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JP2002082692

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DESCRIPTION JP2002082692
[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a
microphone device provided with a microphone array constituted by a plurality of microphones.
[0002]
2. Description of the Related Art Conventionally, as a voice detector for detecting only voice
signals from a predetermined direction, a microphone device provided with a microphone array
constituted by a plurality of microphones has been used. And, microphone devices are used in
applications that require speech detection. An example of the application is a voice recognition
device, and a microphone device is used as a voice detector of a voice recognition device for a
vehicle. Since there are many noises such as engine noise and wind noise in the passenger
compartment, such a microphone device is provided with a signal processing unit that removes
noise from an audio signal detected by the microphone array. That is, the conventional
microphone device includes a microphone array and a signal processing unit.
[0003]
However, in such a microphone device, since audio signals detected by a plurality of
microphones are processed, the frequency characteristic of the audio signal is changed from the
original sound at the time of the signal processing in the signal processing unit. There was a risk
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of change. Therefore, when the conventional microphone device is used for the voice recognition
device, there is a possibility that the recognition rate of the voice recognition device may be
lowered.
[0004]
Also, in recent years, it has been considered to use a microphone device together with a voice
recognition device for a hands-free telephone for a vehicle. That is, it has been considered to use
the microphone device as a voice detector for multiple applications. And if the said problem
arises in this case, while the recognition rate of a speech recognition apparatus will fall, there
exists a possibility that the hearing sense of hands-free telephone may worsen.
[0005]
Furthermore, the required frequency band may be different between the voice recognition device
and the handsfree telephone. That is, there are cases where the frequency band that can be easily
recognized by the speech recognition apparatus is different from the audible frequency band. For
this reason, for example, even if the frequency characteristic of the microphone device is optimal
for the speech recognition device, it is not optimal for the hands-free telephone. Therefore, it has
been difficult to improve both the recognition rate of the voice recognition device and the
audibility of the hands-free telephone.
[0006]
The present invention has been made in view of the above problems, and an object thereof is to
provide a microphone device capable of correcting the frequency characteristic of a detected
audio signal so as to be optimal for a plurality of applications. It is.
[0007]
SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, in the invention
according to claim 1, a plurality of microphones and a signal for removing noise contained in an
audio signal detected by the microphones. A microphone device comprising a processing unit,
comprising: a plurality of frequency characteristic correction means for respectively correcting
the frequency characteristic of the audio signal in a desired frequency band; and a starting means
for starting and stopping the respective frequency characteristic correction means Make it a gist.
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2
[0008]
According to the second aspect of the present invention, in the microphone device according to
the first aspect, the frequency characteristic correction means corrects the frequency
characteristic of the voice signal detected by the microphone so as to be optimal for a speech
recognition device. The gist of the present invention comprises at least a voice recognition
correction means, and an anti-person correction means for correcting the frequency
characteristic of the sound signal detected by the microphone so as to be optimum in the audio
frequency band.
[0009]
According to the third aspect of the present invention, in the microphone device according to the
first or second aspect, the frequency characteristic correction means corrects the frequency
characteristic of the audio signal processed by the signal processing means. As the abstract.
[0010]
Hereinafter, the "action" of the present invention will be described.
According to the first aspect of the present invention, the frequency characteristics of the
detected audio signal are corrected in the desired frequency band by the plurality of frequency
characteristic correction means.
And these frequency characteristic correction means are started by the starting means.
Therefore, when the microphone device is used for a plurality of applications requiring voice
detection, the frequency characteristics of the voice signal can be corrected to be optimal for
each application.
[0011]
According to the second aspect of the present invention, the frequency characteristic of the
speech signal is corrected by the speech recognition correction means so as to be optimal for the
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speech recognition device.
Further, the frequency characteristic of the audio signal is corrected by the interpersonal
correction means so as to be optimal in the audio frequency band. For this reason, when the
microphone device is used for the voice recognition device for a vehicle and the hands-free
phone for a vehicle, the recognition rate of the voice recognition device is improved, and the
audibility of the phone is improved.
[0012]
According to the third aspect of the present invention, even if the frequency characteristic of the
audio signal detected by each microphone changes due to signal processing, the frequency
characteristic of the audio signal is corrected, so that the frequency characteristic of the audio
signal Can be corrected with high accuracy.
[0013]
BEST MODE FOR CARRYING OUT THE INVENTION An embodiment in which the present
invention is embodied in a vehicle microphone device will be described in detail with reference to
FIGS. 1 and 2. FIG.
