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DESCRIPTION JP2014175806

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DESCRIPTION JP2014175806
Abstract: PROBLEM TO BE SOLVED: To suppress a standing wave generated in a cabinet by using
an acoustic tube and to suppress a vibration of the cabinet. SOLUTION: Two L-shaped acoustic
tubes 121 and 122 are fixed on the back side of a front part F of a cabinet 100 to form a square
surrounding a woofer 101. The acoustic tube 121 is hollow and has a half-wave tube length of a
standing wave to be suppressed. The acoustic tube 121 has openings 121a and 121b at both
ends, the opening 121a is located on the antinode of the sound pressure of the standing wave,
and the opening 121b is located on the node of the sound pressure. The same applies to the
acoustic tube 122. In this acoustic device, the standing waves generated between the ceiling T
and the bottom D of the cabinet 100 are suppressed by the acoustic tubes 121 and 122.
Moreover, the vibration of the front part F of the cabinet 100 is suppressed by the acoustic tubes
121 and 122. [Selected figure] Figure 25
Sound equipment
[0001]
The present invention relates to a technique for suppressing standing waves using tube
resonance.
[0002]
In a space surrounded by walls in an acoustic device etc., when a sound wave of natural
frequency is emitted in the space, a standing wave is generated due to the reciprocation of the
sound wave between the wall faces of the space, which adversely affects its acoustic
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characteristics It has been known.
Patent documents 1 to 3 disclose a technique for suppressing a standing wave in a speaker
which is one of the acoustic devices. The speaker device disclosed in Patent Document 1 includes
a speaker unit, a cabinet including the speaker unit, and a Helmholtz resonator provided inside
the cabinet. In this speaker device, its neck length L and cavity volume V are designed such that
the Helmholtz resonator resonates at the same frequency as the standing wave generated in the
cabinet. According to this speaker device, when a standing wave is generated in the cabinet, the
Helmholtz resonator exhibits a resonance phenomenon, and the standing wave is attenuated by
this resonance phenomenon. The speaker device disclosed in Patent Document 2 includes a
speaker unit, a cabinet incorporating the same, and an acoustic pipe (closed pipe) having an open
end and a closed end. The acoustic tube of this speaker device has a tube length L which is 1/4
of the lowest resonance mode of the standing wave generated in the cabinet. The acoustic tube is
housed in the cabinet in a posture in which the position of the open end is close to the position of
the antinode (node of particle velocity) of the sound pressure of the standing wave in the cabinet.
In this speaker device, when a standing wave (a standing wave having a wavelength of 4 times
the tube length L) is generated in the cabinet, a resonance wave is generated in the acoustic pipe.
The resonance wave has a node of sound pressure (antinode of particle velocity) at the open end
of the acoustic tube and has an antinode (node of particle velocity) of the closed end. Therefore,
according to this speaker device, the bias of the sound pressure distribution in the cabinet is
alleviated, and the standing wave in the cabinet is attenuated. Patent Document 3 also discloses
the same technology as Patent Document 2.
[0003]
Patent No. 2606447 gazette Patent No. 3763682 gazette JP, 2008-131199, A
[0004]
By the way, in the speaker device, in addition to the above-described standing waves, vibrations
generated in the casing of the speaker device adversely affect the acoustic characteristics.
In order to suppress the vibration of the housing, it is conceivable to provide a beam in the
housing to increase the strength of the housing. However, if such a method is adopted, the
interior of the housing may be congested due to the provision of the beam and the acoustic tube,
and the acoustic characteristics may be deteriorated. In addition, there is a problem that such a
speaker device having a complicated structure inside the housing is difficult to manufacture.
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[0005]
The present invention has been made in view of such problems, and it is an object of the present
invention to provide a technical means for suppressing standing waves generated in a housing of
a speaker device and suppressing vibration of the housing itself. Do.
[0006]
The present invention has a housing including a space surrounded by at least a pair of opposing
surfaces, and first and second openings located in the space, and at least one of the inner wall
surfaces of the housing An acoustic tube whose outer surface is fixed to an inner wall surface,
having a tube length that is an integral multiple of approximately a half wavelength of a standing
wave generated in the space, the standing wave generated in the space by the first opening And
an acoustic tube disposed at a position substantially on the antinode.
[0007]
According to the present invention, when the standing wave is generated in the space, the
standing wave which can not coexist with the standing wave is generated in the acoustic pipe, so
the standing wave generated in the space is reduced.
Further, since the outer surface of the acoustic tube is fixed to at least one of the inner wall
surfaces of the casing, the vibration of the casing is suppressed by the acoustic tube.
[0008]
In a preferred aspect, the acoustic tube is fixed to a pair of opposing surfaces in a housing.
[0009]
In another preferred embodiment, the second opening is disposed at a position substantially at a
node of a standing wave generated in the space.
Further, in another preferable aspect, the first and second openings are provided at respective
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positions separated by a length that is an odd multiple of about a quarter wavelength of the
standing wave in the opposing direction of the pair of opposing surfaces. To position.
[0010]
In another preferred embodiment, the second opening is disposed at a position substantially
antinode to a standing wave generated in the space.
[0011]
In another preferred embodiment, all or a part of one or both of the first and second openings is
covered with a breathable sound absorbing material.
[0012]
It is a front view of the speaker which is one embodiment of the present invention.
It is a front view of the speaker which is the 1st example of the embodiment.
It is a figure which shows the frequency response which is a 1st verification result of the effect of
the same speaker.
It is a figure which shows the positional relationship of the standing wave in the speaker, and the
opening end of an acoustic pipe. It is a figure which shows the waveform of the resonant wave in
the acoustic pipe | tube of the same speaker. It is a figure which shows the frequency response
which is a verification result of the 2nd verification of the effect of the same speaker. It is a
perspective view of the bass reflex type speaker created for the 3rd verification of the effect of
the speaker. It is a figure which shows the frequency response which is a verification result of the
3rd verification of the effect of the same speaker. It is a figure which shows the frequency
response which is a verification result of the 3rd verification of the effect of the same speaker. It
is a figure which shows the frequency response which is a verification result of the 3rd
verification of the effect of the same speaker. It is a front view of the speaker which is the 2nd
example of the embodiment. It is a figure which shows the frequency response which is a
verification result of the effect of the same speaker. It is a figure which shows the positional
relationship of the standing wave in the speaker, and the opening end of an acoustic pipe. It is a
figure which shows the waveform of the resonant wave in the acoustic pipe | tube of the same
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speaker. It is a front view of the speaker which is the 3rd example of the embodiment. It is a
figure which shows the frequency response which is a verification result of the same speaker. It
is a front view of the speaker which is the 4th example of the embodiment. It is a figure which
shows the frequency response which is a verification result of the same speaker. It is a figure
which shows the frequency response which is a verification result of the same speaker. It is a
figure which shows the frequency response which is a verification result of the same speaker. It
is a front view of the speaker which is another example of the embodiment. It is a figure which
shows typically and comprehensively the relationship of the standing wave and acoustic tube
which generate | occur | produce in the space in a housing | casing in the audio equipment by
this invention. It is a figure which illustrates the installation mode of the reinforcing material in
the housing | casing of a speaker. It is a figure which shows the effect of installation of a
reinforcing material. It is a figure which shows the 1st example of the installation aspect as a
reinforcing material of the acoustic pipe in the embodiment. It is a figure which shows the 2nd
example of the installation aspect as a reinforcing material of the acoustic pipe in the
embodiment. It is a figure which shows the modification of the 2nd example. It is a figure which
shows the 3rd example of the installation aspect as a reinforcing material of the acoustic pipe in
the embodiment. It is a figure which shows the modification of the 3rd example of the same. It is
a figure which shows the 4th example of the installation aspect as a reinforcing material of the
acoustic pipe in the embodiment. It is a figure which shows the modification of the 4th example.
It is a figure which shows the other example of the installation aspect as a reinforcing material of
the acoustic pipe in the embodiment. It is a figure which shows the other example of the acoustic
pipe in the embodiment.
[0013]
Hereinafter, embodiments of the present invention will be described with reference to the
drawings. <Structure of Acoustic Tube and Acoustic Characteristics> The acoustic device
according to the present invention uses an acoustic tube having two openings. These two
openings may be provided at the end of the acoustic tube or may be provided halfway between
the ends of the acoustic tube. The first feature of the acoustic device according to an embodiment
of the present invention is the position of the two openings of the acoustic tube in the housing
and the pipe length between the two openings in the acoustic tube. The acoustic characteristics
of the acoustic tube are determined by the position of the two openings of the acoustic tube in
the housing and the pipe length between the two openings in the acoustic tube. Hereinafter, a
first example of the acoustic device according to the present embodiment will be described by
taking a specific example.
