JP2012118334A - Noise canceling device and electrical equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable those present in a prescribed area under a noisy environment to listen to a prescribed sound.SOLUTION: A noise canceling device comprises: a microphone which, after detecting a first propagation sound wave from a surrounding noise source, converts the first propagation sound wave into a first electrical signal; a signal generating unit which, after receiving the first electrical signal converted into by the microphone, generates a first reverse phase electrical signal opposite to the first electrical signal; a first speaker which, after converting the first reverse phase electrical signal into a first interference sound wave to cancel the first propagation sound wave, outputs the first interference sound wave to a prescribed space; a second speaker which outputs a second interference sound wave to cancel a second propagation sound wave from a prescribed speaker to the microphone.

Description

  The present invention relates to a noise canceling device and an electrical apparatus, and more particularly to a technique preferably applied to reduce ambient noise and make it easier for listeners to listen to predetermined sounds and music.

  2. Description of the Related Art Conventionally, a noise canceling function (noise reduction function) for reducing ambient noise is mounted on headphones used when listening to music with a portable music player or a mobile phone. Also, a feedback method is known as a noise canceling function that is currently in practical use.

  In this feedback system, a microphone is installed inside the headphones, and an electrical signal (noise cancel signal) having an opposite phase is generated by inverting the phase of the electrical signal (noise signal) collected by the microphone. By supplying this noise cancellation signal to the headphone driver unit, an interfering sound wave that cancels the noise is output from the headphone, so that the noise heard by the user can be reduced.

  For example, Patent Document 1 discloses a noise canceling apparatus capable of performing noise cancellation that maximizes the effect of noise canceling at a point away from a microphone and a speaker. The noise canceling device includes a microphone, a main speaker, and a sub-speaker, outputs a noise cancellation signal having a phase opposite to that of the noise signal from the main speaker, and a signal having a low sound pressure in the same phase as the noise signal ( (Normal phase signal) is output. The noise cancellation signal and this positive phase signal are input to the microphone, and the noise cancellation signal having the same amplitude level as the noise cancellation signal observed at the observation point reaches the microphone by attenuating the noise cancellation signal with the positive phase signal. Like to do.

JP 2009-262887 A

  For example, at home appliance mass retailers, in addition to advertisements broadcasted at the mass retailers themselves, various sounds such as voices of customers and store clerk and sounds (voices and music) from products are mixed. Even in such a situation, it is desirable for manufacturers and sales companies that provide products to be able to allow customers who are interested to listen to explanation voices and advertising videos of certain products. It can be said that the noise canceling function is effective for the request. In other words, in order to let a customer hear a predetermined voice, a noise is collected and an interference sound wave that cancels the ambient noise is emitted to create a quiet state.

  The problem here is that, as shown in FIG. 5, the sound that is output for the customer to listen to reaches the microphone that collects the ambient noise to be canceled, and as a result, is directed to the customer. That is, an interference sound wave that cancels the generated voice is generated and output. That is, the voice that the customer originally listens to is canceled together with the surrounding noise, and only a quiet state is generated around the product.

  The invention of Cited Document 1 is a microphone provided at a point (near the speaker installation location) away from the observation point (where the user listens to the sound), and is equivalent to a noise cancellation signal that should be observed at the observation point. It is something that makes it possible to detect a noise cancellation signal of amplitude level (in other words, it actually creates a situation as if a microphone at a distant point is installed at the observation point), and in a noisy state This is not applicable when a person in a predetermined area wants to listen to a predetermined sound. Further, since the microphone is configured to detect not only ambient noise but also a noise cancellation signal from the main speaker, howling may occur.

  Therefore, in view of the circumstances described above, an object of the present invention is to enable a person in a predetermined area in a noisy state to listen to a predetermined sound.

