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JPH06269082

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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
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DESCRIPTION JPH06269082
[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a
microphone apparatus capable of preferentially collecting a sound in a target direction among
sounds generated from multiple directions, and a directivity conversion method thereof.
[0002]
2. Description of the Related Art Conventionally, non-directional microphone devices
(microphones) collect surrounding sound at the same level, so sounds generated from multiple
directions, for example, when many people hold a table around a table Assuming that the
microphone is placed at the center of the table, it is possible to easily pick up the sound without
moving the microphone regardless of who is at any position. By the way, the sound other than
the person who speaks is quite loud, and each person may use a dedicated microphone. In this
case, it is necessary to operate the on / off of the speaker's microphone.
[0003]
On the other hand, directional microphones are used in sports grounds to record the player's
voice except for cheers on the audience seats, and are also used to record the voices of wild birds
that keep people away . In this case, since the distance between the microphone and the sound
source is long, even if the player or the wild bird moves, the angle for changing the direction of
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the microphone can be small.
[0004]
As described above, when a nondirectional microphone or the like is used for a conference, it is
necessary to prepare a microphone for each seat and to pay attention to the routing of the
microphone cord In addition, it may be an obstacle when spreading materials etc. on the table. In
addition, when the directional microphone is placed at the center of the table, a device for
mechanically adjusting the direction of the directional microphone is also required.
[0005]
An object of the present invention is to provide a microphone device capable of mainly collecting
sound in a target direction without moving a microphone even when installed at the center of a
table, and a directivity conversion method thereof.
[0006]
According to the present invention, in order to achieve the above object, a plurality of sound
receiving elements are arranged in parallel in the x direction and the y direction, respectively,
and the outputs of the plurality of sound receiving elements are synthesized. And a circuit for
extracting output signals of nondirectional characteristics, bidirectional characteristics in the x
and y directions and high-order bidirectional characteristics, and their synergistic characteristics,
and a plurality of these output signals And a circuit that outputs an output signal of high-order
synthesized directivity characteristics.
[0007]
Also, in this device, output signals of non-directional characteristic, bi-directional characteristic in
x and y directions, high-order bi-directional characteristic, and their synergistic directivity
characteristic are obtained by a plurality of sound receiving elements. The present invention is
characterized in that high-order combined directivity characteristics in the target direction are
obtained by combining the output signals after performing coordinate conversion operations in
the target direction.
[0008]
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According to the present invention, with the above-described configuration, the microphone
device has high-order combined directivity characteristics by combining the outputs of the
plurality of sound receiving elements with the set circuit.
Therefore, sound in a specific direction can be collected.
In addition, since the pointing direction of the combined directivity characteristic is changed by
performing an arbitrary coordinate conversion operation, it is possible to match the direction of
the directivity characteristic according to the voice direction of the target direction by the
constant of the coordinate conversion operation. .
[0009]
DESCRIPTION OF THE PREFERRED EMBODIMENT The present invention will now be described
by way of example with reference to the accompanying drawings.
First, as shown in FIG. 2, a part of the nondirectional sound receiving elements 1 (1a, 1b) which
constitute the microphone device are arranged at an interval k. The respective output terminals
are connected to the input terminals of the addition circuit 3 and the subtraction circuit 4 via the
buffer 2. The output of the adder circuit 3 has a nondirectional characteristic R shown in FIG. 3
and the output of the subtractor circuit 4 has a bidirectional characteristic S in the x direction.
[0010]
Next, in order to obtain high-order bi-directional characteristics in the x direction, as shown in
FIG. 4, the sound receiving elements 1 with non-directional characteristics are arranged in
parallel in the x direction. Then, the bi-directional characteristic cos θ is obtained by subjecting
each output to a subtraction process, and this output is further subjected to a subtraction process
to obtain a quadratic bi-directional characteristic cos 2 θ. Furthermore, by subtracting the two
outputs, the third-order bi-directional characteristic cos 3 θ can be obtained.
[0011]
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In addition, as shown in FIG. 5, high-order bi-directional characteristics in the y direction
(direction orthogonal to the x direction) are obtained by juxtaposing the sound receiving
elements 1 having nondirectional characteristics in the y direction. Since the bi-directional
characteristic sin θ is obtained by subtracting, the output is further subtracted to obtain the
second-order bi-directional characteristic sin 2 θ. Furthermore, by subtracting the two outputs,
the third-order bi-directional characteristic sin3θ can be obtained.
[0012]
As for the synergetic directivity characteristic, for example, as shown in FIG. The two bidirectional characteristics sin θ are obtained by subtracting the output of. By subjecting these
two outputs to subtraction processing, the co-directivity characteristic cosθ sinθ can be
obtained.
[0013]
Next, a method of combining the directivity characteristics obtained as described above to obtain
high-order sharp directivity characteristics will be described using second-order characteristics
and third-order characteristics. A sharper directional characteristic can be obtained as the order
is higher, but there is also a problem that the S / N ratio in the low-pitched part becomes difficult,
and the description in the high order is omitted.
