JP4742064B2 - Noise canceling device and noise canceling method - Google Patents

Description

  The present invention relates to a noise canceling apparatus and a noise canceling method for canceling noise from a space such as a room.

  2. Description of the Related Art An active noise control device has been conventionally proposed in which a compensation sound having an equal sound pressure with a phase opposite to that of noise generated from a sound source is output from a speaker to cancel the noise. (For example, refer to Patent Document 1).

  FIG. 6 shows an outline of the configuration of the proposed noise canceling apparatus. The noise canceling apparatus 100 includes a canceling sound generating speaker 101 for canceling noise and a noise collecting microphone 102 for detecting and feeding back a residual sound whose noise has been canceled. The control unit 103 that performs overall control of the noise cancellation apparatus 100 includes an adaptive filter 104, first and second low-pass filters 105 and 106, a sampling frequency variable unit 107, and a transfer characteristic simulation unit 108. It is connected.

  Among these, the adaptive filter 104 is provided in order to form a compensation sound and make the filter length variable. The adaptive filter 104 receives a filter coefficient update from the coefficient update unit 111. The first and second low-pass filters 105 and 106 each have a variable cut-off frequency, and aliasing as a phenomenon in which the original signal cannot be correctly reproduced from the sampling point by changing the sampling frequency ( aliasing) can be prevented. The sampling frequency variable unit 107 converts an analog signal obtained by amplifying the sound picked up by the noise collecting microphone 102 by the first amplifier circuit 112 into a digital signal, and an output of the AD converter circuit 113 as a first signal. The sampling frequency of the DA conversion circuit 114 that converts the digital signal of the cancellation sound obtained through the low-pass filter 105, the coefficient update unit 111, the adaptive filter 104, and the second low-pass filter 106 in this order into an analog signal. It is supposed to change. The output of the DA conversion circuit 114 is amplified by the second amplification circuit 115 and output from the canceling sound generation speaker 101. The transfer characteristic simulation unit 108 simulates the transfer characteristic corresponding to the variable sampling frequency.

The conventional noise canceling apparatus 100 shown in FIG. 6 outputs a sound having a sound pressure opposite to that of the noise from the canceling sound generating speaker 101 with such a configuration, and effectively reduces the noise according to the change in the frequency of the noise. Can be canceled.
Japanese Patent Laid-Open No. 06-167986 (paragraph 0014, FIG. 1)

  Such a conventional noise canceling apparatus 100 is mainly used to cancel a sound having a large noise level such as a noise generated by an internal combustion engine. For this reason, the canceling sound generating speaker 101 is a relatively large and high output speaker among normal speakers having a diaphragm using a voice coil and cone paper. Accordingly, the size of the canceling sound generating speaker 101 itself is large, and it is necessary to secure an installation space. In addition, there is a problem in that there are many cases where the installation of the canceling sound generation speaker 101 is not possible due to restrictions for securing the appearance of the installation place of the cancellation sound generating speaker 101.

  In addition, when a noise canceling device is used for a traffic vehicle such as a private car or a work-use vehicle such as a heavy machine for construction, even a warning sound such as a horn may be canceled as noise, thereby inducing a personal injury. There was a risk of doing. For this reason, there existed a problem that the noise cancellation apparatus 100 could not be easily installed in spaces, such as in a motor vehicle.

  Accordingly, a first object of the present invention is to provide a noise canceling apparatus and a noise canceling method capable of coping with a relatively loud sound that does not normally occur.

  A second object of the present invention is to provide a noise canceling device that can be easily installed in various places and a noise canceling method that can be realized in various places.

In the present invention , (b) a microphone that inputs ambient sound, and (b) a sound pressure determination unit by frequency that determines whether the sound input from the microphone is equal to or higher than a preset sound pressure, (C) a cancel sound generating means for generating a cancel sound for canceling a sound having a frequency lower than the preset sound pressure determined by the frequency-specific sound pressure determining means; and (d) the cancel sound generating means. The noise canceling device is provided with a speaker that outputs the sound generated by.

  That is, in the present invention, the sound pressure discrimination means for each frequency discriminates for each frequency whether the sound input from the microphone is equal to or higher than a preset sound pressure. Then, a cancel sound for canceling the sound having a frequency lower than the preset sound pressure is generated by the cancel sound generating means, and is output from the speaker. As a result, when a relatively loud sound that does not normally occur is generated, this can be dealt with. The speaker is not limited to a flat speaker and may be of any type.

