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JP2015052702

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DESCRIPTION JP2015052702
An object of the present invention is to provide a noise reduction device that reduces noise by
outputting a sound wave having a waveform that is in reverse phase to a waveform due to noise,
and can realize a sound field area with reduced noise with a simple configuration. SOLUTION: In
the noise reduction device 1, the microphone 20 collects noise outside the sound field area 50
where noise is reduced, and the phase of the noise waveform collected by the ultrasonic wave
generation unit 10 is opposite to that of the noise. Sound waves are generated by ultrasound.
Then, the ultrasonic speakers 30 and 31 output sound waves to generate the sound field area 50.
According to the noise reduction device 1 as described above, since the anti-phase wave of noise
is generated by ultrasonic waves, the sound field area 50 can be generated by utilizing the
straightness of the ultrasonic waves. In this configuration, since it is not necessary to provide a
wall surface, the sound field area 50 with reduced noise can be realized with a simple
configuration. [Selected figure] Figure 2
Noise reduction device
[0001]
The present invention relates to a noise reduction device that reduces noise by outputting a
sound wave having a waveform that is in reverse phase to the waveform due to noise.
[0002]
As the above-mentioned noise reduction device, there is known a device in which small rooms
separated by walls are made to flow sound waves of opposite phase of noise into the small rooms
(for example, see Patent Document 1).
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[0003]
Patent No. 3275486 gazette
[0004]
However, in the above-mentioned noise reduction device, since it is necessary to make a small
room, facilities become complicated and the place which can be installed is limited.
Also, if the wall surface of the small room is simply removed in order to simplify the equipment,
the generated sound waves are diffused, making it difficult to obtain the effect of noise reduction.
[0005]
Therefore, in view of such problems, in a noise reduction device that reduces noise by outputting
a sound wave having a waveform that is in reverse phase to the waveform due to noise, a sound
field area with reduced noise can be realized with a simple configuration It is an object of the
present invention to
[0006]
In the noise reduction device of the present invention configured to achieve the above object, the
sound collection unit collects noise outside the sound field area where the noise is reduced, and
the antiphase wave generation unit collects the noise. A sound wave having an opposite phase to
the waveform of the generated noise is generated by ultrasonic waves.
And a sound wave output part outputs a sound wave, and generates a sound field field.
[0007]
According to such a noise reduction device, since an anti-phase wave of noise is generated by
ultrasonic waves, it is possible to generate a sound field area by using the straightness of
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ultrasonic waves.
In this configuration, since it is not necessary to provide a wall surface, a sound field region with
reduced noise can be realized with a simple configuration.
[0008]
The description of each claim can be arbitrarily combined as much as possible.
Under the present circumstances, you may exclude a one part structure in the range which can
achieve the objective of invention.
[0009]
1 is a block diagram showing a schematic configuration of a noise reduction device 1 to which
the present invention is applied. It is explanatory drawing which shows an example of the
waveform which the ultrasonic wave production ¦ generation part 10 processes. It is explanatory
drawing which shows arrangement ¦ positioning and the characteristic of an ultrasonic speaker
in embodiment. It is a schematic diagram which shows the example of arrangement ¦ positioning
of the component of the noise reduction apparatus 1 in embodiment. It is a schematic diagram
which shows the example of arrangement ¦ positioning of the component of the noise reduction
apparatus 1 in a modification. It is explanatory drawing which shows arrangement ¦ positioning
and the characteristic of an ultrasonic speaker in a modification. It is an explanatory view
showing an application example of the present invention.
[0010]
Embodiments of the present invention will be described below with reference to the drawings.
[Configuration of the Present Embodiment] The noise reduction device 1 to which the present
invention is applied outputs a sound wave (a sound wave having a waveform for canceling a
sound pressure due to noise) having a waveform having an opposite phase to the waveform due
to noise. To reduce noise. As shown in FIG. 1, the noise reduction device 1 includes an ultrasonic
wave generator 10, a microphone 20, ultrasonic amplifiers 25 and 26, and ultrasonic speakers
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30 and 31.
[0011]
The microphone 20 is configured as a known microphone that converts air vibration into an
electrical signal. The ultrasonic wave generation unit 10 is configured as a known computer
provided with a memory 12 such as a CPU 11, a ROM, a RAM, and the like.
