Sound source exploration device

Abstract

To solve the problem that it is difficult to specify a position of a sound source that generates an abnormal sound with a relatively low sound pressure buried in an ambient sound.SOLUTION: A sound source exploration device includes an acoustic acquisition unit 1 having a rod portion 11B in which a plurality of microphone elements arranged at intervals along a directivity direction are arranged at a tip portion thereof and a handle portion 12 continuous from a rear end of the rod portion 11B, a signal processing unit 2 that outputs an acoustic signal obtained by processing acoustic signals from a plurality of microphone elements 111 and 112 using an acoustic beamforming technique, and a receiver 3 that receives the acoustic signal from the signal processing unit 2.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a sound source tracking device used to identify the position of a sound source (sound source localization). [Background technology]

[0002] The sound source tracking device shown in Patent Document 1 is equipped with a microphone array in which eight sound sensors are arranged in a ring shape (annular) on the first surface of the baffle section at least a predetermined length inward from the outer edge, for example, microphone elements which are microphone chips having a diaphragm that displaces due to sound pressure and have the function of converting sound signals into electrical signals, a signal processing section that A / D (Analog to Digital) converts the signals output from the eight microphone elements and converts them into time signals or frequency domain signals, and then performs calculation processing based on the phase difference between the eight sound sensors to localize and identify the direction from which the sound is coming, and a display section that displays the processing results of the signal processing section. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2017-49225 Summary of the Invention [Problem to be solved by the invention]

[0004] The sound source tracking device shown in Patent Document 1 locates the location of a sound source using the strength of sound waves from the sound source measured by a microphone element (sound pressure level: sound intensity), making it difficult to locate a sound source that emits an abnormal sound with a relatively low sound pressure that is buried in ambient sounds.

[0005] The present disclosure has been made in consideration of the above points, and aims to provide a sound source tracking device that can be used to identify the location of a sound source that generates an abnormal sound that one wishes to find, to identify the location of a sound source that generates a sound that is fainter than the surrounding sounds, or to identify the location of a sound source that generates an abnormal sound due to a difference in tone among a plurality of sound sources (targets). [Means for solving the problem]

[0006] The sound source tracking device according to the present disclosure includes an acoustic acquisition unit having a rod portion at the tip of which a plurality of microphone elements are arranged at intervals along a directional direction, and a handle portion continuing from the rear end of the rod portion, a signal processing unit that processes acoustic signals from the plurality of microphone elements using acoustic beamforming technology and outputs the processed acoustic signals, and a receiver that receives the acoustic signals from the signal processing unit. [Effects of the Invention]

[0007] According to the present disclosure, the present invention can be used to identify the location of any of the following sound sources: a sound source that generates an abnormal sound; a sound source that generates a sound that is faint compared to the surrounding sounds; or a sound source that generates an abnormal sound due to a difference in tone among a group of multiple sound sources. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a configuration diagram showing an example of the configuration of a sound source tracking device according to a first embodiment. [Figure 2] FIG. 2 is a perspective view showing a sound acquisition unit in the sound source tracking device according to the first embodiment. [Figure 3] FIG. 2 is a perspective view showing a microphone unit of a sound acquiring unit in the sound source tracking device according to the first embodiment. [Figure 4] FIG. 2 is a configuration diagram showing an example of the configuration of a beamforming signal processing unit of the signal processing unit in the sound source tracking device according to the first embodiment. [Figure 5] FIG. 2 is a diagram showing an example of an addition output by a beamforming signal processing unit of the signal processing unit in the sound source tracking device according to the first embodiment. [Figure 6] FIG. 4 is a diagram showing an example of a subtraction output by a beamforming signal processing unit of the signal processing unit in the sound source tracking device according to the first embodiment. [Figure 7] FIG. 2 is an outline view showing a housing of the sound source tracking device according to the first embodiment. [Figure 8] FIG. 2 is a perspective view showing headphones in the sound source tracking device according to the first embodiment. [Figure 9] FIG. 10 is a configuration diagram showing another example of the configuration of the beamforming signal processing unit of the signal processing unit in the sound source tracking device according to the first embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] Embodiment 1 The sound source tracking device according to the first embodiment will be described with reference to FIGS. The sound source tracking device according to the first embodiment is used particularly to identify the position of the source (sound source) of a target sound (for example, an abnormal sound) in a noisy environment. The sound source tracking device according to the first embodiment is used particularly to search for the source (sound source) of an abnormal sound in a product and to identify the location where the source (sound source) of the abnormal sound has occurred.