[0014]
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<< First Example >> FIG. 1A is a front view of a speaker 9 which is a first example of an acoustic
device according to an embodiment of the present invention. The speaker 9 has a cabinet 1, a
speaker unit 2 fixed to the outside of the cabinet 1, and an acoustic tube 10 housed in a space S
in the cabinet 1. The cabinet 1 is a member serving as a housing of the speaker 9. The cabinet 1
has a hollow rectangular parallelepiped shape surrounded by wall surfaces 4U and 4D opposed
in the vertical direction, wall surfaces 4F and 4B opposed in the front-rear direction, and wall
surfaces 4L and 4R opposed in the left-right direction. The vertical width H (the distance between
the wall surfaces 4U and 4D: for example, H = 1050 mm) in the space S in the cabinet 1 is the
depth width L (the distance between the wall surfaces 4F and 4B: for example, L = 200 mm) It is
sufficiently larger than the lateral width W (the distance between the wall surfaces 4L and 4R: for
example, W = 300 mm).
[0015]
The speaker unit 2 is a device serving as a sound source of the speaker 9. The speaker unit 2 is
embedded substantially in the center of the wall 4U of the cabinet 1 with the sound emitting
surface facing outward. An electrical signal is input to the speaker unit 2 from an audio device
(not shown). The speaker unit 2 emits this electric signal as a sound wave. Here, when a sound
wave of the same frequency as the natural frequency is transmitted from the speaker unit 2 to
the space S, the sound wave reciprocates between the wall surfaces 4U and 4D of the space S,
and a plurality of sound waves reciprocate between the wall surfaces 4U and 4D are combined.
Standing waves SWk (k = 1, 2...) Having a wavelength λk (k = 1, 2...) 2 / k (k = 1, 2. .
[0016]
The acoustic tube 10 is a member that plays a role in reducing the standing wave SWk. The
acoustic tube 10 has a tube length corresponding to about half a wavelength of the lowest-order
standing wave SWk to be suppressed (in the example of FIG. 1A, the first-order standing wave
SW1). . The acoustic tube 10 has a J-shape bent 90 degrees at two points on the way from one
open end 11 to the other open end 12. The acoustic tube 10 is housed in the space S in such a
posture as to satisfy two conditions a1 and b1 described below. a1. One open end 11 and the
other open end 12 are respectively arranged at the positions of the substantially antinode LP and
the approximately node ND of the sound pressure of the lowest one of the standing waves SWk
to be suppressed in the space S b1. One open end 11 and the other open end 12 are respectively
disposed at positions separated by approximately a quarter wavelength of standing wave SWk in
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the opposing direction of the two opposing surfaces of wall surfaces 4U and 4D in space S To
[0017]
The above is the details of the configuration of the speaker 9 according to the present
embodiment. Here, in the example of FIG. 1A, the opening end 11 is disposed at the position of
the belly LP1-1 on the side of the wall surface 4U among the two belly LP1-1 and LP1-2 of the
primary standing wave SW1. The open end 12 is disposed at the position of the node ND1-1
between the two belly LP1-1 and LP1-2. However, as shown in the example of FIG. 1B, the
attitude is such that the open end 11 is disposed at the position of the belly LP1-2 on the side of
the wall 4D and the open end 12 is disposed at the position of the node ND1-1. You may By
placing the acoustic tube 10 in the space S in a posture as shown in FIGS. 1A and 1B, it is
possible to reduce the primary or higher standing waves SWk in the space S. Also, as is well
known, when there is a sound source at the position of the node ND1-1 of the primary standing
wave SW1 on the wall surfaces 4U, 4D, 4L, 4F, 4B forming the cabinet 1 of the speaker 9, the
space S The odd-order standing waves SW1, SW3, SW5 .. inside are suppressed by the vibration
of the sound source (see Patent Document 3 for details). Therefore, as for the speaker 9A in the
example of FIG. 2, in the case where the speaker unit 2 is at the position of the node ND1-1 of
the primary standing wave SW1, an approximately half wavelength of the secondary standing
wave SW2 is provided. The acoustic tube 20 having a tube length may be accommodated in the
space S in a posture that satisfies the above-described conditions a1 and b1. Also by placing the
acoustic tube 20 in the space S in such a posture, it is possible to reduce the standing wave SWk
of the first or higher order in the space S.
[0018]
Here, the inventors conducted three verifications to confirm the effects of the present
embodiment. First, the contents of the first verification will be described. In the first verification,
for the speaker 9 in the example of FIG. 1A, the inventors input a test sound signal ST (for
example, white noise) to the speaker unit 2, and sound waves emitted from the speaker unit 2 are
Input signal ST when measured at measurement point P in space S (more specifically, at
measurement point P near the inner side of the position where wall surfaces 4D, 4B, and 4R
intersect (see FIG. 1A)) The frequency response R-9, which is the difference of the spectrum of
the measurement signal SM, was calculated by simulation. Similarly, for the speaker 9 ′
obtained by removing the sound tube 10 from the speaker 9, the test sound signal ST is input to
the speaker unit 2, and the sound signal emitted from the speaker unit 2 is measured at the
measurement point P The frequency response R-9 ', which is the difference between the ST and
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the spectrum of the measurement signal SM, was calculated by simulation. FIG. 3 shows the
frequency responses R-9 and R-9 'with their frequency axes aligned.
[0019]
Referring to FIG. 3, peaks appear at around 160 Hz, 320 Hz, 480 Hz, 650 Hz, 820 Hz, and 960
Hz in any of the frequency responses R-9 and R-9 '. And in the frequency response R-9, although
the peak amplitude around 650 Hz is almost the same as that of the frequency response R-9 ′,
the peak amplitude around 160 Hz, 320 Hz, 480 Hz, 820 Hz and 970 Hz is the frequency
response R− It's smaller than 9's. In frequency response R-9, peaks near 160 Hz, 320 Hz, 480
Hz, 820 Hz, and 970 Hz are broken. From this, the first-order standing wave SW1 (160 Hz), the
second-order standing wave SW2 (320 Hz), the third-order standing wave SW3 (480 Hz), the
fifth-order standing wave in the space S by the speaker 9 It was confirmed that SW5 (820 Hz)
and sixth order standing wave SW6 (970 Hz) can be suppressed.
[0020]
Based on the verification result of the first verification, the inventors next explain the reason why
the standing waves SW1, SW2, SW3, SW5, and SW6 are suppressed except the fourth order by
the speaker 9 of the example of FIG. I guessed like. As shown in FIG. 4, in the speaker 9, the open
end 11 of the acoustic tube 10 in the space S is disposed at the position of the antinode LP1-1 of
the standing wave SW1. The position of the belly LP1-1 of the standing wave SW1 corresponds
to the belly LP2-1, LP3-1, LP4-1, LP5-1... Of the standing waves SW2, SW3, SW4, SW5. In
addition, the open end 12 of the acoustic tube 10 in the space S is disposed at the position of the
node ND1-1 of the standing wave SW1. The position of the node ND1-1 of the standing wave
SW1 is the antinode LP2-2 and LP4-3 of the second and subsequent even-order standing waves
SW2 and SW4, and the odd-order standing wave SW3, and the third and subsequent orders. This
corresponds to the sections ND3-2 and ND5-3 of SW5. Therefore, when standing waves SWk (k =
1, 2...) Are generated in the space S, the medium (air) in the vicinity of the open end 11 of the
acoustic tube 10 is the antinode of the odd and even standing waves SWk. The sound pressure is
changed by the sound pressure change at the position of LP, and the medium (air) near the open
end 12 is excited by the sound pressure change at the position of the antinode LP of the even
standing wave SWk.
