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JP2009135593

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This translation is machine-generated. It cannot be guaranteed that it is intelligible, accurate,
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DESCRIPTION JP2009135593
To emphasize and output a sound from a sound source existing in a target direction. A phase
difference correction unit (20) extracts discrete values of first and second observation signals
generated by first and second directional microphones (10, 11), and detects a discrete value of a
second observation signal. Shift by the phase difference when the sound source is present in the
target direction. The sound source direction determination unit 21 calculates first and second
observation power values that are power values of the first and second observation signals. If at
least one of the first and second observed power values is less than or equal to the threshold
value, it is determined that no sound source exists in the target direction, and both of the first
and second observed power values are greater than the threshold value; If the relative ratio of
the observed power values is smaller than the other threshold value, it is determined that the
sound source is in the target direction. The output operation unit 22 amplifies and outputs the
combined signal of the first and second observation signals at a large amplification factor when
the sound source is present in the target direction, and outputs the combined signal when the
sound source is not present in the target direction. It amplifies and outputs with a small
amplification factor. [Selected figure] Figure 1
Sound input device
[0001]
The present invention relates to an audio input device that emphasizes and outputs a sound from
a sound source present in a predetermined target direction.
[0002]
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1
A sound input device for collecting a sound from a sound source is, for example, provided in a
door phone handset of an intercom system, etc., and the voice (sound) of a specific speaker
(sound source) existing in front of the door phone handset is collected There is something to do.
The sound input device provided in such a door phone handset collects only the voice of the
speaker and does not collect any sound other than the voice of the speaker (for example, the
reflected sound from the wall or the surrounding noise). For this purpose, it is necessary to
predict in advance the direction in which the speaker is present (the target direction), and to
direct directivity to the predicted target direction.
[0003]
As a conventional sound input device for collecting a sound from a sound source present in a
target direction, there is one that collects sound using a single directional microphone. The
directional microphone can collect sound from a sound source present in a sound collection area
with a somewhat small directivity angle.
[0004]
In addition, as another example of a conventional acoustic input device for collecting sound from
a sound source, Patent Document 1 discloses a nondirectional microphone which is a pressure
type microphone, a bidirectional microphone which is a speed type microphone, and There is
disclosed a sound source direction determination device including a phase comparator which
determines whether a phase of a waveform signal of a bidirectional microphone is advanced or
delayed with respect to a waveform signal of a directional microphone.
[0005]
In the sound source direction determination device of Patent Document 1, the waveform signal of
the bi-directional microphone (velocity type microphone) is non-directional when there is a
sound source on the front side of the two microphones (the non-directional microphone and the
bi-directional microphone). When the sound source exists on the back side of the two
microphones, the phase is 90 degrees behind the waveform signal of the nondirectional
microphone.
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When the phase comparator determines that the phase of the waveform signal of the bidirectional microphone leads the waveform signal of the non-directional microphone, the phase
comparator determines that the sound source is present on the front side, whereas the waveform
of the non-directional microphone If it is determined that the sound source is late, it is
determined that the sound source is present on the back side.
[0006]
From the above, according to the sound source direction determination device of Patent
Document 1, it can be determined whether the sound source is present on the front side or the
back side of the two microphones. JP 2003-333680 A (paragraphs 0028 to 0048 and FIGS. 1 to
3)
[0007]
However, although the conventional sound input device using one microphone can collect and
output the sound from the sound source existing within a certain range, it is not sufficient from
the practical point of view. There is a problem that noises and the like present in directions other
than the target direction are emphasized and output as well as the sound from a sound source
present in the target direction (for example, the voice of a specific speaker).
[0008]
As a conventional means for solving the above problems, it is conceivable to lengthen the
acoustic tube of the microphone, but this is not practical.
In addition, although signal processing such as noise removal may be performed, a new problem
that the amount of calculation becomes excessive occurs.
[0009]
Further, although the sound source direction determination device of Patent Document 1 can
determine whether the sound source is present on the front side or the back side of the two
microphones, the sound source may be determined from a sound source present in a specific
target direction. I was unable to emphasize the sound and output it.
04-05-2019
3
[0010]
The present invention has been made in view of the above-mentioned point, and an object
thereof is to provide an acoustic input device capable of emphasizing and outputting a sound
from a sound source existing in a target direction.
[0011]
The invention according to claim 1 is disposed close to each other so that each has a sound
collection area of a predetermined directivity angle, and a part of each sound collection area
overlaps with a predetermined target direction. A first directional microphone and a second
directional microphone that generate an observation signal based on the received sound wave
and receive a first observation signal from the first directional microphone; A first observation
when a second observation signal is received from the second directional microphone, a phase
difference between the received first observation signal and the second observation signal is
received, and a sound source is present in the target direction The sound source includes the
phase difference correction unit that corrects only the phase difference between the signal and
the second observation signal, and the first observation signal and the second observation signal
after being corrected by the phase difference correction unit. Sound source direction
determination unit that determines whether or not the target direction exists When it is
determined by the sound source direction determination unit that the sound source is present in
the target direction, at least one of the first observation signal and the second observation signal
is amplified by a first amplification factor and output. When it is determined by the sound source
direction determination unit that the sound source is not present in the target direction, the
phase difference between the first observation signal and the second observation signal is
corrected by the phase difference, and after correction. And an output operation unit configured
to amplify and output a composite signal of the first observation signal and the second
observation signal at an amplification factor smaller than the first amplification factor.
[0012]
According to the invention of claim 2, in the invention of claim 1, the sound source direction
determination unit is a first observation power value which is a power value of the first
observation signal corrected by the phase difference correction unit; Any one of the second
observation power values, which is the power value of the second observation signal corrected
by the phase difference correction unit, is greater than a predetermined threshold value, and the
first observation power value and the second observation power If the relative ratio of the values
is less than a predetermined set value, it is determined that the sound source is present in the
target direction, while if the condition is not satisfied, it is determined that the sound source is
not present in the target direction It is characterized by
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[0013]
According to the invention of claim 3, in the invention of claim 1, the sound source direction
determination unit determines the discrete value x1 of the first observation signal and the
discrete value of the second observation signal after being corrected by the phase difference
correction unit. The correlation function R ij (i = 1, 2) represented by Formula 3 is determined
using x 2, and the condition that the cross correlation function R 12 is equal to or more than a
predetermined set value set based on the autocorrelation function R 11 or the autocorrelation
function R 22 If the condition is satisfied, it is determined that the sound source is present in the
target direction, and if the condition is not satisfied, it is determined that the sound source is not
present in the target direction.
[0014]
[0015]
According to the invention of claim 4, in the invention of claim 1, the sound wave received from
the sound source and installed at an intermediate position between the first directional
microphone and the second directional microphone is received. The phase difference correction
unit receives the reference observation signal, and the phase difference between the received
reference observation signal and the first observation signal is directed to the target direction.
Only the phase difference between the reference observation signal and the first observation
signal when there is a sound source is corrected, and the sound source direction determination
unit is a reference observation that is the power value of the reference observation signal after
being corrected by the phase difference correction unit. The relative ratio of the first observed
power value, which is the power value of the first observed signal corrected by the phase
difference correction unit with respect to the power value, is included in the first range set in
advance, and the reference observed power value The phase against When the relative ratio of
the second observation power value, which is the power value of the second observation signal
corrected by the correction unit, satisfies the condition included in the second range set in
advance, the sound source is in the target direction It is determined that the sound source is not
present in the target direction if the condition is not satisfied.
