JPH10332807A - Sound source direction detector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable detecting of the direction of a sound source positioned in an arbitrary direction in a three-dimensional apace by specifying the sequence of microphones corresponding to the sequence of arrival of sound signals as detected by respective microphones arranged three-dimensionally. SOLUTION: For example, a sound source collector 1 has microphones A-H arranged at respective eight tops of a solid box body. The microphones A-H herein used are non-directional and arranged three dimensionally to allow detecting of a sound signal with any of the microphones even when the signal arrives from an arbitrary direction in the entire space. The direction of the sound source thereof is judged based on the sequence of the microphones A-H corresponding to the sequence of the arrival of the sound signal detected by the microphones A-H. A signal detection processor 2 performs an analog/digital conversion to produce a digital signal with an A/D conversion processing part 21. The digital signal processing part 22 is made up of a microcomputer to perform a processing for the judgment of the sound source or the like.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sound source direction detecting device, and more particularly, to a sound source direction detecting device that three-dimensionally detects a sound source direction using a plurality of microphones.

[0002]

2. Description of the Related Art Conventionally, there has been a sound source direction detecting device which detects a direction of a sound source by arranging a plurality of microphones two-dimensionally. FIG. 17 is an explanatory diagram of a conventional sound source direction detection method. A plurality of microphones m are two-dimensionally arranged at equal intervals on a certain plane PL as shown in the figure. Microphone m
When a sound signal is emitted from a sound source SD that is separated from the sound source by an appropriate distance, the sound signal is received by each microphone m. However, since the acoustic signals received by each microphone m are observed at different positions on the same plane, the acoustic signals observed by each microphone m have a phase difference or a time difference. Conventionally, the direction of the sound source has been detected by performing a predetermined calculation based on the phase difference or the time difference.

[0003]

In such a conventional detection method, since the microphone m is arranged on the same plane, the sound source existing in one direction from the plane on which the microphone is arranged in the direction of the three-dimensional space. Only the direction can be specified. That is, in the detection method shown in FIG. 17, when the sound source exists in the right direction of the plane PL, that is, in the space where x> 0, the direction of the sound source can be specified. However, when a sound source exists in a space of x <0, each microphone m cannot directly receive an acoustic signal from the sound source. In this case, since the microphone m receives a signal reflected or refracted by a wall or the like among the acoustic signals from the sound source, the direction of the sound source cannot be detected.

[0004] In order to solve this problem, for example, the entire microphones arranged on one plane are placed in the Z direction shown in FIG.
A method of rotating around an axis is conceivable. According to this, a sound source existing in the x <0 direction can be detected, but since rotation takes some time, a sound source may not be detected at a certain time. Further, if microphones having the same configuration are arranged in the x <0 direction in FIG. 17 and the same sound source detection processing is performed, the sound source direction can be detected in all three-dimensional directions. However, this method requires twice the configuration and processing of the microphone and the like, and increases the cost.

The present invention has been made in view of the above circumstances, and focuses on the arrival order of acoustic signals by arranging microphones three-dimensionally at predetermined positions of a three-dimensional casing. Accordingly, it is an object to provide a sound source direction detecting device capable of detecting a direction of a sound source located in an arbitrary direction in a three-dimensional space.

[0006]

According to the present invention, the direction of a sound source is determined based on a plurality of microphones arranged three-dimensionally and a permutation of microphones corresponding to the arrival order of acoustic signals detected by the microphones. And a sound source direction detecting device.

Here, the direction determining unit measures time of arrival of an acoustic signal detected by each microphone, and permutation specifying means for specifying a permutation of the microphones in order of earliest arrival time measured by the time measuring means. And sound source direction information uniquely determined from the permutation of the microphone, permutation rule storage means pre-stored for each permutation,
The sound source direction information corresponding to the specified permutation of the microphones may be configured to be retrieved from the permutation rule storage means.

In particular, a microphone is arranged at each vertex of a cubic casing, and the sound source direction information retrieved by the search means from the permutation rule storage means is uniquely determined by the permutation of the top three microphones. It may be directional information.