[0021]
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Here, focusing on the relationship between the primary standing wave SW1 in the space S and
the behavior of the medium (air) in the acoustic tube 10, in the acoustic tube 10, the medium
(air) in the vicinity of the opening end 11 is Due to the change in sound pressure of the belly LP
1-1 of the standing wave SW 1, a traveling wave TW 1 is generated that travels from the open
end 11 to the open end 12. The traveling wave TW1 travels in the acoustic tube 10 and reaches
the open end 12. Since the position at which the open end 12 of the acoustic tube 10 is disposed
in the space S is the position of the node ND1-1 of the standing wave SW1, even if the traveling
wave TW1 reaches the open end 12, the vicinity of the open end 12 The medium (air) hardly
vibrates. Therefore, when the traveling wave TW1 reaches the opening end 12, a reflected wave
RW1 is generated at the opening end 12. Then, when the reflected wave RW1 and the traveling
wave TW1 are combined in the acoustic tube 10, a resonant wave XW1 having the same
wavelength λ1 as the standing wave SW1 is generated. Since this resonance wave XW1 is
formed by combining the traveling wave TW1 and the reflected wave RW1 which reflects the
traveling wave TW1 at the opening end 12, as shown in FIG. 5A, this resonance wave The side of
the open end 11 and the side of the open end 12 in the XW 1 become nodes ND. Therefore, the
sound pressure distribution of the standing wave SW1 is relaxed at the position of the opening
end 11. The inventors speculated that the standing wave SW1 is attenuated due to the above
reasons. Further, the presence of the node ND at the position of the opening end 12 is the same
as for all the standing waves SWk of odd-order. Therefore, the inventors speculated that the third
or higher order odd-order standing waves SW3, SW5, SW7,... Are also attenuated for the same
reason as the standing wave SW1.
[0022]
Next, focusing on the relationship between the secondary standing wave SW2 in the space S and
the behavior of the medium (air) in the acoustic tube 10, in the acoustic tube 10, the medium (air
in the vicinity of the open ends 11 and 12) ) Are excited by the sound pressure changes of the
belly LP2-1 and LP2-2 of the standing wave SW2, and the traveling directions are opposite and
the traveling waves TW2 and TW2 ′ ′ are generated with a phase difference of π between
each other Do. The traveling waves TW2 and TW2 ′ ′ have a phase difference of π because
the sound pressure of two adjacent belly LP in the standing wave k changes with a phase
difference of π. Then, when the traveling waves TW2 and TW2 ′ ′ are combined in the
acoustic tube 10, a resonance wave XW2 having the same wavelength λ2 as the standing wave
SW2 is generated. Since this resonance wave XW2 is formed by combining the traveling waves
TW2 and TW2 ′ ′ with a phase difference of π, as shown in FIG. 5B, between the opening
ends 11 and 12 in this resonance wave XW2 The middle is the section ND. In addition, since the
tube length of the acoustic tube 10 (the tube length of a half wavelength of the primary standing
wave SW1) is the same as the wavelength λ2 of the standing wave SW2 (λ2 = λ1 / 2), the
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distance between the open ends 11 and 12 is If the middle becomes a node ND, the side of the
open ends 11 and 12 also becomes a node ND. Therefore, the sound pressure distribution of the
standing wave SW2 is relaxed at the positions of the open ends 11 and 12. The inventors
speculated that the standing wave SW2 is attenuated due to the above reasons. In addition, the
sound pressure at the position of the opening end 11 and the sound pressure at the position of
the opening end 12 change with a phase difference of π similarly for the sixth order standing
wave SW6 and the tenth order standing wave SW10. is there. Therefore, the inventors estimated
that the sixth standing wave SW6 and the tenth standing wave SW10 are also attenuated for the
same reason as the second standing wave SW2.
[0023]
Next, focusing on the relationship between the fourth-order standing wave SW4 in the space S
and the behavior of the medium (air) in the acoustic tube 10, the medium (air in the vicinity of
the open ends 11 and 12 in the acoustic tube 10) ) Are excited by the sound pressure changes of
the belly LP4-1 and 4-3 of the standing wave SW4, and traveling waves TW4 and TW4 'having
the same traveling direction and the same traveling direction are generated. The traveling waves
TW4 and TW4 'are in phase because the sound pressures of the two belly LPs separated by one
belly LP in the standing wave k are changing at the same phase. . Then, when the traveling waves
TW4 and TW4 'are combined in the acoustic tube 10, a resonance wave XW4 having the same
wavelength λ4 as the standing wave SW4 is generated. Since this resonance wave XW4 is
formed by combining the traveling waves TW4 and TW4 'having the same phase, as shown in
FIG. 5C, the middle between the open ends 11 and 12 in the resonance wave XW4 is an antinode.
Become an LP. In addition, since the tube length of the acoustic tube 10 (the tube length for a
half wavelength of the primary standing wave SW1) is twice the wavelength λ4 (λ4 = λ1 / 4)
of the standing wave SW4, between the open ends 11 and 12 When the center of the is the belly
LP, the sides of the open ends 11 and 12 also become the belly LP. Therefore, the sound pressure
distribution of the standing wave SW4 is not relaxed at the positions of the open ends 11 and 12.
The inventors speculated that the attenuation was not caused by the fourth order standing wave
SW4 because of the above reasons. Further, the sound pressure at the position of the opening
end 11 and the sound pressure at the position of the opening end 12 change in the same phase,
as in the case of the eighth standing wave SW8. Therefore, the inventors estimated that the
eighth standing wave SW8 would not be attenuated for the same reason as the fourth standing
wave SW4.
[0024]
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Next, the contents of the second verification will be described. In the second verification, for the
speaker 9A shown in FIG. 2, the inventors input the test sound signal ST to the speaker unit 2,
and the sound wave emitted from the speaker unit 2 is measured at the measurement point P in
the space S Specifically, frequency response R which is a difference between the spectrum of
input signal ST and that of measurement signal SM when measured at measurement point P (see
FIG. 2) near the inside of the position where wall surfaces 4D, 4B, and 4R intersect. -9A was
calculated by simulation. Similarly, for the speaker 9A ′ obtained by removing the acoustic tube
10 from the speaker 9A, the test sound signal ST is input to the speaker unit 2, and the sound
signal emitted from the speaker unit 2 is measured at the measurement point P The frequency
response R-9A ', which is the difference between the ST and the spectrum of the measurement
signal SM, was calculated by simulation. FIG. 6 shows the frequency responses R-9A and R-9A
'with the frequency axes aligned.
[0025]
Referring to FIG. 6, although peaks appear at around 160 Hz, 320 Hz, 480 Hz, 650 Hz, 820 Hz
and 970 Hz in any of the frequency responses R-9 A and R-9 A ′, 160 Hz in the frequency
response R-9 A. The amplitudes of peaks near 320 Hz, 480 Hz, 650 Hz, 820 Hz and 970 Hz are
smaller than those of the frequency response 9-A '. Further, in the frequency response R-9A,
peaks near 320 Hz, 480 Hz, 650 Hz, 820 Hz, and 970 Hz are broken. From this, it was confirmed
that the first to sixth standing waves SW1 to SW6 in the space S can be suppressed by the
speaker 9A.
[0026]
Next, the contents of the third verification will be described. In the third verification, the
inventors put an acoustic tube having a tube length of about a half wavelength of the secondary
standing wave SW2 in a bass reflex type speaker, and measured the frequency response. More
specifically, as shown in FIG. 7, the dimensions of the space S (vertical width H (H = 1050 mm),
horizontal width W (W = 200 mm), depth L (L = 300 mm) inside the bass reflex type speaker
SPBS The speaker 9ABS is one in which an acoustic tube OP having a tube length of about half a
wavelength of the secondary standing wave SW2 is accommodated in the space S) in a posture
such that the conditions a1 and b1 are satisfied. Moreover, what remove | eliminated the acoustic
pipe OP from speaker 9ABS was made into speaker 9ABS '.
[0027]
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Then, the position in the vicinity of the front of the center speaker unit SUCNT in the speakers
9ABS and 9ABS 'is taken as a first measurement point P-1, and the position in the vicinity of the
front of the bass reflex port BP in the speakers 9ABS and 9ABS' is measured secondly A point P-2
is taken, and a position substantially inside the center of the wall opposite to the side where the
speaker unit SUCNT is present is taken as a third measurement point P-3. And a sound signal was
inputted into speaker unit SUCNT of speaker 9ABS and 9ABS ', and the sound wave radiated from
speaker unit SUCNT according to this sound signal was measured by measurement point P-1, P2, and P-3.