[0016]
According to the invention of claim 5, according to the invention of claim 1, the sound wave
received from the sound source and installed at an intermediate position between the first
directional microphone and the second directional microphone is received. A non-directional
microphone for generating a reference observation signal based on the reference signal, the
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phase difference correction unit extracting discrete values of the received first observation signal
at predetermined time intervals, and receiving the received second observation signal Discrete
values of the second observation signal are extracted at the predetermined time interval, the
reference observation signal is received, discrete values of the reference observation signal are
extracted at the predetermined time interval, and the extracted first observation The phase
difference between the discrete value of the signal and the second observation signal is corrected
by the phase difference between the first observation signal and the second observation signal
when the sound source is present in the target direction, and the extracted reference observation
signal Discrete value and first observation signal The phase difference is corrected only by the
phase difference between the reference observation signal and the first observation signal when
the sound source is present in the target direction, and the sound source direction determination
unit corrects the phase difference after correction by the phase difference correction unit. Using
the discrete value x1 of the observed signal of 1, the discrete value x2 of the second observed
signal corrected by the phase difference correction unit, and the discrete value x0 of the
reference observed signal corrected by the phase difference correction unit The correlation
function R ij (i, j = 0, 1, 2) represented by equation 4 is determined, and the relative ratio of the
cross correlation function R01 to the autocorrelation function R00 is included in a first set preset
range. If the relative ratio of the cross-correlation function R02 to the function R00 satisfies the
condition included in the second range set in advance, the sound source is determined to be
present in the target direction, while the sound source is not satisfying the condition. Exist in the
target direction And judging that there is no.
[0017]
[0018]
According to the invention of claim 6, in the invention of any one of claims 1 to 5, when the
sound source direction determining unit determines that the sound source is not present in the
target direction, the sound source is in the target direction. If the sound source direction judging
unit judges that the sound source is present in the vicinity of the target direction, the output
operation unit determines whether the first sound source is away from the target direction. The
synthetic signal is amplified and output at an amplification factor of a continuous change
characteristic which monotonously decreases from the amplification factor of.
[0019]
According to the invention of claim 7, in the invention of claim 1, the sound wave received from
the sound source and installed at an intermediate position between the first directional
microphone and the second directional microphone is received. The phase difference correction
unit receives the reference observation signal, and the phase difference between the received
04-05-2019
6
reference observation signal and the first observation signal is directed to the target direction.
Only the phase difference between the reference observation signal and the first observation
signal when there is a sound source is corrected, and the sound source direction determination
unit is the power value of the first observation signal after correction by the phase difference
correction unit. Both the first observation power value and the second observation power value
which is the power value of the second observation signal corrected by the phase difference
correction unit are larger than a predetermined threshold value, and the first Observation power
value and the second observation power When the relative ratio of values is equal to or greater
than a predetermined first set value, the cross-correlation function of the first observation signal
and the second observation signal is the autocorrelation function of the first observation signal
or the first correlation value of the first observation signal. When it is determined that the sound
source is present in each of the target direction and other areas other than the target direction,
when the condition which is equal to or greater than a predetermined second set value
determined from the autocorrelation function of two observed signals is determined; When it is
determined that the sound source is not present in the target direction when the condition is not
satisfied, and the sound source is determined to be present in each of the target direction and
other areas other than the target direction, the phase difference correction unit The relative ratio
of the first observed power value to the reference observed power value, which is the power
value of the reference observed signal after being corrected by is included in a preset range, and
It is determined that the sound source is present in the sound collection region of the first
directional microphone when the relative ratio of the observed power values of the first to the
second observed power values is not included in the range. When the relative ratio is included in
the range and the relative ratio of the first observed power value to the reference observed
power value is not included in the range, the sound source is present in the sound collection
region of the second directional microphone It is characterized in that it judges.
[0020]
According to the invention of claim 8, according to the invention of claim 7, the output operation
unit causes the sound source to be present in the sound collection area of the first directional
microphone or the second directional microphone by the sound source direction determination
unit. When it is determined, the observation signal of the directional microphone in which the
sound source is not present in the sound collection region is amplified at the first amplification
factor and output.
[0021]
The invention according to claim 9 is the invention according to claim 7, further comprising:
driving means for inclining the directional axis of the first directional microphone or the second
directional microphone, wherein the sound source direction determining unit is configured to
When it is determined that the target direction and the sound collection area of the first
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directional microphone or the second directional microphone among the other areas are present,
the first observed power value and the first observation power value The drive unit is controlled
until the relative ratio of the second observation power value is less than the first set value, and
the output operation unit is configured to control the first directional microphone or the first
directional microphone by the sound source direction determination unit. When it is determined
that the sound source is present in the sound collection region of the second directional
microphone, a composite signal of the first observation signal and the second observation signal
after driving of the driving means is While amplifying and outputting with an amplification factor
of 1, when the sound source direction determination unit determines that the sound source is not
present in the target direction, a second amplification smaller than the first amplification factor is
performed on the combined signal. It is characterized in that it is amplified at a rate and output.
[0022]
According to the invention of claim 10, according to the invention of claim 1, the sound wave
received from the sound source and installed at an intermediate position between the first
directional microphone and the second directional microphone is received. The phase difference
correction unit receives the reference observation signal, and the phase difference between the
received reference observation signal and the first observation signal is directed to the target
direction. Only the phase difference between the reference observation signal and the first
observation signal when there is a sound source is corrected, and the sound source direction
determination unit is the power value of the first observation signal after correction by the phase
difference correction unit. In the case where both the first observation power value and the
second observation power value which is the power value of the second observation signal
corrected by the phase difference correction unit are larger than a predetermined threshold
value, The first observation signal and the above When the cross-correlation function of the two
observed signals meets or exceeds a predetermined set value determined from the
autocorrelation function of the first observed signal or the autocorrelation function of the second
observed signal, the sound source is not While it is determined that the target direction and the
other area other than the target direction are present, when the condition is not satisfied, it is
determined that the sound source is not present in the target direction, and the sound source
indicates the target direction and the target And a relative ratio of the first observed power value
to a reference observed power value which is a power value of the reference observed signal
corrected by the phase difference correction unit when it is determined that each of the regions
other than the direction is present. And each of the relative ratios of the second observed power
value to the reference observed power value is included in a preset range, the first directional
microphone and the second directional microphone Determining that the sound source to each of
the sound collection region of the directional microphone is present and said.
[0023]
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8
The invention of claim 11 is the invention according to claim 10, further comprising: driving
means for tilting the directional axis of the first directional microphone or the second directional
microphone; When it is determined that the target direction and the sound collection area of the
first directional microphone and the second directional microphone among the other areas are
present, the two sound sources are selected from the target direction. The relative ratio of the
first observed power value to the second observed power value when the first directional
microphone and the second directional microphone are separated by a half or more of the
maximum value of the directivity angle. Control the drive unit until the condition that the value is
less than a predetermined set value, and the output operation unit is configured to control the
first directional microphone or the second directivity by the sound source direction
determination unit. When it is determined that the sound source is present in the sound
collection region of the iclophone, a composite signal of the first observation signal and the
second observation signal after driving of the driving means is amplified by the first amplification
factor While outputting, when the sound source direction determination unit determines that the
sound source is not present in the target direction, the synthesized signal is amplified and output
at a second amplification factor smaller than the first amplification factor. It is characterized by
[0024]
According to the invention of claim 1, it is determined whether or not the sound source is present
in the target direction using the observation signals from the two microphones, and the
amplification factor when the sound source is present in the target direction (first amplification
The sound from the sound source present in the target direction can be emphasized and output
by making the ratio (A) larger than the amplification factor when the sound source does not exist
in the target direction.
