JP2017009835A - Noise suppression device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a noise suppression device capable of reducing load in signal processing for calculating inverse phase signals.SOLUTION: The noise suppression device includes: a noise wave separation part (22) that separates noises detected by plurality of microphones (11) into plural noise waves by means of a filter circuit; an inverse phase wave generation part (23) that generates inverse phase signals of the noises by using plural inverse phase waves of the noise waves; and a speaker control unit (24) that controls to output the inverse phase signals.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a noise suppression device, for example, a noise suppression device that suppresses noise by superimposing a sound wave having a phase opposite to the noise on the noise.

  As described in Non-Patent Document 1 below, the ANC (active noise control) technique is to superimpose a sound wave having a phase opposite to that of the noise (hereinafter sometimes referred to as an anti-phase wave) on the noise. This is a technology to suppress or mute noise. The noise signal that is the subject of the ANC technique includes, for example, the exhaust sound of a vacuum cleaner and the blowing sound of an air conditioner in addition to the driving sound of a motor provided in home appliances.

  Patent Document 1 discloses an active silencer that suppresses or silences noise using ANC technology. Specifically, the active silencer described in Patent Document 1 captures noise waveform data (noise signal) using a single microphone, and performs frequency analysis on the captured noise signal, thereby reducing noise. An antiphase signal corresponding to the signal is generated. The generated antiphase signal is output from one speaker and joined to the noise to cancel the noise.

Japanese Patent Laid-Open No. 9-297585 (published on November 18, 1997)

Basic Study on Active Acoustic Shielding (Improving Noise Reducing Performance in Low Frequency Region) Tatsuya Murao (Tottori Univ.), Masaharu Nishimura (Tottori Univ.); Japan Society of Mechanical Engineers China Shikoku Branch 50th General Meeting / Lecture (held on March 7 and 8, 2012)

  The noise signal may include noise waves from a plurality of noise sources. In this case, the frequency analysis for generating the antiphase signal from the noise signal is a signal processing with a heavy load. For this reason, the active silencer described in Patent Document 1 needs to include a large circuit board that can withstand heavy load signal processing, and thus there is a problem that it is difficult to reduce the size (space saving).

  The present invention has been made in view of the above problems, and an object of the present invention is to perform signal processing for calculating an antiphase signal in a noise suppression apparatus that suppresses the noise signal by superimposing the antiphase signal on the noise signal. It is to reduce the load.

  In order to solve the above problem, a noise suppression device according to one aspect of the present invention includes a noise wave extraction unit that extracts a plurality of noise waves having different frequency components from different noise signals detected by a plurality of microphones. An antiphase wave generation unit that generates a plurality of antiphase waves having opposite phases to the plurality of noise waves extracted by the noise wave extraction unit, and the plurality of antiphases generated by the antiphase wave generation unit And an anti-phase signal output unit that outputs an anti-phase signal that works to weaken the noise signal when it overlaps the noise signal.

  According to one embodiment of the present invention, it is possible to reduce a load of signal processing for calculating an antiphase signal.

It is a block diagram which shows the structure of the active silencer which concerns on Embodiment 1. FIG. It is a flowchart which shows the flow of the noise suppression process which the control part of the active silencer which concerns on Embodiment 1 performs. It is a figure explaining operation | movement of the muffling unit in the noise suppression process which concerns on Embodiment 1. FIG. It is a figure which shows one example of application of this invention, and is a figure which shows the cleaner which concerns on Embodiment 1. FIG. It is a flowchart which shows the flow of the noise suppression process in case the "apparatus containing a noise source" of FIG. 3 is a cleaner. It is a figure which shows an example of each frequency characteristic of the noise which the cleaner which concerns on Embodiment 1 generate | occur | produces, and the noise suppressed by the active silencer. It is a figure which shows an example of an experimental result, and is a graph which shows the relationship between the distance between two speakers, and the measured sound pressure. It is a figure which shows one example of application of this invention, and is a figure which shows the cleaner which concerns on Embodiment 2. FIG. It is a figure which shows the example of 1 application of this invention, and is a figure which shows the air conditioner which concerns on Embodiment 3. FIG. It is a flowchart which shows the flow of the noise suppression process in case the "apparatus containing a noise source" of FIG. 3 is an air conditioner. It is a figure which shows an example of each frequency characteristic of the noise which the air conditioner which concerns on Embodiment 3 generate | occur | produces, and the noise suppressed by the active silencer. It is a figure which shows one example of application of this invention, and is a figure which shows the washing machine which concerns on Embodiment 4. FIG. It is a flowchart which shows the flow of the noise suppression process in case the "apparatus containing a noise source" of FIG. 3 is a washing machine. It is a figure which shows an example of each frequency characteristic of the noise which the washing machine which concerns on Embodiment 3 generate | occur | produces, and the noise suppressed by the active silencer. It is a figure which shows the example of 1 application of this invention, and is a figure which shows the outdoor unit which concerns on Embodiment 5. FIG. It is a flowchart which shows the flow of the noise suppression process in case the "apparatus containing a noise source" of FIG. 3 is an outdoor unit. It is a figure which shows an example of each frequency characteristic of the noise which the outdoor unit which concerns on Embodiment 5 generate | occur | produces, and the noise suppressed by the active silencer.

