JPH0830959B2 - Silencer - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a muffling device that reduces only noise in a listening room where stereo music signals and noise are mixed, for example, in a listening room of a general home or an automobile room.

2. Description of the Related Art Conventionally, noise has been a big social problem, and there has been a strong demand for reducing noise in living spaces. Until now, as a method of reducing the noise level, interior materials and sound insulation materials have been installed in the room, and surroundings of the noise source have been surrounded by sound insulation material such as metal or concrete. Due to the development of signal processing, silence technology using sounds with opposite phases has come to be used.

Hereinafter, a conventional silencer will be described with reference to the drawings.

FIG. 3 is a block diagram of a conventional silencer. In FIG. 3, 1a and 1b are microphones, 2 is an adaptive filter, 4 is a power amplifier, and 5 is a speaker.

The operation of the muffling device configured as described above will be described below.

The noise signal detected by the microphone 1a is input to the adaptive filter 2. The signal adaptively controlled here is reproduced by the power amplifier 4 and the speaker 5. Then, the reproduced sound and the noise from the noise source interfere with each other, and the interference sound is detected by the microphone 1b. The detected signal controls the adaptive filter 2. Therefore, the adaptive filter 2 adaptively controls the input signal so as to reduce the control signal, whereby the noise at the listening point cancels the reproduced sound and the noise is attenuated.

SUMMARY OF THE INVENTION However, the above-mentioned configuration has a problem that only noise cannot be attenuated in a space in which a necessary signal such as a music signal and noise are mixed.

The present invention is to solve the above-mentioned problems, and by using electroacoustic means, only noise is reduced and S / N is reduced.
The present invention provides a silencer that achieves the first object of improving the sound quality and the second object of further attenuating the crosstalk component of the music signal to improve the localization feeling.

Means for Solving the Problems To achieve the first object, a silencer of the first aspect of the present invention is a noise detector for detecting noise from a noise source, and a noise detector for adaptively controlling the detected noise signal. First and second L channel adaptive filters, first and second R channel adaptive filters which also adaptively control noise signals, and first and second L channel music signals which control L channel music signals from a sound source such as a CD player. A signal processing circuit,
The third that also controls the R channel music signal from the sound source
And a fourth signal processing circuit, and the first and second L
Output of channel adaptive filter and L from sound source
A first adder for adding the channel signal and a second adder for adding the outputs of the first and second R channel adaptive filters and the R channel signal from the sound source, and the first and second Amplifiers for amplifying the outputs of the respective adders, L-channel and R-channel speakers for reproducing the respective outputs, L- and R-channel error detectors for detecting noise at the listening point, and L-channel error detection First subtractor for subtracting the outputs of the first and fourth signal processing circuits from the output of the first and fourth signal processing circuits to obtain the control signals of the first L channel adaptive filter and the second R channel adaptive filter, and the R channel as well. Subtracting the outputs of the second and third signal processing circuits from the output of the error detector of the first R channel adaptive filter and the second R channel adaptive filter. And a second subtractor to control signals of the channel adaptive filter.

In order to achieve the first and second objects, a silencer of the second aspect of the present invention is a noise detector for detecting noise from a noise source and an L channel adaptive for adaptively controlling the detected noise signal. A filter, an R channel adaptive filter which adaptively controls a noise signal, a first signal processing circuit which controls an L channel signal from a sound source such as a CD player, and a second signal processing circuit which similarly controls an R channel signal from the sound source. A signal processing circuit, a first adder for adding the output of the L channel adaptive filter and the L channel signal from the sound source, and a first adder for similarly adding the output of the R channel adaptive filter and the R channel signal from the sound source. Second adder, a third signal processing circuit that controls the output of the first adder, and a fourth signal that controls the output of the second adder. A processing circuit, a first subtractor for subtracting the output of the fourth signal processing circuit from the output of the first adder, and a first subtractor for subtracting the output of the third signal processing circuit from the output of the second adder 2 subtractors, power amplifiers for amplifying the outputs of the first and second subtractors, L and R channel speakers for reproducing the outputs, and L and R channels for detecting noise at a listening point Error detector of
A third subtractor that subtracts the output of the first signal processing circuit from the output of the L channel error detector to obtain a control signal for the L channel adaptive filter, and similarly, outputs a second signal from the output of the R channel error detector. And a fourth subtractor which subtracts the output of the processing circuit to obtain a control signal for the R channel adaptive filter.