[0010] The sound source tracking device according to the first embodiment is a portable sound source tracking device that is easy to carry. The sound source tracking device according to embodiment 1 is characterized in that it is a sound source tracking device that can target and pick up sound sources and distinguish the tone of the picked-up sound sources, rather than capturing a wide area in the entire space when searching for the source (sound source) of an abnormal sound.

[0011] As shown in FIG. 1, the sound source tracking device according to the first embodiment includes a sound acquiring unit 1, a signal processing unit 2, a receiver 3, and a housing 4 (shown in FIG. 7). The sound acquiring unit 1 is a beamforming microphone having a plurality of microphone elements 111, 112 with the same characteristics arranged at an interval d along the directivity direction. In the first embodiment, a case where the number of microphone elements 111 and 112 is two will be described, but the basic concept is the same even when the number is three or more. In the following description, the microphone element 111 is referred to as a first microphone element, and the microphone element 112 is referred to as a second microphone element.

[0012] As shown in FIGS. 1 and 2, the sound acquiring unit 1 has a pole 11 having a microphone unit 11A at the tip thereof, a handle unit 12, and a fan 13 for preventing wind noise. The rod 11 has a microphone portion 11A and a cylindrical rod portion 11B that is continuous with the microphone portion 11A. The microphone part 11A and the rod part 11B have the same axis.

[0013] As shown in Figures 1 and 3, the microphone unit 11A has a flat surface, and a first microphone element 111 and a second microphone element 112 are mounted on the flat surface at an interval d along the directivity direction, i.e., the axial direction of the rod 11. The characteristics of the first microphone element 111 and the characteristics of the second microphone element 112 are the same.

[0014] When a plane wave arrives at the first microphone element 111 and the second microphone element 112 from a direction of incidence angle θ with respect to a plane perpendicular to the directivity direction, the second microphone element 112 receives this plane wave with a delay time of a path difference δ (= d sin θ) relative to the first microphone element 111.

[0015] The acoustic signal output from the second microphone element 112 is output with a delay time of the path difference δ relative to the acoustic signal output from the first microphone element 111 . The distance d between the first microphone element 111 and the second microphone element 112 is equal to or less than half the wavelength of the highest frequency component of the target sound source, and is 10 mm in this example. In this example, the rod portion 11B has a diameter of 5 mm and a length of 300 mm. The rod portion 11B may have a structure that allows it to be extended and retracted.

[0016] The handle portion 12 is formed continuously from the rear end of the rod portion 11B of the rod 11. By gripping the handle 12, the measurer can easily point the microphone 11A in various directions, for example, toward a sound source where an abnormal sound is suspected, making it easy to search for the source (sound source) of the abnormal sound. A wind noise prevention fan 13 is attached so as to cover the microphone portion 11A, thereby preventing the influence of wind noise.

[0017] In this way, the acoustic acquisition unit 1 has a structure including a rod 11 having a microphone unit 11A at the tip and a handle unit 12 formed continuously from the rear end of the rod 11, so that it can be easily aimed at the target sound source, and the tone from the targeted sound source can be picked up from multiple microphone elements 111, 112 arranged at an interval d along the directional direction of the microphone unit 11A, i.e., the axial direction of the rod 11.

[0018] The signal processing unit 2 includes a beamforming signal processing unit 21, a headphone amplifier 22, and a mobile battery 23. The beamforming signal processing unit 21 processes the acoustic signals from the first microphone element 111 and the second microphone element 112 using a directivity control technique based on acoustic beamforming technology, and outputs the processed acoustic signals.