In the present invention , (a) a microphone that inputs ambient sounds, and (b) sound pressure determination means by frequency that determines whether the sound input from the microphone is equal to or higher than a preset sound pressure. (C) warning sound registration determining means for determining whether a sound having a frequency equal to or higher than the preset sound pressure determined by the frequency-specific sound pressure determining means is registered as a warning sound; ) Exceeding the previously set sound pressure other than the sound having a frequency lower than the previously set sound pressure determined by the sound pressure determining means for each frequency and the sound registered as the warning sound by the warning sound determining means A noise canceling means for generating a canceling sound for canceling a sound of a certain frequency, and (e) a speaker for outputting the sound generated by the canceling sound generating means. It is provided in the device.

  That is, in the present invention, the sound pressure discrimination means for each frequency discriminates for each frequency whether the sound input from the microphone is equal to or higher than a preset sound pressure. Further, the warning sound registration determining means determines whether or not a sound having a frequency equal to or higher than the preset sound pressure determined by the frequency sound pressure determining means is registered as a warning sound. Other than the sound having a frequency lower than the preset sound pressure determined by the sound pressure determination means and the sound registered as the warning sound by the warning sound determination means, the frequency of the frequency which is equal to or higher than the preset sound pressure. The sound is canceled using a speaker. Accordingly, a relatively loud warning sound is reproduced from the speaker, so that the warning can be dealt with. The speaker is not limited to a flat speaker and may be of any type.

Furthermore, in the present invention , (b) a microphone that inputs ambient sounds, and (b) sound pressure determination means by frequency that determines whether the sound input from the microphone is equal to or higher than a preset sound pressure. (C) Continuous sound discriminating means for discriminating whether or not a sound having a frequency equal to or higher than the preset sound pressure discriminated by the frequency-specific sound pressure discriminating means is continuously input for a predetermined time or more. And (d) canceling a sound having a frequency lower than the preset sound pressure determined by the sound pressure determining means for each frequency and a sound having that frequency after the time determined as a continuous sound by the continuous sound determining means. The noise canceling device includes a canceling sound generating means for generating a canceling sound, and (e) a speaker for outputting the sound generated by the canceling sound generating means. .

  That is, in the present invention, the sound pressure discrimination means for each frequency discriminates for each frequency whether the sound input from the microphone is equal to or higher than a preset sound pressure. Further, a continuous loud sound is discriminated by a continuous sound discriminating means, and for such a sound, the sound having the frequency after the time determined as the continuous sound is canceled using a speaker. Therefore, since such a sound is output from the speaker as a normal sound until it is determined as a continuous sound, it can be noticed and dealt with. The speaker is not limited to a flat speaker and may be of any type.

In the present invention , (a) a sound pressure determination step by frequency for determining whether the sound input from the microphone is equal to or higher than a preset sound pressure, and (b) a sound pressure determination step by frequency. The noise canceling method includes a canceling sound output step of generating a canceling sound for canceling the sound having a frequency lower than the preset sound pressure and outputting the canceling sound from the flat speaker.

  That is, in the present invention, in the sound pressure discrimination step for each frequency, it is discriminated by frequency whether the sound input from the microphone is equal to or higher than a preset sound pressure, and the sound having a frequency lower than the preset sound pressure is canceled. To generate a canceling sound and output it from a flat speaker. As a result, when a relatively loud sound that does not normally occur is generated, this can be dealt with. In addition, since the speaker is a flat speaker, members that partition a space such as a curtain, a wall, a ceiling, a floor, and a window glass can be used.

Further, according to the present invention , (a) a sound pressure determination step for each frequency for determining whether the sound input from the microphone is equal to or higher than a preset sound pressure, and (b) a sound pressure determination step for each frequency. A warning sound registration determination step for determining whether a sound having a frequency equal to or higher than the preset sound pressure is registered as a warning sound, and (c) the sound pressure determination step for each frequency described above. Generates a cancel sound for canceling a sound with a frequency higher than the preset sound pressure other than a sound with a frequency less than the preset sound pressure and a sound registered as a warning sound in the warning sound discrimination step. Then, the noise canceling method includes a canceling sound output step of outputting the generated canceling sound from the flat speaker.