[0009] Further, the direction judging unit measures time of arrival of an acoustic signal detected by each microphone, and for a predetermined adjacent two microphones,
A time difference calculating means for calculating a time difference between arrival times of the acoustic signals measured by the time measuring means; and a sound source for a plane where the two microphones are present, based on the time difference calculated for the two microphones and the distance between the two microphones. Direction calculation means for obtaining a direction may be provided.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail based on an embodiment shown in the drawings. Note that the present invention is not limited to this. As described above, when the microphones are arranged at the respective vertices of the cube-shaped housing, the microphones are arranged outward at the positions of the eight vertices of the cube-shaped housing. Here, the housing means a hollow box, a mounting base for a microphone, and the like, and constitutes a sound source collection unit. Microphone arrangement is 3
What is necessary is just to be able to specify the sound source direction in a dimension, and it is not limited to the vertices of the cube. A plurality of microphones may be arranged at predetermined positions of a rectangular parallelepiped or another three-dimensional shape. Alternatively, the microphones may be suspended or fixed so that they can be detached and attached while keeping the distance between them constant.

The direction determining unit determines the direction of the sound source by using an analog sound signal input from each microphone and A / D-converted and digitized signal. A so-called microcomputer can be used. The microcomputer is a CPU
And a ROM, a RAM, a timer, an I / O interface, and the like. The permutation rule storage means stores
AM or a hard disk can be used.

A so-called timer can be used as the timer, and the measured arrival time may be stored in a memory such as a RAM. The sound source direction information extracted by the search means may be output using a display panel, a sound, an LED lamp, or the like, in addition to a printer, a CRT, or the like. Also, the extracted sound source direction information may be temporarily stored in a memory, and this information may be used for various control processes or transmitted to another device using a communication line. The permutation specifying unit, the time difference calculating unit, the direction calculating unit, and the searching unit are C
It can be realized by a PU and a control program stored in a RAM or a ROM in advance.

FIG. 1 is a schematic block diagram of a sound source direction detecting apparatus according to the present invention. The sound source direction detection device according to the present invention includes a sound source collection device 1 and a signal detection processing device 2. Sound source collection device 1
Is a cubic housing in which a microphone for receiving an acoustic signal emitted from a sound source is arranged at a predetermined position.
In the following description, it is assumed that the sound source collection device 1 has microphones (A to H) arranged at eight vertices of a cubic casing, but the present invention is not limited to this. The microphones (A to H) are omnidirectional and are located at appropriate positions on the housing so that even if an acoustic signal arrives from any direction in the entire space, the acoustic signal can be detected by any of the microphones. What is necessary is just to arrange three-dimensionally.

The signal detection processing device 2 mainly comprises an AD conversion processing unit 21 and a digital signal processing unit 22. The signal detection processing device 2 may be arranged separately from the sound source collection device 1 in a separate housing, or may be arranged inside the sound source collection device 1. The acoustic signal received by the microphone is converted into an electric analog signal, and the signal A of the signal detection processor 2 is output through an output signal line for each microphone.
The data is sent to the D conversion processing unit 21.

The AD conversion processing section 21 converts the analog signal into A
/ D conversion to generate a digital signal. The converted digital signal is sent to the digital signal processing unit 22. The digital signal processing unit 22 can be constituted by a microcomputer centered on a CPU, and performs processing such as measurement of the arrival time of a digital signal for each microphone, determination of the direction of a sound source, and the like. Although not shown, an output unit such as a CRT may be provided inside or outside the signal detection processing device 2 in order to output the determination result of the direction of the sound source.

FIG. 2 is an external view of an embodiment of a sound source direction detecting apparatus according to the present invention. As described above, the sound source collection device 1 is the cubic casing 11, and non-directional microphone elements (A to H) are adhered to respective vertices. Case 11
Is a small cube with a side of several cm and a side of several m
Large cubes can be used for various purposes. Here, it is preferable that the microphone elements A to H are adhered in such a direction that a line connecting the vertices from the center point of the cube is set as the normal direction. Note that the microphone element H is not shown, but exists at the vertex of a cube not visible in the figure.

The sound source collection device 1 may be installed in a space at a predetermined distance from the table 6 via the support 4. Wires for power supply, signal output, and ground are connected to each microphone element. These wires are bundled for each microphone element inside the cubic housing and passed through the support 4 from the lower part of the cubic housing 11. The signal detection processing device 2, the DC power supply 3, and the terminal block 5 are arranged on the table 6.