Action With the configuration of the first aspect of the present invention, the signal detected by the error detector is converted into only the noise signal by the signal processing circuit and the subtractor, and the noise signal is detected by the noise detector by using it as the control signal of the adaptive filter. The generated noise signal is adapted to reduce the noise at the listening point, and if it is added to the input signal such as the music signal and reproduced from the speaker, the noise in the room is reduced and the S / N is improved. The Rukoto.

According to the second aspect of the present invention, the signal detected by the error detector is converted into only the noise signal by the signal processing circuit and the third and fourth subtractors, which is used as the control signal of the adaptive filter. Allows the noise signal detected by the noise detector to be adapted to reduce the noise at the listening point,
If it is added to an input signal such as a music signal and reproduced from a speaker, noise in the room is reduced and S / N is improved. After the music signals are added, the crosstalk components of the L and R channels are canceled by the third and fourth signal processing circuits and the first and second subtractors. Since the components are attenuated, the sound image localization is improved.

Embodiment One embodiment of the first aspect of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram of a silencer according to an embodiment of the first invention. In FIG. 1, 1a, 1b,
1c is a microphone, 2a to 2h are adaptive filters, 3
a and 3b are adders, 4a and 4b are power amplifiers, 5a and 5b are speakers,
6a and 6b are subtractors, 7a to 7j are switches, 8 is a sound source device, and 9
Is a noise source.

The operation of the muffling device configured as described above will be described below. Here, in order to simplify the explanation, consider a case where the engine sound in the vehicle interior is silenced.

First, the engine is turned off, the switches 7i and 7j are turned to the b side, and the switches 7c and 7d are turned on. Other switches are turned off and the sound source device 8 is operated to reproduce only the L channel. Then, the signal reproduced from the L channel speaker 5a is detected by the microphone 1b, passes through the subtractor 6a and the switch 7i, and becomes a control signal for the adaptive filter 2c. The adaptive filter 2c adjusts the output so as to minimize this control signal. When the adjustment is completed, the switch 7c is turned off to stop the adaptation. As a result, the adaptive filter 2c moves from the adder 3a to the microphone 1b.
Approximate the transfer function up to. Similarly, the L-channel reproduced sound detected by the microphone 1c passes through the subtractor 6b and the switch 7j and becomes a control signal for the adaptive filter 2d. The adaptive filter 2d adjusts the output so as to minimize this control signal. Switch when adjustment is completed
Turn off 7d to stop adaptation. Thereby, the adaptive filter 2d approximates the transfer function from the adder 3a to the microphone 1c. Next, the switches 7e and 7f are turned on to reproduce only the R channel from the sound source device 8. As a result, similarly, the adaptive filter 2e approximates the transfer function from the adder 3b to the microphone 1b, and the adaptive filter 2f approximates the transfer function from the adder 3b to the microphone 1c.

