JP6909988B2 - Sound source exploration device - Google Patents

Description

The present invention relates to a sound source exploration device.

A sound source exploration device that performs sound source exploration based on the phase difference of sound (sound wave) generated when reaching a microphone array arranged in the same plane has been proposed (for example, Patent Document 1).

The sound source exploration device as disclosed in Patent Document 1 has an advantage that the structure is simple and the installation is high.

Japanese Unexamined Patent Publication No. 2011-124949

However, in the conventional sound source exploration device as disclosed in Patent Document 1, the phase difference of the sound waves from the sound sources (the sound source on the front side and the sound source on the back side) that are plane-symmetrical with respect to the arrangement surface of the microphone array is large. There is a problem that they cannot be distinguished because they are equal. That is, the conventional sound source exploration device may be affected by the sound source on the back side of the sound source exploration device that is not the exploration target area, and may not be able to search the sound source in the space on the front side of the sound source exploration device that is the exploration target area. be.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a sound source exploration device capable of more reliably exploring a sound source in an exploration target area.

In order to achieve the above object, the sound source exploration device according to one embodiment of the present invention has a plurality of microphone elements, a first surface and a second surface opposite to the first surface, and the first surface. A baffle unit for fixing the plurality of microphone elements arranged two-dimensionally on a surface is provided, and the baffle unit causes the plurality of microphone elements to pick up the direct sound of a sound source on the first surface side, and , The direct sound from the sound source on the second surface side is not picked up.

It should be noted that some specific embodiments of these may be realized by using a recording medium such as a system, a method, an integrated circuit, a computer program, or a computer-readable CD-ROM, and the system, the method, the method, and the like. It may be implemented using any combination of integrated circuits, computer programs and recording media.

According to the present invention, it is possible to realize a sound source exploration device capable of more reliably exploring a sound source in an exploration target area.

FIG. 1 is a diagram showing an example of the configuration of the sound source exploration device according to the embodiment. FIG. 2 is an overview view showing an example of the sound collecting device according to the embodiment. FIG. 3 is a diagram showing an installation example of the sound collecting device and the area to be searched for the sound source in the embodiment. FIG. 4A is a diagram showing an installation example of the sound collecting device according to the embodiment. FIG. 4B is a side view of the sound collecting device shown in FIG. 4A. FIG. 5A is a diagram showing another installation example of the sound collecting device according to the embodiment. FIG. 5B is a side view of the sound collecting device of FIG. 5A. FIG. 6 is a diagram for explaining the relationship between the sound source having the maximum phase difference of the sound waves arriving at the sound collecting device 10 shown in FIG. 3 and the arrangement of the plurality of microphone elements. FIG. 7 is a diagram for explaining the relationship between the size of the baffle portion and the sound source in which the phase difference of the sound wave arriving at the sound collecting device 10 shown in FIG. 3 is minimized. FIG. 8 is a diagram showing a search direction of the sound collecting device shown in FIG. FIG. 9 is a diagram showing the relationship between the search direction of the sound collecting device shown in FIG. 8 and the angular resolution. FIG. 10 is a diagram showing a circular array microphone array in a comparative example. FIG. 11 is a diagram for explaining the phase difference of sound waves arriving from a sound source in the plane-symmetrical direction in the circular array microphone array in the comparative example shown in FIG. FIG. 12 is a diagram showing an arrangement example of the microphone array of the sound collecting device in the first modification. FIG. 13 is a diagram showing an example of a baffle portion of the sound collecting device in the modified example 2. FIG. 14 is a diagram showing an arrangement example of the microphone array of the sound collecting device in the modified example 3.

(Knowledge that became the basis of the present invention)
As described above, for example, in the conventional sound source exploration device disclosed in Patent Document 1, sound waves from sound sources (sound source on the front side and sound source on the back side) that are plane-symmetric with respect to the arrangement surface of the microphone array. Since the phase difference (arrival time difference) of is equal, there is a problem that they cannot be distinguished. In other words, when the conventional sound source exploration device is affected by the sound source on the back side of the sound source exploration device which is not the exploration target area and cannot search the sound source in the space on the front side of the sound source exploration device which is the exploration target area. There is a problem that there is.

As a method for solving the above problem, it is conceivable to arrange a plurality of microphone elements (microphones) constituting the microphone array in three dimensions.