  That is, according to the present invention, in addition to the invention described in claim 6, when a sound having a frequency equal to or higher than a preset sound pressure is a warning sound, the sound is not canceled and other preset sounds are set. The sound over pressure is canceled. Thereby, since a relatively loud sound other than the warning sound is also subject to cancellation, noise removal can be executed more effectively.

  As described above, according to the present invention, since the sound pressure and frequency of the sound input from the microphone are analyzed and the sound to be canceled is selected, the situation that the necessary sound cannot be heard is generated. It is possible to prevent the noise and to spread the technology for canceling noise to various applications. Further, by configuring the flat speaker with a member that partitions a space such as furniture, a canceling sound can be output from a wide area, and noise can be effectively canceled.

  Hereinafter, the present invention will be described in detail with reference to examples.

  FIG. 1 shows a main part of a room using a noise canceling apparatus according to an embodiment of the present invention. In this embodiment, the noise canceling apparatus 200 includes a plurality of strip-shaped flat speakers 201, 201,..., A control box 203 connected by these flat speakers 201, 201,. The microphone device 205 communicates with the antenna 204 attached to the.

  Here, the flat speakers 201, 201,... Are accommodated by providing pockets (not shown) on the lining side of the accordion curtain 214 suspended from the curtain rail 211 via the runner 212 and the hook 213. Further, the respective flat speakers 201, 201,... Are connected by a cable 202 so as not to stand out on the lining side of the accordion curtain 214.

  The microphone device 205 is possessed when the user 216 of this room wants to cancel the noise in the room. The microphone device 205 picks up the surrounding sound and transmits it as noise information to the control box 203 by short-range wireless communication. Yes. For example, the microphone device 205 may be attached to a strap of a mobile phone (not shown) or may be configured as an accessory such as a necklace.

  FIG. 2 shows the configuration of the flat speaker of this embodiment. The flat speaker 201 has a configuration in which an exciter 232 is attached to the upper end of a rectangular acrylic plate 231 and a connector 233 for connecting the cable 202 is disposed near the exciter 232. By adopting a structure in which the cable 202 is connected to the connector 233, an arbitrary number of planar speakers 201 can be coupled as shown in FIG. Further, the addition of the flat speaker 201 is easy. Furthermore, when the cable 202 is damaged for some reason, the cable 202 can be easily repaired by replacing the connector 233 including the damaged portion with a new one.

  It is important for the acrylic plate 231 to ensure its rigidity for transmission of vibration, but it can be made flexible by reducing its thickness to some extent. Therefore, even when the accordion curtain 214 shown in FIG. 1 is swung by an external force such as wind, it is possible to realize a natural movement. Moreover, by incorporating the acrylic plate 231 into the accordion curtain 214, the crease in the fabric is stabilized for a long period of time.

  The exciter 232 has a structure in which a giant magnetostrictive element (not shown) made of an intermetallic compound based on a lanthanoid element and an iron group element is processed into a cylindrical shape and a coil (not shown) is wound around it. When a noise cancellation signal for generating sound for canceling noise from the cable 202 flows to the coil, the exciter 232 expands and contracts, and the acrylic plate 231 vibrates accordingly. Thereby, sound is generated from the flat speaker 201. The exciter 232 does not necessarily have to be attached to the upper end of the acrylic plate 231 and may be attached to another place where vibration is efficiently generated.

  FIG. 3 shows the configuration of the control box of this embodiment. The control box 203 includes a control unit 243 including a CPU (Central Processing Unit) 241 and a control program storage unit 242. The control program storage unit 242 is configured by, for example, a ROM (Read Only Memory) or a RAM (Random Access Memory), and the CPU 241 executes the control program stored therein to perform noise cancellation processing. ing. A part of the memory area of the control program storage unit 242 is a working memory.

  The control unit 243 is connected to each unit of the control box 203 and performs these controls. Among these, the 1st amplification part 245 amplifies the noise information from the microphone apparatus 205 (FIG. 1) which the noise collection receiver 246 provided with the antenna 204 received. The AD conversion unit 247 performs sampling and quantization for converting the analog level noise information amplified by the first amplification unit 245 into digital information. The frequency analysis / sound pressure measurement unit 248 performs frequency analysis on the digital noise information input from the AD conversion unit 247 and measures the sound pressure level. The analyzed frequency component and the sound pressure level of each frequency component are notified to the control unit 243.