Embodiment 1
Hereinafter, embodiments of the present invention will be described in detail with reference to FIGS.

(Active silencer 100)
The configuration of the active silencer 100 (noise suppression device) according to the present embodiment will be described with reference to FIG. FIG. 1 is a block diagram showing the configuration of the active silencer 100. As shown in FIG. 1, the active silencer 100 includes a plurality of silencer units 10 and one control unit 20. All of the plurality of silencer units 10 included in the active silencer 100 are controlled by the same control unit 20. In FIG. 1, the number of the muffler units 10 provided in the active muffler 100 is three. However, the active silencer 100 may include three or more and seven or less silencers 10, for example. In particular, the active silencer 100 may include a number of silencer units 10 corresponding to the number of noise sources.

  FIG. 3 is a diagram showing the muffler unit 10 attached to a device including a noise source. As shown in FIG. 3, the silencer unit 10 of the active silencer 100 superimposes (superimposes) a sound wave (antiphase signal) having a phase opposite to the noise generated by the device including the noise source. To suppress or mute noise.

  As shown in FIGS. 1 and 3, each silencer unit 10 of the active silencer 100 includes a microphone 11 (in FIG. 1, a first microphone, a second microphone, and a third microphone) and a speaker 12. . However, the muffling unit 10 only needs to include the same number of microphones 11 and speakers 12, and may include a plurality of each. As shown in FIG. 3, the silencer unit 10 is configured such that the device, the microphone 11, and the speaker 12 are arranged in this order when attached to a device including a noise source. The speaker 12 is arranged so that the sound output surface faces the apparatus side. The microphone 11 and the speaker 12 are disposed on opposing surfaces. The surface on which the microphone 11 is disposed is in contact with a device including a noise source. A desirable range of the distance a between the microphone 11 and the speaker 12 and a desirable range of the thickness b of the muffler unit 10 (or the distance between the speaker 12 and the apparatus) will be described at the end of this embodiment. To do.

  Although not shown, the active silencer 100 may further include an error microphone that detects suppressed noise. Alternatively, the microphone 11 of the mute unit 10 may function as an error microphone. In this configuration, the active silencer 100 compares the noise detected by the error microphone with the noise detected by the microphone 11 to determine whether or not the antiphase signal output from the speaker 12 actually suppresses the noise. Can be confirmed. Moreover, it can be judged from the result of the confirmation whether or not a failure has occurred in the speaker 12.

  The control unit 20 of the active silencer 100 controls the plurality of silencer units 10 included in the active silencer 100 to perform noise suppression processing for suppressing or silencing noise waves generated from a plurality of noise sources. As shown in FIG. 1, the control unit 20 includes a noise wave data acquisition unit 21, a noise wave separation unit 22 (noise wave extraction unit), an antiphase wave generation unit 23 (, an antiphase wave generation unit, an antiphase signal output unit). ), And a speaker control unit 24. In addition, operation | movement of each part of the control part 20 is demonstrated with description of the flow of a noise suppression process below.

(Noise suppression processing)
The flow of the noise suppression process executed by each unit (see FIG. 1) of the control unit 20 described above will be described with reference to FIGS. FIG. 2 is a flowchart showing the flow of noise suppression processing. FIG. 3 is a diagram for explaining the operation of the silencer unit 10 in the noise suppression process. As shown in FIG. 3, it is assumed that a plurality of (two in FIG. 3) muffler units 10 are attached to an apparatus including a plurality of noise sources.

  As shown in FIG. 2, in the noise suppression processing, first, the noise wave data acquisition unit 21 generates waveform data (noise signal) of noise (hereinafter referred to as original noise) detected by the microphone 11 of each silencing unit 10. Obtain (S1). As shown in FIG. 3, the original noise detected by each microphone 11 includes noise waves from two noise sources. The noise wave data acquisition unit 21 outputs the acquired plurality of noise signals to the noise wave separation unit 22.