However, when a plurality of microphone elements are arranged three-dimensionally, the structure of the sound source exploration device becomes not simple, and a new problem arises that the installability becomes low. Specifically, for example, when a plurality of microphone elements are arranged three-dimensionally, the structure of the microphone array is acoustically satisfied so that sound waves from all directions reach each microphone element without disturbing the phase difference. Moreover, it is necessary to satisfy the conditions such as maintaining the strength of the microphone array. However, installing a microphone array that satisfies these conditions requires complicated work, which reduces the installability.

The present invention has been made in view of the above circumstances, and by suppressing the influence of sound waves arriving from the back side of a microphone array composed of a plurality of microphone elements, the sound source in the exploration target area can be more reliably obtained. An object of the present invention is to provide a sound source exploration device capable of exploration.

The sound source exploration device according to one aspect of the present invention has a plurality of microphone elements, a first surface and a second surface which is a surface opposite to the first surface, and the plurality of microphone elements are arranged two-dimensionally on the first surface. The baffle portion includes a baffle portion for fixing the microphone element of the above, and the baffle portion causes the plurality of microphone elements to pick up the direct sound of the sound source on the first surface side and is on the second surface side. Do not pick up the direct sound from the sound source.

That is, by providing the baffle portion, it is possible to cause the sound waves emitted by the sound source on the second surface side to wrap around, and the phase difference of the sound waves reaching the plurality of microphone elements is the first with respect to the first surface side. The phase difference on the two-sided side can be increased. As a result, the influence of sound waves arriving from the second surface (back side) can be suppressed, so that the sound source on the first surface (front side), that is, the sound source in the search target area can be searched more reliably.

Here, for example, the plurality of microphone elements are arranged inside the outer edge of the baffle portion by a predetermined length or more.

As a result, in the phase difference of the sound waves reaching the plurality of microphone elements, the phase difference on the second surface side can be more reliably increased with respect to the first surface side.

Further, for example, even if a support member for supporting the baffle portion is provided so that the first surface of the baffle portion and the installation surface which is the surface on which the sound source exploration device is installed have a predetermined angle. good.

As a result, in the phase difference of the sound waves reaching the plurality of microphone elements, the phase difference on the second surface side can be more reliably increased with respect to the first surface side.

Further, for example, the baffle portion may be a circular plate-shaped member, and the diameter of the baffle portion may be calculated based on the maximum length of the distance between the plurality of microphone elements and the predetermined angle. ..

Here, for example, when the diameter of the baffle portion is d ₁ , the maximum length is d ₀ , and the predetermined angle is θ _c , the relationship of (d ₀ / COS (θ _c )) <d _{1 is satisfied.} There is.

Further, for example, the baffle portion is a rectangular plate-shaped member, and the length of the side of the baffle portion is calculated based on the maximum length of the distance between the plurality of microphone elements and the predetermined angle. May be.

Here, for example, when the length of the side of the baffle portion is d ₁ , the maximum length is d ₀ , and the predetermined angle is θ _c , the relationship of (d ₀ / COS (θ _c )) <d ₁ Meet.

Further, for example, the plurality of microphone elements may be embedded in the baffle portion so that the sound hole portions of the plurality of microphone elements are exposed on the first surface and not exposed on the second surface. good.

It should be noted that some specific embodiments of these may be realized by using a recording medium such as a system, a method, an integrated circuit, a computer program, or a computer-readable CD-ROM, and the system, the method, the method, and the like. It may be implemented using any combination of integrated circuits, computer programs or recording media.

Hereinafter, the sound source exploration device according to one aspect of the present invention will be specifically described with reference to the drawings. It should be noted that all of the embodiments described below show a specific example of the present invention. Numerical values, shapes, materials, components, arrangement positions of components, and the like shown in the following embodiments are examples, and are not intended to limit the present invention. Further, among the components in the following embodiments, the components not described in the independent claims indicating the highest level concept are described as arbitrary components. Moreover, in all the embodiments, each content can be combined.

In the embodiment described below, the distance of the sound source explored by the sound source exploration device is sufficiently long with respect to the size of the microphone array, and the sound wave reaching the microphone array from the sound source is a distance that can be regarded as a plane wave. Assuming a relationship. More specifically, it is assumed that the distance is about 3 to 5 times or more the size of the microphone array.