[0014]
First, when the combined output of the sound receiving element 1 is limited to the second order
term, the combined directivity characteristic is expressed by the following. S (θ) = A + B cos θ +
C sin θ + D cos 2θ + E sin 2θ + F cos θ sin θ Here, S (θ) is a combined directivity
characteristic, and θ is an angle measured from the x axis. Further, A to F are constants
indicating the synthesis amount of each directivity characteristic, and the ratio of these
influences the synthesis output of the synthesis directivity characteristic. For example, assuming
that the constants are A = -1, B = 2, C = 0, D = 4, E = 0, and F = 0, this directivity characteristic is
synthesized at an angle of 0 degrees as shown in FIG. It becomes a pattern that the output is
maximum.
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[0015]
In order to obtain the same pattern as this in any direction, if a coordinate transformation
operation associated with that direction is performed, the relationship between any direction and
A to F is as follows.
[0016]
For example, the constants at 225 degrees are A = -1, B = -1.414, C = -1.414, D = 2, E = 2, F = 4,
and the pattern in the direction of 225 degrees shown by a dotted line in FIG. Is obtained.
In addition, the directivity can be freely changed by setting sets A to F with respect to several
directions such as 0 degree, 45 degrees, 90 degrees, and 135 degrees. Furthermore, since the
relationship between the direction angle (φ) and A to F in this case changes continuously as
shown in the right end of Table 1, the directivity direction can be changed continuously using a
pan pot or the like. it can. In the above example, since sin 2θ = 1−cos 2θ, the constant of sin
2θ is divided into the first term and the cos 2θ term, and the term of sin 2θ does not have to
be considered. Therefore, the above equation may be S (θ) = A + B cos θ + C sin θ + D cos 2 θ
+ F cos θ sin θ. In this case, the directivity characteristic in the x-axis direction is obtained by
dividing the constant of sin 2θ into 0 degrees in Table 2. However, as is easily understood, the
form of the directivity characteristic shown in Tables 1 and 2 is completely It is the same.
[0017]
In addition, the coordinate conversion operation referred to here is a condition (S.phi. (. Theta. +.
Phi.) = SO.sub.2 (.theta.)) That any directivity direction characteristic (S.phi. (. Theta.)) Is equal to
the directivity characteristic (SO (.theta.)) In the x-axis direction. It is obtained from
[0018]
Next, when the combined output of the sound receiving element 1 is used up to the third order
term as the second embodiment, the directivity characteristic becomes considerably sharp.
In this case, cos 2 θ sin θ and cos θ sin 2 θ can also be considered as third-order terms, but
these can be distributed to other terms from cos 2 θ sin θ = sin θ-sin 3 θ and cos θ sin 2 θ =
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cos θ-cos 3 θ as in sin 2 θ. It can handle. Therefore, taking this into consideration, S (θ) can
be expanded to S (θ) = A + B cos θ + C sin θ + D cos 2 θ + F cos θ sin θ + G cos 3 θ + H sin
3 θ.
[0019]
Here, if the constants are taken as A = -1, B = -4, C = 0, D = 4, F = 0, G = 8, H = 0, this directivity
characteristic is as shown in FIG. When the angle is 0 degrees, the pattern is the maximum
output. When coordinate conversion calculation for obtaining the same directivity characteristic
in any direction is performed, the relationship between the direction φ and A to H is as shown in
Table 3.
[0020]
Assuming that each constant is A = 1, B = -5.656, C = 5.656, D = 0, F = -4, G = 5.656, H = -5.656,
taking 135 degrees as an example from Table 3, for example. The directivity characteristic of
135 degrees direction shown by the dotted line of 8 is obtained.
[0021]
The following is the third embodiment, and the constants for the case of an angle of 0 degrees
are A = -0.5, B = -1, C = 0, D = 3, F = 0, G = 4, H = It is a directivity characteristic set to 0, and is
shown in FIG.
The relationship between the directional directions (φ) and A to H having the same directional
characteristics as this is shown in Table 4. Also in this third embodiment, the same directivity
characteristic having an arbitrary pointing direction can be obtained as in the first and second
embodiments.
[0022]
Thus, the direction of directivity can be changed by replacing the constant, and in fact, as shown
in FIG. 1, the attendee P (P1, P2...) Encloses the table 5, and the microphone device 6 When
placed at the center of the table 5, the composite directivity characteristic J facing in the
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direction of the attendee P1 can be the composite directivity characteristic J facing in the
direction of the attendee P2. Moreover, the sound receiving element 1 for this may use at least
one non-directional sound receiving element 1, and the other plural sound receiving elements 1
may use a bidirectional sound receiving element 1. .
[0023]
As the present invention is configured as described above, by installing a microphone device
composed of a plurality of sound receiving elements, the synthetic directivity characteristic in the
desired direction can be obtained for each of the sound receiving elements. Since the output
signal is obtained by combining the output signals in a predetermined size, there is an effect that
the mounting operation is simple and the operation is easy.
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