  A noise canceling apparatus according to one aspect of the present invention acquires a first electric signal converted by a microphone, which detects a first propagation sound wave from a surrounding noise source and converts it into a first electric signal, A signal generation unit that generates a first negative-phase electric signal that has a phase opposite to that of the first electric signal, and a first interference sound wave that cancels the first propagation sound wave from the first negative-phase electric signal generated by the signal generation unit And a second speaker that outputs a second interfering sound wave for canceling the second propagation sound wave from the predetermined speaker toward the microphone.

  In the noise canceling device, the signal generation unit acquires a second electric signal that is an electric signal of the second propagation sound wave, and generates a second negative-phase electric signal that is opposite in phase to the second electric signal. The second speaker may convert the second reversed-phase electric signal generated by the signal generation unit into a second interference sound wave for canceling the second propagation sound wave, and output it to the microphone.

  In the noise canceling apparatus, the microphone may be disposed on the side opposite to the side where the first speaker outputs the first interfering sound wave.

  In the noise canceling apparatus, a soundproof wall for blocking the first interfering sound wave output from the first speaker may be disposed between the first speaker and the microphone.

  In the noise canceling device, the predetermined speaker may be a third speaker that is provided as a speaker of the own device and outputs the second propagation sound wave.

  An electric apparatus according to one aspect of the present invention is equipped with the above-described noise canceling device.

  According to the present invention, it becomes possible for a person in a predetermined area in a noisy state to listen to a predetermined sound.

It is a figure for demonstrating the mechanism of the noise canceling apparatus which concerns on embodiment of this invention. It is the block diagram which showed the structure of the noise canceling apparatus which concerns on embodiment of this invention. It is a basic diagram which showed the signal waveform of the propagation sound wave and interference sound wave of noise and advertisement sound in the embodiment of the present invention. It is the block diagram which showed the structure of the information processing apparatus which concerns on embodiment of this invention. It is a figure for demonstrating the mechanism of the conventional noise canceling apparatus.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is a diagram for explaining a mechanism of a noise canceling apparatus according to an embodiment of the present invention. Conventionally, as shown in FIG. 5, the sound detected by the microphone 110 as a canceling target includes voices from the store advertisement speakers 81 a and 81 b, voices uttered by store clerk and customers, and from the product explanation speaker 51. There is a problem in that the output sound is included, and an interference sound wave that cancels the sound of the explanation about the product or the advertisement is output from the speaker 120, so that the customer cannot hear the sound such as the product description.

  In the present invention, as shown in FIG. 1, an interference sound wave that cancels the sound that the customer wants to listen to is output to the microphone 11, and the sound (propagation sound wave) from the product explanation speaker 51 in the detection area of the microphone 11. ) Is negated. Then, the microphone 11 can detect a sound group other than the sound from the product explanation speaker 51 as ambient noise. With this configuration, the interference sound wave generated based on the propagation sound wave detected by the microphone 11 and output from the speaker a12 does not include a sound wave that cancels the sound of the product description from the product description speaker 51. A customer in the vicinity of a product in a bustling state at a mass store or the like can listen to the sound of the product description.

  Further, interference sound waves generated from sound waves detected by the microphone 11 reach the microphone 11 and are not detected. With this configuration, howling can be prevented.

  FIG. 2 is a block diagram showing the configuration of the noise canceling apparatus according to the embodiment of the present invention. The noise canceling apparatus 1 according to the present embodiment includes a microphone 11, a speaker a12, a speaker b13, a signal generation unit 15, an amplifier a16, an amplifier b17, and a communication unit 18. As shown in FIG. 1, the noise canceling apparatus 1 includes a soundproof wall 14 between a microphone 11 and a speaker a12.

  The microphone 11 detects a propagation sound wave from a surrounding sound source as noise to be canceled, and converts the detected sound wave into an electric signal (audio signal). The signal generation unit 15 receives an audio signal of ambient noise (hereinafter referred to as a noise audio signal) from the microphone 11 and generates an audio signal (hereinafter referred to as a noise cancellation signal) having an opposite phase to the noise audio signal. Output to a16. The amplifier a16 amplifies the noise cancellation signal input from the signal generation unit 15 and outputs the amplified signal to the speaker a12. The speaker a12 converts the noise cancellation signal input from the amplifier a16 into a sound wave, and outputs the sound wave as an interference sound wave that cancels the propagation sound wave detected by the microphone 11.

