WO2005043510A1 - 低周波騒音抑制機構を有する装置 - Google Patents
低周波騒音抑制機構を有する装置 Download PDFInfo
- Publication number
- WO2005043510A1 WO2005043510A1 PCT/JP2004/010418 JP2004010418W WO2005043510A1 WO 2005043510 A1 WO2005043510 A1 WO 2005043510A1 JP 2004010418 W JP2004010418 W JP 2004010418W WO 2005043510 A1 WO2005043510 A1 WO 2005043510A1
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- WO
- WIPO (PCT)
- Prior art keywords
- noise
- sound
- speaker
- frequency
- noise source
- Prior art date
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Classifications
-
- G—PHYSICS
- G10—MUSICAL INSTRUMENTS; ACOUSTICS
- G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
- G10K11/00—Methods or devices for transmitting, conducting or directing sound in general; Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
- G10K11/16—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
- G10K11/175—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general using interference effects; Masking sound
- G10K11/178—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general using interference effects; Masking sound by electro-acoustically regenerating the original acoustic waves in anti-phase
- G10K11/1785—Methods, e.g. algorithms; Devices
- G10K11/17853—Methods, e.g. algorithms; Devices of the filter
- G10K11/17854—Methods, e.g. algorithms; Devices of the filter the filter being an adaptive filter
-
- G—PHYSICS
- G10—MUSICAL INSTRUMENTS; ACOUSTICS
- G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
- G10K11/00—Methods or devices for transmitting, conducting or directing sound in general; Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
- G10K11/16—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
- G10K11/175—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general using interference effects; Masking sound
- G10K11/178—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general using interference effects; Masking sound by electro-acoustically regenerating the original acoustic waves in anti-phase
- G10K11/1785—Methods, e.g. algorithms; Devices
- G10K11/17857—Geometric disposition, e.g. placement of microphones
-
- G—PHYSICS
- G10—MUSICAL INSTRUMENTS; ACOUSTICS
- G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
- G10K11/00—Methods or devices for transmitting, conducting or directing sound in general; Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
- G10K11/16—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
- G10K11/175—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general using interference effects; Masking sound
- G10K11/178—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general using interference effects; Masking sound by electro-acoustically regenerating the original acoustic waves in anti-phase
- G10K11/1787—General system configurations
- G10K11/17873—General system configurations using a reference signal without an error signal, e.g. pure feedforward
-
- G—PHYSICS
- G10—MUSICAL INSTRUMENTS; ACOUSTICS
- G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
- G10K2210/00—Details of active noise control [ANC] covered by G10K11/178 but not provided for in any of its subgroups
- G10K2210/10—Applications
Definitions
- the present invention relates to a device having a low-frequency noise source such as a blower, and particularly to a technology for reducing the low-frequency noise.
- the noise problem is a major environmental problem, and various countermeasures are being studied.
- the best-known method is to use a sound-absorbing or sound-insulating material to control noise.
- Such noise control which suppresses noise by receiving and absorbing and blocking generated noise, can be compared to passive noise control.
- ANC Active Noise Control
- ANC technology generates signals with the same amplitude and opposite phase as noise, and reduces noise by sound wave interference.It is used for noise reduction in cars and environmental noise in headphones used outdoors. .
- ANC has been attracting attention as a method that can cope with so-called low-frequency noise of about 500 Hz or less. That is, since low frequency noise has high diffractive properties and transmittance, it is difficult to attenuate it with a sound insulating material or a sound insulating material. Need to be done. Also, since the distance attenuation is small, it is not very effective to move the noise source away.
- noise control using ANC is a method of suppressing noise using sound wave interference, and therefore, in principle, an effect can be expected irrespective of the frequency of noise.
- various studies and proposals have been made on noise suppression technology using ANC.
- low-frequency noise (one-dimensional noise) transmitted in one direction such as noise transmitted in a duct, may have an effect, and there are already some examples.
- Patent Document 1 discloses that a plurality of speakers surrounding a noise source are directed toward a single noise source. 3D noise is reduced by emitting a control output signal (neutral sound) 3 A three-dimensional active silencer is disclosed.
- Patent Document 1 Japanese Patent Application Laid-Open No. 2003-91287
- Patent Document 1 uses a plurality of speakers, there is a portion where the sound waves generated by the speakers interfere with each other and are amplified, resulting in a low sound deadening effect. There is also a limit on the place for disposing, and it is disadvantageous in terms of cost.
- the present invention has been made in view of such problems of the related art, and a main object thereof is to effectively suppress three-dimensional low-frequency noise.
- the above-described object is to provide a noise source that emits three-dimensional low-frequency noise, a noise-reduction generating unit that observes three-dimensional low-frequency noise, generates a de-noising sound of the three-dimensional low-frequency noise, and outputs the de-noising sound.