When the adjustment of the adaptive filters 2c to 2f is completed, the switches 7i and 7j are turned to the a side and the switches 7a, 7b, 7g and 7h are turned on. All other switches are off. Here, the engine, which is the noise source, is turned on, and the sound source device 8 is also operated normally to output a stereo music signal. Microphone 1a
The noise signal detected by the adaptive filter 2a, 2b,
Input to 2g, 2h. The outputs are the adders 3a and 3b, respectively.
Then, the L channel music signal and the R channel music signal are added. And they are reproduced from the speakers 5a and 5b,
It is detected by the microphones 1b and 1c. In the subtractor 6a, the output of the microphone 1b is converted to the adaptive filter 2
The outputs of c and 2e are subtracted and used as the control signals of the adaptive filters 2a and 2h. Here, this control signal is only a noise signal because the crosstalk component of the L channel music signal reproduced from the speaker 5a and the R channel music signal reproduced from the speaker 5b to the microphone 1b has been canceled. Similarly, the control signals of the adaptive filters 2b and 2g are only noise signals. Therefore, only the noise signal is adaptively controlled by the four adaptive filters 2a, 2b, 2g, 2h. Here, if the noise signal in the microphone 1b becomes large, there are three possible causes. One is the fluctuation of the noise source 9, and one is the speaker.
This is an error of the noise control signal from 5a, and the other is an error of the noise control signal from the speaker 5b by the amount of crosstalk. For the first two, the adaptive filter 2a works to suppress it, and for the other one, the adaptive filter 2h works to suppress it. The same applies to the R channel. Therefore, the four adaptive filters 2a, 2b, 2g, 2h adapt so that the noises in the microphones 1b, 1c are attenuated.

As described above, according to the present embodiment, in the subtractors 6a and 6b, only the noise signal can be extracted by subtracting the outputs of the adaptive filters 2c to 2f from the signals detected by the microphones 1b and 1c, and The noise signal detected by the microphone 1a is adaptively controlled by the adaptive filters 2a, 2b, 2g, 2h by these control signals, and the noise signal is attenuated only at the listening point by adding the music signal with the adders 3a, 3b. Can be made. Therefore, you can enjoy a good S / N sound.

In the present embodiment, the transfer function from the adder 3a to the microphone 1b, the transfer function from the adder 3a to the microphone 1c, the transfer function from the adder 3b to the microphone 1c, and the adder 3b to the microphone 1b. The adaptive filters 2c to 2f were used to find the transfer function, but if these transfer functions are known from the beginning, the FI with fixed coefficients is used.
An R filter may be used.

Next, an embodiment of the second invention will be described with reference to the drawings.

FIG. 2 is a block diagram of a silencer according to an embodiment of the second invention. In FIG. 2, 1a, 1b,
1c is a microphone, 2a to 2f are adaptive filters, 3
a and 3b are adders, 4a and 4b are power amplifiers, 5a and 5b are speakers,
6a, 6b, 6c and 6d are subtractors, 7a to 7j are switches, 8 is a sound source device, and 9 is a noise source.

The operation of the muffling device configured as described above will be described below. Here, in order to simplify the explanation, consider a case where the engine sound in the vehicle interior is silenced.
First, the engine is turned off, the switches 7i and 7j are turned to the b side, and the switches 7c, 7f and 7h are turned on. The other switches are turned off and the sound source device 8 is operated to reproduce only the L channel. Then, the signal reproduced from the L channel speaker 5a is detected by the microphone 1b,
Adaptive filter 2c through subtractor 6a and switch 7i
Control signal. The adaptive filter 2c adjusts the output so as to minimize this control signal. Further, the crosstalk component detected by the microphone 1c is adjusted by the adaptive filter 2f to be minimum. When the adjustment is completed, the switches 7c and 7f are turned off to stop the adaptation. As a result, the adaptive filter 2c operates in the adder 3a.
To the transfer function from microphone to microphone 1b. Similarly, the adaptive filter 2f approximates the transfer function from the subtractor 6c to the microphone 1c. Next, the switches 7d, 7e,
Turn on 7g and play only the R channel from the sound source device 8. Accordingly, similarly, the adaptive filter 2d is
Approximate the transfer function from the adder 3b to the microphone 1b,
The adaptive filter 2e is connected to the microphone from the adder 6b.
Approximate the transfer function up to 1b.

