close

Вход

Забыли?

вход по аккаунту

JP2008301401

код для вставкиСкачать
Patent Translate
Powered by EPO and Google
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 JP2008301401
The present invention provides an acoustic device that does not increase noise and the like even
when a plurality of directional microphones pick up voices from equal distances. An audio signal
output from each microphone array is phase-shifted by phase shift circuits 211A to 211H and
synthesized by an adder 212. The phase shift circuits 211A to 211H shift the phase according to
the installation position of each microphone array. The phase shift circuit 211A shifts by 0
degrees, the phase shift circuit 211B shifts by 45 degrees, and the phase shift circuit 211C shifts
by 90 degrees, and shifts sequentially to the phase shift circuit 211H according to the rotation
angle. [Selected figure] Figure 3
Sound equipment
[0001]
The present invention relates to an acoustic device mainly intended to collect voice, and more
particularly to an acoustic device provided with a plurality of directional microphones.
[0002]
BACKGROUND In recent years, in order to conduct an audio conference (communication
conference), an audio conference device integrally provided with a speaker and a microphone
has become widespread.
The audio conference apparatus transmits the sound collected by the microphone to the
04-05-2019
1
connection destination, and emits the sound received from the connection destination from the
speaker. When a conference is conducted by a plurality of people, such an audio conference
device is often installed at the center of the conference participants (the center of the conference
desk, etc.). Therefore, it is desirable that such an audio conference apparatus be miniaturized,
and for example, as shown in Patent Document 1, there is proposed an audio conference
apparatus which is miniaturized by omitting a speaker box.
[0003]
Also, in consideration of being placed at the center of the conference desk, a device may be
considered in which a plurality of directional microphones are directed toward the periphery of
the device. JP-A-8-204803
[0004]
However, according to the configuration of Patent Document 1, although the configuration is
compact, the speaker and the microphone come close to each other, and the wraparound volume
increases.
[0005]
On the other hand, in a device in which a plurality of directional microphones are installed
toward the periphery of the device, voices emitted at positions (or areas near this position)
equidistant from all the directional microphones are collected in the same phase. Because of this,
there was a problem that only a specific area was picked up at a very large level.
For this reason, for example, the noise and the like of the air conditioner installed on the ceiling
are collected at a particularly large level, which is annoying.
[0006]
Therefore, an object of the present invention is to provide an acoustic device that does not
increase noise and the like even when a plurality of directional microphones pick up voices from
equal distances.
04-05-2019
2
[0007]
The acoustic device according to the present invention is arranged on a circumference centered
on one axis, and in a plane perpendicular to the axis, a plurality of sound collection units whose
sound collection directions are set in the normal direction of the circumference. And an audio
signal processing unit that rotates the phase of the audio signal output from each sound
collection unit according to the angle on the circumference of the installation position of each
sound collection unit, and then synthesizes the signal. I assume.
[0008]
In this configuration, the plurality of sound collecting units are respectively installed on a
circumference centered on the axis.
Each sound collection unit is installed in the direction normal to the circumference (for example,
in the case of a disk-like housing, in the side surface direction of the housing) in a plane
perpendicular to this axis.
The audio signals output from these sound pickup units are phase-shifted according to the
installation position (angle on the circumference) of each sound pickup unit. For example, if the
installation position is rotated 180 degrees, the phase is also shifted 180 degrees. The sound
emitted at a position (axial direction) extending from the center position of the housing to the
upper surface and lower surface direction is canceled by almost all the sound collection units, but
is canceled because it is synthesized after phase shift. . On the other hand, since the sound
emitted on the side is collected at a high level in the sound collection unit closest to the position,
it is not canceled after the synthesis.
[0009]
Further, according to the present invention, the sound collection unit further includes a
microphone array formed by arranging a plurality of microphone units, and a directivity of the
sound collection unit by delaying and combining an audio signal collected by each microphone
unit. And a delay processing unit for providing
[0010]
04-05-2019
3
The sound pickup unit of this configuration includes a microphone array in which microphone
units are arranged and a delay processing unit.
