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JPH1021047

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Notice
This translation is machine-generated. It cannot be guaranteed that it is intelligible, accurate,
complete, reliable or fit for specific purposes. Critical decisions, such as commercially relevant or
financial decisions, should not be based on machine-translation output.
DESCRIPTION JPH1021047
[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is used in
voice communication and voice recognition which a user implements toward a display such as a
computer, and in particular, suppresses noise and suppresses noise for appropriately collecting
the voice of the user. The present invention relates to a sound collecting device.
[0002]
2. Description of the Related Art In recent years, with the progress of multimedia technology,
voice communication and voice recognition are becoming possible by connecting a microphone
and a speaker to a computer. In that case, there is a demand for a sound collection device that
collects only target sound such as voice without collecting unnecessary sound such as air
conditioning sound and keyboard typing sound. Also, in the case of a loud-phone call using a
speaker and a microphone, the voice of the other party (callee) emitted from the speaker is often
picked up by the microphone and often becomes an obstacle, so the target utterer does not pick
it up. There is a need for a sound collection device that collects only voice.
[0003]
As an example of such a sound collection device, there is a sound collection device that installs a
plurality of microphones (microphone arrays) and processes the outputs of the microphones to
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extract a target sound. There are many known signal processing methods for suppressing noise
and extracting the target sound using such a microphone array, such as the delay sum method
and AMNOR, but in the delay sum method, for example, the target sound is extracted as follows
Do.
[0004]
FIG. 3A is a diagram for explaining the principle of target sound extraction according to the delay
and sum method. The sound pickup unit (microphone array) 1 is configured such that the
microphones 21, 22, ..., 2M (M is the number of microphones) are linearly arranged at equal
intervals d, and the sound wave s (t) (t represents time) is It is assumed that the microphones that
are linearly arranged come from a distance at an angle θ. At this time, the distance that the
sound wave that has reached the microphone 21 propagates until it reaches the microphone 22
is represented by dsinθ from the microphone distance d and the arrival angle θ. Similarly, the
distance that the sound wave that has reached the microphone 21 propagates until it reaches the
i-th microphone 2i (i = 2,..., M) is represented by (i-1) d sin θ. Therefore, the delay time τi until
the sound wave reaching the microphone 21 reaches the microphone 2i (i = 2,..., M) is expressed
by the following equation (1) by dividing this propagation distance by the speed of sound c.
[0005]
τ i = (i−1) d sin θ / c (1) Here, when the output signal from each microphone 2 i (i = 1,..., M) is
represented by xi (t), this means that the sound wave s (t) is τ i Because it is delayed, it becomes
like a following formula (2). xi (t) = s (t-τi) (2) Here, the output signal xi (t) of each microphone
2i is added by the adder 4 through the delay unit 3i, respectively, and the delay unit 3i (i = 1, 2, ,
M), the output signal 5 can be obtained as the output of the adder 4 by emphasizing only the
sound wave coming from the θ direction. This is shown below.
[0006]
The delay amount Di of the delay device 3i (i = 1, 2,..., M) is set as in the following equation (3). Di
= Do-.tau.i (3) Do is a fixed delay amount to be added in order to prevent the accuracy in realizing
the delay characteristic with a digital filter when the value of .tau.i is too small.
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[0007]
At this time, the output of the delay device 3i (i = 1, 2,..., M) is given by the following equation (4)
since the delay Di of the equation (3) is generated in the signal of the equation (2) . xi (t-Di) = s (tτi-Di) = s (t-τi-(Do-τi)) = s (t-Do) (4) That is, regardless of the number i of the microphone 2i
(T) becomes the same signal delayed by Do.
[0008]
After the phases are aligned in this way, the signals are added together by the adder 4 and the
sound waves coming from this θ direction are emphasized by the added amount. On the other
hand, since the sound waves coming from the θN direction different from the θ direction are
received with a delay time τN different from τi, the delay amount of equation (3) does not
match the phase, and the adder 4 adds the signals. It will not be emphasized even in combination.
[0009]
Thus, in the delay-sum method, the sound wave coming from the target direction θ is
emphasized, and the noise coming from the other direction θN is relatively suppressed. That is,
the delay unit 3i and the adder 4 constitute a noise suppression unit 6. Conventionally, it has
been proposed that a microphone array used in this delay-sum system be disposed at the upper
end of the display 11 as being arranged linearly as shown in FIG. 3B.
[0010]
SUMMARY OF THE INVENTION The conventional microphone array suppresses noise and the
like generated from the cooling fan of a device such as a printer disposed around the display
when the sound is collected. It was effective. However, a sufficient noise suppression effect has
not been obtained with respect to air conditioning noise blown out from the ceiling and noise
such as keying sound generated from the computer keyboard. The following causes were found
as a result of examining for what reason a sufficient noise suppression effect could not be
obtained.
