JP2005250389A - Sound leakage preventive device and its method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sound leakage preventive device which is used to prevent the leakage of sound while appropriately processing necessary sound in accordance with the purpose. <P>SOLUTION: The sound leakage preventive device is provided with: a microphone 110 for catching sound waves S1 from a sound source 100 and to convert the sound waves to electric signals and output the signals, a signal processor 130 for generating sound signals having inverse phases of the sound waves S1 from the sound source 100 based on the electric signals outputted from the microphones 110; and a speaker 140 for outputting sound waves S2 based on the sound signals from the signal processors 130. In the space behind the speaker 140, sound waves S1 from the sound source 100 are canceled by the sound waves S2 outputted from the speaker 140 and the sound waves S1 are muffled or reduced. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an apparatus and a method for preventing voices such as voices and sounds from being leaked to another person while capturing them with a microphone or a recording device.

  A mobile phone is a convenient device that allows you to talk to and communicate with the other party anytime, anywhere, but in places where there are many people or where quietness is required, there is a problem that utterances may be annoying to others. In many cases, use is prohibited. For this reason, there is a situation in which contact cannot be made despite urgent business. Moreover, if the utterance reaches the people around when using the mobile phone, there is a possibility that it may be a secret leak, which may cause a problem.

  As a method for avoiding such a problem of the mobile phone, Patent Document 1 discloses a leakage sound prevention device for a mobile phone. This device has a joint portion that can be fitted to the speaker's mouth and a soundproof tube connected to the joint portion, a sound collecting microphone is installed inside the soundproof tube, and a sound absorbing material behind the soundproof tube The muffler exhaust port with the attached is connected. A speaker speaks with a soundproof tube attached to his / her mouth so that the content of the utterance does not leak to others.

  Further, Patent Document 2 discloses a technique for muting or canceling an undesired sound such as noise. The electronic silencer of the same document radiates an additional sound having an opposite phase and the same sound pressure with respect to noise from a noise source, and forcibly produces a silencing effect by the sound wave interference.

  Patent Document 3 discloses a circuit for calculating a difference between a signal directly received by a first microphone and an output signal obtained through an adaptive filter from a second microphone as a general noise cancellation technique. Disclosure.

  Furthermore, Patent Document 4 discloses a crosstalk type microphone in which sound is confined in a loud sound environment and a receiver can recognize a target sound. Patent Document 5 discloses a structure in which a cup attached to an ear is attached to an end of a headband by an adjustable connector in a headset for reducing sound.

JP 2000-349882 A Patent 2541020 US Pat. No. 4,912,767 US Patent 6560345B1 US Pat. No. 4,756,028

  However, the leakage prevention method disclosed in Patent Document 1 requires that the sound speaker be attached to the mouth exactly so that the utterance content does not leak, which is unpleasant for the user and hinders the movement of the mouth itself. Therefore, there are problems such as difficulty in speaking and difficulty in breathing. Patent Documents 2 and 3 are techniques related to noise removal, and do not prevent a voice necessary for communication, recording, or the like from being leaked to others. Furthermore, the microphones and headset structures disclosed in Patent Documents 4 and 5 do not disclose or suggest a technique for preventing necessary voice leakage.

  The present invention solves the above-described conventional problems, and provides a sound leakage apparatus and method for preventing such sound leakage while appropriately processing sound such as necessary voice and sound according to the purpose. The purpose is to do.

  The sound leakage prevention apparatus according to the present invention captures sound waves from a sound source, converts at least one sound wave into an electric signal, and outputs the sound, and the sound from the sound source based on the electric signal output from the microphone. A signal processing unit that generates an audio signal having a phase opposite to that of the wave, and at least one speaker that outputs an audio wave based on the audio signal from the signal processing unit, and from the speaker in a space behind the at least one speaker. The sound wave from the sound source is canceled by the sound wave to be output. Thereby, at least in the space behind the speaker, the sound emitted from the sound source can be muted or reduced, and the leakage of the sound from the sound source behind the speaker can be prevented.

  The sound leakage prevention apparatus further includes a holding member that surrounds the sound source. At least one microphone is attached to the inside of the holding member, and at least one speaker is attached to the outside of the holding member. Outside, the sound wave of the sound source is canceled by the sound wave output from the at least one speaker. Since the sound from the sound source propagates radially, a microphone and a speaker are installed at the corresponding position, and the sound wave with the opposite phase is output therefrom, so that the sound can be effectively muted or reduced. it can.