  Next, as shown in FIG. 2, the noise wave separation unit 22 converts the noise signal input from the noise wave data acquisition unit 21 into the noise wave (waveform 1 and waveform 2 in FIG. 3) generated by each noise source. Each waveform data is separated (S2). Specifically, the noise wave separation unit 22 extracts a plurality of frequency components different from each other from the noise signal of the original noise detected by each microphone 11 using a known filter circuit. The extracted specific frequency component corresponds to one noise wave. Here, the noise wave separation unit 22 can use, for example, an independent component analysis method or a blind sound source separation method in order to separate a plurality of noise waves from the noise signal.

  The noise wave separation unit 22 outputs a plurality of noise waves separated from the noise signal to the antiphase wave generation unit 23.

  Thereafter, the antiphase wave generation unit 23 generates an antiphase wave having a phase opposite to that of the noise wave for each of the plurality of noise waves separated by the noise wave separation unit 22. Then, by combining the generated waveform data of a plurality of anti-phase waves after applying a weighting factor, an anti-phase wave (an anti-phase signal) (see FIG. 3) whose phase is opposite to that of the original noise. Waveform data is generated (S3). The anti-phase wave generator 23 outputs the generated anti-phase signal to the speaker controller 24. Here, when the original noise changes (for example, when the volume of one noise wave included in the original noise increases), the anti-phase wave generation unit 23 changes the original by changing the weighting factor. The anti-phase signal is made to correspond to the noise.

  The speaker control unit 24 uses the antiphase signal input from the antiphase wave generation unit 23 to output the antiphase signal from the speaker 12 of the silencer unit 10 so that the antiphase signal is superimposed on the noise from the noise source. (S4). Since the output antiphase signal overlaps the original noise, the original noise is canceled out. That is, the original noise is suppressed or silenced.

  This is the end of the noise suppression process.

(Application to vacuum cleaner 1)
An application example of the active silencer 100 to a device including a plurality of noise sources will be described with reference to FIG. FIG. 4 is a view showing the cleaner 1 equipped with the active silencer 100. The vacuum cleaner 1 in FIG. 4 corresponds to the “device including a noise source” in FIG.

  As shown in FIG. 4, an active silencer 100 including a plurality of (three in FIG. 4) silencer units 10 and one control unit 20 is attached to the main body of the vacuum cleaner 1. A motor 30 for operating the cleaner 1 is mounted inside the main body of the cleaner 1. The vacuum cleaner 1 sucks air from the suction nozzle, removes dust from the air, and then discharges air from the exhaust path. While the vacuum cleaner 1 is operating, the noise generated by the vacuum cleaner 1 includes (iii) a noise generated by the motor 30 and (ii) a sound of air flowing through the exhaust path. The sound that the unit 10 operates is included.

(Noise suppression processing in an application example to the vacuum cleaner 1)
FIG. 5 is a flowchart showing the flow of noise suppression processing when the “device including a noise source” in FIG. 3 is the vacuum cleaner 1 in FIG. 4. Here, in each block indicated by a broken line in FIG. 5, which block (step) corresponds to the block among S1 to S4 shown in FIG.

  As shown in FIG. 5, in the noise suppression process in the application example to the vacuum cleaner 1, the plurality of microphones 11 (the first microphone, the second microphone, and the third microphone in FIG. 5) of the mute units 10 are respectively The original noise including the three types of noise waves (i), (ii), and (iii) described above is detected (S1).

  The original noise detected by each of the plurality of microphones 11 is separated into three types of noise waves (i) (ii) (iii) by the filtering process of the noise wave separation unit 22 (S2).

  By the matching process of the anti-phase wave generator 23, the anti-phase signals of the three types of noise waves are weighted and added to generate an anti-phase signal having a phase opposite to that of the original noise. (S3). For example, the antiphase signal output from the speaker 12 closest to the motor 30 is weighted so as to mainly suppress noise waves having the motor 30 as a noise source. The weighting coefficient added to each noise wave represents the ratio of the output of each noise wave (the antiphase wave) in the output of the antiphase signal.

  Here, as a case where the weight coefficient is larger than 1, for example, the output of the speaker 12 may be reduced due to a failure of the speaker 12. When the weighting coefficient of a certain noise wave (its antiphase wave) exceeds 1, the volume of the noise including that noise wave exceeds the upper limit of the volume that can be output by the speaker 12, and the speaker 12 It is considered that an antiphase signal for sufficiently suppressing the noise wave cannot be output. On the other hand, when the weight coefficient exceeds 1, the volume of the antiphase signal output from the speaker 12 becomes very large. Therefore, when the weight coefficient of at least one type of noise wave is greater than 1, the noise suppression process may be stopped.