  The communication unit 18 acquires the audio data from the external device 5 that holds the product description audio data output from the product description speaker 51, and outputs the acquired audio data to the signal generation unit 15. The signal generation unit 15 receives an audio signal for product description (hereinafter referred to as an explanation audio signal) from the communication unit 18, generates an audio signal having an opposite phase to the explanation audio signal (hereinafter referred to as an explanation cancellation signal), and an amplifier. Output to b17. The amplifier b17 amplifies the explanation cancellation signal input from the signal generation unit 15, and outputs the amplified signal to the speaker b13. The speaker b13 converts the explanation cancellation signal input from the amplifier b17 into a sound wave, and outputs the sound wave as an interference sound wave that cancels the propagation sound wave (sound of the product explanation) from the product explanation speaker 51.

  Here, although the product explanation speaker 51 and the store advertisement speakers 81a and 81b may be ordinary speakers, the speaker a12 that outputs an interfering sound wave for noise and an interfering sound wave for the product description and advertisement sound are output. The speaker b13 to be used is preferably a super-directional speaker. As a space to create a quiet state, it is appropriate that it is a limited area rather than a wide area, and it is sufficient in the vicinity of the product for the purpose of listening to the explanation of the product and advertising in a noisy state. is there. Further, it is necessary to prevent the interference sound wave for the product description and the advertisement sound from reaching only the microphone 11 and not to the customer who listens to the sound. For this reason, as shown in FIG. 1, a super-directional speaker that can radiate interference sound waves from the speaker a12 only to the space near the product and radiate interference sound waves from the speaker b13 only to the space near the microphone 11. Is preferred.

  Ordinary speakers can emit sound waves in the audible band directly into a medium such as air through the diaphragm, and can propagate sound waves in the audible band in a relatively wide range by a diffraction effect. On the other hand, a super directional speaker is also called a parametric speaker, which modulates an audible band signal into an ultrasonic band signal as a carrier wave, amplifies it at a specific magnification, and then converts the modulated signal into an ultrasonic wave. The sound is input to a sound emitting unit composed of a vibrator or the like and radiated as a sound wave in an ultrasonic band into a medium such as air. The super directional speaker uses the nonlinearity of the medium through which sound waves propagate and the high directivity of the ultrasonic waves, and can transmit sound waves in the audible band only to persons within a specific spatial range. . Superdirective speakers have already been put into practical use and are not directly related to the features of the present invention.

  Note that the microphone 11 is non-directional and can detect sound around 360 °. The soundproof wall 14 is made of a material that reflects or absorbs sound, and prevents the interfering sound wave from the speaker a12 from reaching the microphone 11 as much as possible.

  FIG. 3 is a schematic diagram showing signal waveforms of propagation sound waves and interference sound waves of noise and advertisement sound in the embodiment of the present invention. FIG. 3A shows each of the propagation sound waves from each sound source. The P wave in the figure is the noise, and the Q wave is the sound propagation sound wave of the product description. In the conventional noise canceling apparatus shown in FIG. 5, the propagation sound waves detected by the microphone 110 are P waves and Q waves, and two waves are combined to detect sound waves having a waveform as shown in FIG. . The conventional noise canceling device generates an audio signal having a phase opposite to that of the propagation sound wave (FIG. 3B) detected by the microphone 110, and an interfering sound wave (waveform is not shown, but FIG. 3B). Output from the speaker 120. For this reason, not only the P wave but also the Q wave is canceled.

