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JPH0936784

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DESCRIPTION JPH0936784
[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a
noise control type handset using active noise control in a noisy environment.
[0002]
2. Description of the Related Art In recent years, there has been proposed an active noise control
type handset that silences the noise at the base of the ear by control noise from a speaker.
[0003]
Heretofore, this type of noise control type handset has generally been configured as shown in
FIG.
The configuration will be described below with reference to FIG. In the figure, the output signal
of the error detector 8 of the handset 13 is processed by the gain phase adjuster 18, a control
sound is produced from the control speaker 6, and is negatively fed back to the error detector 8.
On the other hand, the signal from the reception signal input terminal 11 is added to the output
of the gain phase adjuster 18 and is produced from the speaker 6. The detection signal of the
transmission microphone 10 is output to the transmission signal output terminal 12.
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[0004]
However, since the above-mentioned conventional noise control type handset is controlled
without making a distinction between the noise and the voice of the person when making a call
in a noisy environment, it is difficult to hear the voice of the person and transmission There was
a problem that noise could be mixed into the speech microphone and it would be difficult for
both parties of the communication to be able to make natural calls.
[0005]
The present invention is intended to solve the above-mentioned problems, and it is an object of
the present invention to provide a noise control type handset capable of hearing the voice of the
person even in a noisy environment and reducing the influence of noise on the other party.
[0006]
SUMMARY OF THE INVENTION In order to achieve the above object, the present invention firstly
provides n (n is an integer, n.gtoreq.1) noise detectors installed outside the handset and A first
adaptive filter group consisting of n pieces for inputting an output signal of each noise detector,
a second adaptive filter group consisting of n pieces for inputting an output signal of each noise
detector, a mouth of a talker A transmission microphone provided in the vicinity, a control
speaker provided near the ear of the handset, and an error detector provided near the ear of the
handset, the first output signal of the transmission microphone A second adaptation such that
the output signal of each of the adaptive filters is subtracted and the coefficients of each of the
first adaptive filters are updated such that the subtracted signal is smaller, and the output signal
of the error detector is smaller. Updating the coefficients of each of the filter groups, each of the
second adaptive filter groups By adding the output signal of the subtraction signal and the
reception signal from the receiver, input to the control speaker, comprising a transmitter output
signal to the transmitter the subtraction signal.
[0007]
Second, noise detectors with n (n is an integer, n 1 1) nondirectional characteristics installed
outside the handset, and n from which the output signals of the noise detectors are input First
adaptive filter group, n second adaptive filter group for inputting the output signal of each noise
detector, bi-directional characteristic with respect to the mouth direction, installed near the
mouth of the speaker A transmitting microphone directed to the direction of maximum
sensitivity, a delay unit for inputting the transmitting microphone signal, a control speaker
installed near the ear of the handset, and an error detector installed near the ear of the handset
And subtracting the output signal of each of the first adaptive filters from the output signal of the
delay, updating the coefficients of each of the first adaptive filters so that the subtracted signal
becomes smaller, and an error detector Of each second adaptive filter group so that the output
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signal of Is updated, the output signal of each of the second adaptive filter group, the subtraction
signal, and the reception signal from the receiver are added and input to the control speaker, and
the subtraction signal is transmitted to the transmitter As.
[0008]
Third, n (n is an integer, n ≧ 1) noise detectors installed outside the handset and a first adaptive
filter comprising n output signals from the noise detectors , A second adaptive filter group
consisting of n pieces for inputting the output signal of each noise detector, a transmitting
microphone installed near the mouth of the transmitter, and a voice detector for inputting the
transmitting microphone signal And 2 n switches for controlling the updating of the coefficients
of each adaptive filter by the output of the voice detector, a control speaker installed near the ear
of the handset, and near the ear of the handset An error detector, and when the output of the
voice detector does not occur, the output signal of the first adaptive filter group is subtracted
from the output signal of the transmitting microphone so that this subtraction signal becomes
smaller. Update the coefficients of each of the first adaptive filter group and The coefficient of
each of the second adaptive filters is updated so that the output signal of the filter becomes
smaller, and the switch is set so as not to update the coefficients of the respective adaptive filters
when the output of the voice detector is generated. The control signal, the output signal of each
of the second adaptive filter group, the subtraction signal, and the reception signal from the
receiver are added and input to the control speaker, and the subtraction signal is used as a
transmission output signal to the transmitter Become.