  Preferably, a plurality of microphones are disposed inside the holding member, and a plurality of speakers are integrally disposed on the back side of the plurality of microphones. Thereby, each speaker can output the sound wave of the opposite phase of the sound wave captured by the respective microphone, and can cancel the sound wave more efficiently.

  Preferably, a signal processing unit is connected to each of the plurality of microphones, and each signal processing unit generates an audio wave having an opposite phase based on an electric signal from each microphone and outputs the sound wave to each speaker. It is possible to generate an audio wave having an opposite phase corresponding to the audio wave captured by each microphone.

  For example, the holding member has a spherical shape, and includes a mesh-like through hole. After the sound waves from the sound source pass through the mesh-shaped through holes, they interfere with the sound waves from the speakers and cancel each other. The holding member may include a sound absorber. Since the sound from the sound source is absorbed by the sound absorber and then canceled by the sound wave from the speaker, the sound can be effectively erased.

  The sound leakage prevention apparatus further includes a headset including a headphone, the headset fixes the holding member, and at least one microphone inside the holding member captures the voice wave of the speaker and is output from the microphone. Sound is output from the headphones based on the received electrical signal. The audio leakage prevention apparatus further has a communication function for transmitting and receiving audio signals to and from the communication terminal, transmits an electric signal of an audio wave captured by the microphone to the communication terminal, and receives sound from the headphones based on the audio signal from the communication terminal. Is output. As a result, the sound leakage prevention device can be applied to a hands-free head system, and the user can make a call without inconvenience.

  An audio leakage prevention method according to the present invention includes a step of capturing an audio wave from an audio source with a microphone, and an audio signal having an audio wave having a phase opposite to that of the audio wave from the audio source based on an electrical signal obtained from the microphone And a step of outputting a sound wave having an opposite phase based on the generated sound signal from the speaker and canceling the sound wave from the sound source by the sound wave from the speaker in a space behind the speaker.

  As described above, according to the present invention, while the sound from the sound source is captured by the microphone, the propagation of the sound to the space behind it is suppressed, or the sound is muted, and the sound source sound leaks. Can be prevented. Preferably, the sound of the sound source can be effectively erased by emitting a sound wave having an opposite phase from a speaker arranged so as to surround the sound source. In addition, by arranging a plurality of speakers and emitting sound waves having opposite phases, it is possible to more effectively erase or mute the sound and prevent leakage.

  Hereinafter, a preferred sound leakage prevention apparatus for preventing sound emitted from a sound source such as a speaker from leaking to the outside will be described.

  FIG. 1 is a block diagram showing an electrical configuration of a sound leakage prevention apparatus according to the first embodiment of the present invention. In FIG. 1, a sound leakage prevention apparatus 1 captures a sound wave from a sound source such as a speaker and converts it into an electric signal, an amplifier 12 that amplifies the electric signal from the microphone 10, and an amplifier 12 A / D converter 14 that converts the analog audio signal into a digital audio signal, and an antiphase that generates an audio signal having an audio wave that is 180 degrees different in phase from the audio wave emitted by the speaker based on the digitally converted audio signal A generator 16, a volume adjuster 18 that adjusts the output of the sound wave output from the speaker based on the digitally converted audio signal, and a D / D that converts the digital audio signal from the antiphase generator 16 into an analog audio signal. An A converter 20, an amplifier 22 that amplifies an analog signal from the D / A converter 20, and a voice based on the signal from the amplifier 22 And outputs the composed and a speaker 30.

  One of the electrical signals converted by the microphone 10 is output from the amplifier 12 to another device 24, and the signal is used for communication or used for recording or the like. Further, an electrical signal is supplied from the amplifier 12 to the antiphase generator 16, where an audio signal having an antiphase with the input audio signal is generated, and this signal is output from the speaker 30. The audio adjustment unit 18 adjusts the volume output from the speaker 30 via the amplifier 22. Thus, the sound wave having the same phase and the same volume as the sound wave of the sound source is output from the speaker 30, and the sound wave of the sound source is canceled by the interference by the sound wave, and mute or suppress the sound propagation is performed. .