  The noise canceling apparatus according to the present embodiment outputs an interfering sound wave (Q ′ wave) having a waveform shown in FIG. The Q ′ wave shown in FIG. 3D is an interfering sound wave that cancels the Q wave in the opposite phase to the propagation sound wave (Q wave) from the product explanation speaker 51. The propagation sound wave (P wave + Q wave) in FIG. 3B and the interference sound wave (Q ′ wave) in FIG. 3D are combined, and only the P wave shown in FIG. Only the waves (propagating sound waves from the store advertisement speakers 81a and 81b) are detected. Then, an audio signal of a P ′ wave (FIG. 3C) having an opposite phase from the P wave detected by the microphone 11 is generated by the signal generation unit 15 and output from the speaker a12.

  The customer in the vicinity of the product reaches the propagation sound wave (P wave + Q wave) shown in FIG. 3B and the interference sound wave (P ′ wave shown in FIG. 3C) output from the speaker 12a. Only the Q wave shown in a) remains, and the customer listens to the Q wave (propagation sound wave from the product explanation speaker 51).

  When the noise source store advertisement speaker 81a (or 81b) and the speaker a12 that outputs noise interference sound waves are disposed relatively close to each other, it can be said that the distance to the customer is substantially the same, and there is almost no time lag. Can think. On the other hand, when both speakers are arranged relatively far away, some time lag occurs.

  For example, when the distance between the customer and the speaker a12 is 2 m and the distance between the customer and the store advertisement speaker 81a is 10 m, the time until the propagation sound wave from the store advertisement speaker 81a reaches the customer is for the customer and the store advertisement. This is obtained by dividing the distance of 10 m from the speaker 81a by the speed of sound (343.26 m / s when considered at a temperature of 20 ° C.). The time until the interference sound wave from the speaker a12 reaches the customer is the sum of the distance between the store advertisement speaker 81a and the speaker a12 (e.g., trigonometric function) and the distance 2m between the speaker a and the customer. The sound wave propagated from the store advertisement speaker 81a reaches the microphone 11 arranged near the speaker a12, and the interference sound wave is generated and output from the speaker a12). These differences are 5.2 ms, which is a time lag (phase difference). Since this 5.2 ms is a minute range as a phase difference, the propagation sound wave from the store advertisement speaker 81a is canceled by the interference sound wave from the speaker a12, and the sound of the product description from the product advertisement speaker 51 can be heard. It is considered that the advertisement sound is muted to a certain extent.

  The numerical value of 10 m is considered as a numerical value that will increase the delay in consideration of the sound in the store. However, in other words, the farther the store advertisement speaker 81 is arranged, the more the sound from the speaker reaches the customer and the speaker a12 at the same time. The time until the customer reaches the customer and the time until the interference sound wave from the speaker a12 reaches the customer is 5.8 ms, which is obtained by dividing the distance 2 m between the customer and the speaker a12 by the sound velocity. In any case, it can be said that the advertising sound is muted in the same manner as described above even though the phase difference is in a very small range.

  The noise canceling device according to the present embodiment may be arranged, for example, at a position 3 to 4 m above the product (about 2 m above the customer's head). This is because, when the display state of the product is considered, a spot at the top can create a spot in front of each product. Of course, since a speaker that outputs an interfering sound wave is closer to the customer, there is no delay in noise cancellation. Therefore, a noise canceling device may be installed in the product or installed in the product.

  FIG. 4 is a block diagram showing the configuration of the information processing apparatus according to the embodiment of the present invention, in which the above-described noise canceling apparatus is mounted. The information processing apparatus 2 of this embodiment is, for example, a PC or the like, such as a microphone 21, a speaker a22, a speaker b23, a signal generation unit 25, an amplifier a26, an amplifier b27, an audio data storage unit 31, an audio signal acquisition unit 32, an amplifier c33, A speaker c34 is provided. The microphone 21, the speaker a22, the speaker b23, the signal generation unit 25, the amplifier a26, and the amplifier b27 have the same functions as the respective units of the noise canceling apparatus 1 in FIG.