[0009]
Fourth, n (n is an integer, n 1 1) noise detectors, a head fixing device to which all or part of the
noise detectors are fixed, and output signals of the respective noise detectors A first adaptive
filter group consisting of n pieces, a second adaptive filter group consisting of n pieces for
inputting the output signal of each noise detector, and a transmitting microphone installed near
the mouth of the transmitter A control speaker installed near the ear of the handset and an error
detector installed near the ear of the handset, and subtracting the output signal of each of the
first adaptive filter group from the output signal of the transmitting microphone Then, the
coefficients of each of the first adaptive filters are updated so that the subtraction signal becomes
smaller, and the coefficients of each of the second adaptive filters are updated so that the output
signal of the error detector becomes smaller, The output signal of each of the second adaptive
filter group and the subtraction signal and the receiver It adds the received signal, input to the
control speaker, comprising a transmitter output signal to the transmitter the subtraction signal.
[0010]
The present invention reduces the noise mixed in the transmitting microphone by the first
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adaptive filter group according to the first configuration described above, and allows the
speaker's voice to be talked back by producing sound from the speaker. Since the voice with
reduced noise is transmitted to the other party of communication, both of the communication
can make a natural call.
[0011]
Further, the noise in the voice can be reduced more accurately by the installation position of the
delay unit and the noise detection microphone of the second configuration, the nondirectional
characteristic and the bi-directional characteristic of the transmitting microphone.
[0012]
In addition, with the voice detector of the third configuration, it is possible to look for a
malfunction due to voice of the adaptive filter, and voice communication with improved clarity
can be achieved.
[0013]
In addition, by increasing the distance between the control speaker and the noise detector by the
head fixing device of the fourth configuration, the calculation time of the adaptive filter can be
spared, the accuracy of the noise control is further improved, and the noise is further enhanced.
It can be reduced.
[0014]
A first embodiment of the present invention will be described with reference to FIG.
[0015]
This embodiment is characterized in that the noise mixed in the transmitting microphone is
reduced to improve the talkback of the voice of the user and the intelligibility of the
communication partner.
[0016]
In FIG. 1, 1 is a noise detector, 3 and 5 are adaptive filters, 6 is a control speaker, 8 is an error
detector, 10 is a transmitting microphone, 11 is a receiving signal input terminal, 12 is a
transmitting signal output terminal, 13 Is a handset.
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[0017]
The noise detector 1 is installed on the outer wall of the handset and detects noise coming from
the outside.
The adaptive filter 3 processes the noise detection signal and outputs a control output to a
control speaker 6 inside the handset.
On the other hand, the error detector 8 detects an error sound synthesized from the noise that
has entered the inside from the outside of the handset and the control sound of the control
speaker, and the LMS (Least Mean Square) method etc. The coefficients of the adaptive filter 3
are adjusted by
This reduces the noise near the ear.
The noise detection signal is also input to the adaptive filter 5, and the processed output signal is
subtracted from the detection signal of the transmitting microphone 10.
By the subtraction signal, the coefficient of the adaptive filter 5 is adjusted by the LMS method or
the like so that the subtraction signal becomes smaller.
As a result, the noise contained in the transmission signal is reduced, and this subtraction signal
is added to the control output signal of the adaptive filter together with the reception signal to
cause the control speaker 6 to produce a sound. As a result, it is possible for a person to realize a
natural communication environment where only the noise is reduced and the voice can be heard
well.
[0018]
Further, by transmitting this subtraction signal as a transmission signal, it is possible for the
communication partner to hear the voice with reduced noise.
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Therefore, by using the apparatuses of the present embodiment with each other even in a noisy
environment, natural calls with a good SN ratio can be made.
[0019]
Next, a second embodiment of the present invention will be described with reference to FIGS.
In addition to the effects of the first embodiment, the present embodiment is characterized in
that residual noise of the subtraction signal can be further reduced.
[0020]
In FIG. 2, 2 is a delay unit.
The noise detector 1 is disposed in the vicinity of the transmitting microphone 10, and its
directivity characteristic is set to the non-directivity shown in FIG.
Also, the characteristic of the transmitting microphone 10 is set to be bi-directional as shown in
FIG. 4, and as shown in FIG. 5, the direction in which the bi-directional positive phase soundvoltage conversion output can be obtained is directed to the mouth ing.
The other configuration is the same as that of the first embodiment.
[0021]
According to this configuration, first, the noise detector 1 is placed in the vicinity of the
transmitting microphone 10, so that the correlation between the output signal of the noise
detector 1 and the noise component of the detection signal of the transmitting microphone 10
becomes high. By delaying the transmission signal by a predetermined time according to 2, since
the calculation time of the adaptive filter 5 can be spared, it is possible to reduce the noise
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component in the transmission signal with high accuracy.