Each wire passed through the column 4 is connected to a separate terminal for each microphone on the terminal block 5. The terminal block 5 is provided with a terminal for supplying the DC power supply 3 to the microphone elements (A to H), a terminal for taking out an output from the microphone element, and a ground terminal. Each terminal has a microphone power supply taken out from the column 4. The wires 7, the microphone output wire 8, and the ground wire 9 are connected. Also,
Each wire of the microphone output 8 is connected to the signal detection processing device 2 via the terminal block 5.

FIG. 3 shows a connection block diagram between the microphone elements (A to H) and the signal detection processing device 2. As described above, the signal detection processing device includes the AD conversion processing unit 21 and the digital signal processing unit 22. A power line 7, a microphone output line 8, and a ground line 9 are connected to the microphone elements (A to H).
Are connected to the AD conversion processing unit 21 separately.
The AD conversion processing unit 21 simultaneously samples the analog audio signal input through the microphone output line 8 in parallel and converts it into a digital signal.

FIG. 4 is a block diagram showing the configuration of the signal detection processor 2. The AD conversion processing unit 21 includes microphones A to
H is composed of AD converters 23 corresponding to each of H. The digital signal processing unit 22 includes a detection unit 24 that detects a digital signal output from the AD converter 23,
4, a timer unit 25 for giving a detection timing and a count time, a detection sequence specifying unit 26 for determining a detection sequence of a sound signal by a microphone from a signal output from each detection unit 24, and a sequence storing rules for determining a sound source direction. A rule storage unit 27, a sound source direction determining unit 28 for determining a sound source direction from a detection permutation determined based on a rule for determining a direction
It is composed of

Here, the permutation rule storage unit 27 uses a RAM, a hard disk, or the like, and the detection permutation identification unit 26 and the sound source direction determination unit 28 can be realized as one function of a CPU.
A plurality of detectors 24 are provided corresponding to the respective AD converters 23, and can be constituted by logic elements such as counters and flip-flops. Count. When a certain detection unit 24 has a count value exceeding a predetermined value, it is determined that an acoustic signal has been input from a microphone corresponding to the detection unit 24, and the detection unit 24 outputs a predetermined detection signal.

The detection permutation specifying unit 26 includes all the detection units 2
4 is constantly monitored for the input timing of the detection signal. That is, the detection permutation specifying unit 26 plays a role of a clock unit that measures the arrival time of the acoustic signal detected for each microphone. Further, the detection permutation specifying unit 26
Specifies the permutation to which the detection signal corresponding to each microphone is input from the difference in the measured arrival times, and stores the permutation in a memory such as a RAM. For example, after a detection signal from the detection unit 24 corresponding to the microphone B is first input, the microphones C, A, E, and C within a predetermined time (for example, one second).
Assuming that the detection signals are input in the order of F and G, the permutation of the microphones is specified and stored as “B, C, A, E, F, G”.

The permutation rule storage unit 27 stores rules that associate the correspondence between the permutations of the microphones and the sound source directions. For example, when the three-dimensional space is divided into 48 regions around the sound source collection device, the microphones B, A,
When an acoustic signal is detected in the order of C, a rule that a sound source exists in the direction of “region 1” is stored. This rule will be described later.

The sound source direction determining unit 28 determines the sound source direction corresponding to the microphone permutation specified by the detection permutation specifying unit 26 with reference to the rules stored in the permutation rule storage unit 27. Information on the determined sound source direction is output to an output device such as a CRT as necessary. The above is the sound source direction determination processing in the digital signal processing unit 22.

Next, a description will be given of a rule relating the correspondence between the microphone permutation and the sound source direction. In FIG.
FIG. 4 shows an explanatory diagram of a rule for determining a sound source direction. Here, a case will be described as an example where the mylocphone at the position B of the eight vertices of the sound source collection device 1 first receives an acoustic signal. Assuming that the sound source collection device 1 is a cube, the sound source directions can be classified into directions passing through six planes (P1 to P6) around the vertex B when viewed from the center O of the cube.

For example, the plane P1 has vertices B ', L',
The plane P6 is a plane formed by the vertices B ′, K ′, and N. Here, J ′, K ′, and L ′ are points corresponding to the center J of the BFGC plane, the center K of the AEFB plane, and the center L of the ABCD plane, respectively. A ', B', C ', D', M,
N and Q are mapping points on the plane such as vertices of the sound source collection device 1.