[0025]
According to the second aspect of the present invention, by evaluating the relative ratio of the
first observation power value and the second observation power value, it can be accurately
determined whether or not the sound source is present in the target direction.
[0026]
According to the invention of claim 3, by evaluating the cross-correlation function of the discrete
values of the first observation signal and the discrete values of the second observation signal, it is
accurately determined whether the sound source is present in the target direction. can do.
[0027]
According to the invention of claim 4, by installing the nondirectional microphone at an
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9
intermediate position between the first directional microphone and the second directional
microphone, the first and second reference observation power values of the nondirectional
microphone can be obtained. It is possible to accurately determine whether the sound source is
present in the target direction by using the observation power value of.
[0028]
According to the invention of claim 5, by using the autocorrelation function of the reference
observation signal or the cross-correlation function of the reference observation signal and the
first and second observation signals, the influence of uncorrelated noise is reduced to achieve
high S / N. It can be made a ratio, and the determination accuracy as to whether or not the sound
source is present in the target direction can be enhanced.
[0029]
According to the invention of claim 6, it is possible to prevent the amplification factor for
amplifying the synthesized signal from becoming discontinuous due to the direction of presence
of the sound source, and as a result, the output signal can always be made a continuous value. .
[0030]
According to the invention of claim 7, one sound source is present in an area where the sound
collecting areas of the first directional microphone and the second directional microphone
overlap, and the first directional microphone and the second directional microphone are
provided. It can be determined that the other sound source is present only in one of the sound
collection areas.
[0031]
According to the invention of claim 8, the signal from the sound source in the target direction
can be amplified and output.
[0032]
According to the invention of claim 9, the signal from the sound source in the target direction
can be amplified and output.
[0033]
According to the invention of claim 10, one sound source is present in an area where the sound
collection areas of the first directional microphone and the second directional microphone
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overlap, and the first directional microphone and the second directional microphone are
provided. It can be determined that the other sound source is present only in one of the sound
collection areas.
[0034]
According to the invention of claim 11, the signal from the sound source in the target direction
can be emphasized and output.
[0035]
First Embodiment First, the configuration of a sound input device according to a first
embodiment will be described with reference to FIGS.
As shown in FIG. 1, this sound input device includes a sound collecting unit 1 for collecting a
sound from a sound source (not shown), and an observation signal x1 (t And x2 (t) to calculate an
output signal y (k, m).
[0036]
The sound collection unit 1 includes a first directional microphone 10 and a second directional
microphone 11 each having a sound collection area of predetermined directivity angles α1 and
α2.
As shown in FIG. 2 (b), the first directional microphone 10 and the second directional
microphone 11 are configured such that a part of the respective sound collection areas is a first
target direction (FIG. 2 (b)). The directional microphones 10 and the second directional
microphone 11 are disposed close to each other so as to overlap and include the direction of the
central axis A).
[0037]
As shown in FIG. 1, the first and second microphones 10 and 11 installed as described above
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11
each receive an acoustic wave from a sound source, and an observation signal x1 (an electrical
signal based on the received acoustic wave) t) Generate x 2 (t).
The first observation signal x1 (t) is output from the first directional microphone 10 to the signal
processing unit 2, and the second observation signal x2 (t) is output from the second directional
microphone 11 to the signal processing unit 2. .
[0038]
By the way, the characteristics of the first and second directional microphones 10 and 11 are, as
shown in FIG. 3, the first and second observation power values Px1 (k , Px2 (k) is high and almost
constant at 0 ° ≦ | φ | <φ1, and decreases rapidly as the angle φ increases at φ1 ≦ | φ |
<φ2, and is low at φ2 <| φ | It is constant.
In FIG. 2B, the angle θ of the area where the respective sound collection areas overlap is 0 °
<θ <min (α1, α2).
In addition, an angle which is a half value of the sensitivity of φ = 0 ° is taken as a directivity
angle α1 (α2).
[0039]
Although the first directional microphone 10 and the second directional microphone 11 of the
present embodiment use microphones having equal sensitivities, even if they have different
sensitivities, the observation signals based on the received sound waves are used. What is
corrected by the sensitivity coefficient may be set as new observation signals x1 (t) and x2 (t).
Specifically, when the sensitivity coefficient of the first directional microphone 10 is m1 and the
sensitivity coefficient of the second directional microphone 11 is m2 (m1 ≠ m2), (the first
directional microphone 10 receives The observation signal x m1) based on the detected sound
wave is taken as the first observation signal x 1 (t) to be transmitted to the signal processing unit
2 (the observation signal x m 2 based on the sound wave received by the second directional
microphone 11) The second observation signal x2 (t) transmitted to the signal processing unit 2
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may be set as
At this time, the sensitivity coefficients m1 and m2 are set to satisfy m1: m2 = ((Px2): √ (Px1)
using Px1 and Px2 described later.
The same applies to the following description.
[0040]
The signal processing unit 2 shown in FIG. 1 receives the first and second observation signals x1
(t) and x2 (t) and receives the discrete value x1 (k, m) of the first observation signal and the
second observation signal. Phase difference correction unit 20 that corrects the phase difference
between discrete values x2 (k, m) of the first and second, the first and second based on the
discrete values x1 (k, m) and x2 (k, m) of the first and second observation signals A sound source
direction determination unit 21 that determines whether a sound source is present in a target
direction using observed power values Px1 (k) and Px2 (k) of 2 and an output signal according to
the determination result of the sound source direction determination unit 21 and an output
operation unit 22 for outputting y (k, m).
[0041]
The phase difference correction unit 20 receives the first observation signal x1 (t) from the first
directional microphone 10, and as shown in FIG. 5 (b), receives the first observation signal x1 (t).
The frame is divided into frames of frame length L, and the discrete value x1 (k, m) of the first
observation signal is extracted at predetermined time intervals Δt for each frame.
Similarly, the second observation signal x2 (t) is received from the second directional microphone
11, this second observation signal x2 (t) is divided into frames of frame length L, and the second
observation signal x2 (t) The discrete values x 2 (k, m) of the observation signal of are extracted
at predetermined time intervals Δt.
The discrete values x1 (k, m) and x2 (k, m) of the first and second observation signals are m-th
discrete values in the k-th frame.
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[0042]
The phase difference correction unit 20 that has extracted discrete values x1 (k, m) and x2 (k, m)
of the first and second observation signals, the discrete value x1 (k, m) of the extracted first
observation signal and The phase difference between the discrete values x2 (k, m) of the second
observation signal and the phase difference between the first observation signal x1 (t) and the
second observation signal x2 (t) when the sound source is present in the target direction Correct
only.
[0043]
For example, as shown in FIG. 4A, when the target direction is a direction B inclined by an angle
φ from the central axis A of the first directional microphone 10 and the second directional
microphone 11, as shown in FIG. As shown in FIG. 3, when the sound source S is present in the
target direction, the first directional microphone 10 and the second directional microphone 11
are disposed close to each other, so the sound waves from the sound source S are incident
approximately in parallel. Do.