Also, by setting the noise detector 1 to non-directionality and the transmitting microphone 10 to
bi-directionality, as the combined directional characteristics of the subtraction signal, as shown in
FIG. Can be made less sensitive to noise.
Here, the direction of the arrow indicating the noise arrival direction, which is shown in FIG. 6,
points in the direction away from the mouth. Therefore, in addition to the first embodiment, this
embodiment can reduce the noise signal of the subtraction signal more greatly.
[0022]
Next, a third embodiment of the present invention will be described with reference to FIG. In
addition to the effects of the second embodiment, the present embodiment is characterized in
that the clarity of the audio signal in the subtraction signal is further improved.
[0023]
In FIG. 7, 15 is a voice detector, and 16 and 17 are switches. The other configuration is the same
as that of the second embodiment. With this configuration, the voice detector 15 detects whether
or not there is a voice signal in the output signal of the transmission microphone, and outputs a
detection signal when there is voice. For this detection, a general method of audio processing can
be used, such as detecting a difference from noise by a pattern of frequency characteristics in an
audio signal band for each time window. The output of the voice detector 15 controls the
opening and closing of the switch 16 and the switch 17. As a result, the input of the error input
signal to the adaptive filter 3 is shut off, and the input of the subtraction signal to the adaptive
filter 5 is shut off, so that the coefficient updating operation of the adaptive filters 3 and 5 is
stopped. As a result, when normal voice is not detected, the adaptive filters 3 and 5 perform
coefficient updating by the noise signal to control and reduce noise and noise signals in the
transmitting microphone, and when voice is detected, The above operation can be paused to
avoid the malfunction of the adaptive filter by voice. By this, it is possible to remove an adverse
effect such as muting of the audio signal, and clear voice communication becomes possible.
[0024]
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Next, a fourth embodiment of the present invention will be described with reference to FIG. The
present embodiment shows a configuration in which the second embodiment is applied to a
headset. In addition to the features of the second embodiment, this embodiment is characterized
by one noise detector for independent noise control of both channels of the headset, and the ear
noise for noise from the front. It has features that can be greatly reduced. In FIG. 8, 4 is an
adaptive filter, 7 is a control speaker, 9 is an error detector, 14 is a headset, and the other
configuration is the same as that of the second embodiment. With this configuration, the noise
detectors 1 of both channels can be shared, and one noise detector can be omitted as compared
with the case where the noise detectors are originally provided independently. In addition, by
installing the common noise detector 1 in the vicinity of the mouth of the transmitter
microphone, it is possible to take a distance from both control speakers at the ear, and the
operation time of the adaptive filter 3 and the adaptive filter 4 has a margin. The noise of both
channels can be reduced accurately.
[0025]
A fifth embodiment of the present invention will now be described with reference to FIG. In the
present embodiment, the noise detector of the fourth embodiment (see FIG. 8) is installed outside
the headset for both channels, ie, two each, and the output signal of each is processed by two
adaptive filters (ie, adaptive filter 4, 34 shows a configuration processed by two 34 and two
adaptive filters 3 and 33). This embodiment is characterized in that by providing two
independent noise detectors, it is possible to further reduce the ear noise to the side noise.
[0026]
In FIG. 9, 1 and 41 are noise detectors, and 33, 34 and 35 are adaptive filters. The other
components are the same as in the fourth embodiment.
[0027]
With this configuration, for example, the output signal of the noise detector 1 is input not only to
the adaptive filters 3 and 5 but also to the adaptive filter 4. Then, the processing output of the
adaptive filter 4 is added to the processing output of the adaptive filter 34 that processes the
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output of the noise detector 41 and is input to the control speaker 7. As a result, the noise from
both the left and right sides can be accurately controlled and reduced by the control sound of the
control speaker 7. Similarly, by performing the same processing on the output signal of the noise
detector 41, the control sound of the control speaker 6 can be accurately controlled and reduced
with respect to noise from both the left and right sides. Further, the noise signal mixed in the
transmitting microphone 10 is controlled by the adaptive filter 5 and the adaptive filter 35 so
that the noise signal remaining in the subtraction signal is better than in the case of one noise
detector. It can be reduced.
[0028]
Next, a sixth embodiment of the present invention will be described with reference to FIG. This
embodiment shows a configuration in which three noise detectors of the first embodiment (see
FIG. 1) are installed outside the handset and each output signal is processed by three adaptive
filters. This embodiment is characterized in that by providing three independent noise detectors,
it is possible to further reduce the ear noise to noise from a plurality of directions.