(Embodiment)
[Overall configuration of sound source exploration device 1]
FIG. 1 is a diagram showing an example of the configuration of the sound source exploration device 1 according to the present embodiment.

The sound source exploration device 1 searches for a sound source and identifies the position of the sound source based on the strength and phase difference of the sound wave collected. In the present embodiment, as shown in FIG. 1, the sound source exploration device 1 includes a sound collecting device 10, a signal processing unit 11, and a display unit 12. Hereinafter, each component will be described in detail.

[Sound collecting device 10]
FIG. 2 is an overview view showing an example of the sound collecting device 10 according to the present embodiment. FIG. 2A shows a case where the sound collecting device 10 is viewed from the front, and FIG. 2B shows a case where the sound collecting device 10 is viewed from the side. FIG. 3 is a diagram showing an installation example of the sound collecting device and the area to be searched for the sound source in the embodiment.

As shown in FIG. 2A, the sound collecting device 10 includes a baffle portion 101 and a microphone array 102.

The microphone array 102 is composed of a plurality of omnidirectional microphone elements having high sensitivity to sound pressure. The plurality of microphone elements are arranged inside the baffle portion 101 by a predetermined length or more from the outer edge. Here, the plurality of microphone elements are, for example, sound sensors. Further, the plurality of microphone elements may be a capacitor type microphone chip manufactured by using a semiconductor manufacturing technique. The microphone chip has a diaphragm that is displaced by sound pressure and has a function of converting a sound signal into an electric signal. Here, the plurality of microphone elements may be embedded in the baffle portion 101 so that the sound hole portions of the plurality of microphone elements are exposed on the first surface and not exposed on the second surface. In the present embodiment, as shown in FIG. 2, the microphone array 102 includes microphone elements m1 to microphone elements m8 (eight microphone elements), and the microphone elements m1 to microphone elements m8 form a ring shape (annular shape). It is arranged like this. Further, the microphone elements m1 to m8 are embedded in the baffle portion 101 so that the sound hole portion of the microphone element is exposed on the first surface (front surface 101a) and not on the second surface (rear surface 101b). There is.

In the following, a case where the microphone array 102 is composed of eight microphone elements m1 to m8 will be described as an example, but the present invention is not limited to this case. The microphone array 102 may be composed of at least three microphone elements, but the larger the number of microphone elements, the more accurately the sound can be picked up.

The baffle portion 101 has a first surface and a second surface opposite to the first surface, and a plurality of microphone elements (microphone elements m1 to m8) arranged two-dimensionally on the first surface are fixed. Then, the baffle unit 101 causes the plurality of microphone elements to collect the direct sound of the sound source on the first surface side and does not collect the direct sound from the sound source on the second surface side. Since the baffle portion 101 can cause the sound waves emitted by the sound source on the second surface side to wrap around, the phase difference of the sound waves reaching the plurality of microphone elements is the second surface rather than the phase difference on the first surface side. This is because the phase difference on the side can be increased. Further, the baffle portion 101 can increase the sensitivity of the microphone array 102 by about 6db due to the baffle effect.

Further, the baffle portion 101 may be arranged so that the first surface and the installation surface on which the sound source exploration device 1 is installed have a predetermined angle θ _c. This is because the phase difference of the sound waves of the sound source on the first surface side can be made smaller than the phase difference of the sound waves of the sound source on the second surface side by being arranged so as to have a predetermined angle.

Here, assuming that the baffle portion 101 is composed of, for example, a circular plate-shaped member, the diameter d _{1 of the baffle portion 101 has a maximum length d 0} of the distance between the plurality of microphone elements and a predetermined angle θ _c . It can be calculated based on. Details will be described later, so the description here will be omitted.

In the present embodiment, the first surface corresponds to the front surface 101a shown in FIG. 2B, and the second surface corresponds to the back surface 101b shown in FIG. 2B. The baffle unit 101, as shown in FIG. 2 (a), for example, a circular plate-like member, as shown in FIG. 3, installed, for example, so as to form a predetermined angle theta _c and the setting surface 51, such as ground Will be done. Further, as shown in FIG. 3, the first surface side (front surface 101a side) of the baffle portion 101 is the sound source search target region X, and the second surface side (rear surface 101b side) of the baffle portion 101 is. This is a region Y that is not subject to sound source exploration. The baffle portion 101 may be made of a member such as a metal, wood, or resin material that does not allow sound waves to pass through or that is sufficiently attenuated even if it passes through. Further, the baffle portion 101 may be composed of a plate-shaped member made of an artificial material such as a particle board, a chip board, a wood wool cement board, an Apiton plywood, or the like, which is formed by hardening homogeneous fibers with an adhesive and applying a high pressure. Further, the baffle portion 101 may be composed of a strong (highly rigid) and heavy (high specific gravity) plate-like member similar to the baffle plate that supports the speaker unit.