[0028]
Then, for the speaker 9ABS, frequency responses R1-9ABS, R2-9ABS, R3-9ABS, which are
differences between the input signal ST of the speaker unit SUCNT and the spectrum of the
measurement signal SM at the measurement points P-1, P-2, P-3. Was calculated. Similarly for
the speaker 9ABS ', frequency responses R1-9ABS' and R2-9ABS 'that are differences between the
input signal ST of the speaker unit SUCNT and the spectrum of the measurement signal SM at the
measurement points P-1, P-2, and P-3. , R3-9 ABS 'was calculated. FIG. 8 shows the frequency
responses R1-9ABS and R1-9ABS 'with their frequency axes aligned. FIG. 9 shows the frequency
responses R2-9ABS and R2-9ABS 'with the frequency axes aligned. FIG. 10 shows the frequency
responses R3-9ABS and R3-9ABS 'with the frequency axes aligned.
[0029]
In frequency response R1-9ABS ', R2-9ABS', R3-9ABS 'in FIG.8, FIG.9, FIG.10, the peak has
generate | occur | produced in 300 Hz vicinity. This indicates that the resonance of the bass
reflex port BP in the bass reflex type speaker SPBS can not effectively suppress the secondary
standing wave SW2. On the other hand, in the frequency responses R1-9ABS, R2-9ABS, R3-9ABS,
the peak is split into two around 300 Hz, and the amplitudes of the respective frequency
responses R1-9ABS ', R2-9ABS', R3-9ABS It's smaller than that of '. From this, it was confirmed
that the secondary standing wave SW2 to be suppressed can be suppressed by the speaker 9ABS.
[0030]
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Here, in the verification result of the second verification described above (FIG. 6), it was
confirmed that the first to sixth standing waves SW1 to SW6 can be suppressed, but the
verification result of the third verification ((6) In FIG. 8, FIG. 9, and FIG. 10), it could not be
confirmed that the third to sixth high-order standing waves SW3 to SW6 can be suppressed. The
inventors speculated that the reason is as follows. If the inside of the speaker 9ABS is a
completely enclosed space, the wavelengths λ2, λ3, λ4 ... of the second and subsequent
standing waves SW2, SW3, SW4 ... are integers of the wavelength λ1 of the first standing wave
SW1. Match the double. However, when there is an additional element such as the bass reflex
port BP of the speaker 9ABS, λ2, λ3 and λ4 of the second and subsequent standing waves
SW2, SW3, SW4... Do not coincide with an integral multiple of the first order standing wave SW1.
There is a case. On the other hand, the wavelengths of the second and subsequent resonance
waves XW2, XW3, XW4... In the acoustic tube OP of the speaker 9ABS always coincide with an
integral multiple of the first resonance wave XW1. For this reason, in the speaker 9ABS,
frequency mismatch may occur between the high-order standing wave SW and the resonance
wave XW. The inventors speculated that the third to sixth standing waves SW3 to SW6 were not
suppressed in the speaker 9ABS from the above reasons.
[0031]
<< Second Example >> FIG. 11A is a front view of a speaker 9B which is a second example of the
acoustic device. The speaker 9B is a space S of the cabinet 1 in the speaker 9 (first embodiment)
(hollow space S surrounded by three pairs of facing surfaces of wall surfaces 4U and 4D, wall
surfaces 4F and 4B, and wall surfaces 4L and 4R) The acoustic tube 10 in the figure is replaced
with an acoustic tube 30. The acoustic tube 30 has a tube length of about half a wavelength of
the primary standing wave SW1. The acoustic tube 30 is U-shaped. And this acoustic tube 30 is
stored in the space S in the attitude | position which satisfy | fills the conditions c1 shown below.
c1. Both open ends 31 and 32 of the acoustic tube 30 are arranged at or near the same belly
LP position of the lowest one of the standing waves SWk to be suppressed in the space S
[0032]
The above is the details of the configuration of the speaker 9B. Here, in the example of FIG. 11A,
the open ends 31 and 32 are at the position of the belly LP1-1 on the side of the wall surface 4U
among the two belly LP1-1 and LP1-2 of the primary standing wave SW1. It is arranged.
However, as shown in the example of FIG. 11 (B), the open ends 31 and 32 may be arranged at
the position of the belly LP1-2 on the side of the wall surface 4D. By placing the acoustic tube 30
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in the space S in a posture as shown in FIG. 11 (A) or FIG. 11 (B), it is possible to reduce primary
or more standing waves SWk in the space S.
[0033]
The inventors input a test sound signal ST to the speaker unit 2 to check the acoustic
characteristics of the speaker 9B in the example of FIG. 11A, and measure the sound wave
emitted from the speaker unit 2 in the space S. Spectra of the input signal ST and the
measurement signal SM when measured at a point P (more specifically, at a measurement point P
near the inner side of the intersection of the wall surfaces 4D, 4B, and 4R (see FIG. 11A)) The
frequency response R-9B, which is the difference between Similarly, for the speaker 9B ′
obtained by removing the acoustic tube 30 from the speaker 9B, the test sound signal ST is input
to the speaker unit 2 and the sound signal emitted from the speaker unit 2 is measured at the
measurement point P The frequency response R-9B ', which is the difference between the ST and
the spectrum of the measurement signal SM, was calculated by simulation. FIG. 12 shows the
frequency responses R-9B and R-9B 'with the frequency axes aligned.
[0034]
Referring to FIG. 12, peaks appear at around 160 Hz, 320 Hz, 480 Hz, 650 Hz, 820 Hz, and 970
Hz in any of the frequency responses R-9B and R-9B '. And in the frequency response R-9B,
although the amplitudes of the peaks near 320 Hz, 650 Hz and 970 Hz are almost the same as
those of the frequency response R-9 B ', the amplitudes of the peaks near 160 Hz, 480 Hz and
820 Hz are the frequency response R- It is smaller than that of 9B '. Further, in the frequency
response R-9B, peaks near 160 Hz, 480 Hz, and 820 Hz are broken. From this, it is confirmed
that the speaker 9B can suppress the first order standing wave SW1 (160 Hz), the third order
standing wave SW3 (480 Hz), and the fifth order standing wave SW5 (820 Hz) in the space S.
The
[0035]
Based on the verification result, the inventors speculated as follows the reason why the standing
waves SW1, SW3 and SW5 are suppressed in the space S of the speaker 9B. As shown in FIG. 13,
in the speaker 9B, both of the two open ends 31 and 32 of the acoustic tube 30 in the space S
are disposed at the position of the antinode LP1-1 of the standing wave SW1. The position of the
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belly LP1-1 of the standing wave SW1 corresponds to the belly LP2-1, LP3-1, LP4-1, LP5-1... Of
the standing waves SW2, SW3, SW4, SW5. Therefore, when standing waves SWk (k = 1, 2...) Are
generated in the space S, the medium (air) in the vicinity of the open ends 31 and 32 of the
acoustic tube 30 is the position of the antinode LP of each standing wave SWk It is excited by the
sound pressure change of.
[0036]
Here, focusing on the relationship between the primary standing wave SW1 in the space S and
the behavior of the medium (air) in the acoustic tube 30, the medium (air in the vicinity of the
open ends 31 and 32 in the acoustic tube 30 (air) ) Is excited by the sound pressure change of
the antinode LP1-1 of the standing wave SW1, and traveling waves TW1 and TW1 ′ are
generated with the traveling directions being opposite and having the same phase. The traveling
waves TW1 and TW1 'have the same phase because the sources of the traveling waves TW1 and
TW1' are the same. Then, when the traveling waves TW1 and TW1 'are combined in the acoustic
tube 30, a resonance wave XW1 having the same wavelength λ1 as the standing wave SW1 is
generated. Since this resonance wave XW1 is formed by combining the traveling waves TW1 and
TW1 'having the same phase, as shown in FIG. 14A, the middle between the open ends 31 and 32
in the resonance wave XW1 is the belly Become an LP. Since the tube length of the acoustic tube
30 is the same as the half-wavelength length λ 1/2 of the standing wave XW 1, when the middle
between the open ends 31 and 32 is the belly LP, the open ends 31 and 32 side is the node ND
Become. Therefore, the sound pressure distribution of the standing wave SW1 is relaxed at the
positions of the open ends 31 and 32. The inventors speculated that the standing wave SW1 is
attenuated due to the above reasons. Also, resonant waves XW 3, XW 5, XW 7... Formed by
exciting the medium (air) in the vicinity of the open ends 31 32 of the acoustic tube 30 by the
standing waves SW 3, SW 5, SW 7. The side becomes a clause ND. Therefore, the inventors
speculated that the third and subsequent odd-order standing waves SW3, SW5, SW7,... Are
attenuated for the same reason as the standing wave SW1.