[0014]
As shown in FIG. 1, the microphone device 1 comprises a microphone array 2, a signal
processing unit 3, a speech switch 4 and a speech switch 5 as activation means, a first AND
circuit 6 and a second AND circuit 7. And a voice recognition correction unit 8 as a frequency
characteristic correction unit and a telephone correction unit 9.
[0015]
The microphone array 2 is composed of a plurality of (four in the present embodiment)
microphones 2a having the same characteristics and disposed at one place.
In the present embodiment, the microphone array 2 is disposed at the steering.
Then, when a voice is emitted from the operator (driver), the microphone array 2 detects the
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voice as coming from the front side.
Each microphone 2 a is electrically connected to an input terminal of the signal processing unit
3, and an audio signal detected by each microphone 2 a is input to the signal processing unit 3.
[0016]
The signal processing unit 3 is composed of an analog circuit, a digital circuit, or a digital signal
processor (DSP). Then, the signal processing unit 3 performs analog processing or digital
processing on the audio signal detected by the microphone array 2 to remove an audio signal
other than the audio signal from the specific direction as noise. Specifically, the signal processing
unit 3 identifies the input direction of the voice from the phase difference of the voice signal
input to each of the microphones 2a. Then, the voice signal other than the specific direction is
removed as noise, and the voice signal from which the noise is removed is output as a noise
removal signal. In the present embodiment, the signal processing unit 3 outputs an audio signal
input from the front to the microphone array 2 as a noise removal signal.
[0017]
The noise removal signal output from the signal processing unit 3 is input to the voice
recognition correction unit 8 via the first AND circuit 6 and to the telephone correction unit 9 via
the second AND circuit 7. It has been input.
[0018]
A speech switch 4 is connected to the input terminal of the first AND circuit 6, and when the
speech switch 4 is operated, the noise removal signal is inputted to the speech recognition
correction unit 8.
That is, the speech switch 4 is a start means for starting and stopping the voice recognition
correction unit 8.
[0019]
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5
A call switch 5 is connected to the input terminal of the second AND circuit 7, and the noise
removing signal is inputted to the telephone correction unit 9 when the call switch 5 is operated.
That is, the call switch 5 is an activation means for activating and stopping the correction unit 9
for telephone.
[0020]
More specifically, the speech switch 4 and the speech switch 5 are composed of push button
switches provided at locations easy to operate by the driver, such as steering, etc. Outputs an H
level signal to the Therefore, the AND circuits 6 and 7 output the noise removal signal to the
corresponding correction units 8 and 9 using the operation of the switches 4 and 5 as a trigger.
In the present embodiment, the noise removal signal is input to the voice recognition correction
unit 8 for a predetermined time when the speech switch 4 is operated. Further, when the call
switch 5 is operated, a noise removal signal is input to the telephone correction unit 9 until the
telephone line of the hands free telephone (not shown) is disconnected.
[0021]
The voice recognition correction unit 8 as a voice recognition correction unit and the telephone
correction unit 9 as an anti-human correction unit are each constituted by an analog circuit, a
digital circuit, or a DSP. The voice recognition correction unit 4 is electrically connected to a
voice recognition device (not shown). The telephone correction unit 5 is electrically connected to
a vehicle hands-free telephone (not shown).
[0022]
The correction units 8 and 9 perform the analog processing or digital processing on the audio
signal (noise removal signal) output from the signal processing unit 3 to obtain the optimum
frequency characteristic of the audio signal. To correct. That is, the speech recognition correction
unit 8 corrects the frequency characteristics of the speech signal so as to be optimum
characteristics in the frequency band in which the speech recognition device can easily recognize
the speech signal. For example, as shown in FIG. 2A, the speech recognition correction unit 8 cuts
frequency components other than between the frequency bands f1 and f2 that the speech
recognition apparatus can easily recognize. Then, the frequency characteristic between the
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frequency bands f1 and f2 is corrected to a desired characteristic. In the present embodiment,
the frequency f1 is set to 200 to 300 Hz, and the frequency f2 is set to 1⁄2 of the sampling
frequency of the speech recognition apparatus. Further, the frequency characteristic between the
frequency bands f1 and f2 is set so that the gain is flat. On the other hand, as shown in FIG. 2B,
the telephone correction unit 5 corrects the frequency characteristic of the audio signal so that
the gain becomes flat in the audio frequency band.