Strong directivity is set in a predetermined direction by delaying and combining the sound
signals collected by the microphone units.
[0011]
Further, the present invention is characterized by further comprising a speaker whose sound
emission direction is set in the direction in which the axis extends.
[0012]
In this configuration, the speaker is installed such that the sound emission surface faces in the
direction in which the axis extends from the center position of the housing.
The direction in which the axis extends includes the upper surface direction, the lower surface
direction, or both directions of the housing. That is, sound may be emitted toward the upper
surface direction of the housing, or may be emitted toward the lower surface direction. Also,
sound may be emitted in both directions. Since the sound emission direction is canceled even if
the sound is collected by the sound collection unit, the generation of echo can be suppressed.
[0013]
Further, the present invention is characterized by further comprising an adaptive echo canceler
which subtracts a pseudo feedback signal obtained by filtering an audio signal input to the
speaker from an output signal of the audio signal processing and outputs the result.
[0014]
In this configuration, a wraparound component from the speaker to the sound collection unit is
estimated, and the echo component is removed by subtracting the estimated wraparound
component from the output signal of the audio signal processing unit.
[0015]
According to the present invention, even when voices emitted at positions of equal distances
04-05-2019
4
from a plurality of directional microphones (sound collection units) are picked up, they are
canceled by synthesizing after phase shift, so at this position It does not pick up the generated
noise etc. at high level.
[0016]
A voice conference apparatus will be described as an embodiment of the audio apparatus of the
present invention.
FIG. 1 is an external view of the audio conference apparatus according to this embodiment,
wherein FIG. 1 (A) is a plan view and FIG. 1 (B) is a side view.
In FIG. 6A, the lower side of the drawing (the sound collecting direction of the microphone array
10A) is set to 0 degrees with the center position of the audio conference apparatus 1 viewed
from the top as the rotation center, and the angle increasing clockwise is θ. .
[0017]
The audio conference device 1 is provided with a disk-shaped case 11.
The housing 11 has a circular shape with a diameter of about 30 cm when viewed from the top.
The area of the upper surface and the lower surface of the housing 11 is smaller than the area of
the midway portion in the vertical direction. The housing 11 has a shape viewed from the side,
which narrows from the predetermined position in the height direction toward the upper surface,
and narrows toward the lower surface. That is, the housing 11 has a shape having inclined
surfaces on the upper side and the lower side from the predetermined position.
[0018]
The eight microphone arrays 10 </ b> A to 10 </ b> H are installed toward the side of the
housing 11 (inside the upper surface of the housing 11). The microphone arrays 10A to 10H are
arranged at equal angular pitches (in this case, approximately 45 degrees in this case) with the
04-05-2019
5
center position of the housing 11 as the center of rotation when viewed from the top. At this
time, the microphone array 10A has a sound collection direction of θ = 0 degrees, and the
microphone arrays 10A to 10H are arranged along the direction in which θ increases by 45
degrees in order.
[0019]
Each of the microphone arrays 10A to 10H has a plurality of (four in the drawing) microphone
units. For example, the microphone array 10A has four microphone units of microphone units
101A to 104A. The voices picked up by these microphone units 101A to 104A are subjected to
delay processing in a delay processing unit (see FIG. 2) and then synthesized (see FIG. 2). By
combining after delay processing, it has strong directivity in a specific direction. The microphone
array 10A has directivity in the direction of θ = 0 degrees, and the direction of 0 degrees is the
sound collecting direction. The number of microphone units is not limited to this example, and
may be appropriately set according to the specification. Also, instead of the microphone array, a
unidirectional microphone may be used.
[0020]
The speaker 13 is installed so that the sound emission direction is directed to the lower surface
of the housing 11. In the case where the voice conference device is simply used as a sound
collection device, the configuration of the speaker 13 (configuration of the sound emission
system) is not essential.