(Installation method)
Hereinafter, a method of installing the sound collecting device 10 so that the baffle portion 101 and the installation surface 51 form a predetermined angle will be described with reference to an example.

FIG. 4A is a diagram showing an installation example of the sound collecting device 10 according to the embodiment. FIG. 4B is a side view of the sound collecting device shown in FIG. 4A. FIG. 5A is a diagram showing another installation example of the sound collecting device according to the embodiment. FIG. 5B is a side view of the sound collecting device of FIG. 5A.

As shown in FIGS. 4A and 4B, for example, the sound collecting device 10 is installed so that the baffle portion 101 and the installation surface 51 form a predetermined angle by the support member 103 that supports the baffle portion 101. The method of installing the baffle portion 101 and the installation surface 51 so as to form a predetermined angle is a case where a support member 103 that supports the second surface (back surface) of the baffle portion 101 is used as shown in FIGS. 4A and 4B. Not limited to. For example, a support member 103A that supports the lower end of the baffle portion 101 as shown in FIGS. 5A and 5B may be used. That is, any support member may be used as long as the baffle portion 101 and the installation surface 51 can be installed so as to form a predetermined angle.

(Calculation method of diameter d _{1)
Next, a method of calculating the diameter d 1} of the baffle portion 101 will be described. _{First, the relationship between the diameter d 1} of the baffle portion 101, _{the maximum length d 0} of the distance between the plurality of microphone elements, and the predetermined angle θ _c will be described with reference to FIGS. 6 and 7, and then the baffle portion 101 The calculation method of the diameter d ₁ of the above will be described.

FIG. 6 is a diagram for explaining the relationship between the sound source having the maximum phase difference of the sound waves arriving at the sound collecting device 10 shown in FIG. 3 and the arrangement of the plurality of microphone elements. _{More specifically, FIG. 6 shows a sound source A in which the phase difference τ A15 of the} sound waves arriving at the microphone element m1 and the microphone element m5 is maximized, and a state in which sound waves arrive at each microphone element from the sound source A. It is shown schematically. In other words, from the sound wave A located in the direction parallel to the arrangement surface (first surface in the present embodiment) of the plurality of microphone elements (microphone elements m1 to microphone element m8) in the area X to be searched for the sound wave, the microphone _{The phase difference τ A15 of the} sound waves arriving at the element m1 and the microphone element m5 is maximized.

_{Therefore, the maximum phase difference (arrival time difference) τ A15} of the sound waves arriving from the sound source in the sound source search target region X (front side) to the microphone element m1 and the microphone element m5 is determined by using the velocity C of the sound in the air. It can be expressed as (Equation 1).

τ _A15 = d ₀ / C (Equation 1)

FIG. 7 is a diagram for explaining the relationship between the size of the baffle portion and the sound source in which the phase difference of the sound wave arriving at the sound collecting device 10 shown in FIG. 3 is minimized. _{More specifically, FIG. 7 shows a sound source B in which the phase difference τ B15 of the} sound waves arriving at the microphone element m1 and the microphone element m5 is minimized, and a state in which sound waves arrive at each microphone element from the sound source B. It is shown schematically. In other words, in the region Y that is not the target of sound wave exploration, the microphone element m1 and the microphone element are transmitted from the sound wave B located in the direction parallel to the installation surface 51 through the arrangement center of the microphone elements (microphone element m1 to microphone element m8). _{The phase difference τ B15 of the} sound wave arriving at m5 is minimized.

_{Therefore, the minimum phase difference τ B15} of the sound waves arriving at the microphone element m1 and the microphone element m5 from the sound source in the region Y (back side) outside the sound source search target can be expressed as in (Equation 2).