[0019] The beamforming signal processing unit 21 receives acoustic signals from the first microphone element 111 and the second microphone element 112, each of which has a delay time of path difference δ relative to the other, compensates for the delay time between the first microphone element 111 and the second microphone element 112, and outputs an acoustic signal obtained by adding or subtracting the acoustic signals from the two beamforming microphones 111 and 112 whose delay times have been compensated.

[0020] As shown in FIG. 4, the beamforming signal processing unit 21 includes a delay circuit (delay unit) 21a, an adder (addition unit) 21b, and a subtractor (subtraction unit) 21c. The delay circuit 21 a delays the acoustic signal from the first microphone element 111 by the delay time of the path difference δ between the first microphone element 111 and the second microphone element 112 . The acoustic signal from the first microphone element 111 is delayed by the delay circuit 21 a, and the delayed acoustic signal has the same timing as the acoustic signal from the second microphone element 112 .

[0021] The adder 21b adds the acoustic signal from the first microphone element 111 and the acoustic signal from the second microphone element 112, which have been delayed by the delay circuit 21a. FIG. 5 shows the acoustic signal added by the adder 21b when the distance d between the first microphone element 111 and the second microphone element 112 is 10 mm. In FIG. 5, the horizontal axis indicates the incident angle θ, the vertical axis indicates the gain, the solid line indicates the sum output result of 4 KHz, and the dashed line indicates the sum output result of 2 KHz.

[0022] As can be seen from Figure 5, the phases of the added acoustic signals arriving from the incident direction θ, or 20 degrees in this example, match, so the signal arriving from the incident direction θ is emphasized. Signals arriving from directions other than the incident direction θ do not match in phase with each other, so they are not emphasized as much as the signal arriving from the incident direction θ.

[0023] Therefore, when the added output (acoustic signal) from the beamforming signal processing unit 21 is used, the added output from the beamforming signal processing unit 21 forms directivity having a beam in the incident direction θ, with the beam in the incident direction θ being the incident direction with high sensitivity, that is, the beam in the direction from which the source of the abnormal sound (sound source) comes.

[0024] Therefore, by directing the microphone part 11A located at the tip of the rod 11 in a direction with high sensitivity, the position of the sound source can be identified. Controlling the beam direction is called beam steering, and the beamforming signal processing unit 21 that handles delayed and summed acoustic signals is called a delay-and-sum beamformer.

[0025] The subtractor 21c subtracts the acoustic signal from the first microphone element 111 delayed by the delay circuit 21a from the acoustic signal from the second microphone element 112. FIG. 6 shows the acoustic signal subtracted by the subtractor 21c when the distance d between the first microphone element 111 and the second microphone element 112 is 10 mm. In FIG. 6, the horizontal axis indicates the incident angle θ, the vertical axis indicates the gain, the solid line indicates the subtraction output result at 4 KHz, and the dashed line indicates the subtraction output result at 2 KHz.

[0026] As can be seen from Figure 6, the subtracted acoustic signal completely cancels the signal arriving from the incident direction θ, in this example 20 degrees, forming a directivity with a null in the incident direction θ as an incident direction with low sensitivity.

[0027] Therefore, when the subtracted output (acoustic signal) from the beamforming signal processing unit 21 is used, the subtracted output from the beamforming signal processing unit 21 forms directivity having a null in the incident direction θ as an incident direction with low sensitivity. The beam with an incident direction θ that shows a null is the direction from which the source of the abnormal sound (sound source) comes. Therefore, by directing the microphone part 11A located at the tip of the rod 11 in a direction with low sensitivity, the position of the sound source can be identified. Controlling the null direction is called null steering.

[0028] The ability to perform beam steering and null steering simultaneously is called adaptive beam forming, and the beam forming signal processing unit 21 shown in FIG. 4 is an adaptive beam former. The beamforming signal processing unit 21 may be a delay-and-sum beamformer that handles delayed and added acoustic signals, omitting the subtractor 21c.