- a noise source that emits three-dimensional low-frequency noise
- a noise-reduction generating unit that observes three-dimensional low-frequency noise, generates a de-noising sound of the three-dimensional low-frequency noise, and outputs the de-noising sound.
- FIG. 1 is a diagram illustrating an environment when measuring a noise-dissipating effect distribution according to a distance from a noise source and a speaker.
- FIG. 2 is a diagram showing a noise-reduction effect distribution measured in the environment of FIG.
- FIG. 3 is a diagram showing FIG. 2 by specific measured values.
- FIG. 4 is a view showing an example of an external appearance of a boiler as an embodiment of the present invention.
- the low-frequency noise targeted by the present invention mainly means noise having a frequency of about 500 Hz or less.
- the present invention is effective for noise having a frequency higher than that, the present invention is particularly effective for low-frequency noise of about 500 Hz or less where the effect of the sound absorbing material and the sound insulating material is small.
- Low-frequency noise is characterized by low directivity, in addition to the high diffractive properties, high transmissivity, and low distance attenuation described above. Therefore, as long as a sound wave having the same amplitude and opposite phase as the noise can be generated, the number of sound wave output sources may be one. However, if the distance between the noise source and the sound-absorbing sound output source (actually a speaker, hereinafter simply referred to as a speaker) increases, the phase shift between the noise and the sound-absorbing sound occurs. The noise is doubled. It is theoretically preferable to place the speaker at the same position as the noise source. However, such an arrangement is not possible in practice.
- an amplification area it is practically most preferable to dispose the speakers so that there is no area where noise is amplified by the sound-absorbing sound to be heard (hereinafter, such an area is referred to as an amplification area).
- the noise cancellation is originally in the opposite phase to the noise, it suffices to satisfy ⁇ ⁇ 60 °.
- the phase difference In order for the phase difference to be less than 60 °, assuming that the wavelength of the noise source (more precisely, the frequency f to be silenced) is ⁇ [m], the distance D [m] between the noise source and the speaker is X 60 ° / 360. Less than, ie
- the maximum value of the difference between the distance from the sound receiving point to the noise source and the distance from the sound receiving point to the speaker is equal to D.
- the silencing effect is also realized.
- D should be 114.3 [mm].
- a region where noise is to be reduced a region where a person exists for a long time and is called a work region
- the speaker is positioned so that it is located directly below or directly above the noise source even if there is an amplification area.
- the noise source and the speaker are arranged at a certain distance D.
- the distance rl to the noise source and the distance to the speaker may be different.
- r 2 is different.
- an appropriate sound-absorbing sound wave that is, sound wave of the same amplitude and opposite phase as the noise
- the noise source 1 is, for example, a blower, a compressor (compressor), a diesel engine, a vacuum pump, a vibrating sieve, a boiler, a mechanical press, and a blower (a device that conveys an empty can by air).
- This is the noise source (noise source) measured by the sound intensity method.
- noise sources are motors, It is often a part that performs rotational or vibrational motion, such as an ann, compressor, engine, or sieve.
- the noise of the boiler fan (projecting from the upper side of the boiler) was recorded in advance, and it was played back from a speaker installed at a height of 1.5 m and used as the noise source 1.
- the recorded boiler noise was a highly periodic noise with a prominent peak around 75.125 Hz.
- the control sound source (speaker) 2 is disposed substantially vertically below the noise source 1 with a processing distance D.
- the sensor microphone 8 is for observing the noise generated by the noise source 1, and is installed near the noise source 1.
- the control unit 9 is a device that generates an appropriate sound deadening sound from the noise acquired by the sensor microphone 8, and includes A / D and D / A conversion, frequency analysis, an adaptive filter, an amplifier, and the like. Since such a control unit 9 is known as an ANC system using adaptive filter control using, for example, the ffltered-x LMS algorithm, the details thereof will not be described.
- the microphone (the sound receiving point 3) was moved to measure the sound volume (sound pressure), and the difference in sound pressure level with the noise reproduced by the noise source 1 was obtained. The result is shown in figure 2.
- FIG. 3 is a diagram showing FIG. 2 with more specific numerical values.
- ⁇ ⁇ ⁇ is I rl-r2
- , f is the frequency to be silenced [Hz]
- c is the speed of sound [mZs]
- ⁇ ' is the initial phase difference (the phase difference between noise and sound extinction, ideally Is 0).
- the arrangement of the speakers 2 can be made so as to satisfy the distance D between the noise source 1 and the speaker 2 that outputs the sound-absorbing sound, that is, D force D ⁇ / 6. It is often considered difficult.
- a region where noise should be reduced (a region where humans exist for a long time and is called a work region) does not usually exist immediately below or directly above the noise source, and a predetermined distance from the noise source.
- the speakers are arranged so that the amplification area is located directly below or directly above the noise source.
- the speaker 2 is arranged substantially vertically above or substantially vertically below the noise source 1.