  The generated antiphase signal is output from the speaker 12 (the first speaker, the second speaker, and the third speaker in FIG. 5) of each silencing unit 10 (S4).

(Effect of the present invention in an application example to the vacuum cleaner 1)
FIG. 6 is a diagram illustrating an example of frequency characteristics of noise generated by a certain cleaner 1 equipped with the active silencer 100 and noise suppressed by the active silencer 100. In FIG. 6, the broken line indicates the frequency characteristic of the original noise generated by the cleaner 1, and the solid line indicates the frequency characteristic of the noise suppressed by the antiphase signal generated by the active silencer 100.

  As shown in FIG. 6, the original noise generated by the cleaner 1 is suppressed by the active silencer 100 particularly in a low frequency region (200 Hz to 1000 Hz). Therefore, the volume of noise generated by the vacuum cleaner 1 can be suppressed to 45 dB or less (a reference value for living noise at midnight in a residential area set by the Ministry of the Environment). The present invention can obtain a great effect particularly when applied to the vacuum cleaner 1 that generates a large volume of noise in a low frequency region.

(Additional explanation regarding the silencer unit 10)
Here, in the muffling unit 10 shown in FIG. 3, the experimental results for the distance a between the microphone 11 and the speaker 12 and the thickness b of the muffling unit 10 (or the distance between the speaker 12 and the apparatus). A desirable range determined based on the above will be described.

  In the experiment, first, two speakers were placed facing each other, and a single frequency antiphase signal corresponding to the sound wave output from the speaker of the other party was output from each speaker. Then, the sound pressure (unit: dB) of the overlapping sound waves was measured by a microphone arranged between the two speakers. The above measurement was repeated while changing the distance between the two speakers within a range of about 5 cm to about 20 cm. Here, one speaker in the experiment corresponds to the speaker 12 of the silencer unit 10, and the other speaker in the experiment is a noise source of the “device including the noise source” (FIG. 3) to which the silencer unit 10 is attached. Correspond.

  FIG. 7 is a graph showing an example of the experimental results, and is a graph showing the relationship between the distance between two speakers and the measured sound pressure. As shown in FIG. 7, the shorter the distance between the two speakers, the smaller the measured sound pressure. For example, when the distance is 10 cm, the sound pressure is reduced by about 10 dB as compared with the case where there is no antiphase signal (that is, when sound waves are output from only one speaker). On the other hand, when the distance was 20 cm, the decrease in sound pressure was reduced to about 5 dB compared to the case where there was no antiphase signal.

  When the decrease in the sound pressure of the noise due to the antiphase signal is 5 dB or more, the silencer unit 10 may be put into practical use. Therefore, according to the above experimental results, it is desirable to set the thickness b of the silencer unit 10 to 20 cm or less. Considering that the microphone 11 is disposed between the speaker 12 and the apparatus, it is desirable that the thickness b is normally set to 10 cm or more. Therefore, the thickness b is desirably 10 cm or more and 20 cm or less.

  The microphone 11 is disposed between the speaker 12 and the apparatus so as not to be affected by the vibration of the apparatus. Therefore, when it is 10 cm or more and 20 cm or less, it is desirable that the distance a between the microphone 11 and the speaker 12 is set to 5 cm or more and 10 cm or less.

[Embodiment 2]
The following will describe another embodiment of the present invention with reference to FIG. For convenience of explanation, members having the same functions as those described in the embodiment are given the same reference numerals, and descriptions thereof are omitted.

  Also in the present embodiment, as in the first embodiment, an application example of the active silencer 100 (see FIG. 1) to a cleaner will be described. However, in the present embodiment, the active silencer 100 is mounted not only on the main body of the cleaner but also on the suction nozzle of the cleaner.

(Application to vacuum cleaner 2)
FIG. 8 is a diagram illustrating the vacuum cleaner 2 according to the present embodiment. As shown in FIG. 8, the cleaner 2 is equipped with an active silencer 100 composed of a plurality of silencer units 10 and one control unit 20 on the main body. Furthermore, the vacuum cleaner 2 is also equipped with an active silencer 100 composed of two silencer units 10A and one control unit 20A on its suction nozzle.