  The amplifier 12, the A / D converter 14, the antiphase generation unit 16, the volume adjustment unit 18, the D / A converter 20, and the amplifier 22 are configured by one or a plurality of arithmetic processing chips 40 using a semiconductor integrated circuit. Can do. For example, the antiphase generation unit 16 can be configured by a processor such as a DSP. As a result, it is possible to output an audio wave having an opposite phase from the speaker in substantially real time from the time when the audio wave is captured by the microphone. For example, if the microphone 10 is installed in the vicinity of the sound source and the speaker 30 is installed within a few centimeters from the microphone 10, the speaker 30 reverses the time during which the sound propagates from the microphone 12 to the speaker 30. It is possible to output an audio wave of phase.

  Next, FIG. 2 shows a specific configuration example of the sound leakage prevention apparatus according to the second embodiment using the configuration of FIG. When the sound source 100 such as a speaker is centered, a plurality of microphones 110 (110-1, 110-2,... 110-n) are arranged at equidistant or concentric positions. The distance from the sound source 100 is within several centimeters, for example, 1 centimeter. These microphones 110 are preferably supported by a hemispherical cup 120. For example, as shown in FIG. 7, the hemispherical cup 120 includes support members 122 and 124 that extend horizontally and vertically, and a plurality of mesh-shaped through holes 126 are formed in places other than the points where the support members 122 and 124 intersect. ing. Each of the microphones 110 is disposed at a concentric equidistant distance from the sound source 100 on a position where the support members 122 and 124 intersect.

  Each microphone 110 is connected to the same number of signal processing devices 130 (130-1, 130-2,... 130-n) as the microphones, and a plurality of speakers so as to receive an output from the signal processing device 130. 140 (140-1, 140-2,... 140-n) are arranged. The signal processing device 130 includes the A / D converter 14, the antiphase generation unit 16, the volume adjustment unit 18, the D / A converter 20 and the like illustrated in FIG. Preferably, the microphone, the signal processing device, and the speaker are integrally formed and attached at a position where the support members 122 and 124 intersect. Note that the sound captured by the microphone 110 is used for feedback to the ear, recording, communication, editing, and the like, in addition to the purpose of calculating the reverse phase.

  The sound S1 emitted from the sound source 100 to an open space propagates radially. The microphone 110 positioned so as to cover the spread of the sound S1 collects the sound S1 and converts it into an electric signal. In addition, the voice S1 passes through the through hole 126 of the cup 120 and travels backward from there. Each signal processing device 130 calculates the reverse phase of the sound S1 based on the electrical signal from the microphone 110, and outputs the sound wave S2 having the reverse phase from the speaker 140 behind the microphone 110.

  Considering the time until the sound S1 passes through the microphone 110 and reaches the speaker 140, the signal processing device 130 generates an audio signal having an opposite phase within the arrival time. Each speaker 140 emits a sound S2 having a phase opposite to that of the sound S1 and the same volume as the sound volume S1. The sound S2 propagates radially from each speaker 140, merges with the sound S1 that has passed through the cup 120, and cancels the sound S1 by interference. Thereby, in the space from the sound source 100 to the cup 120, the sound S1 is preferably caught by the microphone 110, and behind the cup 120, the sound S1 is effectively canceled and silenced by the sound S2, and its propagation is suppressed. Is done. Since the sound waves S2 having opposite phases are emitted radially from the plurality of speakers 140, it is more effective to eliminate the sound S1.

  In FIG. 2, the microphone 110 and the speaker 140 that are positioned equidistantly or concentrically with respect to the sound source 100 are integrated with each other, but in addition to this, the microphone 110 and the speaker 140 have a certain distance. It can also be separated. For example, one microphone may be installed in the vicinity of the sound source 100 and an electric signal from the microphone may be transmitted to each signal processing device and the speaker. Alternatively, a signal processing device may be connected to a microphone, and an audio signal having an opposite phase may be output from the signal processing device to a plurality of speakers. In addition, when the microphone 110 and the speaker 140 are integrated with each other, the position where the microphone 110 and the speaker 140 are disposed is not necessarily equidistant or concentric with respect to the sound source 100, and the distance from the sound source 100 is It can be set freely. For example, the microphone and the speaker may be two-dimensionally or three-dimensionally arranged with respect to the sound source 100, and the number of the microphones and the speaker can be freely selected as appropriate.