[0037]
Next, focusing on the relationship between the secondary standing wave SW2 in the space S and
the behavior of the medium (air) in the acoustic tube 30, the medium (air in the vicinity of the
open ends 31 and 32 in the acoustic tube 30) ) Is excited by the sound pressure change of the
belly LP2-1 of the standing wave SW2, and traveling waves TW2 and TW2 'are generated with
the traveling directions being opposite and having the same phase. Then, when the traveling
waves TW2 and TW2 'are combined in the acoustic tube 30, a resonance wave XW2 having the
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same wavelength λ2 as the standing wave SW2 is generated. As shown in FIG. 14 (B), the middle
between the open ends 31 and 32 in this resonance wave XW2 is the belly LP. Since the tube
length of the acoustic tube 30 is the same as the wavelength λ2 of the standing wave XW2, if
the middle between the open ends 31 and 32 is the belly LP, the side of the open ends 31 and 32
will also be the belly LP. Therefore, the sound pressure distribution of the standing wave SW2 is
not relaxed at the positions of the open ends 31 and 32. The inventors speculated that the
attenuation of the standing wave SW2 does not occur because of the above reasons. Also,
resonance waves XW 4, XW 6, XW 8... Formed by exciting the medium (air) in the vicinity of the
open ends 31 and 32 of the acoustic tube 30 by the standing waves SW 4, SW 6, SW 8. The side
becomes belly LP. Therefore, the inventors inferred that even-order standing waves SW4, SW6,
SW8,... For fourth and subsequent ones do not attenuate for the same reason as the standing
wave SW2.
[0038]
<< Third Example >> FIG. 15 is a front view of a speaker 9D which is a third example of the
acoustic device. The speaker 9D has a cabinet 1 ', a speaker unit 2' fixed to the outside of the
cabinet 1 ', and an acoustic tube 40' housed in a space S 'in the cabinet 1'. The cabinet 1 'is a
hollow rectangular parallelepiped surrounded by wall surfaces 4U' and 4D 'opposed in the
vertical direction, wall surfaces 4F' and 4B 'opposed in the front-rear direction, and wall surfaces
4L' and 4R 'opposed in the left-right direction. It has made a letter. The width W 'in the space S'
in the cabinet 1 '(the distance between the wall surfaces 4L' and 4R ': for example, W' = 430 mm)
is the depth width L '(the distance between the wall surfaces 4F' and 4B '): For example, it is
larger than L ′ = 200 mm. Further, the vertical width H '(the distance between the wall surfaces
4U' and 4D ': for example, H' = 1050 mm) in the space S is larger than the horizontal width W '.
[0039]
The speaker unit 2 'of the speaker 9D is fixed substantially at the center of the wall surface 4F' of
the cabinet 1 '(the position of the node ND1-1 of the primary standing wave SW1 generated in
the space S'). The acoustic tube 40 'of the speaker 9D has a linear shape having a tube length
equivalent to about a half wavelength of the secondary standing wave SW2 generated in the
space S'. The acoustic tube 40 'is fixed on the wall surface 4F' in the space S 'in a posture inclined
with respect to the opposing direction of the two opposing surfaces of the wall surfaces 4U' and
4D '. The open end 41 'of the acoustic tube 40' is disposed at the position of the approximate
node ND2-1 of the standing wave SW2, and the open end 42 'is disposed at the position of the
approximate belly LP2-2 of the standing wave SW2 There is. According to this speaker 9D, it is
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possible to suppress the standing wave SWk generated in the opposing direction of the wall
surfaces 4U 'and 4D'. Further, in the speaker 9D, since the acoustic pipe 40 'is in a straight line,
the processing of the acoustic pipe 40' can be performed more easily than in the case of the
speakers 9 to 9B.
[0040]
The inventors input a test sound signal ST to the speaker unit 2 ′ to check the acoustic
characteristics of the speaker 9D shown in FIG. 15, and measure the sound wave emitted from
the speaker unit 2 ′ in the space S ′. The spectrum of the input signal ST and the measurement
signal SM when measured at a point P (more specifically, at a measurement point P in the vicinity
of the intersection of the wall surfaces 4D ′, 4B ′, and 4R ′ (see FIG. 15)) The frequency
response R-9D, which is the difference between Similarly, for the speaker 9D ′ obtained by
removing the acoustic pipe 40 ′ from the speaker 9D, the test sound signal ST is input to the
speaker unit 2 ′ and the sound wave emitted from the speaker unit 2 ′ is measured at the
measurement point P The frequency response R-9D ', which is the difference between the
spectrum of the input signal ST and the spectrum of the measurement signal SM, was calculated
by simulation. FIG. 16 shows the frequency responses R-9D and R-9D 'with their frequency axes
aligned.
[0041]
Referring to FIG. 16, a peak appears in the vicinity of 300 Hz in both frequency responses R-9D
and R-9D '. However, in the frequency response R-9D, the peak amplitude around 300 Hz is
smaller than that of the frequency response R-9D. Further, in the frequency response R-9D, the
peak near 300 Hz is broken. From this, it was confirmed that the secondary standing wave SW2
in the space S 'can be suppressed by the speaker 9D.
[0042]
<< Fourth Example >> FIG. 17 is a front view of a speaker 9E which is a fourth example of the
acoustic device according to the present embodiment. This speaker 9E is obtained by covering
both open ends of the acoustic tube 20 in the speaker 9A shown in FIG. 2 with a breathable
sound absorbing material (for example, a non-woven fabric). In the example shown in FIG. 17, all
the open ends of the sound tube 20 are covered with the breathable sound absorbing material,
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but only a part of the open ends may be covered by the breathable sound absorbing material. As
is well known, the breathable sound absorbing material has the property of causing peaks and
dips in the frequency response of the space separated from the outside. Therefore, according to
the present embodiment, the suppression amount of the second standing wave SW2 can be made
larger than that in the first example.
[0043]
The inventors conducted the following verification to confirm the acoustic characteristics of the
acoustic device. First, in the speaker 9ABS used in the verification of the first example, both open
ends of the acoustic pipe OP were covered with a breathable sound absorbing material to obtain
a speaker 9EBS. Furthermore, for this speaker 9EBS, frequency response R1-9EBS, R2-9EBS,
which is a difference between the input signal ST of the speaker unit SUCNT and the spectrum of
the measurement signal SM at the measurement points P-1, P-2, P-3. R3-9 EBS was calculated.
FIG. 18 shows the frequency response R1-9EBS and the frequency response R1-9ABS '(FIG. 8)
used in the verification of the first embodiment with the frequency axes aligned. FIG. 19 shows
the frequency response R2-9EBS and the frequency response R2-9ABS '(FIG. 9) used in the
verification of the first embodiment with the frequency axes aligned. FIG. 20 shows the frequency
response R3-9EBS and the frequency response R3-9ABS '(FIG. 10) used in the verification of the
first example with the frequency axes aligned.
[0044]
Referring to FIGS. 18, 19 and 20, in the frequency responses R1-9ABS ', R2-9ABS' and R3-9ABS ',
a sharp peak is generated near 300 Hz, whereas the frequency response R1-9EBS is generated. ,
R2-9 EBS, R3-9 EBS, the amplitude around 300 Hz is substantially flat. From this, it was
confirmed that in the speaker 9EBS, the amount of suppression of the secondary standing wave
SW2 is increased as compared with the bass reflex speaker 9ABS shown in FIG.
[0045]
<Modified example regarding an acoustic pipe> As mentioned above, although the 1st-4th
example of an acoustic pipe was demonstrated, the following modified examples can be
considered regarding an acoustic pipe.
[0046]
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18
(1) The sound tubes 10 and 20 in the space S of the above-described speakers 9 and 9A may be
replaced with ones having a shape different from the J shape.
For example, as in a loudspeaker 9F shown in FIG. 21, the acoustic pipe 20 of the loudspeaker 9A
of FIG. 2 may be replaced with an acoustic pipe 20 ′ ′ having a spiral shape. In this case, the
open end 21 ′ ′ of the acoustic tube 20 ′ ′ may be disposed at the position of the
substantially antinode LP of the standing wave SW2 in the space S, and the open end 22 ′ ′
may be disposed at the position of the approximately node ND of the standing wave SW2. . This
configuration can also achieve the same effect as that of the first example. In addition, the
acoustic tube 10 and the acoustic tube 20 may be zigzag (for example, W-shaped, N-shaped, Zshaped, S-shaped, etc.). Also, the speakers 9, 9A, 9B, 9D, 9E are shaped such that a part of the
bent portions of the acoustic tubes 10, 20, 30, 40 in the cabinet 1 protrude to the outside of the
cabinet 1, 20, 30, 40 may be used as handles for gripping the speakers 9, 9A, 9B, 9D, 9E.