[0021]
FIG. 2 is a block diagram showing the configuration of the audio conference device 1. The audio
conference apparatus 1 includes a microphone signal processing circuit 21 connected to the
microphone arrays 10A to 10H, an echo canceller 22 connected to the microphone signal
processing circuit 21, and an input / output I / F 23 connected to the echo canceller 22. There is.
In the figure, the signal is supplied to the front end amplifier that amplifies the audio signal
collected by the microphone unit, the A / D converter that converts the analog audio signal to
digital, the D / A converter that converts the digital audio signal to analog, and the speaker. The
power amplifier etc. which amplify the audio ¦ voice signal which carries out are abbreviate ¦
omitted, and when there is no description in particular, the audio ¦ voice signal transmitted inside
04-05-2019
6
the audio conference apparatus 1 shall be a digital audio ¦ voice signal.
[0022]
The input / output I / F 23 is installed on any surface of the housing 11, and includes a network
connection terminal (not shown), a digital audio terminal, an analog audio terminal, and the like.
The voice conference device 1 can be connected to another device by connecting a network cable
or the like to the input / output I / F 23.
[0023]
The microphone arrays 10A to 10H each have a plurality of microphone units as described
above, and have a delay processing unit that delays the sound signals collected by the
microphone units, combines them, and outputs the result to the subsequent stage. For example,
the microphone array 10A has four microphone units 101A to 104A, and the delay processing
unit 111A performs delaying and combining processing. A signal synthesized by the delay
processing unit of each of the microphone arrays 10A to 10H is input to the microphone signal
processing circuit 21.
[0024]
The microphone signal processing circuit 21 phase shifts the voice signals output from the
microphone arrays 10A to 10H, combines them, and outputs the result to the echo canceller 22
in the subsequent stage. A detailed block diagram of the microphone signal processing circuit 21
is shown in FIG. The microphone signal processing circuit 21 includes phase shift circuits 211A
to 211H and an adder 212.
[0025]
The audio signals output from the microphone arrays 10A to 10H are input to the phase shift
circuits 211A to 211H, respectively. The output signals of the phase shift circuits 211A to 211H
are input to the adder 212, respectively. The adder 212 synthesizes the output signals of the
phase shift circuits 211A to 211H, and outputs the result to the echo canceller 22 in the
04-05-2019
7
subsequent stage.
[0026]
The echo canceller 22 estimates a wraparound component from the speaker 13 to the
microphone arrays 10A to 10H, and subtracts the estimated wraparound component from the
output signal of the microphone signal processing circuit 21 to remove an echo component. The
echo canceller 22 incorporates an adaptive filter for filtering the signal supplied to the speaker
13, and estimates the transfer function of the sound transmission system (sound propagation
path from the speaker to the microphone array) to obtain a wraparound component from the
speaker to the microphone. Generate a simulated signal. This simulated signal is subtracted from
the output signal of the microphone signal processing circuit 21. The transfer function is updated
using the residual signal after subtraction of the echo component. The signal from which the
echo component has been removed is input to the input / output I / F 23 and transmitted to
another device.
[0027]
In FIG. 3, phase shift circuits 211A to 211H are composed of FIR filters or the like, perform
phase shift operation in the entire frequency band (wide frequency band, for example, several
tens Hz to several kHz), and shift the phase of the audio signal. Here, the phase shift circuits
211A to 211H rotate the phase in accordance with the angle corresponding to the sound
collection direction of each microphone array.
[0028]
That is, the phase shift circuit 211A sets the angle of 0 degree in the sound collection direction of
the microphone array 10A as the rotation angle. That is, the phase shift circuit 211A does not
perform phase shift. The phase shift circuit 211B sets an angle of 45 degrees in the sound
collection direction of the microphone array 10B as a rotation angle. In other words, the phase is
delayed 45 degrees. Similarly, the phase shift circuit 211C delays the phase by 90 degrees, the
phase shift circuit 211D delays the phase by 135 degrees, and the phase shift circuit 211E
delays the phase by 180 degrees. In addition, the phase shift circuit 211F delays the phase by
225 degrees, the phase shift circuit 211G delays the phase by 270 degrees, and the phase shift
circuit 211H delays the phase by 315 degrees.