- the amplification area appears on the straight line connecting the speaker 2 and the noise source 1 and appears behind the speaker 2 toward the noise source 1.Therefore, by arranging the speaker 2 in this way, the amplification area Is located directly below or directly above the noise source, and the effect of the amplification area on the work area existing in a space at a predetermined distance from the noise source can be substantially ignored.
- whether the speaker 2 is arranged above or below the noise source 1 and the distance D between the speaker 2 and the noise source 1 are determined in consideration of a range in which a noise reduction effect is desired.
- a noise reduction effect is desired.
- the operation is performed in a factory where workers are present, in order to reduce noises experienced by the workers, sufficient noise is suppressed within a range in which the heads of the workers are considered to be present. Make settings to obtain the effect.
- a height of 1 ⁇ 0.5 m In an environment where the worker mainly works in a sitting position, for example, a height of 1 ⁇ 0.5 m, In an environment where work is performed in a standing position, for example, a height of 1.5 ⁇ 0.5 m is sufficient (for example, -6 dB or more, which is a sensible noise power of S1 / 2), and the work area (a predetermined distance from the noise source) The distance D between the noise source 1 and the loudspeaker 2 is determined so that it can be obtained within a distance. It goes without saying that the height range can be competed in other ranges.
- the noise targeted by the present invention has a low frequency, there is no need to consider the directivity of the speaker 2 in any direction.
- FIG. 4 shows an example of the appearance of a boiler as one embodiment of the present invention.
- Boiler B usually has a blower 1, and the main low-frequency noise source of the boiler is blower 1. Therefore, the speaker 2 (and the control unit 9) is installed almost vertically below the blower 1 as a noise source. Further, the sensor microphone 8 is provided near the blower 1. As a result, a sufficient noise reduction effect can be obtained near the head of the worker H.
- the amplification region 10 exists only near the boiler and toward the floor, and the effect on the worker H can be ignored.
- the same concept may be applied to arrange the power supply 12.
- the same concept may be applied to arrange the power supply 12.
- the three-dimensional sound intensity may be measured by a known method.
- the three-dimensional sound intensity can be measured using a three-dimensional sound intensity probe MI-6420 of Ono Sokki Co., Ltd.
- the speaker may be placed with the part specified by the measurement as a noise source.
- the noise source can be specified without measuring the 3D sound intensity, it is not necessary to specify the noise source by measuring the 3D sound intensity.
- the speaker In order to keep the region where the amplification region is generated away from the region where the worker's head is located, it is preferable that the speaker is disposed vertically above or below the noise source. If such an arrangement is not possible, it may be arranged at a position shifted from the vertical direction. Further, when the noise source exists inside the apparatus, the speaker may be arranged inside the apparatus.
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- Physics & Mathematics (AREA)
- Engineering & Computer Science (AREA)
- Acoustics & Sound (AREA)
- Multimedia (AREA)
- Soundproofing, Sound Blocking, And Sound Damping (AREA)
Abstract
Description
Claims
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP2003370571A JP2005134632A (ja) | 2003-10-30 | 2003-10-30 | 低周波騒音抑制機構を有する装置 |
JP2003-370571 | 2003-10-30 |
Publications (1)
Publication Number | Publication Date |
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WO2005043510A1 true WO2005043510A1 (ja) | 2005-05-12 |
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PCT/JP2004/010418 WO2005043510A1 (ja) | 2003-10-30 | 2004-07-22 | 低周波騒音抑制機構を有する装置 |
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WO (1) | WO2005043510A1 (ja) |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN110056495A (zh) * | 2018-12-25 | 2019-07-26 | 浙江零跑科技有限公司 | 新能源车电动真空泵用主动降噪装置 |
Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPH08185190A (ja) * | 1994-12-28 | 1996-07-16 | Shinko Electric Co Ltd | 消音装置 |
JPH1165574A (ja) * | 1997-08-25 | 1999-03-09 | Shinko Electric Co Ltd | 消音装置 |
JP2003186479A (ja) * | 2001-12-20 | 2003-07-04 | Mitsubishi Heavy Ind Ltd | 能動消音装置 |
-
2003
- 2003-10-30 JP JP2003370571A patent/JP2005134632A/ja active Pending
-
2004
- 2004-07-22 WO PCT/JP2004/010418 patent/WO2005043510A1/ja active Application Filing
Patent Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPH08185190A (ja) * | 1994-12-28 | 1996-07-16 | Shinko Electric Co Ltd | 消音装置 |
JPH1165574A (ja) * | 1997-08-25 | 1999-03-09 | Shinko Electric Co Ltd | 消音装置 |
JP2003186479A (ja) * | 2001-12-20 | 2003-07-04 | Mitsubishi Heavy Ind Ltd | 能動消音装置 |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN110056495A (zh) * | 2018-12-25 | 2019-07-26 | 浙江零跑科技有限公司 | 新能源车电动真空泵用主动降噪装置 |
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JP2005134632A (ja) | 2005-05-26 |
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