  The band elimination filter unit 249 is a filter that removes signal components in a predetermined frequency band instructed by the control unit 243 from the digital noise information input from the frequency analysis / sound pressure measurement unit 248. The number of frequency bands that can be removed simultaneously by the band elimination filter unit 249 is arbitrary, and there may be no frequency band to be removed, or a plurality of frequency bands may be set to be removed simultaneously. The band elimination filter unit 249 and the frequency analysis / sound pressure measurement unit 248 constitute a circuit portion that is a feature of the present embodiment.

  The anti-phase canceling sound generating unit 250 generates digital anti-phase noise information having a phase opposite to that of the digital noise information input from the band elimination filter unit 249. The DA conversion unit 251 converts the digital antiphase noise information input from the antiphase cancellation sound generation unit 250 into analog antiphase noise information. The second amplification unit 252 is an amplifier that amplifies the analog antiphase noise information input from the DA conversion unit 251. The amplification factor of the second amplification unit 252 can be controlled from the control unit 243. The cable 202 is connected to the output side of the second amplifying unit 252 so that the amplified analog antiphase noise information is sent to this.

  The display unit 253 is composed of a display such as a liquid crystal display, and various visual information such as operation status, operation status, and setting status of the noise canceling apparatus 200 is displayed here. The operation unit 254 is an input unit for the user 216 of the room shown in FIG. 1 or a maintenance inspector to input various information as necessary, and includes a plurality of input keys (not shown).

  In the control box 203 of the present embodiment, an audio input unit 255 is also connected to the control unit 243. The audio input unit 255 changes the frequency characteristics by inputting audio signals such as music input from the input terminals 256 and 257 while the control unit 243 is in the audio output mode by the operation of the operation unit 254. The data is output to the second amplifying unit 252. This is because the flat speakers 201, 201,... Shown in FIG. 1 are used as audio speakers. Even when the control unit 243 is in the audio output mode, the noise is canceled. In this embodiment, the noise signal input from the microphone 261 and the audio signal such as music input from the audio input terminals 256 and 257 are input to the control box 203 as separate signals. In addition, the output from the audio input unit 255 reaches the second amplification unit 252 via a path that does not pass through the antiphase cancellation sound generation unit 250 and also reaches the antiphase cancellation sound generation unit 250 at the same time. At this time, the anti-phase cancellation sound generator 250 subtracts the signal component input via the audio input unit 255 from the signal input via the microphone 261 path. This is because the noise signal input through the microphone 261 path already includes audio signal components such as music sounded from the flat speakers 201, 201,... Of course, the sound pressure level of the audio signal to be subtracted can be appropriately adjusted using the operation unit 254. Next, an antiphase cancellation sound is generated based on the signal after the audio signal component is subtracted. The cancellation sound generated in this way hardly includes an antiphase component that becomes a cancellation sound for the signal input via the audio input unit 255. Therefore, the signal input via the audio input unit 255 can be left as an audible sound as the original sound, and in a situation where the noise is canceled, for example, music can be listened to and karaoke can be enjoyed.

  FIG. 4 shows the configuration of the microphone device. The microphone device 205 includes a microphone 261, an amplifier 262 that amplifies the noise information collected by the microphone 261, and a transmission unit 264 that transmits the noise information output from the amplifier 262 through the built-in antenna 263. The amplifier 262 and the transmission unit 264 are connected to the operation unit 265. The operation unit 265 is connected to a battery 266, and supplies power to the amplifier 262 and the transmission unit 264 when canceling noise, and adjusts the amplification factor. Here, the microphone 261 collects a mixture of both the surrounding sounds and the sounds output from the flat speakers 201, 201,... Shown in FIG.

  The operation when the noise canceling apparatus 200 configured as described above is set to a noise canceling mode other than the audio output mode will be described with reference to FIGS. The accordion curtain 214 shown in FIG. 1 is disposed immediately inside a window glass (not shown), and it is assumed that noise enters the room from the outside of the window.

  The microphone 261 of the microphone device 205 collects sound in a state where analog antiphase noise output from the flat speakers 201, 201,... And ambient noise including noise that has entered from the outside are mixed in the air. To do. The amplifier 262 amplifies these sounds and sends them to the transmission unit 264, which outputs them from the built-in antenna 263 as noise information.