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[0011]
Now, as shown in FIG. 3C, the microphone 1i (i = 1, 2,..., M) is installed parallel to the x-axis in the
coordinate axes x, y, z of the three-dimensional rectangular coordinate system. It comes from
within the plane. That is, the target sound and noise both come from the yz plane perpendicular
to the microphone array 1i parallel to the x axis. This corresponds to the situation in FIG. 3A in
which both the target sound and the noise are coming from the same θ = 0 ° direction. At this
time, according to the equation (1), the arrival delay times τs and τN to the respective
microphones 2i are both zero for the target sound arriving from the θs direction and the noise
arriving from the θN direction. That is, both the target sound and the noise reach the
microphones 2i simultaneously. Since the delay times .tau.s and .tau.N of the target sound and
the noise are equal as described above, the noise can not be suppressed because the noise is
enhanced together with the target sound even if the signals having the same phase are added by
the noise suppression unit 6.
[0012]
In the linear microphone array in which the microphones are arranged horizontally in this
manner, it is apparent from the above consideration that noise suppression can not be performed
when both the target sound and the noise are incident from within a plane perpendicular to the
microphone array. became.
[0013]
According to the present invention, according to the present invention, a frame is provided which
is externally attached to a display, and a plurality of microphones are vertically and horizontally
arranged and attached to the frame, and the outputs of these microphones are output. Is input to
the noise suppression unit, and only the sound in the target direction is intensified or the noise
component is weakened, and the sound in the target direction is extracted.
[0014]
The outer frame of the display filter is used as the frame.
For example, as shown in FIG. 1A, the microphones 121, 122,..., 12M are horizontally arranged
on the display 11 for noise coming from within the same vertical plane as the target signal. 13N
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are aligned in the vertical direction (direction along the y-axis).
In order to simplify the explanation, the microphones of both microphone arrays are all equally
spaced d, and the target sound comes along the z axis (θ s = 0 °) and the noise is the angles θ
N and x in the yz plane. The case of coming from an angle .phi.N in the -z plane is taken as an
example. The target sound arriving along the z axis simultaneously reaches the microphones
121, 122, ..., 12M in the horizontal direction and the microphones 131, 132, ..., 13N in the
vertical direction, so the noise suppressor 14 is described in Fig. 3A. When the delay and sum
method is used, by setting the delay amounts of the delay units to all zero, it is possible to
emphasize the target sound by adding the target sounds all in phase. On the other hand, the
noise coming from the angle .phi.N in the xz plane (horizontal plane), when reaching the
microphones 121, 122,..., 12M in the horizontal direction, is (i-1) dsin .phi.N (i = Since the arrival
time differences of (2,..., M) are generated, the noise suppression unit 14 of the delay-and-sum
method is to add up in a state where the phases are not aligned. For this reason, the target sound
is not emphasized and noise is relatively suppressed. Also, for noise coming from an angle θN in
the yz plane (vertical plane), when reaching the microphones 131, 132, ..., 13N, (i-1) d sin θN (i
= 2) with respect to the microphone 131 ,..., N) are generated, and in this case also in the delayand-sum noise suppressing unit 14, they are added together in a state where the phases are not
aligned. Therefore, in this case as well, the target sound is not emphasized and noise is relatively
suppressed.
[0015]
As described above, by providing the microphone array not only in the horizontal direction but
also in the vertical direction, noise can be suppressed not only for noise coming from the angle
φN in the horizontal direction but also for noise coming from the angle θN in the vertical
direction. It will be possible. Therefore, not only against noise generated from fans of devices
arranged on the side of the display 11, but also from air conditioning noise blown out from the
ceiling and noise coming from the lower front of the display 11 such as keyboard typing sound.
Noise can also be suppressed.
[0016]
For example, the microphone array is integrated into the mounting frame of a display filter that
is externally attached to the display to protect the eyes from the light of the display. In this case,
no special means for mounting the microphone array is required, the appearance is good, and it
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can be easily mounted on existing displays. In addition, when it was found that a microphone was
placed on the lower side of the display filter when tapping a keyboard of a computer or the like
in the vicinity of the display, it was found that it was easy to pick up this tapping sound. In this
case, it is effective not to arrange the microphone at the lower side of the display filter. That is, in
order to reduce the mixing of the keying sound, microphones are installed on the upper side, the
right side and the left side of the display filter.
[0017]
According to such a configuration, the frame portion in which the microphone array in the
vertical and horizontal directions is embedded, for example, the outer frame portion of the
display filter, is mounted on the hand-held display, and the signal from the microphone array is
By processing, noise coming from not only the horizontal direction but also the vertical direction
can be suppressed. Further, since the frame in which the microphone array is embedded is
simply mounted on a hand-held display, a complicated jig is not required, the apparatus is not
large-scaled, and the appearance is not unsightly. There is also the advantage that the user can
utilize his or her display without replacing it. In addition, in the case of pressing a keyboard of a
computer or the like, unnecessary keyboard sound may not be collected if a microphone is not
provided on the lower side of the display filter. That is, by installing a microphone on the upper
side of the frame and the upper half of each of the right side and the left side, collection of
unnecessary keyboard sound is prevented.