[0029] The beamforming signal processing unit 21 may be configured as a microprocessor-based beamforming processor having an A / D converter that performs analog-to-digital (A / D) conversion on the acoustic signal from the first microphone element 111 and an A / D converter that performs analog-to-digital (A / D) conversion on the acoustic signal from the second microphone element 112, and having the functions of a delay circuit (delay unit) 21a, an adder (addition unit) 21b, and a subtractor (subtraction unit) 21c for converting the digitized acoustic signal from the first microphone element 111 and the digitized acoustic signal from the second microphone element 112.

[0030] The headphone amplifier 22 amplifies the added acoustic signal or the subtracted acoustic signal from the beamforming signal processing unit 21 and outputs the amplified signal to the receiver 3 . The beamforming signal processing unit 21 and the headphone amplifier 22 are mounted on a printed circuit board. The mobile battery 23 supplies power to the beamforming signal processing unit 21 and the headphone amplifier 22 .

[0031] The beamforming signal processing unit 21, headphone amplifier 22, and mobile battery 23, which are mounted on a printed circuit board, are housed in a housing 4 shown in FIG. Although not shown, the housing 4 is provided with a jack for electrically connecting the first microphone element 111 and the second microphone element 112 of the acoustic acquisition unit 1, a jack for electrically connecting to the receiver 3, power switches for the beamforming signal processing unit 21 and the headphone amplifier 22, and a volume switch for the headphone amplifier 22.

[0032] In addition, a shoulder belt 41 is attached to the housing 4. The outer shape of the housing 4 is 240 mm wide, 165 mm long, and 60 mm thick. Therefore, the person making the measurement can carry the housing 4 by putting the shoulder belt 41 on their shoulder, and by inserting the plug of the acoustic acquisition unit 1 and the plug of the receiver 3 into the respective jacks provided in the housing 4, the source (sound source) of the abnormal sound can be searched for and the location where the source (sound source) of the abnormal sound is generated can be identified with good mobility.

[0033] As shown in FIG. 8, the receiver 3 is a highly airtight headphone with a noise canceling function. When the person wearing the headphones, which are the receiver 3, blocks (reduces) external noise, the person can selectively hear only the acoustic signal input from the beamforming signal processing unit 21 via the headphone amplifier 22.

[0034] The added output from the beamforming signal processing unit 21 is easy to hear as sound intensity, that is, the incident direction with high sensitivity shown in Figure 5, and since it is heard as sound, the tone of the sound can also be heard, making it easy to find the sound source that is generating abnormal sounds due to differences in tone among a number of sound sources lined up. The receiver 3 may be an inner-ear type with a noise canceling function and a tight seal.

[0035] Next, the operation of the sound source tracking device according to the first embodiment will be described. As a preliminary preparation, the plug of the acoustic acquisition unit 1 and the plug of the receiver 3 are attached to the respective jacks in the housing 4 that houses the beamforming signal processing unit 21, the headphone amplifier 22, and the mobile battery 23. The subject places the housing 4 on the shoulder using the shoulder strap 41 , puts the headphones serving as the receiver 3 on the ears, and grasps the handle 12 of the sound acquisition unit 11 .

[0036] The measurer points the microphone unit 11A in the acoustic acquisition unit 1 toward the target (sound source) and searches for the source (sound source) of the targeted sound (such as an abnormal sound) while listening to the acoustic signal from the headphones, that is, locating the sound source.

[0037] As an example, when the beamforming signal processing unit 21 in the signal processing unit 2 receives an acoustic signal from the first microphone element 111 and an acoustic signal from the second microphone element 112 in the microphone unit 11A, the beamforming signal processing unit 21 delays the acoustic signal from the first microphone element 111, adds the delayed acoustic signal from the first microphone element 111 and the acoustic signal from the second microphone element 112, and outputs the added acoustic signal.