  In the control box 203, the noise collection receiver 246 receives this noise information. The control unit 243 amplifies the received analog level noise information to an appropriate level according to a set value of a volume (not shown) of the operation unit 254. The AD conversion unit 247 converts the analog signal into a digital signal by sampling and quantizing the analog signal. The frequency analysis / sound pressure measurement unit 248 performs frequency analysis on the digital noise information and measures the sound pressure level for each frequency. Then, these results are notified to the control unit 243 at a predetermined cycle.

  The control unit 243 determines whether or not the frequency analysis / sound pressure measurement unit 248 notifies the frequency where the sound pressure exceeding the predetermined threshold value meets a specific condition every time notification is made. Band attenuation setting information is output to the band elimination filter unit 249 according to the individual determination results.

  FIG. 5 shows a state of output control of band attenuation setting information by the control unit. This will be described with reference to FIG. When the control unit 243 receives the notification from the frequency analysis / sound pressure measurement unit 248 (step S301: Y), the notification includes a sound whose sound pressure exceeds a predetermined threshold at a specific frequency registered in advance. It is checked whether or not (step S302). If there is a sound with such a specific frequency and sound pressure (Y), it is determined as a warning sound, and signal attenuation is prohibited for the corresponding specific frequency (step S303). Note that the sound pressure serving as the threshold can be adjusted by the user 216 using the operation unit 254. The user 216 can also perform new registration of a specific frequency and deletion of a registered specific frequency by using the operation unit 254. Of course, the maintenance inspector can also perform such adjustment based on the request of the user 216.

  If the above process is performed, the control part 243 will determine whether the sound of the sound pressure which exceeded the above-mentioned threshold value with frequencies other than a specific frequency continues (step S304). This determination is made every time a notification is received in step S301, when there is a sound whose sound pressure exceeds the threshold value at a frequency other than the specific frequency, this frequency is stored in the working memory of the control program storage unit 242. This is performed by processing that the sound of the frequency continues when the same frequency is stored continuously for a predetermined number of times. When it is determined that the sound having a sound pressure exceeding the threshold value is continued at a frequency other than the specific frequency as a result of this determination (Y), the frequency of the sound is stored in the work memory, and step S301 is performed. The signal of the frequency is attenuated by a predetermined length equal to or longer than the period in which the notification is received (step S305). Note that the sound information stored in the work memory may be deleted when the sounds are not continued.

  Next, the control unit 243 creates band attenuation setting information incorporating the content of the attenuation inhibition determined in step S303 and the content of attenuation determined in step S305 in this way, and sends the band attenuation setting information to the band elimination filter unit 249. (Step S306).

  The band elimination filter unit 249 receives this band attenuation setting information at the notification period in step S301 in FIG. Then, the frequency for prohibiting the attenuation and the frequency for the attenuation are set, the digital noise information passing through the frequency analysis / sound pressure measuring unit 248 is filtered according to the set content, and the anti-phase canceling sound generating unit 250. Therefore, when a warning sound having a sound pressure exceeding the threshold value is generated, the warning sound is output as it is from the flat speakers 201, 201,... And gives a warning to the user 216 in the room.

  In addition, when a sound having a sound pressure exceeding the above-described threshold is suddenly generated and continues for a predetermined time or longer, the start portion of the sound is not canceled by the flat speakers 201, 201,. The sound is output and recognized by the user 216 in the room, but the flat sound speakers 201, 201,... Therefore, the room user 216 recognizes the beginning of the sound, but no longer hears the sound. The start part of the sound is recognized. When a sound with a sound pressure exceeding the above-mentioned threshold value arrives, it is impossible to deal with various dangers by completely blocking the sound. This is a consideration. The operation unit 254 can be used to adjust the length of time to leave the start portion of the sound.

  The anti-phase canceling sound generation unit 250 generates digital anti-phase noise information having a phase opposite to that of the input digital audio signal, and supplies the digital anti-phase noise information to the DA conversion unit 251. The DA conversion unit 251 converts the digital antiphase noise information into analog antiphase noise information, and the second amplifying unit 252 amplifies it and outputs it to the cable 202.