When the adjustment of the adaptive filters 2c to 2f is completed, the switches 7i and 7j are turned to the a side and the switches 7a, 7b, 7g and 7h are turned on. All other switches are off. here,
The engine, which is a noise source, is turned on, and the sound source device 8 is also operated normally to output a stereo music signal. Microphone
The noise signal detected by 1a is applied to the adaptive filters 2a, 2
Entered in b. The respective outputs are adders 3a and 3b,
The L channel music signal and the R channel music signal are added. Further, its output is controlled by the adaptive filters 2e, 2f, and the subtracters 6c, 6d subtract the outputs of the adaptive filters 2e, 2f from the outputs of the adders 3a, 3b.
Then, they are reproduced from the speakers 5a and 5b, respectively, and detected by the microphones 1b and 1c. Where this detection signal is
The crosstalk components of the L channel and the R channel are canceled by the adaptive filters 2e and 2f. Next, in the subtractor 6a, the output of the adaptive filter 2c is subtracted from the output of the microphone 1b to obtain a control signal for the adaptive filter 2a. Here, this control signal is only a noise signal because the crosstalk component of the L channel music signal reproduced from the speaker 5a and the R channel music signal reproduced from the speaker 5b to the microphone 1b has been canceled. Similarly,
The control signal of the adaptive filter 2b is also only the noise signal. Then, these two adaptive filters 2a and 2b perform adaptive control so that only the noise signal is attenuated.

As described above, according to the present embodiment, the crosstalk components of the L channel and the R channel are canceled by the subtracters 6c, 6d and the adaptive filters 2e, 2f, and they are canceled by the subtractors 6a, 6b. Only the noise signal can be taken out by subtracting the outputs of the adaptive filters 2c and 2d from the detection signal.Furthermore, the noise signal detected by the microphone 1a is adaptively controlled by the adaptive filters 2a and 2b by these control signals, and the adder is added. 3a, 3b
Only the noise signal can be attenuated at the listening point by adding to the music signal at. Therefore, you can enjoy a good S / N sound. In addition, by using the signal after adding the music signals to cancel the crosstalk component of the L and R channels, the crosstalk component of the music signal itself is reduced, so a sound field with an excellent localization feeling is created. realizable.

In this embodiment, the transfer function from the adder 3a to the microphone 1b, the transfer function from the adder 3a to the microphone 1c, the transfer function from the subtractor 6c to the microphone 1c, and the subtractor 6d to the microphone 1b. The adaptive filters 2c to 2f were used to find the transfer function, but if these transfer functions are known from the beginning, the FI with fixed coefficients is used.
An R filter may be used.

As described above, according to the first aspect of the present invention, the music signal is controlled by the signal processing circuit, and the music signal is subtracted from the signal detected by the error detector by the subtracter, so that the L channel and the R channel are separated. Noise signals can be extracted by canceling the crosstalk between the music signal and the L and R channels, and the noise detected by the L and R channel noise detectors can be controlled by controlling the adaptive filter using this control signal. Only the noise can be attenuated at the L and R channel listening points by adapting the signals to be attenuated, and adding the signals and the music signals by an adder to reproduce. Further, since the field back from the error detector is used as the control signal of the adaptive filter, it is possible to realize a silencer capable of obtaining a number of excellent effects such as stable operation.

The second aspect of the present invention cancels the crosstalk between the L and R channels by the third and fourth signal processing circuits and the first and second subtractors, and the first and second signal processing circuits. To control the music signal and subtract it from the signal detected by the error detector by the third and fourth subtractors to cancel the L channel and R channel music signals and extract only the noise signal. By controlling the adaptive filter using this control signal, the noise signal detected by the L and R channel noise detectors is adapted to be attenuated respectively, and the signal and the music signal are added by the adder. L and R
Only noise can be attenuated at the channel listening point. Further, since the field back from the error detector is used for the control signal of the adaptive filter, it is possible to realize a silencer capable of obtaining various excellent effects such as stable operation.