Therefore, a phase difference 2d sin φ (2d: distance between the first directional microphone 10
and the second directional microphone 11) is generated between the first observation signal x1
(t) and the second observation signal x2 (t). .
Assuming that the speed of sound is c, a time shift occurs by time τ = 2 dsin φ / c (see FIG. 5A).
From the above, as shown in FIG. 5B, the discrete value x 2 (k, m) of the second observation
signal is delayed by time τ, and the discrete value x 2 ′ (k, By setting m) = x 2 (k, m-τ / Δt),
the phase difference between the discrete value x 1 (k, m) of the first observation signal and the
discrete value x 2 (k, m) of the second observation signal Can be corrected.
[0044]
In the present embodiment, as shown in FIG. 2B, since the target direction is the direction of the
central axis A of the first directional microphone 10 and the second directional microphone 11,
the sound source is directed to the target direction. Since there is no phase difference between
the first observation signal x1 (t) and the second observation signal x2 (t) in the presence of S1,
x2 '(k, m) = x2 (k, m) .
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[0045]
The discrete values x 1 (k, m) and x 2 ′ (k, m) of the first and second observation signals
corrected by the phase difference correction unit 20 are output to the sound source direction
determination unit 21.
[0046]
The sound source direction determination unit 21 shown in FIG. 1 calculates the average value of
the square sum of the discrete values x1 (k, m) of the first observation signal for a predetermined
time (frame length) for each frame as shown in Equation 5. The first observation power value
Px1 (k) is calculated, and the average value of the square sum of the discrete values x2 '(k, m) of
the second observation signal in a predetermined time is calculated for Let it be an observation
power value Px2 (k).
In equation 5, i = 1 and 2.
[0047]
[0048]
The sound source direction determining unit 21 that has calculated the first and second observed
power values Px1 (k) and Px2 (k) uses the first and second observed power values Px1 (k) and
Px2 (k) to generate a sound source. It is determined whether it exists in the target direction.
[0049]
Here, as shown in FIG. 2B, in the area where the sound collection area of the first directional
microphone 10 and the sound collection area of the second directional microphone 11 overlap
(φ1 in FIG. 2B), The relative ratio between the first observed power value Px1 (k) and the second
observed power value Px2 (k) is small, and in the other areas (for example, φ2 in FIG. 2B), the
first observed power value Px1 The relative ratio between (k) and the second observation power
value Px2 (k) is increased.
[0050]
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15
Therefore, in the sound source direction determination unit 21 shown in FIG. 1, both of the first
and second observed power values Px1 (k) and Px2 (k) are larger than the predetermined
threshold Pth, and the first observed power value Px1 (k ) And the relative ratio of the second
observation power value Px2 (k) | 10 log 10 (P x 1 (k) / P x 2 (k)) | (dB) 0 or more and less than
a predetermined set value ε (dB) (0 | | 10 log 10 When the condition that Px1 (k) / Px2 (k) |
<ε) is satisfied, it is determined that the sound source is present in the target direction.
On the other hand, when the above condition is not satisfied, the sound source direction
determination unit 21 determines that the sound source does not exist in the target direction.
[0051]
The output operation unit 22 receives the first observation signal x1 (t) from the first directional
microphone 10 and the second observation signal x2 (t) from the second directional microphone
11, and It is called "DSP" below.
Discrete value x 1 (k, m), x 2 (k, m) of the first and second observed signals from the first and
second observed signals x 1 (t), x 2 (t) using The discrete value x 2 (k, m) of the observation
signal of is delayed by time τ to obtain the discrete value x 2 ′ (k, m) = x 2 (k, m−τ / Δt) of
the new second observation signal, The sum (x1 (k, m) + x2 '(k, m)) of the discrete values x1 (k,
m) and x2' (k, m) of the first and second observation signals is determined.
In the present embodiment, no delay occurs, so x2 '(k, m) = x2 (k, m).
[0052]
When the sound source direction determination unit 21 determines that the sound source is
present in the target direction, the output calculation unit 22 determines that the discrete value
x1 (k, m) of the first observation signal and the discrete value x2 'of the second observation
signal are The combined signal (x1 (k, m) + x2 '(k, m)) of (k, m) is amplified at a first amplification
factor G1 and output as an output signal y (k, m) of a digital output signal.
04-05-2019
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On the other hand, when the sound source direction determination unit 21 determines that the
sound source is not present in the target direction, the output calculation unit 22 performs the
first amplification on the combined signal (x1 (k, m) + x2 ′ (k, m)). It amplifies with the 2nd
amplification factor G2 smaller than the factor G1, and outputs as an output signal y (k, m).
[0053]
Next, the operation of the sound input device of the present embodiment will be described using
FIG.
First, when the first and second microphones 10 and 11 of the sound collection unit 1 receive
sound waves from the sound source, the first and second observation signals x1 (t) and x2 (t) are
processed from the sound collection unit 1 Sent to Part 2.
In the signal processing unit 2, the phase difference correction unit 20 extracts discrete values
x1 (k, m) and x2 (k, m) of the first and second observation signals (S1, S2).
After that, the phase difference correction unit 20 shifts the discrete value x 2 (k, m) of the
second observation signal by the phase difference in the case where the sound source is present
in the target direction. The discrete value is x2 '(k, m) (S3).
[0054]
The sound source direction determination unit 21 calculates the first and second observation
power values Px1 (k) and Px2 (k) for each frame (S4, S5).
Thereafter, the sound source direction determination unit 21 examines whether the first and
second observed power values Px1 (k) and Px2 (k) satisfy the condition that both are greater
than the threshold Pth (S6).
If the above condition is not satisfied, it is determined that the sound source is present in a
direction other than the target direction (outside the sound collection area) (S9).
04-05-2019
17
On the other hand, when the above condition is satisfied, the sound source direction
determination unit 21 examines whether the relative ratio | 10 log 10 (Px1 (k) / Px2 (k)) |
satisfies the condition that it is less than the threshold ε (S7).
If the above condition is satisfied, it is determined that the sound source is present in the target
direction (within the sound collection area) (S8). If the above condition is not satisfied, it is
determined that the sound source is present in the direction other than the target direction (S9).
[0055]
When it is determined that the sound source is present in the target direction, the output
operation unit 22 outputs G1 (x1 (k, m) + x2 '(k, m)) as the output signal y (k, m) (S10) If it is
determined that the sound source is not present in the target direction, G2 (x1 (k, m) + x2 '(k, m))
is amplified and output as the output signal y (k, m) (S11).
[0056]
As described above, according to the present embodiment, observation signals (first observation
signal x1 (k, m), second observation) from two microphones (the first directional microphone 10
and the second directional microphone 11) It is determined whether or not the sound source is
present in the target direction using the signal x2 (k, m)), and the amplification factor (first
amplification factor G1) when the sound source is present in the target direction is By making the
amplification factor (the second amplification factor G2) larger than that in the direction, it is
possible to emphasize and output the sound from the sound source present in the target
direction.
[0057]
Also, by evaluating the relative ratio | 10 log 10 (Px1 (k) / Px2 (k)) | of the first observed power
value Px1 (k) and the second observed power value Px2 (k), the sound source is directed in the
desired direction. It can be accurately determined whether or not it exists.
[0058]
Furthermore, by arranging the two microphones 10 and 11 so that parts of the respective sound
collection areas overlap with each other, sharper directivity can be obtained as compared to the
case of a single directional microphone.
04-05-2019
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[0059]
The directivity angles α1 and α2 of the first and second directional microphones 10 and 11 in
the first embodiment may have various directivity angles.