If it is determined that there is a sound source in the direction passing through the plane P1 when viewed from the center O, the distance between the sound source and each vertex is closest to the vertex B, then to the vertices A, C,. The order is as follows. FIGS. 6 and 12 show explanatory diagrams in this case. FIG. 12 is a plan view of FIG. 5 as viewed from above the ABCD plane. In FIG. 12, the position of the sound source is ABC
The positions projected on the D plane are S1, S2, and S3.
Now, considering a case where the sound source is located at the position S1, S ₁ B <
A distance relationship of S ₁ A <S ₁ C <S ₁ D is established. Therefore, if the sound source is at the position of S _1, microphone B, A, C, acoustic signals are received in the order of D.

Here, the sound source S1 is a position representing the area of the plane P1, and if there is a sound source in this area, the microphones B, A, C and D are received in this order. When the sound source is located at the position S2, that is, when the sound source is located in the area of the plane P2, the acoustic signals are received in the order of the microphones B, C, A, and D. Further, when the sound source is at the position of S3,
That is, when the microphone is in the area of the plane P7, the acoustic signals are received in the order of the microphones A, B, C, and D.

By the way, in this embodiment, the sound source direction can be determined based on the order of the three most significant microphones among the order of the microphones that have received the acoustic signal specified by the detection permutation specifying unit 26. For example, when the sound source is located at the position S1 in FIG. 12, the sound signals are received in the order of the microphones B, A, and C.
It can be determined that there is a sound source in the direction passing through 1. Therefore, as a rule in this case, as a rule, "if the detection sequence of the acoustic signal is the order of the microphones B, A, and C, it is determined that the sound source exists in the direction passing through the plane P1 as viewed from the center O of the cube." The rule holds.

FIG. 7 is an explanatory diagram showing the range of the sound source direction when the microphone at the vertex B receives the earliest sound and the sound source is in the direction of the plane P2 when viewed from the center O. In this case, the acoustic signals are received in the order of the microphones B, C, and A. FIG. 8 is an explanatory diagram showing the range of the sound source direction when the microphone at the vertex B receives the earliest and the sound source is in the direction of the plane P3 when viewed from the center O. In this case, the acoustic signals are received in the order of the microphones B, C, and F.

FIG. 9 is an explanatory diagram showing the range of the sound source direction when the microphone at the vertex B receives the earliest sound and the sound source is in the direction of the plane P4 when viewed from the center O. In this case, the acoustic signals are received in the order of the microphones B, F, and C. FIG. 10 is an explanatory diagram showing the range of the sound source direction when the microphone at the vertex B receives the earliest and the sound source is in the direction of the plane P5 when viewed from the center O. In this case, the acoustic signals are received in the order of the microphones B, F, and A. FIG. 11 is an explanatory diagram showing the range of the sound source direction when the microphone at the vertex B receives the earliest sound and the sound source is in the direction of the plane P6 when viewed from the center O. In this case, the acoustic signals are received in the order of the microphones B, A, and F.

From the above considerations, when the microphone at the vertex B receives the earliest, the following six rules hold. Rule 1: If the receiving sequence of microphones is B, A, C,
There is a sound source in a direction passing through the plane P1 when viewed from the center O. Rule 2: If the permutation B, C, A of the microphone,
There is a sound source in a direction passing through the plane P2 when viewed from the center O. Rule 3: If the microphone permutations B, C, and F,
There is a sound source in a direction passing through the plane P3 when viewed from the center O. Rule 4: If the receiving sequence of microphones is B, F, C,
There is a sound source in a direction passing through the plane P4 when viewed from the center O. Rule 5: If the permutation B, F, A of the microphone,
There is a sound source in a direction passing through the plane P5 when viewed from the center O. Rule 6: If the receiving sequence of microphones is B, A, F,
There is a sound source in a direction passing through the plane P6 when viewed from the center O.

Similarly, from the symmetry of the cube,
For the other vertices A, C, D, E, F, G, and H, the sound source directions can be classified into directions passing through six planes around the vertices. And for each vertex,
One of the six sound source directions is specified from the order of the three microphones received first. That is, there are rules for specifying six sound source directions for each of the eight vertices, and the sound source direction in the three-dimensional space when viewed from the center O is 6
(Direction) × 8 (vertex) = 48 directions can be divided and determined. In the case of the first embodiment, 48 rules are stored in the permutation rule storage unit 27. According to the present invention, by providing such a configuration and processing, it is possible to detect a sound source direction obtained by dividing the direction of the three-dimensional space into 48 ways.