  The silencer unit 10 attached to the main body of the cleaner 2 and the silencer unit 10A attached to the suction nozzle of the cleaner 2 operate separately from each other. The silencer unit 10 attached to the main body of the cleaner 2 suppresses or silences the three types of noise waves described in the first embodiment. Moreover, the silencing unit 10A attached to the suction nozzle of the cleaner 2 suppresses or silences the noise wave (for example, the rotation sound of the brush) generated by the suction nozzle of the cleaner 2. The configurations of the silencer unit 10A and the control unit 20A are the same as the configurations of the silencer unit 10 and the control unit 20 described in the first embodiment.

  According to the configuration of the present embodiment, not only the three types of noise waves described in the first embodiment, but also the noise waves generated by the suction nozzle can be suppressed or silenced. Therefore, the daily noise generated by the vacuum cleaner can be further reduced. Note that the active silencer 100 may be mounted not only on the suction nozzle of the cleaner 2 but also on other parts that generate noise waves instead of the suction nozzle.

[Embodiment 3]
The following will describe another embodiment of the present invention with reference to FIGS. For convenience of explanation, members having the same functions as those described in the embodiment are given the same reference numerals, and descriptions thereof are omitted.

  In the present embodiment, an application example of the active silencer 100 (see FIG. 1) to an air conditioner will be described.

(Application to air conditioner 3)
FIG. 9 is a diagram illustrating the air conditioner 3 according to the present embodiment. As shown in FIG. 9, the air conditioner 3 is equipped with an active silencer 100 including a plurality of silencer units 10 and a single control unit 20 on the main body. 8 or more and 16 or less of the muffler units 10 are arranged so as to surround the periphery of the main body of the air conditioner 3.

  In the muffling unit 10, the distance a between the microphone 11 and the speaker 12 may be 5 cm <= a <= 20 cm. Further, the thickness b of the silencer unit 10, that is, the distance between the speaker 12 and the apparatus may be 10 cm <= b <= 20 cm. The width of the silencing unit 10 in the vertical and horizontal directions may vary depending on the number of the silencing units 10 attached to the air conditioner 3 and the size of the air conditioner 3.

  As shown in FIG. 9, the noise source of the air conditioner 3 is the motor 30 and the air outlet provided in the air conditioner 3. Noise detected by the microphone 11 of the muffler unit 10 attached to the air conditioner 3 includes (i) a sound driven by the motor 30, (ii) a sound flowing out of the air from the air outlet, and (iii) each muffler unit. 10 sounds are included.

(Noise suppression processing in an application example to the air conditioner 3)
FIG. 10 is a flowchart showing the flow of noise suppression processing when the “device including a noise source” in FIG. 3 is the air conditioner 3 in FIG. 9. Here, in each block indicated by a broken line in FIG. 10, which block (step) corresponds to the block among S1 to S4 shown in FIG.

  As shown in FIG. 10, in the noise suppression processing in the application example to the air conditioner 3, the plurality of microphones 11 (the first microphone, the second microphone, and the third microphone in FIG. 10) of the plurality of silencers 10 are The original noise including the three types of noise waves (i), (ii), and (iii) described above is detected (S1).

  The original noise detected by each of the plurality of microphones 11 is separated into three types of noise waves (i) (ii) (iii) by the filtering process of the noise wave separation unit 22 (S2).

  By the matching process of the anti-phase wave generation unit 23, the waveform data of the three types of noise waves are weighted and added to generate an anti-phase signal having a phase opposite to that of the original noise ( S3). Here, when the weight coefficient of at least one kind of noise wave is larger than 1, the noise suppression process may be stopped.

  The generated antiphase signal is output from the speaker 12 (in FIG. 10, the first speaker, the second speaker, and the third speaker) of each silencer unit 10 (S4).

(Effect of the present invention in an application example to the air conditioner 3)
FIG. 11 is a diagram illustrating an example of frequency characteristics of noise generated by a certain air conditioner 3 equipped with the active silencer 100 and noise suppressed by the active silencer 100. In FIG. 11, the broken line indicates the frequency characteristic of the original noise generated by the air conditioner 3, and the solid line indicates the frequency characteristic of the noise suppressed by the antiphase signal generated by the active silencer 100.

  As shown in FIG. 11, the original noise generated by the air conditioner 3 is suppressed by the active silencer 100 particularly in a low frequency region (200 Hz to 1000 Hz). Therefore, the volume of noise generated by the air conditioner 3 can be suppressed to 45 dB (a reference value for late-night living noise in residential areas determined by the Ministry of the Environment) or less. The present invention can obtain a great effect particularly when applied to the air conditioner 3 that generates noise of a large volume in a low frequency region.

[Embodiment 4]
The following will describe another embodiment of the present invention with reference to FIGS. For convenience of explanation, members having the same functions as those described in the embodiment are given the same reference numerals, and descriptions thereof are omitted.