  The information processing apparatus 2 has a function of outputting the description of the own device, the sound of advertisements, or arbitrary contents (music, movies, etc.). The audio data storage unit 31 holds these audio data. The audio signal acquisition unit 32 acquires audio data reproduced from the audio data storage unit 31 and output from the speaker, and outputs the audio data to the signal generation unit 25 and the amplifier c33 as an audio signal. The reason for outputting to the signal generation unit 25 is to cause the signal generation unit 25 to generate a cancel signal for outputting as an interference sound wave from the speaker b23. The amplifier c33 amplifies the audio signal input from the audio signal acquisition unit 32 and outputs the amplified audio signal to the speaker c34. The speaker c34 converts the sound signal input from the amplifier c33 into a sound wave, and outputs the sound signal as an explanation of the own device, a sound of an advertisement, or an arbitrary content.

  The information processing apparatus 2 in FIG. 4 includes both a speaker c34 that outputs the description of the own device, the sound of advertising, or arbitrary content, and a speaker b23 that outputs an interfering sound wave that cancels them, but the microphone 21 is connected to the speaker a22. FIG. 1 is described by devising the arrangement of the microphone 21, the speaker a 22, and the speaker b 23, such as providing at a position where the output does not reach, and providing the speaker b 23 at a position where the output does not reach the customer and reaches the microphone 21. The present invention has a unique configuration.

  That is, an interference sound wave that cancels the sound that the customer wants to listen to is output from the speaker b 23 to the microphone 21 so that the sound (propagation sound wave) from the speaker c 34 is canceled in the detection area of the microphone 11. Then, the microphone 21 can detect a sound group other than the sound from the speaker c34 as ambient noise. Further, the interference sound wave output from the speaker a22 reaches the microphone 21 and is not detected, thereby preventing howling.

  The above-described embodiment is a preferred embodiment of the present invention, and the scope of the present invention is not limited to the above-described embodiment alone, and various modifications are made without departing from the gist of the present invention. Implementation is possible. For example, examples of the device equipped with the noise canceling device include electric devices such as a television device and an audio component in addition to the information processing device.

DESCRIPTION OF SYMBOLS 1 Noise canceling apparatus 2 Information processing apparatus 5 External apparatus 11, 21, 120 Microphone 12, 22 Speaker a
13, 23 Speaker b
14 Soundproof wall 15, 25 Signal generator 16, 26 Amplifier a
17, 27 Amplifier b
18 Communication unit 31 Audio data storage unit 32 Audio signal acquisition unit 33 Amplifier c
34 Speaker c
51 Speaker for product explanation 81 Speaker for store advertisement 110 Speaker

Claims (6)

A microphone that detects a first propagation sound wave from a surrounding noise source and converts it into a first electrical signal;
A signal generation unit that acquires the first electric signal converted by the microphone and generates a first negative-phase electric signal having a phase opposite to that of the first electric signal;
A first speaker that converts the first reversed-phase electrical signal generated by the signal generation unit into a first interference sound wave for canceling the first propagation sound wave, and outputs the first interference sound wave toward a predetermined space;
A second speaker that outputs a second interfering sound wave for canceling the second propagating sound wave from the predetermined speaker toward the microphone;
A noise canceling apparatus comprising: The signal generation unit acquires a second electric signal that is an electric signal of the second propagation sound wave, generates a second negative-phase electric signal that is opposite in phase to the second electric signal,
The second speaker converts the second antiphase electric signal generated by the signal generation unit into a second interference sound wave for canceling the second propagation sound wave, and outputs the second interference sound wave toward the microphone. The noise canceling device according to claim 1.   3. The noise canceling apparatus according to claim 1, wherein the microphone is disposed on a side opposite to a side where the first speaker outputs a first interference sound wave. 4. The sound insulation wall for interrupting | blocking the 1st interference sound wave output from the said 1st speaker is arrange | positioned between the said 1st speaker and the said microphone, The any one of Claim 1 to 3 characterized by the above-mentioned. The noise canceling device according to item.   5. The noise canceling apparatus according to claim 1, wherein the predetermined speaker is a third speaker that is provided as a speaker of its own device and outputs the second propagation sound wave. 6.   An electrical apparatus comprising the noise canceling device according to any one of claims 1 to 5.

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