  As a result, the flat speakers 201, 201,... Output noise information having the same sound pressure level in the opposite phase to the noise at the window that is likely to be a noise entrance. For this reason, the actually generated noise and the noise information output from the flat speakers 201, 201,... Are mixed in the air and cancel each other, thereby obtaining a noise canceling effect.

  Of course, the canceling sound output from the flat speakers 201, 201,... In this embodiment is a sound obtained by removing the audio component that satisfies the specific condition from the original noise and performing the anti-phase processing. Yes. Therefore, noise that satisfies a specific condition, such as a warning sound with a registered frequency, does not include an anti-phase component that becomes a cancellation sound, and these sounds can be left as audible sounds as original sounds. Similarly, since the sound input from other than the microphone is not subject to cancellation, for example, the audio can be used to play music from the flat speakers 201, 201,.

Thus, according to the noise canceling apparatus of the present embodiment, the exciter 232 shown in FIG. 2 is used for the flat speakers 201, 201,... Since the exciter 232 vibrates the acrylic plate 231 to output sound, the flat speakers 201, 201,... Can be included in the curtain, and there is no need to provide a new installation space. Noise can be canceled in an intact state.

  Moreover, the curtain is usually arranged on the window side of a room where noise often enters, and the area occupied in the room is often large. Therefore, compared with the case where a conventional box-type speaker is used, analog anti-phase noise information having a phase opposite to that of noise can be output from a wide area with essentially omnidirectional characteristics. For this reason, the listening angle can be expanded, flat frequency characteristics, and uniform sound pressure distribution are possible, so that a natural sound spreading space can be obtained, and a sound field with a little sense of incongruity can be created over a wide area. it can.

  In this embodiment, the signal sound pressure and duration of the noise are measured, and the frequency analysis is performed, so that the canceling sound having the opposite phase is not generated for the noise satisfying the specific condition. For this reason, sounds that are not desired to be canceled, such as warning sounds, can be excluded from cancellation.

  Furthermore, in the embodiment, even if it is not a sound of a frequency registered in advance, a sound that is continuously generated at a sound pressure exceeding a predetermined threshold is deleted except for its start time. Therefore, even when sound generation has an important meaning, it can be heard without missing it. In addition, when sounds other than the registered frequency are continuously generated as noise, they are often generated by work, so that this sound can be canceled from a certain point to ensure a quiet environment. .

  In the embodiment, since the audio input unit 255 is provided in the control box 203, music can be played or karaoke can be enjoyed using the flat speakers 201, 201,. Further, when a plurality of flat speakers 201, 201,... Are used as in the embodiment, it is possible to enjoy not only stereo reproduction but also audio reproduction using many speakers such as 5.1 channels. it can. Of course, when different sounds are output from a plurality of speakers, it is necessary to increase the number of circuits and cables for amplification.

  In the embodiment, the flat speaker 201 is included in the accordion curtain 214. However, the flat speaker may be similarly incorporated in a strip-shaped member constituting the blind. Further, the curtains other than the accordion curtain 214 can be divided into finely divided flat speakers so that sound can be output without disturbing the swing of the curtain fabric.

  Further, the exciter 232 shown in FIG. 2 is attached to a partition member such as a window glass, a floor, or a ceiling for partitioning a space in a place such as a house, an automobile, an airplane, or a railway vehicle, and without worrying about the installation space. , Noise can be eliminated. Thereby, for example, noise can be eliminated near a window of a conference room, a hotel lobby, a guest room of a bullet train, a window of a study, a shop window facing a road, or a passenger car window.

  Further, even when such a partition member is used as a flat speaker, frequency analysis is performed as in the present embodiment so that a canceling sound having an opposite phase is not generated for noise satisfying a specific condition. Thus, for example, a warning sound such as a horn of another vehicle when the present invention is applied to the vehicle can be secured. As a result, even the warning sound is not erased as noise or suppressed to a small sound that is difficult to hear, and the risk of causing a serious accident related to the human body can be avoided.

  In the embodiment, the control box 203 and the microphone device 205 are connected wirelessly. For example, a microphone may be attached to a table or stool (not shown) and wired to the control box 203 by wire. This eliminates the problem of battery exhaustion when the microphone device 205 is used, and also protects privacy because the microphone is not worn.