  In the present embodiment, an application example of the active silencer 100 (see FIG. 1) to a washing machine will be described.

(Application to washing machine 4)
FIG. 12 is a diagram illustrating the washing machine 4 according to the present embodiment. As shown in FIG. 12, the washing machine 4 is equipped with an active silencer 100 composed of a plurality of silencer units 10 and one control unit 20 on the main body. 5 to 10 are arranged so that the silencer unit 10 may surround the periphery of the main body of the washing machine 4.

  In the muffling unit 10, the distance a between the microphone 11 and the speaker 12 may be 5 cm <= a <= 20 cm. Further, the thickness b of the silencer unit 10, that is, the distance between the speaker 12 and the apparatus may be 10 cm <= b <= 20 cm. The width of the sound deadening unit 10 in the vertical and horizontal directions may vary depending on the number of the sound deadening units 10 attached to the washing machine 4 and the size of the washing machine 4.

  As shown in FIG. 12, the noise source of the washing machine 4 is the motor 30 and the drainage path provided in the washing machine 4. Noise detected by the microphone 11 of the silencer unit 10 attached to the washing machine 4 includes (i) a sound driven by the motor 30, (ii) a sound of water flowing through the drainage path, and (iii) each silencer unit 10 Includes sound that works.

(Noise suppression processing in an application example to the washing machine 4)
FIG. 13 is a flowchart showing the flow of noise suppression processing when the “device including a noise source” in FIG. 3 is the washing machine 4 in FIG. Here, in each block indicated by a broken line in FIG. 13, which block (step) corresponds to the block among S1 to S4 shown in FIG.

  As shown in FIG. 13, in the noise suppression processing in the application example to the washing machine 4, the plurality of microphones 11 (the first microphone, the second microphone, and the third microphone in FIG. 13) of the plurality of mute units 10 are respectively The original noise including the three types of noise waves (i), (ii), and (iii) described above is detected (S1).

  The original noise detected by each of the plurality of microphones 11 is separated into three types of noise waves (i) (ii) (iii) by the filtering process of the noise wave separation unit 22 (S2).

  By the matching process of the anti-phase wave generation unit 23, the waveform data of the three types of noise waves are weighted and added to generate an anti-phase signal having a phase opposite to that of the original noise ( S3). Here, when the weight coefficient of at least one kind of noise wave is larger than 1, the noise suppression process may be stopped.

  The generated anti-phase signal is output from the speaker 12 (in FIG. 13, the first speaker, the second speaker, and the third speaker) of each silencer unit 10 (S4).

(Effect of the present invention in an application example to the washing machine 4)
FIG. 14 is a diagram illustrating an example of frequency characteristics of noise generated by a certain washing machine 4 to which the active silencer 100 is mounted and noise suppressed by the active silencer 100. In FIG. 14, the broken line indicates the frequency characteristic of the original noise generated by the washing machine 4, and the solid line indicates the frequency characteristic of the noise suppressed by the antiphase signal generated by the active silencer 100.

  As shown in FIG. 14, the original noise generated by the washing machine 4 is suppressed by the active silencer 100 particularly in a low frequency region (200 Hz to 1000 Hz). Therefore, the volume of the noise generated by the washing machine 4 can be suppressed to 45 dB or less (a reference value for midnight living noise in a residential area set by the Ministry of the Environment) or less. The present invention can achieve a great effect particularly when applied to the washing machine 4 that generates a loud noise at a low frequency region.

[Embodiment 5]
The following will describe another embodiment of the present invention with reference to FIGS. For convenience of explanation, members having the same functions as those described in the embodiment are given the same reference numerals, and descriptions thereof are omitted.

  In the present embodiment, an application example of the active silencer 100 (see FIG. 1) to an outdoor unit will be described.

(Application to outdoor unit 5)
FIG. 15 is a diagram illustrating the outdoor unit 5 according to the present embodiment. Although not shown, the outdoor unit 5 is connected to an air conditioner through a pipe through which air passes. As shown in FIG. 15, the outdoor unit 5 is equipped with an active silencer 100 composed of a plurality of silencer units 10 and one control unit 20 in the main body. 5 or more and 10 or less of the muffler units 10 are arranged so as to surround the periphery of the main body of the outdoor unit 5.

  In the muffling unit 10, the distance a between the microphone 11 and the speaker 12 may be 5 cm <= a <= 20 cm. Further, the thickness b of the silencer unit 10, that is, the distance between the speaker 12 and the apparatus may be 10 cm <= b <= 20 cm. The width of the silencing unit 10 in the vertical and horizontal directions may vary depending on the number of the silencing units 10 attached to the outdoor unit 5 and the size of the washing machine 4.