[0038] The acoustic signal that has been added by the beamforming signal processing unit 21 is input to the headphones, which are the receiver 3, via the headphone amplifier 22, and the person measuring hears the acoustic signal that has been added together from the acoustic signal from the first microphone element 111 and the acoustic signal from the second microphone element 112 of the acoustic acquisition unit 1, which have the characteristics shown in Figure 5, without being affected by external noise. Therefore, the measurer can know the direction of the strongest sound, that is, the incident direction with high sensitivity, and can know the direction from which the source of the abnormal sound (sound source) is coming.

[0039] Furthermore, because the person making the measurement listens to the added acoustic signal through headphones, tone can also be added as a factor in determining whether an abnormal sound is present. This makes it easy to identify the source of the abnormal sound that the person is trying to find, to identify the location of a sound that is faint compared to the surrounding sounds, and to identify the source (sound source) of an abnormal sound by differences in tone among a line of multiple individuals (targets: sound sources).

[0040] In short, the sound source tracking device according to embodiment 1 can be used by a measurer holding the handle 12 of the acoustic acquisition unit 11, wearing headphones on their ears, and hanging the housing 4 containing the signal processing unit 2 on their shoulder. By pointing the microphone unit 11A of the acoustic acquisition unit 1 toward the target (sound source) and listening to the intensity and tone of the sound from the sound source through the headphones, the source (sound source) of the abnormal sound can be identified with high accuracy.

[0041] The sound source tracking device according to the first embodiment comprises an acoustic acquisition unit 1 having a rod portion 11 at the tip of which a plurality of microphone elements 111, 112 are arranged at intervals along the direction of directivity, and a handle portion 12 continuous with the rear end of the rod portion 11; a signal processing unit 2 that processes acoustic signals from the plurality of microphone elements 111, 112 using acoustic beamforming technology and outputs the processed acoustic signals; and a receiver 3 that receives the acoustic signals from the signal processing unit 2. Therefore, the acoustic signals processed using acoustic beamforming technology can be heard by the receiver 3, and the source (sound source) of abnormal sounds can be identified with high accuracy.

[0042] Furthermore, the sound source tracking device according to embodiment 1 has multiple microphone elements 111, 112 arranged at the tip of the rod 11 as the sound acquisition unit 1, and is therefore able to receive acoustic signals from a sound source located in a relatively narrow space. Furthermore, in the sound source tracking device according to the first embodiment, the signal processing unit 2 is housed in a housing, making it possible to carry the signal processing unit 2 and to search for a sound source with good mobility.

[0043] In the sound source tracking device according to the first embodiment, two cases have been mainly described regarding the number of microphone elements 111 and 112 arranged at the tip of the rod part 11 of the sound acquiring unit 1. However, it is also possible to arrange M (a natural number equal to or greater than 3) microphone elements 111 to 112 with the same characteristics at equal intervals d along the directivity direction at the tip. M may be arranged.

[0044] M microphone elements 111 to 11 M For the acoustic acquisition unit 1 in which the beamforming signals are arranged, the beamforming signal processing unit 21A in the signal processing unit 2 has the configuration shown in FIG. The beamforming signal processing unit 21A is a delay-and-sum beamformer that handles delayed and summed acoustic signals. The beamforming signal processing unit 21A processes the first microphone element 111 to the (M-1)th microphone element 11 M-1 The first delay circuit 21a1 to the (M-1)th delay circuit 21a M-1and an adder 21bA.

[0045] The first delay circuit 21a1 to the M-th delay circuit 21a M-1 The delay time of each microphone element is the reference microphone element, for example, the Mth microphone element 11 M The delay time δ1 to δ for the acoustic signal from M-1 is set to

[0046] The adder 21bA adds the delays of the first delay circuit 21a1 to the (M-1)th delay circuit 21a M-1 The first microphone element 111 to the (M-1)th microphone element 11 M-1 The acoustic signal from each of the M microphone elements 11 M The acoustic signals from The acoustic signal added by the adder 21bA is amplified by a headphone amplifier 22 and input to a receiver 3, which is a highly sealed headphone with a noise canceling function.