[0012]
The ultrasonic wave generation unit 10 realizes functions as the waveform analysis unit 13 and
the ultrasonic wave amplitude modulation unit 14 based on the program stored in the memory
12. Here, in the function as the waveform analysis unit 13, for example, the waveform of noise
(the strength of the sound pressure) having a waveform as shown in FIG. 2A is analyzed
according to the electric signal generated by the microphone 20.
[0013]
Then, in the function as the ultrasonic amplitude modulation unit 14, as shown in FIG. 2 (b), the
waveform of the ultrasonic wave of constant amplitude having a predetermined frequency (for
example, 40 kHz) is amplitude-modulated as shown in FIG. As shown in c), a waveform whose
amplitude is changed so as to be opposite to the phase of the noise waveform is generated. In
order to generate this waveform, after the waveform of the ultrasonic wave of constant amplitude
is amplitude-modulated, the portion where the output level is negative is inverted to a positive
value. That is, the absolute value of the waveform after amplitude modulation is taken.
[0014]
The ultrasonic amplifiers 25 and 26 amplify the waveform of the ultrasonic wave generated by
the ultrasonic wave generation unit 10 so as to be approximately equal to the sound pressure
level of noise, and output from the ultrasonic speakers 30 and 31, respectively. Do. In the present
embodiment, since the two ultrasonic amplifiers 25 and 26 and the ultrasonic speakers 30 and
31 corresponding to the respective amplifiers 25 and 26 are provided, ultrasonic waves having
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two different types of waveforms can be output. it can. If it is only necessary to output one type
of ultrasonic wave, only one ultrasonic amplifier may be provided.
[0015]
The ultrasonic speakers 30, 31 are ultrasonic generators that generate air vibrations having a
frequency (20 kHz or higher) higher than the human audible range, and for example,
piezoelectric speakers (ceramic speakers, piezo speakers, etc.) suitable for ultrasonic wave
reproduction Is configured as). As shown in FIG. 3A, the ultrasonic speakers 30, 31 constitute an
array speaker in which a plurality of speakers are regularly arranged on a certain plane.
[0016]
When sound waves of the same waveform are output from the ultrasonic speakers 30 and 31 in
such an array speaker, the outputs from the ultrasonic speakers 30 and 31 are amplified as
shown in FIG. It will be possible to reach the sound wave. When ultrasonic waves of about 40
kHz are output in the present configuration, the range in which the ultrasonic waves are diffused
is approximately in the range of 20 degrees.
[0017]
The microphone 20 and the ultrasonic speakers 30, 31 of such a noise reduction device 1 are
disposed as shown in FIG. 4, for example. That is, the microphone 20 is disposed outside the
sound field area 50 which is a range in which the sound waves from the ultrasonic speakers 30
and 31 are diffused (a range where noise reduction is performed), and can accurately pick up the
noise to be suppressed. It is considered.
[0018]
The ultrasonic speakers 30 and 31 are arranged so that the sound waves are output downward
on the user's head (above the sound field area 50). Further, on the floor surface to which the
sound waves from the ultrasonic speakers 30, 31 are applied, a carpet 40 for attenuating the
ultrasonic waves is disposed. The carpet 40 diffuses the ultrasonic wave to suppress the adverse
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effect of the reflected wave on the sound field area 50.
[0019]
[Effects of the Present Embodiment] In the noise reduction device 1 described in detail above, the
microphone 20 collects noise outside the sound field area 50 where noise is reduced, and the
ultrasonic wave generation unit 10 generates a waveform. Using the functions of the analysis
unit 13 and the ultrasonic wave amplitude modulation unit 14, a sound wave having an opposite
phase to the waveform of the collected noise is generated as an ultrasonic wave. Then, the
ultrasonic speakers 30 and 31 output sound waves to generate the sound field area 50.
[0020]
According to the noise reduction device 1 as described above, since the anti-phase wave of noise
is generated by ultrasonic waves, the sound field area 50 can be generated by utilizing the
straightness of the ultrasonic waves. In this configuration, since it is not necessary to provide a
wall surface, the sound field area 50 with reduced noise can be realized with a simple
configuration.
[0021]
The noise reduction device 1 further includes a carpet 40 disposed at a position facing the sound
wave output unit in the sound field area 50 to attenuate the sound wave. According to the noise
reduction device 1 as described above, the reflection of the ultrasonic wave generated can be
suppressed by providing the carpet 40 at the opposing position, so that the ultrasonic wave can
be made less likely to leak out of the sound field area 50 .