  As shown in FIG. 15, the noise source of the outdoor unit 5 is the motor 30 and the drainage path provided in the outdoor unit 5. Noise detected by the microphone 11 of the silencer unit 10 attached to the outdoor unit 5 includes (i) a sound driven by the motor 30, (ii) a sound rotated by the fan of the outdoor unit 5, and (iii) each silencer unit. 10 sounds are included.

(Noise suppression processing in an application example to the outdoor unit 5)
16 is a flowchart showing the flow of noise suppression processing in the case where the “device including a noise source” in FIG. 3 is the outdoor unit 5 in FIG. Here, in each block indicated by a broken line in FIG. 16, which block (step) corresponds to the block among S1 to S4 shown in FIG.

  As shown in FIG. 16, in the noise suppression process in the application example to the outdoor unit 5, the plurality of microphones 11 (the first microphone, the second microphone, and the third microphone in FIG. 16) of the plurality of muffler units 10 are respectively The original noise including the three types of noise waves (i), (ii), and (iii) described above is detected (S1).

  The original noise detected by each of the plurality of microphones 11 is separated into three types of noise waves (i) (ii) (iii) by the filtering process of the noise wave separation unit 22 (S2).

  By the matching process of the anti-phase wave generation unit 23, the waveform data of the three types of noise waves are weighted and added to generate an anti-phase signal having a phase opposite to that of the original noise ( S3). Here, when the weight coefficient of at least one kind of noise wave is larger than 1, the noise suppression process may be stopped.

  The generated antiphase signal is output from the speaker 12 (in FIG. 16, the first speaker, the second speaker, and the third speaker) of each silencing unit 10 (S4).

(Effect of the present invention in an application example to the washing machine 4)
FIG. 17 is a diagram illustrating an example of frequency characteristics of noise generated by a certain outdoor unit 5 to which the active silencer 100 is attached and noise suppressed by the active silencer 100. In FIG. 17, the broken line indicates the frequency characteristic of the original noise generated by the outdoor unit 5, and the solid line indicates the frequency characteristic of the noise suppressed by the antiphase signal generated by the active silencer 100.

  As shown in FIG. 17, the original noise generated by the outdoor unit 5 is suppressed by the active silencer 100 particularly in a low frequency region (200 Hz to 1000 Hz). Therefore, the volume of noise generated by the outdoor unit 5 can be suppressed to 45 dB or less (a reference value for midnight living noise in a residential area set by the Ministry of the Environment). The present invention can obtain a great effect particularly when applied to the outdoor unit 5 that generates noise with a large volume in a low frequency region.

[Example of software implementation]
The control unit 20 of the active silencer 100 may be realized by a logic circuit (hardware) formed in an integrated circuit (IC chip) or the like, or may be realized by software using a CPU (Central Processing Unit). Good.

  In the latter case, the active silencer 100 includes a CPU that executes instructions of a program that is software that implements each function, and a ROM (Read Only Memory) in which the program and various data are recorded so as to be readable by a computer (or CPU). Alternatively, a storage device (these are referred to as “recording media”), a RAM (Random Access Memory) that expands the program, and the like are provided. And the objective of this invention is achieved when a computer (or CPU) reads the said program from the said recording medium and runs it. As the recording medium, a “non-temporary tangible medium” such as a tape, a disk, a card, a semiconductor memory, a programmable logic circuit, or the like can be used. The program may be supplied to the computer via an arbitrary transmission medium (such as a communication network or a broadcast wave) that can transmit the program. The present invention can also be realized in the form of a data signal embedded in a carrier wave in which the program is embodied by electronic transmission.

[Summary]
The noise suppression device according to aspect 1 of the present invention includes a noise wave extraction unit that extracts a plurality of noise waves having different frequency components from different noise signals detected by a plurality of microphones, and the noise wave extraction unit extracts An anti-phase wave generation unit that generates a plurality of anti-phase waves having opposite phases to the plurality of noise waves, and the noise signal using the plurality of anti-phase waves generated by the anti-phase wave generation unit An anti-phase signal output unit that outputs an anti-phase signal that acts to weaken the noise signal when they overlap.

  According to said structure, the noise signal containing several noise waves is detected by several microphones. A plurality of different noise waves are extracted from each of the noise signals detected by the plurality of microphones. And the antiphase signal of a noise signal is produced | generated using the antiphase wave of the extracted several noise wave. Therefore, compared to a configuration in which an antiphase signal is generated from a noise signal detected by one microphone, it is possible to reduce a load of signal processing for generating an antiphase signal. Further, the generated antiphase signal is output and overlapped with the noise signal, whereby the noise signal can be suppressed or silenced.

