 of different lengths may be respectively connected to a plurality of communication holes 117 provided in the reflection member 110.

[0034] Further, the reflection member 110 may be provided with a bass-reflex port different from the communication holes 117, and may have holes communicating with the reflection space 101 other than the communication holes 117.

Industrial Applicability

[0035] The present invention can be used in a cabinet of a speaker system, a housing of a home appliance product such as a television to which a speaker unit is attached, a listening room, a practice studio, and the like.

Explanation of Symbols

[0036] 100 Acoustic device 101 Reflection space 110 Reflection member 111 Top panel 112 Bottom panel 113 Front panel 114 Rear panel 115 Side panel 116 Mounting hole 117 Communication hole 120 Acoustic tube 121 Sound path 122 Acoustic tube plate 123 Partition plate 127 Opening 128 Central portion 129 Closing portion 130 Sound-absorbing material 200 Speaker unit 210 Stereo system 301 Dip

Claims

1. An acoustic device comprising a plurality of reflecting members that reflect sound output from a speaker unit, and forming a reflection space surrounded by the reflecting members, a tubular acoustic pipe having one end opening connected to a communication hole provided in the reflecting member and having a closed portion at the other end, a sound absorbing material disposed at the center of a sound path formed by the acoustic pipe, and an acoustic device comprising the same.

2. The length of the sound path formed by the acoustic pipe is 50% or more of the length between any pair of opposing positions within the reflecting member The acoustic device according to Claim 1.

3. The opening area of the communication hole is an area included in the range of 5% or more and less than 50% of the area of the reflecting member provided with the communication hole The acoustic device according to Claim 1 or 2.

4. Comprising the speaker unit mounted in a state of being inserted into a mounting hole provided through the reflecting member The acoustic device according to any one of Claims 1 to 3.

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