[0018]
Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1B shows a first embodiment of the present invention. The noise suppressing and collecting
device 15 of this embodiment outputs the display filter 16, the microphone array 17 as a sound
collecting unit, the noise suppressing circuit 18 as a noise suppressing unit, and an external
device such as a voice recognition device. It is comprised from the connector part 19 used. The
display filter 16 is composed of an outer frame portion 16a and a glass portion 16b held so as to
close the outer frame portion 16a. The user mounts the display filter 16 on a hand-held display
and uses it. For this reason, the user can use the present noise suppression and sound pickup
device without replacing the display on hand. The microphone array 17 picks up the voice of the
user who is the target sound together with the ambient noise, and outputs the voice to the noise
suppression circuit 18. For the noise suppression circuit 18, for example, the delay and sum
method shown in FIG. 3A may be used. The microphone array 17 is embedded in the outer frame
portion 16 a of the display filter 16 and arranged in the horizontal and vertical directions.
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Therefore, not only noise in the horizontal direction but also noise coming from the vertical
direction can be suppressed. When ambient noise comes from above like air conditioning noise
or from below like keyboard typing sound and the user's voice which is the target sound comes
from the front of the display, the noise suppression circuit 18 is a delay-sum system. When the
user's voice coming from the front of the display is in-phase added, they are set to emphasize the
desired voice. At this time, ambient noise is not emphasized because it is not in phase, and noise
is relatively suppressed.
[0019]
FIG. 2A shows a second embodiment of the present invention. In the embodiment of FIG. 1B, in
addition to the sound collecting system, speakers 21 are attached to the left and right sides of the
outer frame portion 16a, and a speaker input connector 22 is connected to the speakers 21. The
speaker input connector unit 22 is connected to, for example, a speaker output of a
communication device or the like, and is used for a speech communication or the like. In other
words, conventionally, the speaker that is emitted to the user has been disposed at an
appropriate place by the user. This kind of speaker may be a noise source with respect to the
microphone 17. However, in the embodiment shown in FIG. 2A, since the position of the speaker
21 with respect to the microphone 17 is fixed, noise from the speaker 21 is a noise suppression
unit The noise suppression unit 14 can be set in advance so as to be suppressed by 14, and that
state is always maintained, and noise suppression can be performed well. Therefore, any part of
the outer frame portion 16a may be used as the speaker 21, and the number is not limited to
two.
[0020]
FIG. 2B shows a third embodiment of the present invention. This is to avoid the microphone
installation on the lower side of the display filter 16 and to minimize the collection of the keying
sound of the computer keyboard. That is, microphones are installed on the upper side of the
outer frame portion 16a of the display filter and on the upper half of each of the right side and
the left side to minimize the collection of the keying sound of the keyboard.
[0021]
The microphone array is not limited to the outer frame portion of the display filter, and the outer
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periphery or front surface of the display may be a frame shape that can be attached so as to
surround the display surface, and the microphone array is vertically as shown in FIG. 1A. What is
extended may be only the left side or the right side, and horizontally extended may be only the
lower side. Accordingly, the mounting outer frame portion to the display may not be a square,
and may not be L-shaped, that is, not closed. Also, the noise suppression unit 14 is not limited to
the one that matches the phase of the sound in the target direction, but the noise component
may be matched in phase and the noise component may be subtracted to suppress the noise and
read out the signal.
[0022]
As described above, according to the present invention, since the microphone array arranged not
only horizontally but also vertically is provided, noise coming from not only horizontally but also
vertically can be suppressed. Can. Moreover, the outer frame array can be easily attached by
attaching the outer frame array to the display. In particular, if the outer frame portion of the
display filter is used as the outer frame portion, no special attachment frame is required, and
simply mounting on a hand-held display, no complicated jig is required, and no increase in size, It
looks unsightly, and the user can use it without having to replace his display because of this
noise suppression and sound pickup device.
[0023]
Brief description of the drawings
[0024]
FIG. 1A is a view for explaining an example of installation of a sound collection unit for enabling
noise suppression according to the present invention, and FIG. 1B is a view showing a first
embodiment of the present invention.
[0025]
2 is a diagram showing another embodiment of the present invention.
[0026]
FIG. 3A is a diagram for explaining the principle of noise suppression and collection by the
conventional delay-sum method, B is a diagram for explaining a conventional microphone array,
and C is an installation example of a sound collection unit incapable of noise suppression and
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collection. It is a figure explaining.
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