τ _B15 = d ₁ * COS (θ _c ) / C (Equation 2)

Here, if the following relationship (Equation 3) is satisfied, it is possible to distinguish even a sound source that is plane-symmetrical with respect to the arrangement surface of the microphone array 102 (plurality of microphone elements). This is because in the sound source exploration device 1 that detects a sound source based on the phase information, the phase difference between the sound source in the area X (front side) that is the sound source exploration target and the sound source in the area Y (rear side) that is not the sound source exploration target is always larger. be.

τ _A15 <τ _B15 (Equation 3)

Therefore, the diameter d ₁ of the baffle portion 101 may be calculated so as to satisfy the relationship of the solved (Equation 4) by substituting (Equation 1) and (Equation 2) into (Equation 3).

d ₀ / COS (θ _c ) <d ₁ (Equation 4)

Here, for example, when the predetermined angle θ _c is 60 °, COS (θ _c ) = 0.5, so that the diameter d _{1 of the baffle portion 101 is the maximum length d 0} of the distance between the plurality of microphone elements. It is calculated to be more than twice as large as. The predetermined angle theta _c is 0 °, but even if it is 90 ° may take theoretically predetermined angle theta _c is 0 ° for reasons discussed below, it may not include the case is 90 °.

(Predetermined angle θ _c )
The relationship between the angular resolution of the sound collecting device 10 and the predetermined angle θ _c will be described with reference to FIGS. 8 and 9. FIG. 8 is a diagram showing the exploration direction θ _d of the sound collecting device 10 shown in FIG. FIG. 9 is a diagram showing the relationship between the search direction of the sound collecting device 10 shown in FIG. 8 and the angular resolution. Here, as shown in FIG. 8, the angle with respect to the normal direction of the first surface (front surface 101a) of the sound collecting device 10, that is, the normal direction of the array surface of the microphone array 102 (several microphone elements) is searched. The direction is θ _d . On the other hand, the graph shown in FIG. 9 shows the exploration when the distance between the two microphone elements constituting the microphone array 102 is Δd = 40 mm and the angular resolution at the time of vertical (θ = 0 °) is 1 °. The angular resolution for each direction θ _{d is shown.} That is, the angular resolution on the vertical axis shown in FIG. 9 indicates an error when a target object separated in the _{exploration direction θ d is detected.} The phase difference between the microphone elements is calculated as constant.

From the graph shown in FIG. 9, the normal direction of the array surface of the microphone array 102 (search direction θ _d = 0 ° in the graph) has the best angular resolution, and when the search direction θ _d = 60 ° is exceeded, the error is doubled. It can be seen that the performance deteriorates extremely because it exceeds.

That is, it can be seen that if the array surface of the microphone array 102 is oriented with an inclination of up to about 60 ° with respect to a certain direction of the object to be searched for the sound source, the sound source can be searched with high accuracy. Therefore, it is not necessary to _{set the predetermined angle θ c} to 0 ° except when there is an object to be searched for the sound source in the direction perpendicular to the installation surface 51 (directly above).

Then, in order to use the sound collecting device 10 having good angular resolution, _{it is preferable to change the predetermined angle θ c according} to the position of the object to be searched for the sound source. For example, in the area X of the sound source exploration target, the sound emitted by a flying object hovering at a position of several hundred meters from the sound source exploration device 1 and an altitude of 10 m from the installation surface 51 (ground) is detected (sound collection). Suppose you want to. In this case, the angle of the flying object from the installation surface 51 is about 10 ° to 20 ° with respect to the point where the sound source exploration device 1 is installed. Therefore, in order to accurately search the sound source at this angle, the predetermined angle θ _c may be set to about 45 ° to 60 °. That is, in order to accurately search for an object to be searched for a sound source at a position away from the sound source search device 1, the search direction θ is directed to the normal direction of the array surface of the microphone array 102 in the direction in which the object is located. _{A predetermined angle θ c} may be determined so that d is about 30 °.

[Signal processing unit 11]
The signal processing unit 11 can identify the sound source and specify the position of the sound source by processing the signals (eight signals in FIG. 1) output from the plurality of microphone elements. More specifically, the signal processing unit 11 converts the signals output from the plurality of microphone elements into A / D (Analog to Digital), converts them into time signals or frequency region signals, and then performs the conversion processing into the plurality of microphones. Calculation processing is performed based on the phase difference between the elements to localize and identify the arrival direction of the sound. The signal processing unit 11 may be an arithmetic unit such as a PC physically connected to a plurality of microphone elements of the sound collecting device 10, and is a central processing unit (CPU) constituting the sound source exploration device 1. May be good.