Specifically, the present invention is not limited to the one shown in FIG. 2, but as shown in FIG.
7 (with a directivity angle of 90.degree.) Or as shown in FIG. 8 (with a directivity angle of
180.degree.) May be.
The same applies to the following embodiments.
[0060]
Further, as a modification of the first embodiment, the output operation unit 22 shown in FIG. 1
does not output the output signal y (k, m) of the digital signal, but the first observation signal x1
(t) and the first observation signal x1 (t) Amplifies the sum (x1 (t) + x2 '(t)) with a new second
observation signal x2' (t) = x2 (t-τ) obtained by delaying the two observation signals x2 (t) by
time τ May be output.
That is, when it is determined that the sound source is present in the target direction, the output
calculation unit 22 outputs the output signal y (t) = G1 (x1 (t) + x2 '(t)), and the sound source is
present in the target direction If it is determined not to output, output signal y (t) = G2 (x1 (t) +
x2 '(t)) (G2 <G1) is output.
The same applies to the following embodiments.
[0061]
Second Embodiment In the sound input device according to the second embodiment, the sound
source direction determining unit 21 illustrated in FIG. 1 is configured of the discrete values x1
(k, m) and x2 '(k, m) of the first and second observation signals. This embodiment differs from
04-05-2019
19
the acoustic input device of the first embodiment in that the cross-correlation function R12
(Equation 6) is calculated for each frame.
The correlation function Rij of Equation 6 is an autocorrelation function when i = j, and is a cross
correlation function when i ≠ j.
In addition, about the component similar to Embodiment 1, the same code | symbol is attached |
subjected and description is abbreviate | omitted.
[0062]
[0063]
As shown in FIG. 9, the cross correlation function R12 has a large value in an area where the
sound collection areas of the first directional microphone 10 and the second directional
microphone 11 overlap (−θ / 2 <φ <θ / 2). In the other areas than the above, the value is
small.
Therefore, the sound source direction determining unit 21 determines that the sound source is
present in the target direction when the condition of cross correlation function R12> threshold
Rth is satisfied, and determines that the sound source is not present in the target direction when
the above condition is not satisfied. Do.
[0064]
The autocorrelation function R11 of the discrete value x1 (k, m) of the first observation signal or
the autocorrelation function R22 of the discrete value x2 (k, m) of the second observation signal
is used to determine the threshold Rth. .
Since the autocorrelation functions R11 and R22 have large values regardless of the direction in
which the sound source is present, Rth = ζRii (i = 1, 2), 0 <決定 <1.
04-05-2019
20
[0065]
As described above, according to the present embodiment, the cross-correlation function R12 of
the discrete value x1 (k, m) of the first observation signal and the discrete value x2 '(k, m) of the
second observation signal is evaluated. It can be accurately determined whether or not the sound
source is present in the target direction.
[0066]
Third Embodiment The sound input device of the third embodiment is installed at an
intermediate position between the first directional microphone 10 and the second directional
microphone 11 in the sound collection unit 1a as shown in FIG. 10A. Different from the acoustic
input device according to the first embodiment (see FIG. 1) in that the omnidirectional
microphone 12 receives an acoustic wave from a sound source and generates a reference
observation signal that is an electrical signal based on the received acoustic wave. doing.
In addition, about the component similar to Embodiment 1, the same code | symbol is attached |
subjected and description is abbreviate | omitted.
[0067]
Although the nondirectional microphone 12 of the present embodiment uses microphones
having the same sensitivity as the first and second directional microphones 10 and 11, even if
the sensitivity is different, it is based on the received sound wave. What is obtained by correcting
the observation signal with the sensitivity coefficient may be set as a new observation signal x0
(t).
Specifically, when the sensitivity coefficient of the nondirectional microphone 12 is m0, (the
observed signal based on the sound wave received by the nondirectional microphone 12 × m0)
is transmitted to the signal processing unit 2a. It may be x 0 (t).
At this time, the sensitivity coefficient m0 is set to satisfy m0: m1 = √ (Px1): √ (Px0) using Px0
described later.
04-05-2019
21
The same applies to the following description.
[0068]
In the signal processing unit 2a of this embodiment, as shown in FIG. 11, the phase difference
correction unit 20a receives the reference observation signal x0 (t) from the nondirectional
microphone 12 and receives the reference observation signal x0 (t). The discrete value x0 (k, m)
of is extracted at a predetermined time interval Δt, and the discrete value x0 (k, m) of the
extracted reference observation signal is the reference observation signal x0 (t) when the sound
source is present in the target direction And the phase difference of the first observation signal
x1 (t).
[0069]
In addition, the sound source direction determination unit 21a calculates an average value in a
predetermined time (frame length L) of the square sum of the discrete values x0 (k, m) of the
reference observation signal shifted by the phase difference correction unit 20a It is assumed
that the power value Px0 (k).
If the distance from the nondirectional microphone 12 to the sound source is constant, the
reference observation power value Px0 (k) is constant regardless of the direction in which the
sound source is present.
[0070]
The sound source direction determining unit 21a that has calculated the reference observed
power value Px0 (k) calculates the relative ratio (Px1 (k) / Px0 (k) of the first observed power
value Px1 (k) to the reference observed power value Px0 (k). Is included in a preset first range,
and the relative ratio (Px2 (k) / Px0 (k)) of the second observed power value Px2 (k) to the
reference observed power value Px0 (k) is previously set. If the condition included in the second
range is satisfied, it is determined that the sound source is present in the target direction.
On the other hand, when the above condition is not satisfied, the sound source direction
determining unit 21a determines that the sound source does not exist in the target direction.
04-05-2019
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[0071]
Here, the first range of the present embodiment is a range (δ <Px1 (k) / Px0 (k) ≦ 1) which is
larger than the initially set threshold value δ and is 1 or less.
The second range of the present embodiment is also a range (δ <Px2 (k) / Px0 (k) ≦ 1) which is
larger than the initially set threshold value δ and is 1 or less.
[0072]
As described above, according to the present embodiment, by installing the nondirectional
microphone 12 at an intermediate position between the first directional microphone 10 and the
second directional microphone 11, the reference observation power value Px0 of the
nondirectional microphone 12 is obtained. By using the first and second observation power
values Px1 (k) and Px2 (k) with respect to (k), it can be accurately determined whether or not a
sound source is present in the target direction.
[0073]
(Fourth Embodiment) In the sound input device according to the fourth embodiment, the sound
source direction determination unit 21a illustrated in FIG. 11 includes the first and second
observation signals x1 (k, m) and x2 (k, m) and the reference observation signal x0. The
correlation function R ij (i, j = 0, 1, 2) expressed by the equation 7 is obtained using (k, m), and
using this correlation function R ij whether or not the sound source exists in the target direction
It differs from the sound input device of the third embodiment in that it is determined.
In addition, about the component similar to Embodiment 3, the same code | symbol is attached |
subjected and description is abbreviate | omitted.
[0074]
[0075]
04-05-2019
23
The correlation function Rij of Equation 7 is an autocorrelation function when i = j, and is a cross
correlation function when i ≠ j.