Next, an application example of the sound source direction detecting apparatus according to the first embodiment will be described. FIG. 13 is an explanatory diagram of an application example in which the first embodiment is applied to a box for detecting the direction of an external sound source. The box in FIG. 13 is large enough to allow a person to enter, and corresponds to the sound source collection device 1 described in FIG. 2 and the like. Here, a component corresponding to the signal detection processing device 2 is not shown, but may be provided in a separate room, for example.

Here, microphones are provided at the eight vertexes of the box to detect the direction of the external sound source. In addition, display panels are installed on the six wall surfaces of the box, and the display panel blinks or displays according to the sound source direction detected by the sound source direction detection device. In this way, it is possible to easily know the direction of the external sound source even on a wall through which sound does not pass. Also, as seen from the person inside the box, the direction of the sound source can be known in units of 48 divided spaces.

FIG. 14 is an explanatory diagram of an application example in which the first embodiment is applied to a self-standing robot. As shown in the figure, a microphone is provided at each of the vertices of the cube. The robot itself is the sound source collection device 1, and the signal detection processing device 2 may be provided inside the robot.

At the top of the robot, a camera section for observing the surroundings is provided, and an up-down rotation mechanism and a left-right rotation mechanism capable of driving the camera section up, down, left and right are provided. If the direction of the sound source detected by the sound source collection device 1 and the camera unit are linked,
The camera unit of the robot can be rotated in the direction of the sound source, so that the camera can always capture images in the direction of the sound source. Therefore, the present invention can be applied to surveillance robots and surveillance cameras for crime prevention and disaster prevention.

Second Embodiment Next, a description will be given of an embodiment in which the time difference between the arrival times of the acoustic signals of adjacent microphones is measured to detect the sound source direction three-dimensionally. FIG. 15 is a block diagram showing the configuration of the signal detection processing device according to the second embodiment. As in FIG. 4, the analog signal received from each microphone is A
The signal is converted into a digital signal by the D converter 23 and
Then, based on the clock given from the timer 25,
It is detected whether an input has been made.

If a detection is made, the corresponding detection unit 2
4 outputs a detection signal to the time difference calculating unit 31 between adjacent elements. The adjacent element time difference calculation unit 31 calculates a detection time difference Δt between adjacent microphones, for example, B and A, B and C, and B and F. Then, the angles of the sound source directions with respect to the three planes can be calculated by mathematical expressions as described later, and the sound source direction can be obtained in detail from these angles.

FIG. 16 is an explanatory diagram of the angle calculation according to the second embodiment. It is assumed that there is a sound source in the direction shown in the figure for the microphones A and B. At this time, let θ be the angle of the sound source direction with respect to the normal direction of the ABCD plane. Assuming that the distance between the microphones A and B is d, the distance until the acoustic signal from the sound source reaches the microphone A than the microphone B is longer by dsinθ. Here, assuming that the sound speed in the air is C, the microphone A detects the acoustic signal later by (dsin θ) / c time.

That is, the detection time difference Δt between the microphones B and A depends on the angle θ and is expressed by the following equation. Δt = (dsin θ) / c (1) Therefore, the angle θ of the sound source direction is obtained by θ = sin ⁻¹ (cΔt / d) (2)

In FIG. 16, adjacent microphones A and B
In the above example, the angle θ of the sound source direction with respect to the ABCD plane is obtained from the detection time difference of the sound source.
The angle of the sound source direction with respect to the BFE plane can be obtained. For example, with respect to the BCGF plane, the angle of the sound source direction is obtained from the detection time difference between the adjacent microphones B and C.

In FIG. 15, the time difference .DELTA.t between adjacent microphones detected by the adjacent element time difference calculating section 31 is given to the angle calculating sections 32, 33, and 34 of the respective planes. , 33, and 34, the angle of the direction of the sound source with respect to each plane can be calculated by the above equation (2). Then, the sound source direction is uniquely determined by the obtained angles θ of the three sound source directions.

Here, the adjacent element time difference calculating section 31, A
The functions of the BCD plane angle calculator 32, the ABFE plane angle calculator 33, and the BCGF plane angle calculator 34 are as follows:
This can be realized by a PU and a program stored in a RAM or the like. Here, three planes (ABCD, AB
FE, BCGF), the same angle calculation can be performed for an arbitrary vertex on three planes including the vertex. Therefore, according to the second embodiment, it is possible to more accurately specify the sound source directions in all directions in the three-dimensional space.