In the present embodiment, the signal processing unit 11 can remove the influence of the sound from the sound source on the back side (region Y) of the sound collecting device 10, so that the sound collecting device 10 can remove the influence of the sound from the sound collecting device 10 on the front side (region X). A sound source that is located at a distant position and has a small sound coming to the sound collecting device 10 can also be identified and the position can be specified. The signal processing unit 11 causes the display unit 12 to display the processing result.

The signal processing unit 11 may generate a sound source image signal indicating the position of the specified sound source as the processing result, and display the processing result on the display unit 12.

Further, in the present embodiment, the sound source search is performed based on the phase difference of the sound waves input to each of the plurality of arranged microphone elements. Here, as a sound source exploration method, methods such as a beamforming method (BF method), a sound intensity (SI method), and an envelope intensity method (EI method) are generally known. With the SI method and the EI method, the direction of arrival of sound can be directly searched. In the BF method, the intensity distribution of the sound pressure can be used, and the direction of the maximum position of the sound pressure can be obtained as a sound source. Since all of these methods are widely known techniques and are not the gist of the present invention, detailed description of the sound source exploration method will be omitted.

[Display unit 12]
The display unit 12 displays the processing result of the signal processing unit 11. The display unit 12 is, for example, a display, and displays, for example, the area X and the position of the sound source in the area X as the processing result of the signal processing unit 11.

[Effects, etc.]
As described above, according to the present embodiment, the influence of the sound wave arriving from the second surface (rear side) can be suppressed, so that the sound source on the first surface (front side), that is, the sound source in the exploration target area. It is possible to realize a sound source exploration device 1 capable of more reliably exploring.

Further, in the sound source exploration device 1 according to the present embodiment, a plurality of microphone elements are arranged inside the outer edge of the baffle portion 101 by a predetermined length or more, and the installation surface, the first surface of the baffle portion 101, and the installation surface have a predetermined angle. Has. As a result, the sound source exploration device 1 can distinguish even a sound source that is plane-symmetrical with respect to the arrangement plane of the microphone array 102 (plurality of microphone elements). In the sound source search device 1 that searches for a sound source based on phase information, the phase difference between the sound source in the area X (front side) that is the target of sound source search and the sound source in the area Y (back side) that is not the target of sound source search is always larger. Because.

On the other hand, as a comparative example, in the conventional sound source exploration device, the phase difference of the sound waves from the sound sources having plane symmetry (the sound source on the front side and the sound source on the back side) is equal to the array surface of the microphone array, so that they are distinguished. Can not. This will be described more specifically with reference to FIGS. 10 and 11. FIG. 10 is a diagram showing a circular array microphone array 802 in a comparative example. FIG. 11 is a diagram for explaining the phase difference of sound waves arriving from a sound source in the plane-symmetric direction in the circular array microphone array 802 in the comparative example shown in FIG. As shown in FIG. 10, the circular array microphone array 802 in the comparative example is composed of eight microphone elements (microphone elements p1 to microphone elements p8), and the maximum length of the distance between the microphone elements is L ₀ . In this case, the phase difference (arrival time difference) of the sound waves arriving from the sound source R on the front side and the sound source S on the back side to the microphone element p1 and the microphone element p5 is τ _R15 = L ₀ * COS (θ _r ) / C, respectively. And τ _S15 = L ₀ * COS (θ _s ) / C. Since the sound source R on the front side and the sound source S on the back side are plane-symmetrical sound sources, θr = θs. That is, since the phase differences are equal (τ _R15 = τ _S15 ), the circular array microphone array 802 in the comparative example cannot distinguish between the sound source R and the sound source S.

Further, in the sound source exploration device 1 of the present embodiment, the phase difference between the sound source in the region X (front side) subject to the sound source exploration and the sound source in the region Y (rear side) not subject to the sound source exploration is always larger, so that the region Y The influence of the sound source (on the back side) can be removed. As a result, the sound source exploration device 1 in the present embodiment can more reliably search for a sound source in the search target area and having a small arrival sound. That is, the area Y (rear side) can be excluded from the sound source search range, and if the sound source is in the area X (front side) to be searched for the sound source, the sound source having a small arrival sound even in a loud noise is searched more reliably. be able to.