  Next, a sound leakage prevention apparatus according to a third embodiment of the present invention is shown in FIG. In the figure, the same components as those in FIG. 2 are denoted by the same reference numerals. In the third embodiment, a sound absorber is further provided on the cup that supports the speaker 140. That is, a plurality of microphones 110 are embedded inside a spherical sound absorber 200 disposed so as to surround a part of the sound source 100. By outputting the sound of the opposite phase of the sound captured by the microphone 110 from the speaker 140, the sound absorber 200 prevents the leakage by the sound absorber 200 and then cancels the sound S1 by the sound S2 having the opposite phase. It is possible to more effectively reduce the voice leakage later.

  Next, an audio leakage prevention apparatus according to a fourth embodiment of the present invention is shown in FIG. In the fourth embodiment, the sound leakage prevention function is applied to the headset, and the voice of the speaker is transmitted to the ear of the speaker, and at the same time, the voice of the speaker is not leaked to the outside. . The headset 300 includes a head belt 310, a pair of headphones 320 connected to both ends of the head belt 310, a support member 330 attached to one of the head belts 310, and a silencer unit 340 attached to the support member. And. The silencer unit 340 has a sound leakage prevention function shown in FIG.

  The muffling unit 340 preferably has a plurality of microphones 344 attached to the inside of a cup-shaped member 342 and a plurality of speakers 346 attached to the back side thereof. In addition, a mute unit 340 accommodates a semiconductor arithmetic chip (not shown) for generating an antiphase audio wave or the like.

  Each microphone 344 of the muffler unit 340 is disposed, for example, at a distance of about 1 centimeter from the mouth of the speaker and captures the voice of the speaker. As in the case of the above embodiment, the electrical signal from the microphone 344 is generated by the semiconductor computing chip as an audio signal having a phase opposite to that of the voice S1 of the speaker. At the same time, the electrical signal from the microphone 344 is transmitted to the headphones 320 and input to the speaker's ear. The sound from the speaker is propagated as usual to the ring-shaped member 342 in the vicinity of the mouth, but is canceled by the sound waves output radially from the speakers 346 outside the cup-shaped member 342. For this reason, the voice of the speaker is prevented from propagating to the space exceeding the cup-shaped member 342, and the leakage of the voice is prevented.

  As in the second embodiment, the cup-shaped member 342 may be a member in which a plurality of mesh-shaped through holes are formed, or a structure using a sound absorber as in the third embodiment. Also good. In the latter case, the leaked voice can be further reduced.

  According to the fourth embodiment, even if the speaker speaks, the surrounding people cannot hear it, so no matter what place the English speaking practice or singing practice is conducted, it will not cause trouble for others. There is an effect. Also, when the voice of the speaker is fed back to the headphones, the pronunciation practice and correction effects can be enhanced by superimposing the pronunciation of the native speaker.

  Next, FIG. 5 shows an audio leakage prevention apparatus according to a fifth embodiment of the present invention. In the fifth embodiment, the fourth embodiment is improved and the headset is applied to a hands-free call system. In addition to the headset function of the fourth embodiment, the hands-free headset 400 has a function of communicating with the communication terminal 410 as shown in FIG.

  FIG. 6 shows an electrical configuration of the sound leakage prevention device used in the hands-free headset 400. In addition to the configuration of FIG. 1, the sound leakage prevention apparatus has a sound signal transmission / reception unit 26 that transmits and receives a sound signal to and from the communication terminal 410. The audio signal transmission / reception unit 26 preferably has a short-range wireless communication function such as Bluetooth, and transmits / receives an audio signal to / from the communication terminal 410. Of course, in addition to this, the communication terminal 410 may be connected by a wired cable. As the communication terminal 410, for example, a mobile phone or a PDA having a communication function can be used.

  The sound emitted from the speaker is converted into an electrical signal by the microphone 10, and the signal is used for preventing sound leakage, and is output from the headphone 24 to the ear of the speaker, and further from the sound signal transmitting / receiving unit 26. It is transmitted to the communication terminal 28. On the other hand, the audio signal received by the communication terminal 28 is received by the audio signal transmitting / receiving unit 26, and the signal is transmitted from the headphones 24 to the speaker. Thus, the speaker can make a call using the handsfree headset 400, and the voice of the speaker is canceled by the sound emitted from the speaker, and leakage to the outside is prevented.