[0029]
In FIG. 10, reference numerals 41, 42 and 43 denote noise detectors, and 33, 34, 35 and 36
denote adaptive filters. The other components are the same as in the first embodiment.
[0030]
With this configuration, not only the output signal of the noise detector 1 is processed by the
adaptive filter 3, but also the outputs of the noise detector 41 and the noise detector 42 are
processed by the adaptive filter 33 and the adaptive filter 34, respectively. The outputs are added
and input to the control speaker 6. As a result, noise coming from a plurality of directions can be
well controlled and reduced by the control sound of the control speaker 6. Further, with regard
to noise mixed in the transmitting microphone 10, noise remaining by subtracting the control
output of the adaptive filters 5, 35 and 36 from the output signal of the delay unit 2 as in the
third embodiment (see FIG. 7) The signal can be reduced well.
[0031]
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Of course, the same effect as that of this embodiment can be obtained by installing an arbitrary
number n (n is an integer, n ≧ 1) of the noise detectors.
[0032]
A seventh embodiment of the present invention will now be described with reference to FIGS.
In this embodiment, when the headset is attached to a hat-shaped head fixing device such as a
helmet, the noise detector of the fifth embodiment (see FIG. 9) is installed on the outer wall of the
head fixing device. Is shown. FIG. 12 further shows a configuration in which the noise detector is
installed at the end of the collar of the head fixing device having the collar. In FIG. The other
components are the same as in the fifth embodiment. The noise detectors 42 and 43 shown in
FIG. 11 have the function of detecting the noise in the upper direction and the backward
direction, respectively, and can control and reduce the noise from all directions by the same
process as the fifth embodiment. Furthermore, as shown in FIG. 12, by installing the noise
detectors 1, 41, 43, 44 at the end of the collar of the head fixing device, the distance between the
control speaker and the noise detector can be extended, which is suitable. There is room for filter
operation time, the accuracy of noise control is improved, and noise can be further reduced.
Although the present embodiment has been described with reference to a hat-shaped head fixing
device, the noise detector may be attached to an antenna or a needle that has a shape that does
not cover the front of the head. Of course, the effect can be exhibited.
[0033]
As is clear from the above embodiments, according to the present invention, first, the voice of the
user is reduced by generating noise from the speaker while reducing the noise mixed in the
transmitting microphone by the adaptive filter group. Is talked back, and the voice with reduced
noise is also transmitted to the other party of communication, so that both of the communication
can make a natural call.
[0034]
Second, due to the installation positions of the delay unit and the noise detection microphone, the
non-directional characteristic and the bi-directional characteristic of the transmitting
microphone, the noise in the voice can be reduced more accurately.
[0035]
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Thirdly, the voice detector makes it possible to look for a malfunction due to the voice of the
adaptive filter, thereby enabling voice communication with improved clarity.
[0036]
Fourthly, by increasing the distance between the control speaker and the noise detector by
means of the head fixing device, the calculation time of the adaptive filter can be spared, the
accuracy of the noise control can be further improved, and the noise can be further reduced. .
[0037]
Brief description of the drawings
[0038]
1 is a block diagram of a first embodiment of the present invention.
[0039]
2 is a block diagram of a second embodiment of the present invention.
[0040]
3 is a directional characteristic diagram of the noise detector of the second embodiment of the
present invention.
[0041]
4 is a directional characteristic diagram of the transmission microphone of the second
embodiment of the present invention.
[0042]
5 is an installation view of a noise detector and a transmitting microphone according to a second
embodiment of the present invention.
[0043]
6 is a directional characteristic diagram of the subtraction signal of the second embodiment of
the present invention.
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[0044]
7 is a block diagram of a third embodiment of the present invention.
[0045]
8 is a block diagram of a fourth embodiment of the present invention.
[0046]
9 is a block diagram of a fifth embodiment of the present invention.
[0047]
10 is a block diagram of a sixth embodiment of the present invention.
[0048]
11 is a block diagram of a seventh embodiment of the present invention.
[0049]
12 is another configuration diagram of the seventh embodiment of the present invention.
[0050]
13 is a block diagram of a conventional noise control type handset.
[0051]
Explanation of sign
[0052]
1, 41, 42 noise detector 2 delay device 3, 4, 5, 33, 34, 35, 36 adaptive filter 6, 7 control speaker
8, 9 error detector 10 transmission microphone 11 reception signal input terminal 12
transmission signal Output terminal 13 Handset 14 Headset 15 Voice detector 16, 17 Switch
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