[Brief description of drawings]

FIG. 1 is a block diagram of a silencer according to an embodiment of the first present invention, FIG. 2 is a block diagram of an embodiment of the second present invention, and FIG. 3 is a block diagram of a conventional silencer. . 1a, 1b, 1c …… Microphone, 2,2a, 2b, 2c, 2d, 2e, 2f, 2g, 2
h ... adaptive filter, 3a, 3b ... adder, 4,4a, 4
b, 4c, 4d …… Power amplifier, 5,5a, 5b …… Speaker, 6a, 6b,
6c, 6d …… Subtractor, 7a, 7b, 7c, 7d, 7e, 7f, 7g, 7h, 7i, 7j ……
Switch, 8 ... Sound source device, 9 ... Noise source.

Front page continuation (72) Tomokazu Suzuki Inventor 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (72) Ryoji Suzuki, 1006 Kadoma, Kadoma City, Osaka Matsushita Electric Industrial Co., Ltd.

Claims (10)

[Claims] 1. A noise detector for detecting noise from a noise source, first and second L channel adaptive filters for adaptively controlling the detected noise signal, and first and second R channel adaptive filters. First and second signal processing circuits for controlling the L channel music signal from the sound source, third and fourth signal processing circuits for controlling the R channel music signal from the sound source, and the first and second A first adder for adding the output of the L channel adaptive filter and the L channel signal from the sound source;
A second adder for adding the outputs of the first and second R channel adaptive filters and the R channel signal from the sound source; and a power amplifier for amplifying the outputs of the first and second adders, respectively. L to play each output
Channel and R channel speakers, L channel and R channel error detectors for detecting noise at the listening point, and outputs of the first and fourth signal processing circuits from outputs of the L channel error detectors. The first
Subtracting the outputs of the second and third signal processing circuits from the outputs of the R channel error detector and the R channel error detector, and the L channel adaptive filter and the second R channel adaptive filter control signals. And a second subtractor which is a control signal for the first R-channel adaptive filter and the second L-channel adaptive filter. 2. The silencer according to claim 1, wherein the first signal processing circuit is a digital filter which approximates a transfer function from the first adder to the L channel error detector. 3. The silencer according to claim 1, wherein the second signal processing circuit is a digital filter which approximates a transfer function from the first adder to the R channel error detector. 4. The silencer according to claim 1, wherein the third signal processing circuit is a digital filter which approximates a transfer function from the second adder to the R channel error detector. 5. The silencer according to claim 1, wherein the fourth signal processing circuit is a digital filter which approximates a transfer function from the second adder to the L channel error detector. 6. A noise detector for detecting noise from a noise source, an L-channel adaptive filter and an R-channel adaptive filter for adaptively controlling the detected noise signal, and a first for controlling an L-channel signal from a sound source.
Signal processing circuit, a second signal processing circuit for controlling the R channel signal from the sound source, a first adder for adding the output of the L channel adaptive filter and the L channel signal from the sound source, and the R channel A second adder for adding the output of the adaptive filter and the R channel signal from the sound source; a third signal processing circuit for controlling the output of the first adder; and an output of the second adder. A fourth signal processing circuit for controlling; a first subtractor for subtracting the output of the fourth signal processing circuit from the output of the first adder; and a third subtracter for outputting the output of the second adder. Second subtractor for subtracting the output of the signal processing circuit, a power amplifier for amplifying the outputs of the first and second subtractors, L and R channel speakers for reproducing the respective outputs, and listening In points An L and R channel error detector for detecting sound, and a third subtraction for subtracting an output of the first signal processing circuit from an output of the L channel error detector to obtain a control signal of the L channel adaptive filter. And a fourth subtractor for subtracting the output of the second signal processing circuit from the output of the R channel error detector to obtain a control signal of the R channel adaptive filter. apparatus. 7. The silencer according to claim 6, wherein the first signal processing circuit is a digital filter which approximates a transfer function from the first adder to the L channel error detector. 8. The silencer according to claim 6, wherein the second signal processing circuit is a digital filter which approximates a transfer function from the second adder to the R channel error detector. 9. The silencer according to claim 6, wherein the third signal processing circuit is a digital filter which approximates a transfer function from the first subtractor to the R channel error detector. 10. The fourth signal processing circuit is a digital filter which approximates a transfer function from the second subtractor to the L channel error detector.
The silencer described.