(Modification example 1)
FIG. 12 is a diagram showing an arrangement example of the microphone array 102A of the sound collecting device 10A in the modified example 1. The same elements as those in FIG. 2 are designated by the same reference numerals, and detailed description thereof will be omitted.

In the above-described embodiment, the plurality of microphone elements constituting the microphone array 102 have been described as being arranged in an annular shape, but the present invention is not limited to this. For example, it may be arranged in a pentagonal shape or an octagonal shape. This is because the distance between the two microphone elements determines the measurable frequency (upper limit of the frequency). Further, for example, as shown in FIG. 12, a plurality of microphone elements constituting the microphone array 102A may be arranged.

In the example shown in FIG. 12, among the plurality of microphone elements constituting the microphone array 102A, the microphone elements m1, m3, m5, m7 are arranged in an annular shape, and the other microphone elements n1, n2, n3, n4 are in the circle. It is arranged inside the ring. In this way, the distance from the outer edge of the baffle portion 101 may be intentionally changed for some of the plurality of microphone elements constituting the microphone array 102A. By doing so, the appearance of the phase difference between the sound wave arriving from the sound source in the area X (front side) of the sound source exploration target and the sound wave arriving from the sound source of the region Y (rear side) not subject to the sound source exploration can be changed. Can have. As a result, the sound source on the first surface (front side), that is, the sound source in the search target area can be searched more reliably.

(Modification 2)
FIG. 13 is a diagram showing an example of the baffle portion 101B of the sound collecting device 10B in the modified example 2.

In the above-described embodiment, the baffle portion 101 has been described as a circular plate-shaped member, but it does not necessarily have to be circular, and may be a rectangular plate-shaped member, for example, as shown in FIG. ..

In this case, the length of the side of the baffle portion 101B can be calculated based on the maximum length of the distance between the plurality of microphone elements and a predetermined angle.

More specifically, the diameter d ₁ of the baffle portion 101 by the length d ₁ of the sides of the baffle unit 101B, may be calculated so as to satisfy the relationship as well (Equation 4). That is, when the length of the side of the baffle portion 101B is d ₁ , the maximum length of the interval between the plurality of microphone elements is d ₀ , and the predetermined angle is θ _c , (d ₀ / COS (θ _c )) < it may be calculated so as to satisfy the relation d _1.

(Modification example 3)
FIG. 14 is a diagram showing an arrangement example of the microphone array 102 of the sound collecting device 10C in the modified example 3.

In the above-described embodiment (for example, FIG. 2 and the like) and modification 2 (for example, FIG. 13), it is assumed that the center position of the baffle portion and the center position of the microphone array (microphone element m1 to microphone element m8) coincide with each other. I explained, but it is not limited to that. As shown in FIG. 14, the center position of the baffle portion 101B and the center position of the microphone array 102 (microphone element m1 to microphone element m8) do not have to coincide with each other.

(Modification example 4)
In the above-described embodiment, the sound collecting device 10 has been described as being installed on the installation surface 51 as it is, but the present invention is not limited to this. The baffle portion 101 may be installed so that the center position is higher than the installation surface 51 by about 1 m.

Although the sound source exploration device and the like according to one or more aspects of the present invention have been described above based on the embodiments and modifications, the present invention is not limited to these embodiments and the like. As long as it does not deviate from the gist of the present invention, one or more of the present embodiments may be modified by those skilled in the art, or may be constructed by combining components in different embodiments. It may be included within the scope of the embodiment. For example, the following cases are also included in the present invention.

(1) For example, the sound source exploration device may further include an imaging means such as a camera. In this case, in the sound source exploration device, the camera may be arranged in the center of the microphone array of the sound collecting device, or the camera may be provided at a position different from the sound collecting device.

More specifically, the captured image obtained by the camera is input to the signal processing unit, and the signal processing unit 11 superimposes the sound source image indicating the position of the specified sound source on the input captured image. The display unit 12 may display the processing result.

(2) Specifically, the signal processing unit may be a computer system including a microprocessor, a ROM, a RAM, a hard disk unit, a display unit, a keyboard, a mouse, and the like. A computer program is stored in the RAM or the hard disk unit. When the microprocessor operates according to the computer program, each device achieves its function. Here, a computer program is configured by combining a plurality of instruction codes indicating instructions to a computer in order to achieve a predetermined function.