[0076]
The sound source direction determination unit 21a of this embodiment differs from the third
embodiment in that a reference observation signal x0 (k, m) with respect to the autocorrelation
function R00 of the reference observation signal x0 (k, m) and the first observation signal x1 (
The relative ratio (R01 / R00) of the cross correlation function R01 of k, m) is included in the
first range set in advance, and the reference observation signal x0 (k, m) and the second
observation with respect to the autocorrelation function R00 If the relative ratio (R02 / R00) of
the cross-correlation function R02 of the signal x2 (k, m) satisfies the condition included in the
second range set in advance, it is determined that the sound source is present in the target
direction.
On the other hand, when the above condition is not satisfied, the sound source direction
determining unit 21a determines that the sound source does not exist in the target direction.
[0077]
Here, the first range of the present embodiment is a range (ξ <R01 / R00 ≦ 1) which is larger
than the initially set threshold ξ and is 1 or less.
The second range of the present embodiment is also a range (ξ <R02 / R00 ≦ 1) which is larger
than the initially set threshold ξ and is 1 or less.
[0078]
As described above, according to the present embodiment, the autocorrelation function R00 of
the reference observation signal x0 (k, m) or the reference observation signal x0 (k, m) and the
first and second observation signals x1 (k, m) and x2 ( By using the cross-correlation function
R01, R02 of k, m), the influence of uncorrelated noise can be reduced to obtain a high S / N ratio,
and it is possible to determine whether the sound source is present in the target direction or not.
It can be enhanced.
04-05-2019
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[0079]
Embodiment 5 In the sound input device according to Embodiments 1 and 3, the output signal y
(k, m) (power value Py of the output signal is output, as shown in FIG. (K) becomes discontinuous.
[0080]
Therefore, in the sound input device according to the fifth embodiment, when the sound source
direction determination unit 21 illustrated in FIG. 1 determines that the sound source does not
exist in the target direction, it determines whether the sound source exists in the vicinity of the
target direction. Point, the continuous change which monotonically decreases between the first
amplification factor G1 and the second amplification factor G2 when the output calculation
section 22 determines that the sound source is present in the vicinity of the target direction by
the sound source direction determination section 21. This embodiment differs from the acoustic
input device of the first embodiment in that the synthesized signal is amplified and output at the
amplification factor of the characteristic.
In addition, about the component similar to Embodiment 1, the same code | symbol is attached |
subjected and description is abbreviate | omitted.
[0081]
As shown in FIG. 12, the amplification factor G is such that the first and second observed power
values Px1 (k) and Px2 (k) are both larger than the predetermined threshold Pth, and the relative
ratio | 10log10 (Px1 (k) / When Px2 (k) | is 0 or more and less than the threshold ε (0 ≦ | 10
log 10 (Px1 (k) / Px2 (k)) | <ε), the first amplification factor G1 is obtained, as in the first
embodiment.
[0082]
On the other hand, when the relative ratio | 10 log 10 (Px 1 (k) / P x 2 (k)) | is equal to or greater
than the threshold ε, first, the relative ratio | 10 log 10 (P x 1 (k) / P x 2 (k)) | When (ε1> ε) is
less than (ε ≦ | 10 log 10 (Px1 (k) / Px2 (k)) | <ε), it is determined that the sound source is in
the vicinity of the target direction, and the amplification factor G is a monotonically decreasing
function f Therefore it fluctuates.
04-05-2019
25
Subsequently, when the relative ratio | 10 log 10 (P x 1 (k) / P x 2 (k)) | is a threshold ε 1 or
more (ε 1 | 10 log 10 (P x 1 (k) / P x 2 (k))), the sound source is the target direction The
amplification factor G is determined to be present at a distant position, and the amplification
factor G becomes the second amplification factor G2.
[0083]
As described above, according to the present embodiment, it is possible to prevent the
amplification factor G for amplifying the composite signal (x1 (k, m) + x2 ′ (k, m)) from
becoming discontinuous due to the direction in which the sound source is present. As a result,
the output signal y (k, m) (power value Py (k) of the output signal) can always be a continuous
value (see FIG. 13).
[0084]
In the acoustic input device of the second embodiment, as shown in FIG. 14, when the cross
correlation function R12> the threshold Rth, the amplification factor G is the first amplification
factor G1 as in the second embodiment.
[0085]
On the other hand, when the cross correlation function R12> the threshold Rth, first, when the
cross correlation function R12 is larger than the threshold Rth1 (Rth1 <Rth) and not more than
the threshold Rth (Rth1 <R12 ≦ Rth), the sound source exists in the vicinity of the target
direction It is determined that the amplification factor G fluctuates according to the
monotonically increasing function e.
Subsequently, when the cross correlation function R12 is greater than or equal to 0 and less than
or equal to the threshold value Rth1 (0 ≦ R12 ≦ Rth1), it is determined that the sound source is
present at a position away from the target direction, and the amplification factor G is the second
amplification factor G2. .
The sensitivities of the first directional microphone 10, the second directional microphone 11,
and the nondirectional microphone 12 are all equal.
04-05-2019
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[0086]
In the sound input device of the third embodiment, as shown in FIG. 15, the amplification factor
G is a relative ratio (Px1 (k) / Px0 (k)) and a relative ratio (Px2 (k) / Px0 (k) In the case where
each of the above is larger than the threshold value δ and not more than 1 (δ <Px1 (k) / Px0 (k)
≦ 1 and δ <Px2 (k) / Px0 (k) ≦ 1), as in the third embodiment, The amplification factor G1 of 1
is obtained.
[0087]
On the other hand, if the relative ratio (Px1 (k) / Px0 (k)) and the relative ratio (Px2 (k) / Px0 (k))
are not in the above ranges, first, the relative ratio (Px1 (k) / Px0 (k) ) Or the relative ratio (Px2
(k) / Px0 (k)) is larger than the threshold δ1 (δ1 <δ) and not more than the threshold δ (δ1
<Px1 (k) / Px0 (k) ≦ δ or δ1 <Px2) When (k) / Px 0 (k) ≦ δ, it is determined that the sound
source is in the vicinity of the target direction, and the amplification factor G fluctuates according
to the monotonically increasing function g.
Subsequently, either the relative ratio (Px1 (k) / Px0 (k)) or the relative ratio (Px2 (k) / Px0 (k)) is
0 or more and the threshold δ1 or less (0 ≦ Px1 (k) / Px0 (k) When it is ≦ δ1 or 0 ≦ Px2 (k) /
Px0 (k) ≦ δ1, it is determined that the sound source is present at a position distant from the
target direction, and the amplification factor G becomes the second amplification factor G2.
The sensitivities of the first directional microphone 10, the second directional microphone 11,
and the nondirectional microphone 12 are all equal.
[0088]
In the acoustic input device according to the fourth embodiment, as shown in FIG. 16, the
amplification factor G is such that both the relative ratio (R01 / R00) and the relative ratio (R02 /
R00) are greater than the threshold value 11 or less ((1) In the case of ξ <R01 / R00 ≦ 1 and ξ
<R02 / R00 ≦ 1), the first amplification factor G1 is obtained, as in the fourth embodiment.
[0089]
On the other hand, when the relative ratio (R01 / R00) and the relative ratio (R02 / R00) do not
04-05-2019
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fall within the above ranges, first, either the relative ratio (R01 / R00) or the relative ratio (R02 /
R00) becomes the threshold ξ1 (ξ1). In the case where R1 and R1 are larger than the threshold
ξ (ξ1 <R01 / R00 ≦ ξ or ξ1 <R02 / R00 ≦ ξ), the sound source is determined to be present
in the vicinity of the target direction, and the amplification factor G follows the monotonically
increasing function h. fluctuate.