[0023]
In the microphone device 1 configured as described above, when the signal processing unit 3 and
the correction units 8 and 9 are formed by analog circuits, a low pass filter, a high pass filter, a
band pass filter, a band elimination filter, A combination of an integration circuit and an addition
circuit is used.
[0024]
When the signal processing unit 3 and the correction units 8 and 9 are constituted by digital
circuits, an FFT (Fast Fourier Transform) filter, an FIR (finite length impulse response) filter, and
an IIR (infinite impulse response) A filter or the like is used.
[0025]
Further, when the signal processing unit 3, the voice recognition correction unit 8 and the
telephone correction unit 9 are constituted by a DSP, an FFT filter, an FIR filter, an IIR filter or
the like constituted by a digital signal processing program is used. .
In this case, the coefficients of each filter for optimally correcting the audio signal are set in
advance as correction data in the processing program, and the frequency characteristics of the
audio signal are corrected based on the correction data.
[0026]
Therefore, according to this embodiment, the following effects can be obtained.
(1) The voice recognition correction unit 8 corrects the frequency characteristics of the voice
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signal detected by the microphone array 2 and subjected to the signal processing by the signal
processing unit 3 so as to be optimal for the voice recognition device. Therefore, the recognition
rate of the speech recognition device can be improved. Further, the frequency characteristic of
the audio signal detected by the microphone array 2 and subjected to the signal processing by
the signal processing unit 3 is corrected by the telephone correction unit 9 so as to be optimum
in the audio frequency band. For this reason, the hearing feeling of the hands-free telephone can
be improved. That is, when the microphone device 1 is used for a plurality of applications
requiring speech detection, the frequency characteristics of the speech signal can be corrected to
be optimal for each application.
[0027]
Furthermore, since the activation of the correction units 8 and 9 can be operated by the speech
switch 4 and the call switch 5, desired correction units 8 and 9 can be selected with certainty.
[0028]
(2) Even if the frequency characteristic of the audio signal detected by the microphone array 2
changes due to the signal processing in the signal processing unit 3, the frequency characteristic
of the changed audio signal is corrected by each of the correction units 8 and 9. Be done.
Therefore, the frequency characteristics of the audio signal can be corrected with high accuracy.
[0029]
(3) The speech switch 4 is provided as the activation means of the voice recognition correction
unit 8, and the call switch 5 is provided as the activation means of the telephone correction unit
9. That is, the respective correction units 8 and 9 are activated by operating the respective
switches 4 and 5. Therefore, the correction units 8 and 9 can be reliably activated, and erroneous
operation of the correction units 8 and 9 is unlikely to occur. Also, each correction unit 8, 9 can
be activated at the same time.
[0030]
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8
The embodiment of the present invention may be modified as follows. In the above embodiment,
the frequency characteristic correction means is embodied by the two correction units of the
speech recognition correction unit 8 and the telephone correction unit 9. However, the frequency
characteristic correction means may be embodied by three or more correction units. Further, the
frequency characteristic correction means may be embodied by only one of the speech
recognition correction unit 8 and the telephone correction unit 9.
[0031]
In the embodiment, the voice recognition correction unit 8 cuts frequency components other
than between the predetermined frequency bands f1 and f2, and the gain of frequency
components between the same frequency bands f1 and f2 is flat. The frequency characteristics
are corrected as follows. However, the speech recognition correction unit 8 may correct the
frequency characteristics of the speech signal in any way as long as the correction is not limited
to such correction but is optimum for the corresponding speech recognition device. For example,
the gain of the frequency component in the frequency band f1-f2 may be corrected to be higher
as the frequency component is higher.
[0032]
In the above embodiment, when the signal processing unit 3, the voice recognition correction
unit 8 and the telephone correction unit 9 are constituted by a DSP, the frequency characteristic
of the voice signal is set based on the preset correction data. I am trying to make corrections.
That is, the correction data is a fixed value. However, for example, the audio signal corrected
based on the correction data may be monitored again, and the correction data may be arbitrarily
changed based on the result. In this way, even if the frequency characteristic of the corrected
audio signal does not become the optimum frequency characteristic, the frequency characteristic
can be recorrected to the optimum one by finely adjusting the correction data. That is, in this
way, even if the degree of correction of the audio signal changes due to aging of the microphone
device 1, etc., the frequency characteristics of the audio signal can always be optimally corrected
by performing the correction in real time again. It will be.