  The noise suppression device according to aspect 2 of the present invention is the noise suppression device according to aspect 1, further comprising the same number of speakers as the microphones for the reverse phase signal output unit to output the reverse phase signal. In the above silencer unit, each of the microphone and the speaker is disposed on an opposing surface, and the microphone and the speaker set each constitute a silencer unit. When the distance to the speaker is not less than 5 cm and not more than 10 cm, and the silencer unit is attached to a device including a noise source, the surface on which the microphone is disposed contacts the device, and the speaker to the device The distance may be 10 cm or more and 20 cm or less.

  According to said structure, a noise can be effectively suppressed with the antiphase signal output from a speaker.

  The noise suppression device according to aspect 3 of the present invention is the noise suppression apparatus according to aspect 1 or 2, wherein the antiphase signal output unit generates the antiphase signal from weighted and synthesized plural noise waves. Good.

  According to said structure, the anti-phase signal for canceling out the noise signal containing a several noise wave can be produced | generated by weighting and synthesizing several noise waves appropriately.

  In the noise suppression device according to aspect 4 of the present invention, in any one of the above aspects 1 to 3, the antiphase wave generated by the antiphase wave generation unit is an antiphase wave of a noise wave generated by an arbitrary noise source. In addition, an antiphase wave of a noise wave generated by the noise suppression device may be included.

  According to said structure, not only the noise which a noise source generate | occur | produces but the noise which a noise suppression apparatus generate | occur | produces with an antiphase wave can be suppressed.

  In the noise suppression device according to aspect 5 of the present invention, in the above aspect 3, when the antiphase signal output unit generates the antiphase signal, a weight coefficient for at least one of the noise waves is greater than 1. The noise suppression device may stop operating.

  According to the above configuration, when the noise wave having a larger amplitude (volume) than the noise is included in the anti-phase wave and the anti-phase wave may not be normally generated, The operation can be stopped.

  The noise suppression device according to each aspect of the present invention may be realized by a computer. In this case, the noise suppression device is operated on each computer by operating the computer as each unit (software element) included in the noise suppression device. The control program of the noise suppression apparatus realized by the above and a computer-readable recording medium on which the control program is recorded also fall within the scope of the present invention.

  The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope shown in the claims, and embodiments obtained by appropriately combining technical means disclosed in different embodiments. Is also included in the technical scope of the present invention. Furthermore, a new technical feature can be formed by combining the technical means disclosed in each embodiment.

  The present invention can be used for a noise suppression device.

DESCRIPTION OF SYMBOLS 10 Silencer unit 11 Microphone 12 Speaker 20 Control part 22 Noise wave separation part (noise wave extraction part)
23 Antiphase wave generator (Antiphase signal output unit)
100 Active silencer (noise suppression device)

Claims (5)

A noise wave extraction unit that extracts a plurality of noise waves having different frequency components from different noise signals detected by a plurality of microphones;
An anti-phase wave generation unit for generating a plurality of anti-phase waves having an anti-phase with the plurality of noise waves extracted by the noise wave extraction unit;
An anti-phase signal output unit that outputs an anti-phase signal that works to weaken the noise signal when overlapped with the noise signal using the plurality of anti-phase waves generated by the anti-phase wave generator A noise suppression device characterized by that. The antiphase signal output unit further includes the same number of speakers as the microphones for outputting the antiphase signal,
In the noise suppression device, a set of one microphone and one speaker each constitutes a mute unit,
In the silencing unit, the microphone and the speaker are respectively disposed on opposing surfaces, and a distance between the microphone and the speaker is 5 cm or more and 10 cm or less,
When the silencer unit is attached to a device including a noise source, the surface on which the microphone is disposed contacts the device, and the distance from the speaker to the device is 10 cm or more and 20 cm or less. The noise suppression device according to claim 1.   3. The noise suppression device according to claim 1, wherein the anti-phase signal output unit generates the anti-phase signal from weighted and synthesized plural noise waves. 4.   The anti-phase wave generated by the anti-phase wave generator includes an anti-phase wave of a noise wave generated by the noise suppression device in addition to an anti-phase wave of a noise wave generated by an arbitrary noise source. The noise suppression device according to any one of claims 1 to 3.   The noise suppression device stops operating when a weighting coefficient for at least one of the noise waves is larger than 1 when the anti-phase signal output unit generates the anti-phase signal. 3. The noise suppression device according to 3.

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