  Further, in the embodiment, for the sound pressure until the threshold value is exceeded, the normal cancellation process is performed on the noise, and the warning sound and the continuous sound are dealt with for the amount exceeding this threshold. Only a warning sound may be processed for a sound pressure exceeding the value, or a cancellation process may be performed only for a sound that continues for a predetermined time or more.

It is a principal part perspective view showing the principal part of the room using the noise cancellation apparatus in one Example of this invention. It is a top view showing the structure of the planar speaker used by a present Example. It is a block diagram showing the structure of the control box of a present Example. It is a block diagram showing the structure of the microphone apparatus of a present Example. It is a flowchart showing the mode of output control of the band attenuation setting information by the control part of a present Example. It is a block diagram showing the outline | summary of the structure of the conventionally proposed noise cancellation apparatus.

Explanation of symbols

200 Noise Canceling Device 201 Flat Speaker 203 Control Box 205 Microphone Device 214 Accordion Curtain 216 Room User 231 Acrylic Plate 232 Exciter 241 CPU
242 Control program storage unit 243 Control unit 246 Noise collection reception unit 248 Frequency analysis / sound pressure measurement unit 249 Band elimination filter unit 250 Antiphase canceling sound generation unit 255 Audio input unit 261 Microphone

Claims (6)

A microphone that inputs ambient sounds;
A sound pressure discriminating means by frequency for discriminating by frequency whether the sound input from the microphone is equal to or higher than a preset sound pressure;
A cancel sound generating means for generating a cancel sound for canceling a sound having a frequency lower than the preset sound pressure determined by the sound pressure determining means for each frequency;
A noise canceling apparatus comprising: a speaker that outputs the sound generated by the canceling sound generating means. A microphone that inputs ambient sounds;
A sound pressure discriminating means by frequency for discriminating by frequency whether the sound input from the microphone is equal to or higher than a preset sound pressure;
Warning sound registration determining means for determining whether a sound having a frequency equal to or higher than the preset sound pressure determined by the sound pressure determining means for each frequency is registered as a warning sound;
The sound pressure is equal to or higher than the preset sound pressure except for the sound having a frequency lower than the preset sound pressure determined by the sound pressure determining means for each frequency and the sound registered as the warning sound by the warning sound determining means. Canceling sound generating means for generating a canceling sound for canceling the sound of the frequency,
A noise canceling apparatus comprising: a speaker that outputs the sound generated by the canceling sound generating means. A microphone that inputs ambient sounds;
A sound pressure discriminating means by frequency for discriminating by frequency whether the sound input from the microphone is equal to or higher than a preset sound pressure;
A continuous sound discriminating means for discriminating whether or not a sound having a frequency equal to or higher than the preset sound pressure discriminated by the frequency-specific sound pressure discriminating means is inputted from the microphone continuously for a predetermined time or more;
A cancel sound is generated for canceling a sound having a frequency lower than the preset sound pressure determined by the sound pressure determining means for each frequency and a sound having that frequency after the time determined as a continuous sound by the continuous sound determining means. Canceling sound generating means;
A noise canceling apparatus comprising: a speaker that outputs the sound generated by the canceling sound generating means. The noise canceling device according to any one of claims 1 to 3, wherein the canceling sound generating means is a means for generating a sound having a phase opposite to that of the sound pressure to be canceled. A sound pressure discrimination step by frequency for discriminating by frequency whether the sound input from the microphone is equal to or higher than a preset sound pressure;
A cancel sound output step for generating a cancel sound for canceling a sound having a frequency lower than the preset sound pressure determined in the sound pressure determination step for each frequency and outputting the cancel sound from a flat speaker
And a noise canceling method. A sound pressure discrimination step by frequency for discriminating by frequency whether the sound input from the microphone is equal to or higher than a preset sound pressure;
A warning sound registration determination step for determining whether a sound having a frequency equal to or higher than the preset sound pressure determined in the sound pressure determination step for each frequency is registered as a warning sound;
The sound pressure is equal to or higher than the preset sound pressure except for the sound having a frequency lower than the preset sound pressure determined in the sound pressure determination step for each frequency and the sound registered as the warning sound in the warning sound determination step. A noise canceling method comprising: a canceling sound output step of generating a canceling sound for canceling a sound having a frequency and outputting the generated canceling sound from a flat speaker.

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