[0033]
In the embodiment described above, the switches 4 and 5 capable of individually activating the
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correction units 8 and 9 are used as the activation means. However, one switch may be used as
the start-up means, and the start and stop of each of the correction units 8 and 9 may be
performed by the switch. Further, activation of the correction units 8 and 9 may be alternatively
switched by the same switch.
[0034]
The application connected to the correction unit 9 for telephones is not limited to hands-free
telephones, but outputs voice signals to people, such as vehicle loudspeakers and voice detectors
for radios for vehicles. Anything is applicable. In this case, the telephone correction unit 9 is a
loudspeaker correction unit or a radio correction unit.
[0035]
In the embodiment, the microphone device 1 for a vehicle is embodied. However, the microphone
device 1 may be embodied as an audio detector for applications other than for vehicles.
[0036]
Next, in addition to the technical ideas described in the claims, the technical ideas grasped by the
above-described embodiment will be listed below together with the effects thereof. (1) In the
microphone device according to any one of claims 1 to 3, the activation means is provided for
each of the frequency characteristic correction means, and the corresponding frequency
characteristic correction means is activated when the activation means is operated. To do.
According to the invention described in this technical idea (1), it is possible to prevent the
erroneous start operation of each correction means.
[0037]
(2) In the microphone device according to any one of claims 1 to 3, technical idea (1), each of the
correction means is constituted by an analog circuit, and the analog circuit processing of the
analog circuit is performed. Correct the frequency characteristics of the audio signal.
[0038]
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(3) In the microphone device according to any one of claims 1 to 3, technical idea (1), each of the
correction means is constituted by a digital circuit, and the digital circuit processing of the digital
circuit is performed. Correct the frequency characteristics of the audio signal.
[0039]
(4) In the microphone device according to any one of claims 1 to 3, technical idea (1), each of the
correction means is constituted by a digital signal processor (DSP), and a digital signal by the
DSP. Correcting the frequency characteristic of the audio signal by processing.
[0040]
(5) In a microphone device comprising a plurality of microphones and a signal processing unit
for removing noise contained in audio signals detected by the microphones, a desired one of the
audio signals processed by the signal processing unit is provided. A frequency characteristic
correction unit that corrects frequency characteristics of a frequency band; and a start unit that
starts and stops the frequency characteristic correction unit.
[0041]
(6) In the microphone device according to any one of the first to third aspects and the technical
idea (1) to (5), the microphone device is a voice detector for a vehicle.
[0042]
(7) A vehicular microphone device comprising a plurality of microphones and a signal processing
unit for removing noise contained in voice signals detected by the microphones, the microphone
device for a vehicle being used as a voice detector of an application for a vehicle A voice
recognition correction means for correcting the frequency characteristic of the voice signal
detected by the microphone to be optimal for the vehicle voice recognition device, and the
frequency characteristic of the voice signal detected by the microphone to be optimal for the car
telephone Correction means for the telephone, and activation means for starting and stopping
the correction means.
[0043]
As described above, according to the first aspect of the present invention, the frequency
characteristics of the detected audio signal can be corrected so as to be optimal for a plurality of
applications.
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[0044]
According to the second aspect of the present invention, when the microphone device is used for
a voice recognition device for a vehicle and a hands-free telephone for a vehicle, the recognition
rate of the voice recognition device and the audibility of the same are surely improved. be able to.
[0045]
According to the third aspect of the present invention, the frequency characteristics of the audio
signal can be corrected with high accuracy.
[0046]
Brief description of the drawings
[0047]
1 is a block diagram showing a schematic configuration of an embodiment of the present
invention is embodied in a vehicle microphone device.
[0048]
FIG. 2 (a) is a characteristic diagram showing the frequency characteristic of the voice signal
corrected by the voice recognition correction unit of the embodiment, and FIG. 2 (b) is the
frequency of the voice signal corrected by the telephone correction unit of the embodiment. The
characteristic diagram which shows a characteristic.
[0049]
Explanation of sign
[0050]
DESCRIPTION OF SYMBOLS 1 ... Microphone apparatus, 2 ... Microphone array, 2a ...
Microphone, 3 ... Signal processing part as a signal processing means, 4 ... Speech switch as a
starting means, 5 ... Call switch as a starting means, 8 ... Frequency characteristic correction
means, A voice recognition correction unit as a voice recognition correction unit, a frequency
correction unit as a frequency characteristic correction unit, and a telephone correction unit as a
personal correction unit.
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