04-05-2019
8
[0029]
FIG. 4 is a diagram showing the signals outputted from the phase shift circuits 211A to 211H as
a result of the phase shift of the audio signals of the microphone arrays 10A to 10H. The same
figure (A) shows the case where sound is collected from the area ¦ region of equal distance from
all the microphone arrays. The area where distances from all the microphone arrays are equal is
an area near the center position (center axis) when the audio conference device 1 is viewed from
the top. For example, as shown in FIG. 5A, the sound emitted in the area 50 in the upper portion
(zenith direction) of the audio conference device 1 is collected.
[0030]
Further, FIG. 4B shows a case where the sound emitted in the area near one of the microphone
arrays is collected. For example, as shown in FIG. 5B, the sound emitted in the area 51 close to
the microphone array 10D is collected.
[0031]
In FIGS. 4A and 5A, the sounds collected by the microphone arrays 10A to 10H are all the same
components. Therefore, when these picked-up sound signals are phase-shifted by the phase shift
circuits 211A to 211H and then synthesized, they cancel each other. For example, since the
sound signal collected by the microphone array 10A and the sound signal collected by the
microphone array 10E are 180 degrees out of phase, they cancel each other.
[0032]
As described above, since the audio signals collected by the microphone arrays 10A to 10H from
the area near the central axis of the device cancel each other after synthesis, the level becomes
extremely small. Therefore, for example, noise and the like of the air conditioner installed on the
ceiling will not be collected at a high level. In addition, since the speaker 13 is installed at the
center position of the audio conference device 1, the emitted sound does not go around and be
collected at a high level. Therefore, the occurrence of echo and howling can be suppressed. Also,
04-05-2019
9
the processing load of the echo canceller 22 can be reduced. The sound emission direction of the
speaker 13 may be the upper surface direction or the lower surface direction. Also, sound may be
emitted in both directions.
[0033]
On the other hand, in FIG. 4B and FIG. 5B, the sound emitted in the area 51 is collected to the
high level by the nearest microphone array 10D, and is collected to the low level according to the
distance from the area 51 Be done. The sound collected at the farthest microphone array 10H is
at the lowest level. Therefore, the voice signal picked up by the microphone array 10D and the
voice signal picked up by the microphone array 10H do not completely cancel each other even if
they are synthesized. Also, the sound collected by the microphone array 10C and the microphone
array 10E is close to the level of the sound collected by the microphone array 10D, but is
completely canceled even if it is synthesized because the phases are close (45 degrees difference)
I can not meet you. Therefore, the sound emitted in the area 51 is collected at a high level.
[0034]
As described above, according to the audio conference apparatus 1 of the present embodiment,
the noise in the zenith direction is not collected, and the sound from the horizontal direction can
be collected at a high level, so that it is stable in all directions. It is possible to realize a sound
collection environment.
[0035]
In addition, since the filter coefficients of the phase shift circuits 211A to 211H are not
dynamically changed, a stable sound collection environment can be realized.
[0036]
It is a figure which shows the external appearance of a voice conference apparatus.
It is a block diagram which shows the structure of a voice conference apparatus.
FIG. 2 is a block diagram showing a configuration of a microphone signal processing circuit 21. It
04-05-2019
10
is a figure which shows the audio ¦ voice signal after phase shift. It is a figure which illustrates a
mode that a sound is collected.
Explanation of sign
[0037]
1-voice conference apparatus 10A to 10H-microphone array 13-speaker 21-microphone signal
processing circuit 22-echo canceller 23-input / output I / F
04-05-2019
11
1/--страниц
Пожаловаться на содержимое документа