[0047]
(2) In the third example, the acoustic tube 40 'is fixed on the wall surface 4F' in the space S 'in a
posture inclined with respect to the opposing direction between the wall surfaces 4U' and 4D '.
However, the acoustic pipe 40 'may be fixed on the wall surface 4B' in the space S 'at an
inclination with respect to the opposing direction between the wall surfaces 4U' and 4D '. Also,
the acoustic pipe 40 'may be accommodated in the space S' in a posture inclined with respect to
the opposing direction between the wall surfaces 4U 'and 4D', and it is not necessary to fix the
acoustic pipe 40 'to the wall surface 4F' or the wall surface 4B '. For example, the open end 41 'of
the acoustic tube 40' may be disposed near the intersection of the wall surfaces 4F 'and 4L', and
the opening end 42 'thereof may be disposed near the intersection of the wall 4B' and 4R '. . Also,
conversely, the open end 42 'of the acoustic tube 40' is disposed in the vicinity of the crossing
position of the wall surfaces 4F 'and 4L', and the opening end 41 'thereof is in the vicinity of the
crossing position of the wall surfaces 4B' and 4R '. It may be located at
[0048]
(3) In the third example, the acoustic tube 40 'is in a straight line. However, the acoustic tube 40
′ may be bent in a J-shape, a U-shape, or another shape.
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[0049]
(4) In the fourth example, both open ends of the sound tube 20 in the speaker 9A are covered
with the breathable sound absorbing material. However, one open end of the acoustic tube 20
may be covered by a breathable sound absorbing material. In addition, one or both open ends of
the acoustic tube 10 of the speaker 9 shown in FIGS. 1A and 1B may be covered with a
breathable sound absorbing material. In addition, one or both open ends of the acoustic tube 30
of the speaker 9B shown in FIGS. 11A and 11B may be covered with a breathable sound
absorbing material. Also, one or both open ends of the sound tube 40 'of the speaker 9D shown
in FIG. 15 may be covered with a breathable sound absorbing material.
[0050]
(5) In the fourth example, both open ends of the sound tube 20 were covered with the nonwoven fabric which is one of the breathable sound absorbing materials. However, open-cell
porous materials such as urethane foam and foamed resin, glass wool, aluminum foam metal,
metal fiber board, wood chips and fragments thereof, wood fibers, pulp fibers, MPP
(Microperforated Panel), cow's wool felt, anti-hair A member having a structure that can be
regarded as a porous material such as felt, wool, cotton, non-woven fabric, cloth, synthetic fiber,
wood powder molding material, paper molding material or the like may be used instead of nonwoven fabric.
[0051]
(6) The acoustic tubes 10 and 30 in the first to fourth examples have a tube length of about half
wavelength of the primary standing wave SW1. However, when it is not necessary to suppress
the first order standing wave SW1, the tube lengths of the acoustic tubes 10 and 30 may be set
to approximately half the wavelength of the second order or later standing waves SWk. Similarly,
the tube lengths of the acoustic tubes 20 and 40 'may be set to approximately half the
wavelength of the third and subsequent standing waves SWk.
[0052]
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20
(7) In the first, second, and fourth examples, a plurality of types of acoustic tubes 10, 20, and 30
having different tube lengths may be accommodated in the space S in the cabinet 1. In the third
example, a plurality of types of acoustic tubes 40 'having different tube lengths may be
accommodated in the space S' in the cabinet 1 '. In the third example, a plurality of types of
standing waves SWk generated in the facing direction of the wall faces 4U ′ and 4D ′, the
facing direction of the wall faces 4F ′ and 4B ′, and the facing direction of the wall faces 4L ′
and 4R ′ In order to suppress the standing wave SWk, a plurality of types of acoustic tubes 40
′ having different inclination directions may be accommodated in the space S ′ in the cabinet
1 ′.
[0053]
(9) In the first, second and fourth examples, the standing waves SWk in the wall surface 4U and
4D directions in the space S in the cabinet 1 are to be suppressed. However, the acoustic tubes
10, 20, and 30 are replaced with the acoustic tubes 10, 20, and 30 for suppressing standing
waves in the wall 4F and 4B directions and standing waves in the wall 4L and 4R directions, and
suppressing these standing waves. Alternatively, it may be accommodated in the space S together
with the acoustic tubes 10, 20, 30.
[0054]
(10) One feature of the present invention is a standing wave which can not coexist with the
identified standing wave as a means for reducing the standing wave generated in the space
surrounded by the pair of facing surfaces of the housing. The point is that the acoustic tube to be
generated is provided in the housing. 22 (a) to 22 (f) are diagrams schematically and
comprehensively showing the relationship between a standing wave and an acoustic tube
generated in a space in a case in the acoustic device according to the present invention. In these
figures, an acoustic pipe L2 provided in a housing of the acoustic device, a first open end N1 and
a second open end N2 of the acoustic pipe L2, and a first opposed direction of a pair of opposing
surfaces in the housing The length L1 from the open end N1 to the second open end N2 is
shown.
[0055]
The example shown in FIG. 22 (a) is the aspect disclosed in the first example (FIG. 1). The
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example shown in FIG. 22 (b) is the aspect disclosed in the third example (FIG. 11). As a
modification of the embodiment shown in FIG. 22 (b), the embodiment shown in FIG. 22 (c) and
the embodiment shown in FIG. 22 (d) can be considered. Also in these embodiments, since the
acoustic tube generates a standing wave that can not coexist with the standing wave generated
between the wall surfaces 4U and 4D, the standing wave generated between the wall surfaces 4U
and 4D is reduced.
[0056]
In this case, the shape of the acoustic tube may be any shape, and it may be out of the cabinet 1
as shown in FIG. Also, as shown in FIG. 22 (f), the acoustic tube may be out of the cabinet 1 and
may be in a wound shape.
[0057]
<Installation Mode as a Reinforcing Material of an Acoustic Tube> In the acoustic device
according to the present invention, the above-described acoustic tube is used as a reinforcing
material for suppressing the vibration of the cabinet. This point is the second feature of the
acoustic device according to the present embodiment. Hereinafter, the second feature will be
described with reference to a specific example.
[0058]
<< Installation Example of Reinforcement Material >> FIG. 23 shows an installation example of a
reinforcement frame 110 using a normal square bar without using an acoustic pipe. In this
example, a reinforcement framework 110 is secured within a 3-way speaker cabinet 100 having
a woofer 101, a squawker 102 and a tweeter 103. The reinforcing framework 110 is configured
of a ceiling portion 110T, a bottom surface portion 110D, a cross rail 110F, a back surface
portion 110B, a left side surface portion 110P, and a right side surface portion 110U. Here, each
of the ceiling portion 110T and the bottom surface portion 110D is configured of two horizontal
bars arranged in parallel in the front and rear direction, and two oblique bars intersecting in an
X-shape between the square bars. Each of the left side surface portion 110P and the right side
surface portion 110U includes two horizontal bars arranged in parallel in the vertical direction,
two vertical bars arranged in parallel in the front and rear direction, and a rectangular diagonal
formed of these horizontal bars and vertical bars. It consists of two diagonal bars that cross in an
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22
X shape. In addition, the back surface portion 110B is formed of two diagonal bars that cross in
an X shape between the vertical bars of the left side surface portion 110P and the vertical bars of
the right side surface portion 110U. The crosspiece 110F is located on the front of the cabinet
100 at the top of the area where the woofer 101 is installed. Therefore, in the front part of the
cabinet 100, the woofer 101 is surrounded by the horizontal bars 110F, the horizontal bars of
the bottom surface portion 110D, the vertical bars of the left side surface portion 110P, and the
vertical bars of the right side surface portion 110U.
[0059]
<< Effect of Reinforcement >> In order to confirm the effect of the reinforcement, the inventors of
the present invention have a state where the cabinet 100 does not have the reinforcement in FIG.
23 and a state where the cabinet 100 is provided with the reinforcement as shown in FIG. The
vibration energy E generated on each surface of the cabinet 100 was determined by simulation
when the woofer 101 emitted sound in each state. FIG. 24 (A) shows the vibration energy E
generated on each side T, F, D, P, U, B of the cabinet 100 in the absence of the reinforcing
material, and FIG. 25 (B) shows the cabinet in the condition where the reinforcing material is
installed. The vibrational energy E generated in each of the faces T, F, D, P, U, B of 100 is shown.