  As described above, since the voice of the speaker does not leak around, there is an effect that even if a mobile phone is used in a public place or on a train, it does not cause trouble for people around.

  The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific embodiments, and various modifications can be made within the scope of the gist of the present invention described in the claims. Deformation / change is possible. In the above embodiment, the leakage of the voice from the speaker has been described, but the target voice may be a sound such as music or performance.

  The sound leakage prevention apparatus according to the present invention can be used in a call system, a sound system, and a sound space that perform sound output in a limited space, and the sound leakage prevention apparatus according to the present invention includes a computer device and a home electronic device. It can be used in combination with a device, a communication terminal, or the like.

It is a figure which shows the electrical constitution of the audio | voice leakage prevention apparatus which concerns on 1st Example of this invention. It is a figure which shows the structure of the audio | voice leakage prevention apparatus which concerns on a 2nd Example. It is a figure which shows the structure of the audio | voice leakage prevention apparatus which concerns on a 3rd Example. It is a figure which shows the structure of the audio | voice leakage prevention apparatus which concerns on a 4th Example. It is a figure which shows the structure of the audio | voice leakage prevention apparatus which concerns on a 5th Example. It is an electrical block diagram of the audio | voice leakage prevention apparatus which concerns on a 5th Example. It is a figure which shows a part of hemispherical cup.

Explanation of symbols

1: Audio leakage prevention device 10: Microphone 16: Reverse phase generation unit 30: Speaker 40: Arithmetic processing chip 100: Audio source 110: Microphone 120: Cup 130: Signal processing device 140: Speaker 300: Headset 400: Hands-free Headset 410: communication terminal

Claims (11)

At least one microphone that captures a sound wave from a sound source, converts the sound wave into an electrical signal, and outputs the electrical signal;
Signal processing means for generating an audio signal having an audio wave having a phase opposite to that of the audio wave from the audio source based on the electrical signal output from the microphone;
Having at least one speaker that outputs an audio wave based on an audio signal from the signal processing means;
An audio leakage prevention apparatus in which an audio wave from an audio source is canceled by an audio wave output from a speaker in a space behind at least one speaker. The sound leakage prevention apparatus further includes a holding member that surrounds the sound source. At least one microphone is attached to the inside of the holding member, and at least one speaker is attached to the outside of the holding member. The sound leakage prevention device according to claim 1, wherein a sound wave of a sound source is canceled by a sound wave output from at least one speaker outside. The sound leakage prevention apparatus according to claim 2, wherein a plurality of microphones are disposed inside the holding member, and a plurality of speakers are disposed on the back side of the plurality of microphones. 4. The signal processing means is connected to each of a plurality of microphones, and each signal processing means generates an audio wave having an opposite phase based on an electric signal from each microphone and outputs the sound wave to each speaker. The audio leakage prevention device according to any one of the above. The sound leakage prevention device according to claim 2, wherein the holding member has a spherical shape and includes a plurality of mesh-shaped through holes. The sound leakage prevention device according to claim 2, wherein the holding member includes a sound absorber. The sound leakage prevention apparatus further includes a headset including a headphone, the headset fixes the holding member, and at least one microphone inside the holding member captures the voice wave of the speaker and is output from the microphone. The sound leakage prevention device according to claim 1, wherein sound is output from the headphones based on the electrical signal. The sound leakage prevention device further includes a communication function for transmitting and receiving a sound signal to and from the communication terminal, transmits an electric signal of a sound wave captured by the microphone to the communication terminal, and outputs a sound signal from the communication terminal from the headphones. The sound leakage prevention device according to claim 7. The sound leakage prevention apparatus according to claim 8, wherein the communication terminal is a mobile phone, and the communication means transmits and receives a sound signal wirelessly with the mobile phone. Capturing sound waves from a sound source with a microphone;
Generating an audio signal having an audio wave in phase opposite to the audio wave from the audio source based on the electrical signal obtained from the microphone;
Outputting a sound wave having an antiphase based on the generated sound signal from the speaker, and canceling the sound wave from the sound source by the sound wave from the speaker in a space behind the speaker;
A method for preventing sound leakage. The audio leakage prevention method according to claim 10, further comprising a step of outputting an electric signal of an audio wave captured by the microphone to another device.

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