Subsequently, if either the relative ratio (R01 / R00) or the relative ratio (R02 / R00) is 0 or more
and the threshold value ξ1 or less (0 ≦ R01 / R00 ≦ ξ1 or 0 ≦ R02 / R00 ≦ ξ1), the sound
source is the purpose The amplification factor G is determined to be present at a position distant
from the direction, and the amplification factor G becomes the second amplification factor G2.
The sensitivities of the first directional microphone 10, the second directional microphone 11,
and the nondirectional microphone 12 are all equal.
[0090]
As described above, even in the case of the acoustic input device as in Embodiments 3 and 4, the
amplification factor G for amplifying the combined signal (x1 (k, m) + x2 ′ (k, m)) as in
Embodiment 5 Can be prevented from becoming discontinuous due to the direction of the sound
source, and as a result, unlike in FIG. 10B, the output signal y (k, m) (power value Py (k) of the
output signal) It can always be a continuous value.
[0091]
Sixth Embodiment In the first to fifth embodiments, the case of one sound source has been
described. In the sixth embodiment, the case of two sound sources will be described.
Here, as a combination in which a plurality of sound sources exist, (1) when only a target sound
source exists, (2) when a target sound source and one noise source exist, (3) a target sound
source and two noise sources exist If (4) there is neither a target sound source nor a noise
source, (5) no target sound source exists, and only one noise source exists, (6) no target sound
source exists, and two noise sources are present. May exist. Among them, the combination of two
sound sources is the case of (2) and (6). Specifically, as shown in FIG. 17A, the target sound
source S exists in an area where the sound collection areas of the first directional microphone 10
and the second directional microphone 11 overlap, and the first directional microphone The case
where the noise source N1 exists only in the ten sound collecting regions will be described.
04-05-2019
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[0092]
In the case shown in FIG. 17A, among the sound source direction determination conditions of the
first embodiment, Px1 (k)> Pth (first condition) and Px2 (k)> Pth (second condition) are satisfied.
The second observation signal x2 (t) of the two directional microphones 11 includes only the
signal based on the target sound source S, while the first observation signal x1 (t) of the first
directional microphone 10 Since not only the target sound source S but also a signal based on
the noise source N1 is included, | 10 log 10 (Px1 (k) / Px2 (k) | <ε (third condition) is not
satisfied.
[0093]
As described above, when the first and second conditions are satisfied but the third condition is
not satisfied, the sound source direction determination condition R12> Rth (fourth condition) of
the second embodiment is further used.
The target sound source S is present in an area where the sound collection areas of the first and
second directional microphones 10 and 11 overlap, and the noise source N1 is present only in
the sound collection area of the first directional microphone 10 Also, since the signal based on
the target sound source S is included in the observation signals x1 (t) and x2 (t) of both of the
first and second directional microphones 10 and 11, the fourth condition is satisfied. Therefore,
the sound source direction determination unit 21 can determine that the target sound source S
exists in an area where the sound collection areas of the first and second directional microphones
10 and 11 overlap.
[0094]
Subsequently, the sound source direction determination unit 21 needs to determine in which
sound collection region the noise source N1 is present among the first and second directional
microphones 10 and 11. Therefore, as shown in FIG. 17A, the nondirectional microphone 12 is
disposed between the first directional microphone 10 and the second directional microphone 11.
Since the omnidirectional microphone 12 is omnidirectional, a signal based on both the target
sound source S and the noise source N1 is included in the reference observation signal x0 (t).
Therefore, the sound source direction determination unit 21 sets δ <Pxi (k) / Px0 (k) ≦ 1 (of the
observation power values Px1 (k) and Px2 (k) of the first and second directional microphones 10
and 11, respectively. It is determined that the noise source N1 exists in the sound collection
region of the first and second directional microphones 10 and 11 that satisfy i = 1, 2) (fifth
04-05-2019
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condition).
[0095]
When it is determined that the target sound source S is present in the area where the sound
collection areas of the first and second directional microphones 10 and 11 overlap and the noise
source N1 is present only in the sound collection area of the first directional microphone 10, The
output operation unit 22 amplifies the discrete value x2 (k, m) of the second observation signal
of the second directional microphone 11 including only the signal based on the target sound
source S by the amplification factor G1, and outputs the output signal y (k). , M) = G1 × x2 (k, m)
is output.
[0096]
On the other hand, when it is determined that the target sound source S does not exist in the area
where the sound collection areas of the first and second directional microphones 10 and 11
overlap, the output operation unit 22 generates the first and second directional microphones 10,
A synthetic signal (x1 (k, m) + x2 (k, m)) of discrete values x1 (k, m) and x2 (k, m) of 11
observation signals is amplified with amplification factor G2 (G1> G2), An output signal y (k, m) =
G2 (x1 (k, m) + x2 (k, m)) is output.
[0097]
As described above, according to the present embodiment, the target sound source S exists in the
area where the sound collection areas of the first and second directional microphones 10 and 11
overlap, and the noise source N1 is the first and second directional microphones 10 and 11. Even
in the case where it exists only in one of the sound collection regions, only the signal based on
the target sound source S can be amplified and output.
[0098]
As a modification of the sixth embodiment, the output signal y (k, m) can also be output as
follows.
The sound source direction determination unit 21 has the target sound source S in an area where
the sound collection areas of the first and second directional microphones 10 and 11 overlap,
and the noise source N1 is present only in the sound collection area of the first directional
microphone 10. When it is determined that the first directional microphones 10 and 11 are
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30
observed after tilting the directivity axis of the first directional microphone 10 until the third
condition is satisfied as shown in FIG. A composite signal (x1 (k, m) + x2 (k, m)) of discrete values
x1 (k, m) and x2 (k, m) of the signal is amplified by amplification factor G1 and output signal y (k,
m) = G1 (x1 (k, m) + x2 (k, m)) is output.
The case where the target sound source S does not exist in the area where the sound collection
areas of the first and second directional microphones 10 and 11 overlap is similar to that of the
sixth embodiment.
[0099]
Seventh Embodiment In the sixth embodiment, the case of two sound sources has been described,
but in the seventh embodiment, the case of three sound sources will be described.
The combination of the three sound sources is (3) only when there are the target sound source
and the two noise sources, but it is necessary to distinguish between the two sound sources ((2),
(6)). Specifically, as shown in FIG. 18A, the target sound source S exists in an area where the
sound collection areas of the first and second directional microphones 10 and 11 overlap, and
the sound collection of the first directional microphone 10 is performed. The case where the
noise source N1 exists only in the region and the noise source N2 exists only in the sound
collection region of the second directional microphone 11 will be described.
[0100]
In the case shown in FIG. 18A, among the sound source direction determination conditions of the
first embodiment, Px1 (k)> Pth (first condition) and Px2 (k)> Pth (second condition) are satisfied.
The first observation signal x1 (t) of the first directional microphone 10 includes a signal based
on the target sound source S and the noise source N1, and the second observation signal x2 (t) of
the second directional microphone 11 Since the signal based on the target sound source S and
the noise source N2 is included, does not necessarily satisfy | 10log10 (Px1 (k) / Px2 (k) | <ε
(third condition).
[0101]
As described above, when the first and second conditions are satisfied but the third condition is
04-05-2019
31
not satisfied, the sound source direction determination condition R12> Rth (fourth condition) of
the second embodiment is further used.