As shown in these figures, as shown in FIG. 23, by providing the cabinet 100 with a reinforcing
material, vibration energy generated on each surface of the cabinet 100 can be totally
suppressed.
[0060]
<Installation Mode of Acoustic Tube Combined with Reinforcement> In the acoustic device
according to the embodiment of the present invention, the acoustic tube having the effect of
suppressing standing waves is disposed in the cabinet 100 as a reinforcement. Hereinafter,
various specific examples are given and the arrangement aspect of the acoustic tube in this
embodiment is demonstrated. In addition, the installation aspect of the various acoustic tubes
demonstrated below may be independently applied to one acoustic device, and may be applied to
one acoustic device combining several types of things. Moreover, what is demonstrated below is
an example of the installation aspect of the acoustic pipe as a reinforcing material. It is possible
to reinforce the cabinet 100 in a mode of fixing various acoustic tubes described with reference
to FIGS. 1 to 22 to the inner wall surface of the cabinet 100, for example, in addition to those
described below.
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[0061]
<< First Example >> FIG. 25 (A) is a front view of the acoustic device, and FIG. 25 (B) is a right
side view. In this example, two acoustic tubes 121 and 122 are fixed to the back side of the front
part F of the cabinet 100 so as to form a square surrounding the woofer 101. Here, the acoustic
tube 121 is a hollow tube consisting of a horizontal portion and a vertical portion and having
openings 121a and 121b at both ends, and one side of the horizontal portion is fixed to the back
of the front portion F of the cabinet 100, The vertical portion has one side fixed to the back of
the front face F of the cabinet 100 and the other side fixed to the back of the left side P of the
cabinet 100. Similarly to the acoustic tube 121, the acoustic tube 122 is a hollow tube
comprising a horizontal portion and a vertical portion and having openings 122a and 122b at
both ends, and the horizontal portion has one side surface of the front portion F of the cabinet
100. The other side is fixed to the back of the bottom part D of the cabinet 100 while the vertical
part is fixed to the back of the front part F of the cabinet 100 and the other side is the cabinet It
is being fixed to the back of right side section U of 100. The opening 121a of the acoustic tube
121 and the opening 122b of the acoustic tube 122 are located at the upper right of the woofer
101 and at an intermediate position between the ceiling T and the bottom D, and the opening
121b of the acoustic tube 121 is The opening 122 a of the sound tube 122 is located at the
lower left of the woofer 101 and near the bottom D.
[0062]
In general, in an acoustic device such as a 3-way speaker, vibration energy generated by the
woofer 101 is large, and stress is concentrated in a region around the woofer 101 on the front
part F of the cabinet 100. In the example shown in FIG. 23, the horizontal bars 110F surrounding
the woofer 101, the horizontal bars of the bottom portion 110D, the vertical bars of the left side
portion 110P, and the vertical bars of the right side portion 110U generate stress concentration
generated in the area around the woofer 101. Play a role in mitigating. And in the example
shown to FIG. 25 (A) and (B), the two L-shaped acoustic tubes 121 and 122 which surround the
woofer 101 relieve | moderate the concentration of the stress generate | occur | produced by the
vibration of the woofer 101 in the front part P. . Therefore, according to this example,
unnecessary vibration of the entire cabinet 100 can be suppressed by suppressing the vibration
generated in the front part F of the cabinet 100.
[0063]
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24
Further, in this example, when a standing wave having a half wavelength λ / 2 between the
ceiling T and the bottom D is generated in the cabinet 100, the openings 121a and 121b of the
acoustic pipe 121 are the standing waves. Are separated by λ / 4 along the wavelength direction
of Further, the length of the sound propagation path from the opening 121a to the opening 121b
in the acoustic tube 121 is λ / 2. The same applies to the acoustic tube 122. Therefore, inside
the cabinet 100, an antinode of the sound pressure of the standing wave is generated in the
vicinity of the openings 121b and 122a, and a node of the sound pressure of the standing wave
is generated in the vicinity of the openings 121a and 122b. The tubes 121 and 122 try to
generate sound pressure waveforms in the opposite phase to the sound pressure waveforms in
the vicinity of the openings 121 b and 122 a in the vicinity of the openings 121 a and 122 b. As
a result, standing waves generated between the ceiling T and the bottom D of the cabinet 100 are
suppressed. Therefore, according to this example, it is possible to suppress the standing wave
generated between the ceiling portion T and the bottom portion D of the cabinet 100 while
suppressing the vibration of the front portion F of the cabinet 100 by the acoustic tubes 121 and
122. .
[0064]
<< Second Example >> In order to suppress the vibration of the wall surface of the cabinet 100, a
reinforcing material composed of two diagonal bars crossing in an X shape like the right side
surface portion 110U of FIG. 23, for example, is fixed to the wall surface It is effective to do FIGS.
26 (A) and 26 (B) show the configuration of reinforcing means in place of the X-shaped
crosspieces, and FIG. 26 (A) is a view of the acoustic device seen from the right side, FIG. B) is a
view from behind. In this example, a combination of two acoustic tubes 123 and 124 is used as a
reinforcing material. The acoustic tubes 123 and 124 are hollow tubes comprising a horizontal
portion and two vertical portions extending parallel to each other from both ends thereof. Here,
the vertical portions of the acoustic tubes 123 and 124 have a half length of the distance from
the inner wall of the ceiling T of the cabinet 100 to the inner wall of the bottom D. Also, each of
the acoustic tubes 123 and 124 has a tube length equal to the distance from the inner wall of the
ceiling T of the cabinet 100 to the inner wall of the bottom D. In the side surface portion of the
acoustic tube 123, openings 123a and 123b are provided at positions near both ends of the
acoustic tube 123, which communicate the space in the tube to the outside. Further, in the side
surface portion of the acoustic tube 124, openings 124a and 124b for communicating the space
in the tube to the outside are provided at respective positions in the vicinity of both ends of the
acoustic tube 124. In the example shown in FIGS. 26 (A) and (B), the horizontal portions of the
acoustic tubes 123 and 124 are fixed to each other, and two parallel longitudinal bars as a whole
and the respective centers of these longitudinal bars are provided. It forms an H-shaped
reinforcement consisting of horizontal bars connecting the two. And in the example shown to
FIG. 26 (A) and (B), the state by which this H-shaped reinforcement was pinched | interposed
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25
between the ceiling part T and the bottom face D (a tension bar between the ceiling T and the
bottom face D In this state, the openings 123a, 123b, 124a, and 124b are directed to the left side
surface P of the cabinet 100 and fixed to the rear side of the right side surface U of the cabinet
100. Although not shown, similar H-shaped reinforcing members may be fixed to the back of the
left side P, the back of the back B, and the back of the ceiling T of the cabinet 100.
[0065]
According to this example, the openings 123a and 123b of the acoustic pipe 123 are in the
vicinity of the ceiling T, and in this position, when standing waves are generated between the
ceiling T and the bottom D, these openings Sound pressure wave antinodes are generated at
123a and 123b. On the other hand, since the acoustic tube 123 has a tube length equivalent to a
half wavelength of the standing wave, the acoustic pressure wave generated in the opening 123a
has a phase opposite to that of the acoustic pressure wave generated in the opening 123b. For
this reason, the standing wave between the ceiling T and the bottom D is suppressed. The same
applies to the acoustic tube 124. Further, according to this example, since the H-shaped
reinforcing material is fixed to the inner wall surface of the cabinet 100, the vibration generated
on the wall surface of the cabinet 100 can be suppressed.
[0066]
In the example shown in FIGS. 26A and 26B, the acoustic tubes 123 and 124 each consisting of
one horizontal portion and two vertical portions are used, but as illustrated in FIG. A combination
of two acoustic tubes 125 and 126 in the shape of a letter may be used as a reinforcement.
[0067]
<< Third Example >> FIGS. 28 (A) and 28 (B) show a third example regarding installation of a
reinforcing material, and FIG. 28 (A) is a front view and a view of an acoustic device. 28 (B) is a
view from above.
In this example, the acoustic tube 127, which is a reinforcing material, is a hollow tube consisting
of a horizontal portion and a vertical portion extending upward from the right end, and an
opening 127a opens at a position near the end of the side of the horizontal portion. An opening
127 b is opened at the end of the vertical portion. The space inside the acoustic tube 127 is in
communication with the outside of the acoustic tube through the openings 127a and 127b.