[0045]

According to the present invention, the microphone is arranged at each vertex of the three-dimensional housing, and the direction of the sound source is determined based on the difference in the arrival time of the received acoustic signal. The direction of the sound source located in an arbitrary direction in the three-dimensional space can be detected. Further, since the sound source direction is obtained by calculating the time difference between the arrival times of the adjacent microphones, the sound source direction can be specified more accurately.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a first embodiment of the present invention.

FIG. 2 is an external view of a sound source direction detecting device according to the first embodiment of the present invention.

FIG. 3 is a connection block diagram of the microphone and the signal detection processing device according to the first embodiment of the present invention.

FIG. 4 is a configuration block diagram of a signal detection processing device according to the first embodiment of the present invention.

FIG. 5 is an explanatory diagram of a sound source direction determination rule according to the first embodiment of the present invention.

FIG. 6 is an explanatory diagram of a range of a sound source direction detected in the first embodiment of the present invention.

FIG. 7 is an explanatory diagram of a range of a sound source direction detected in the first embodiment of the present invention.

FIG. 8 is an explanatory diagram of a range of a sound source direction detected in the first embodiment of the present invention.

FIG. 9 is an explanatory diagram of a range of a sound source direction detected in the first embodiment of the present invention.

FIG. 10 is an explanatory diagram of a range of a sound source direction detected in the first embodiment of the present invention.

FIG. 11 is an explanatory diagram of a range of a sound source direction detected in the first embodiment of the present invention.

FIG. 12 is an explanatory diagram of a sound source direction determination rule according to the first embodiment of this invention.

FIG. 13 is an explanatory diagram of an application example of the first embodiment of the present invention.

FIG. 14 is an explanatory diagram of an application example of the first embodiment of the present invention to a self-standing robot.

FIG. 15 is a configuration block diagram of a signal detection processing device according to a second embodiment of the present invention.

FIG. 16 is an explanatory diagram of angle calculation according to the second embodiment of the present invention.

FIG. 17 is a configuration diagram of a conventional sound source direction detection device.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 sound source collection device 2 signal detection processing device 3 power supply 4 support 5 terminal block 6 units 7 microphone power line 8 microphone output line 9 ground line 11 cubic housing 21 AD conversion processing unit 22 digital signal processing unit 23 AD converter 24 detection Unit 25 timer 26 detection permutation identification unit 27 permutation rule storage unit 28 sound source direction determination unit 31 time difference calculation unit between adjacent elements 32 angle calculation unit on ABCD plane 33 angle calculation unit on ABFE plane 34 angle calculation unit on BCGF plane

Claims (4)

[Claims] 1. A microphone comprising: a plurality of microphones arranged three-dimensionally; and a direction determination unit for determining a direction of a sound source based on a permutation of microphones corresponding to an arrival order of acoustic signals detected by the microphones. A sound source direction detection device, characterized in that: 2. The apparatus according to claim 1, wherein the direction determining unit measures time of arrival of the acoustic signal detected by each microphone, and permutation specifying means that specifies a permutation of the microphones in order of earliest arrival time measured by the time measuring means. The sound source direction information uniquely determined from the permutation of the microphones, permutation rule storage means pre-stored for each permutation, and the sound source direction information corresponding to the specified permutation of the microphones from the permutation rule storage means. 2. The sound source direction detecting device according to claim 1, further comprising a retrieval unit for extracting the sound source direction. 3. A sound source in which the microphones are arranged at respective vertices of a cubic-shaped casing, and sound source direction information retrieved by the search means from the permutation rule storage means is uniquely determined by a permutation of the top three microphones. The sound source direction detecting device according to claim 2, wherein the direction information is direction information. 4. The time determining means for measuring the arrival time of the sound signal detected by each microphone, and the arrival time of the sound signal measured by the time measuring means for two predetermined adjacent microphones. Time difference calculating means for calculating a time difference between
2. The sound source direction detecting device according to claim 1, further comprising: a direction calculating unit that obtains a sound source direction with respect to a plane on which the two microphones are located from a time difference calculated for the two microphones and a distance between the two microphones.