[0022]
Furthermore, in the noise reduction device 1 described above, the sound wave output unit is
disposed on the ceiling, and the carpet 40 is disposed on the floor. According to such a noise
reduction device 1, it is possible to suppress that ultrasonic waves are reflected and interfere on
the floor of the sound field area 50.
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[0023]
In the noise reduction device 1, the ultrasonic speakers 30, 31 include a plurality of speakers
arranged in an array. According to the noise reduction device 1 as described above, the output of
ultrasonic waves can be easily controlled by causing the outputs of the plurality of speakers to
interfere with each other.
[0024]
[Other Embodiments] The present invention is not interpreted in any way as limited by the
embodiments described above. Moreover, the aspect which abbreviate ¦ omitted a part of
structure of said embodiment as long as a subject is solvable is also embodiment of this
invention. In addition, an aspect configured by appropriately combining the plurality of
embodiments described above is also an embodiment of the present invention. In addition, any
aspect that can be considered without departing from the essence of the invention specified by
the terms set forth in the claims is also an embodiment of the present invention. Moreover,
although the code ¦ symbol used by description of said embodiment is suitably used also in a
claim, it is used in order to make an understanding of the invention which concerns on each
claim easy, and it is an invention which concerns on each claim It is not intended to limit the
technical scope of
[0025]
In the above embodiment, the ultrasonic speakers 30 and 31 are arranged above the sound field
area, but as shown in FIG. 5, for example, when arranged on the wall of a dresser having a mirror
55, it is directed to the floor direction The ultrasonic speakers 30, 31 may be disposed so as not
to occur. In this case, instead of the carpet 40, a curtain 41 or the like suspended from a position
higher than the position where the ultrasonic speakers 30, 31 are disposed may be used.
[0026]
According to such a noise reduction device 1, the sound field area 50 can be surrounded with a
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simpler configuration than in the case of arranging a strong wall surface or the like. Moreover, in
the said embodiment, although the sound wave of the antiphase of noise was output from all the
ultrasonic speakers 30 and 31, it is not necessary for all the speakers to output the sound wave
of an antiphase. For example, as shown in FIG. 6A, sound waves of reverse phase are output from
the ultrasonic speaker 30 to which the ultrasonic amplifier 25 corresponds, and ultrasonic waves
from the ultrasonic speaker 31 to which the ultrasonic amplifier 26 corresponds are of opposite
phase. The sound waves may be generated out of phase with each other.
[0027]
When sound waves of different phases are 180 degrees out of phase with sound waves of
opposite phase, a sound field area as shown in FIG. 6B is formed. That is, it can be seen that the
sound field area 50 is within a range of about 45 degrees from the sound source (place where
the ultrasonic speakers 30, 31 are arranged) to the front of the traveling direction of the sound
wave.
[0028]
By causing the sound waves output from the ultrasonic speakers 30 and 31 to interfere with
each other as described above, it is possible to adjust how the sound field area 50 spreads (the
size of the area). In the above embodiment, the configuration including one set of ultrasonic
speakers 30 and 31 has been described. For example, as shown in FIG. 7, a plurality of sets of
ultrasonic speakers 30 and 31 are used to generate a plurality of ultrasonic speakers. The sound
field area 50 may be formed. In this way, each of a plurality of passengers such as a railway car,
an aircraft, or a passenger car can be accommodated in the sound field area 50. In such a
configuration, the ultrasound is attenuated by the cloth of the clothes and the seat.
[0029]
[Correspondence Between Configuration of Embodiment and Configuration of Present Invention]
The microphone 20 in the above embodiment corresponds to the sound collecting unit in the
present invention, and the waveform analysis unit 13 and the ultrasonic amplitude modulation
unit 14 in the above embodiment are It corresponds to the anti-phase wave generation unit in
the present invention. Further, the ultrasonic speakers 30, 31 in the above embodiment
correspond to the sound wave output section in the present invention, and the carpet 40 and the
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curtain 41 in the above embodiment correspond to the attenuation member in the present
invention.
[0030]
DESCRIPTION OF SYMBOLS 1 ... Noise reduction apparatus, 10 ... Ultrasonic wave generation
part, 11 ... CPU, 12 ... Memory, 13 ... Waveform analysis part, 14 ... Ultrasonic wave amplitude
modulation part, 20 ... Microphone, 25, 26 ... Ultrasonic wave amplifier, 30, 31 ... ultrasonic
speaker, 40 ... carpet, 41 ... curtain, 50 ... sound field area, 55 ... mirror.
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