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[0068]
The horizontal portion of the acoustic tube 127 has a length that just fits between the inner wall
of the left side P and the inner wall of the right side U of the cabinet 100. Further, the vertical
portion of the acoustic tube 127 has a length of about 1/2 of the distance from the inner wall of
the ceiling T of the cabinet 100 to the inner wall of the bottom D. The acoustic tube 127 has a
tube length substantially equal to the distance from the inner wall of the ceiling T of the cabinet
100 to the inner wall of the bottom D.
[0069]
The acoustic tube 127 keeps the horizontal portion with the opening 127a horizontal and is
positioned halfway between the ceiling T and the bottom D in the cabinet 100, and the opening
127b of the vertical portion is positioned near the ceiling T And is fixed at a substantially central
position in the longitudinal direction in the cabinet 100. More specifically, the side surface of the
vertical portion of the acoustic tube 127 is fixed to the inner wall of the right side surface portion
U of the cabinet 100, and is fixed to the inner wall of the left side portion P of the cabinet 100 of
the horizontal portion of the acoustic tube 127.
[0070]
According to this example, since the horizontal portion of the acoustic pipe 127 is sandwiched
between the inner wall of the left side surface portion P of the cabinet 100 and the inner wall of
the right side surface portion U, the vibration of one of the left side surface portion P and the
right side surface portion U An effect to be suppressed occurs. Further, in this example, since the
side surface of the vertical portion of the acoustic pipe 127 is fixed to the right side surface U of
the cabinet 100, the vibration of the right side surface U can be suppressed.
[0071]
Furthermore, in this example, when a standing wave is generated between the ceiling T and the
bottom D of the cabinet 100, an antinode of the sound pressure of the standing wave is
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generated in the opening 127b of the acoustic tube 127, and the opening 127a is generated.
While a node of sound pressure is generated, the acoustic tube 127 tries to generate a sound
pressure wave of the opposite phase to the sound pressure wave generated in the opening 127a
in the opening 127b. For this reason, the standing wave between the ceiling T and the bottom D
of the cabinet 100 is suppressed.
[0072]
In the example shown in FIGS. 28A and 28B, the acoustic pipe 127 consisting of the horizontal
portion and the vertical portion is sandwiched between the left side surface P and the right side
surface U of the cabinet 100, but FIGS. A similar acoustic tube 128 may be sandwiched between
the front part F and the back part B of the cabinet 100 as illustrated in B).
[0073]
<< Fourth Example >> FIGS. 30 (A) and 30 (B) show a fourth example regarding installation of a
reinforcing material, and FIG. 30 (A) is a view of the acoustic device as viewed from the right, 30
(B) is a view of the acoustic device as viewed from above.
In this example, an acoustic tube 131 as a diagonal bar extending from the left end of the back
surface B of the cabinet 100 to the center of the front surface F at a central height position
between the ceiling T and the bottom B of the cabinet 100 An acoustic tube 132 is provided as a
diagonal bar from the right end of the back surface B to the center of the front surface F. These
acoustic tubes 131 and 132 have a role of suppressing standing waves between the left side P
and the right side U of the cabinet 100. An opening 131 a is open at a position near the end fixed
to the back surface B on the side surface of the acoustic tube 131. In addition, when the
wavelength of the standing wave to be suppressed is λ, the opening 131 b is opened on the side
surface of the acoustic tube 131 at a position separated by λ / 2 from the opening 131 a. The
opening 131 b is spaced from the left side P of the cabinet 100 by λ / 4. The tube length of the
acoustic tube 131 is λ / 2. That is, the propagation path of the sound inside the acoustic tube
131 is from the opening 131a to the opening 131b, and the portion beyond the opening 131b is
closed by the wall. Acoustic tube 132 also has openings 132a and 132b similar to those of
acoustic tube 131.
[0074]
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28
According to this example, when a standing wave is generated between the left side P and the
right side U of the cabinet 100, an antinode of a sound pressure wave is generated at the opening
131a of the acoustic tube 131 and a sound pressure wave is generated at the opening 131b. . On
the other hand, since the acoustic tube 131 has a tube length equivalent to a half wavelength of
the standing wave, the acoustic pressure wave generated in the opening 131a has a phase
opposite to that of the acoustic pressure wave generated in the opening 131b. For this reason,
the standing wave between the left side P and the right side U is suppressed. The same applies to
the acoustic tube 132.
[0075]
Further, according to this example, since the V-shaped acoustic tubes 131 and 132 are
sandwiched between the front part F and the back part B of the cabinet 100, the front part F and
the back part B are synchronized in the same direction. The vibration in the translational drum
mode that shakes can be suppressed.
[0076]
FIGS. 31 (A) and (B) are obtained by modifying the examples shown in FIGS. 30 (A) and (B).
In the example shown in FIGS. 31 (A) and (B), the acoustic tube 132 in FIG. 30 (B) is replaced
with a horizontal beam 133 extending from the center of the back surface B to the center of the
front surface F. Also in this example, the same effects as those shown in FIGS. 30 (A) and (B) can
be obtained.
[0077]
<Other Embodiments> The embodiments of the present invention have been described above, but
other embodiments can be considered in the present invention. For example:
[0078]
(1) The opening of the acoustic tube may be provided not in the end of the acoustic tube but in
the middle of the acoustic tube. FIG. 32 shows an acoustic tube consisting of horizontal parts
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29
141, 142 and 143 and vertical parts 144, 145, 146 and 147. FIG. In the acoustic tube, an
opening 140 a is provided at the lower end of the vertical portion 144, and an opening 140 b is
provided in the middle of the vertical portion 145. The space in the vertical portion 144
communicates with the outside through the opening 140 a. The space in the vertical portion 144
is in communication with the space in the horizontal portion 142, and the space in the horizontal
portion 142 is in communication with the space up to the opening 140 b of the vertical portion
145. The propagation path of the sound in the acoustic tube is from the opening 140a to the
opening 140b. The length of this section and the distance between the openings 140a and 140b
in the vertical direction in the drawing are determined by the wavelength of the standing wave to
be suppressed. The vertical portions 146 and 147 and the horizontal portion 143 are not
provided for suppressing standing waves, but only for reinforcing the cabinet. The length from
the horizontal portion 141 to the horizontal portion 143 is, for example, a length that matches
the distance between the two opposing surfaces in the cabinet.
[0079]
(2) The acoustic tube may be shaped like a triangular corner fixed to a corner formed by two
inner walls crossing each other in a cabinet. FIGS. 33 (A) and (B) show an example of such an
acoustic tube. The acoustic tube has a triangular prism portion 151 and a curved portion 152
branched from the middle of the triangular prism portion 151. The curved portion 152 is a
hollow tube, and its tip end is an opening 150 b. The inside of the triangular prism 151 is also
hollow, and the hollow region communicates with the hollow region in the curved portion 152. In
the triangular prism 151, the region above the connection with the curved portion 152 is
separated by the region below it and the wall. An opening 150 a is provided on the side surface
near the lower end portion of the triangular prism 151. The acoustic tube has a sound
propagation path from the opening 150 b at the tip of the bending portion 152 to the opening at
the lower end of the triangular prism 151. The length of the sound propagation path and the
distance between the opening 150 b and the opening 150 a in the vertical direction in the
drawing are determined by the wavelength of the standing wave to be suppressed. The portion of
the triangular seed column 151 above the connection with the curved portion 151 is not
provided for suppressing standing waves, but only for reinforcing the cabinet. The length of the
triangular column 151 is, for example, a length that matches the distance between the two
opposing surfaces in the cabinet.
[0080]
As shown in FIG. 33 (B), the triangular prisms 151 are fixed to the corner formed by, for
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example, the right side surface U and the back surface B, which intersect with each other in the
cabinet 100. According to this aspect, since two surfaces of the cabinet are fixed by one
triangular column 151, a high reinforcing effect can be obtained.
[0081]
DESCRIPTION OF SYMBOLS 1, 100 ... Cabinet, 2 ... Speaker unit, 101 ... Woofer, 102 ... Scouka,
103 ... Tweeter, 4U, 4D, 4F, 4B, 4L 20, 30, 40 ', 121 to 128, 131, 132: acoustic tube, 11, 12, 31,
32, 41, 42: open end, 121a, 121b, 122a, 122b, 123a, 123b, 124a, 124b, 127a, 127b, 131a,
131b, 132a, 132b ... openings.
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