(3) A part or all of the components constituting the signal processing unit may be composed of one system LSI (Large Scale Integration). The system LSI is an ultra-multifunctional LSI manufactured by integrating a plurality of components on one chip, and specifically, is a computer system including a microprocessor, a ROM, a RAM, and the like. .. A computer program is stored in the RAM. When the microprocessor operates according to the computer program, the system LSI achieves its function.

(4) A part or all of the components constituting the signal processing unit may be composed of an IC card or a single module that can be attached to and detached from each device. The IC card or the module is a computer system composed of a microprocessor, a ROM, a RAM, and the like. The IC card or the module may include the above-mentioned super multifunctional LSI. When the microprocessor operates according to a computer program, the IC card or the module achieves its function. This IC card or this module may have tamper resistance.

The present invention can be used for a sound source exploration device using a plurality of microphone elements, and in particular, a sound source having a small arrival sound in a search target area such as a radio-controlled helicopter, a drone, a helicopter, or an airplane located relatively far from the sound source exploration device. It can be used as a sound source exploration device that can be explored.

1 Sound source exploration device 10, 10A, 10B, 10C Sound pickup device 11 Signal processing unit 12 Display unit 51 Installation surface 101 Baffle unit 101a Front 101b Back 102, 102A Microphone array 103, 103A Support member 802 Circular array microphone array

Claims (3)

With multiple microphone elements
A baffle portion having a first surface and a second surface opposite to the first surface and fixing the plurality of microphone elements arranged two-dimensionally on the first surface, and a baffle portion.
With
The plurality of microphone elements are embedded in the baffle portion so that the sound hole portions of the plurality of microphone elements are exposed on the first surface and not exposed on the second surface.
The baffle unit causes the plurality of microphone elements to collect the direct sound of the sound source on the first surface side and does not collect the direct sound from the sound source on the second surface side. By causing the sound emitted by the sound source on the two surface side to wrap around, the second surface is relative to the sound emitted by the sound source on the first surface side in the phase difference of the sound arriving at the plurality of microphone elements. to increase the phase difference of the sound emitted by the sound source on the side,
Further, a support member for supporting the baffle portion is provided so that the first surface of the baffle portion and the installation surface, which is the surface on which the sound source exploration device is installed, have a predetermined angle.
The baffle portion is a circular plate-shaped member.
The diameter of the baffle portion is calculated based on the maximum length of the distance between the plurality of microphone elements and the predetermined angle.
When the diameter of the baffle portion is d ₁ , the maximum length is d ₀ , and the predetermined angle is θ _c , the relationship of (d ₀ / COS (θ _c )) <d _{1 is satisfied.}
Sound source exploration device. With multiple microphone elements
A baffle portion having a first surface and a second surface opposite to the first surface and fixing the plurality of microphone elements arranged two-dimensionally on the first surface, and a baffle portion.
With
The plurality of microphone elements are the plurality of microphone elements.
The sound hole portion is embedded in the baffle portion so that the sound hole portion is exposed on the first surface and not exposed on the second surface.
The baffle unit causes the plurality of microphone elements to collect the direct sound of the sound source on the first surface side and does not collect the direct sound from the sound source on the second surface side. By causing the sound emitted by the sound source on the two surface side to wrap around, the second surface is relative to the sound emitted by the sound source on the first surface side in the phase difference of the sound arriving at the plurality of microphone elements. Increase the phase difference of the sound emitted by the sound source on the side,
Further, a support member for supporting the baffle portion is provided so that the first surface of the baffle portion and the installation surface, which is the surface on which the sound source exploration device is installed, have a predetermined angle.
The baffle portion is a rectangular plate-shaped member, and is
The length of the side of the baffle portion is calculated based on the maximum length of the distance between the plurality of microphone elements and the predetermined angle.
When the length of the side of the baffle portion is d ₁ , the maximum length is d ₀ , and the predetermined angle is θ _c , the relationship of (d ₀ / COS (θ _c )) <d ₁ is satisfied.
Sound source exploration device . The plurality of microphone elements are arranged inside by a predetermined length or more from the outer edge of the baffle portion.
The sound source exploration device according to claim 1 or 2.

Images