The target sound source S is present in the area where the sound collection areas of the first and
second directional microphones 10 and 11 overlap, and the noise source N1 is present only in
the sound collection area of the first directional microphone 10. Even when the noise source N2
exists only in the sound collection region of the directional microphone 11, the signal based on
the target sound source S is the observation signal x1 (t1 of both the first and second directional
microphones 10 and 11). And x2 (t), so the fourth condition is satisfied. Therefore, the sound
source direction determination unit 21 can determine that the target sound source S exists in an
area where the sound collection areas of the first and second directional microphones 10 and 11
overlap.
[0102]
Subsequently, as in the sixth embodiment, whether the noise source N1 exists in any one of the
sound collection areas of the first and second directional microphones 10 and 11 as in the sixth
embodiment Thus, it is necessary to determine whether different noise sources N1 and N2 exist
in the respective sound collection areas of the first and second directional microphones 10 and
11, respectively. Therefore, as shown in FIG. 18A, the nondirectional microphone 12 is disposed
between the first directional microphone 10 and the second directional microphone 11. Since the
nondirectional microphone 12 is nondirectional, the signal based on the target sound source S
and the noise sources N1 and N2 is included in the reference observation signal x0 (t), and the
first directional microphone 10 includes the target sound source S and the noise source N1. The
second directional microphone 11 includes a signal based on the target sound source S and the
noise source N2 in a second observation signal x2 (t). Therefore, the sound source direction
determination unit 21 determines the nondirectional microphone 12 and the first directivity
when the noise sources N1 and N2 exist outside the sound collecting area of the first directional
microphone 10 and the second directional microphone 11. Power values Px1 (k) and Px2 of the
first and second directional microphones 10 and 11 with the ratio .delta.2 of the observation
power values of the dynamic microphone 10 or the nondirectional microphone 12 and the
second directional microphone 11 as a threshold. When k) satisfies δ2 <Pxi (k) / Px0 (k) ≦ δ (i
= 1, 2) (fifth condition), the sound collecting regions of the first and second directional
microphones 10 and 11 are respectively It is determined that different noise sources N1 and N2
exist.
[0103]
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The target sound source S exists in an area where the sound collection areas of the first and
second directional microphones 10 and 11 overlap, and the noise sources N1 and N2 are
respectively the collection of the first directional microphone 10 and the second directional
microphone 11 When it is determined that the noise sources exist only in the sound area, as
shown in FIG. 18A, the noise sources N1 and N2 are from the central axis of the area where the
sound collection areas of the first and second directional microphones 10 and 11 overlap. When
the distance is not less than Max (α1 / 2, α2 / 2), as shown in FIG. 18B, the directivity axes of
the first and second directional microphones 10 and 11 are inclined to satisfy the third condition,
Only signals based on the target sound source S can be collected by the first and second
directional microphones 10 and 11. At this time, the output operation unit 22 generates a
composite signal (x1 (k, m) + x2) of discrete values x1 (k, m) and x2 (k, m) of the observation
signals of the first and second directional microphones 10 and 11. (K, m) is amplified at an
amplification factor G1, and an output signal y (k, m) = G1 (x1 (k, m) + x2 (k, m)) is output.
[0104]
On the other hand, when it is determined that the target sound source S does not exist in the area
where the sound collection areas of the first and second directional microphones 10 and 11
overlap, the output operation unit 22 generates the first and second directional microphones 10,
A composite signal (x1 (k, m) + x2 (k, m)) of discrete values x1 (k, m) and x2 (k, m) of the 11 first
and second observation signals is amplified by an amplification factor G2 (G1> G2) And outputs
an output signal y (k, m) = G2 (x1 (k, m) + x2 (k, m)).
[0105]
As described above, according to the present embodiment, the target sound source S exists in an
area where the sound collection areas of the first and second directional microphones 10 and 11
overlap, and the first directional microphone 10 and the second directional microphone 11 The
signal based on the target sound source S can be emphasized and output even when different
noise sources N1 and N2 exist in the respective sound collection regions of.
[0106]
As shown in FIGS. 19 (a) and 19 (b), at least one of the noise source N1 and the noise source N2
is Max from the central axis of the area where the sound collection areas of the first and second
directional microphones 10 and 11 overlap. When not separated by (α1 / 2, α2 / 2) or more,
only the signal of the target sound source S can not be collected even if the directional axes of
04-05-2019
33
the first and second directional microphones 10 and 11 are inclined.
However, the signal based on the target sound source S is included in both the first and second
observation signals x1 (t) and x2 (t), and the signal based on the noise source N1 is only the first
observation signal x1 (t), Since the signal based on the noise source N2 is included only in the
second observation signal x2 (t), the composite signal (x1) of the discrete values x1 (k, m) and x2
(k, m) of the first and second observation signals By amplifying (k, m) + x 2 (k, m) by the
amplification factor G 1 and outputting it, it is possible to emphasize a signal based on the target
sound source S more than when collecting sound with the nondirectional microphone 12 alone. .
[0107]
In the sound input devices according to the sixth and seventh embodiments, (1) when only the
target sound source exists, (2) when the target sound source and one noise source exist, by
performing the determination operation as shown in FIG. (3) If there is a target sound source and
two noise sources, (4) If there is neither a target sound source nor a noise source, (5) If there is
no target sound source but only one noise source, The target sound source is not present, and
the case where two noise sources are present can be separated and determined.
[0108]
It is a block diagram which shows the structure of the sound input device of Embodiment 1,2.
It is a figure for demonstrating the operation | movement of an acoustic input device same as the
above.
It is a figure for demonstrating the characteristic of a 1st directional microphone and a 2nd
directional microphone in the acoustic input device of Embodiment 1-8. It is a figure for
demonstrating a phase adjustment in the acoustic input device same as the above. It is a figure
for demonstrating a phase adjustment in the acoustic input device same as the above. 5 is a
flowchart showing the operation of the sound input device of the first embodiment. It is a figure
for demonstrating the characteristic of the modification of a 1st directional microphone and a
2nd directional microphone in the acoustic input device of Embodiment 1-8. It is a figure for
demonstrating the characteristic of the other modification of a 1st directional microphone and a
2nd directional microphone in the acoustic input device of Embodiment 1-8. FIG. 8 is a diagram
for explaining the operation of the sound input device of the second embodiment. FIG. 14 is a
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34
diagram for explaining the operation of the sound input device of the third embodiment. It is a
block diagram which shows the structure of the sound input device of Embodiment 3,4. FIG. 18 is
a diagram showing an amplification factor in the acoustic input device of the fifth embodiment. It
is a figure which shows the output signal in an acoustic input device same as the above. It is a
figure which shows the amplification factor in the sound input device of the modification same as
the above. It is a figure which shows the gain in the sound input device of the other modification
of the same as the above. It is a figure which shows the gain in the sound input device of the
other modification of the same as the above. FIG. 18 is a diagram for explaining the operation of
the sound input device of the sixth embodiment. FIG. 18 is a diagram for explaining the operation
of the acoustic input device of the seventh embodiment. It is a figure for demonstrating the
operation | movement of an acoustic input device same as the above. 21 is a flowchart showing
the operation of the sound input device of the sixth and seventh embodiments.
Explanation of sign
[0109]
1, 1a sound collection unit 10 first directional microphone 11 second directional microphone 12
nondirectional microphone 2, 2a signal processing unit 20, 20a phase difference correction unit
21, 21a sound source direction determination unit 22 output calculation unit
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