[0047] M microphone elements 111 to 11 M When the above-described embodiment is used and the beamforming signal processing unit 21A is configured as a delay-and-sum beamformer, it has the same effects as the embodiment using the two microphone elements 111 and 112 described above, and in addition, it has a higher degree of spatial freedom and makes it easier to obtain sharp directivity.

[0048] In the beamforming signal processing unit 21A shown in FIG. 9, the first delay circuit 21a1 to the M-th delay circuit 21a M-1 A buffer circuit that does not transmit the influence of the subsequent stage to the preceding stage may be disposed between each output and the input of the adder 21bA.

[0049] M microphone elements 111 to 11 M For the acoustic acquisition unit 1 in which the above-mentioned signals are arranged, the beamforming signal processing unit 21B in the signal processing unit 2 may be a filter-and-sum beamformer in which acoustic signals are added after filtering. M microphone elements 111 to 11M When the above-described embodiment is used and the beamforming signal processing unit 21B is configured as a filter-and-sum beamformer, the same effects as those of the embodiment using the two microphone elements 111 and 112 described above can be obtained, and the use of a filter can also change the relationship between frequency and directivity.

[0050] In the embodiments, any of the components of the embodiments may be modified or omitted. [Industrial Applicability]

[0051] The sound source tracking device according to the present disclosure is applied to a sound source tracking device used to search for the source (sound source) of an abnormal sound, identify the position of the sound source (sound source localization), and identify the location of the source (sound source) of an abnormal sound. [Explanation of symbols]

[0052] 1 Acoustic acquisition unit, 11 Rod, 11A Microphone unit, 111 First microphone element, 112 Second microphone element, 11B Rod unit, 12 Handle unit, 2 Signal processing unit, 21 Beamforming signal processing unit, 22 Headphone amplifier, 23 Mobile battery, 3 Receiver, 4 Housing.

Claims

1. a sound acquisition unit having a rod on the tip of which a plurality of microphone elements are arranged at intervals along the direction of directivity, and a handle portion continuous with the rear end of the rod; a signal processing unit that processes acoustic signals from the plurality of microphone elements using an acoustic beamforming technique and outputs the processed acoustic signals; a receiver that receives an acoustic signal from the signal processing unit; A sound source detection device comprising:

2. 2. The sound source tracking device according to claim 1, wherein the rod has a microphone portion having a flat surface on which the plurality of microphone elements are arranged in an axial direction, and a cylindrical rod portion having the same axis as the microphone portion and positioned between the microphone portion and a handle portion.

3. 2. The sound source tracking device according to claim 1, wherein the receiver is a headphone with a noise canceling function.

4. The sound source tracking device according to claim 1, wherein the intervals at which the plurality of microphone elements are arranged are equal to or less than half the wavelength of the highest frequency component of the target sound source.

5. 2. The sound source tracking device according to claim 1, wherein the acoustic signal processed by the signal processing unit using acoustic beamforming technology is an acoustic signal obtained by compensating for delay times due to path differences between acoustic signals from the plurality of microphone elements and acoustic signals from other microphone elements relative to an acoustic signal from a reference microphone element, and adding together the acoustic signals from the plurality of microphone elements whose delay times have been compensated.

6. a rod having a plurality of microphone elements arranged at intervals along a directivity direction at a tip end thereof, and a sound acquisition unit having a handle portion continuing from a rear end of the rod; a signal processing unit that compensates for delay times due to path differences between the acoustic signals from the plurality of microphone elements and the acoustic signals from the other microphone elements relative to the acoustic signal from a reference microphone element, and outputs acoustic signals that have been processed using an acoustic beamforming technique in which the acoustic signals from the plurality of microphone elements whose delay times have been compensated are added together; a receiver that is a headphone with a noise canceling function that receives the acoustic signal from the signal processing unit; A sound source detection device comprising:

7. The sound source tracking device according to claim 1 , wherein the signal processing unit is mounted in a housing to which a shoulder belt is attached.

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