Sound source detection device

Abstract

It is difficult to identify the position of a sound source that generates a relatively low sound pressure abnormal sound buried in ambient sound. 【Solution means】The sound source detection device includes an acoustic acquisition unit 1 having a rod portion 11B in which a plurality of microphone elements arranged at intervals along the directivity direction are arranged at the tip, and a handle portion 12 continuous from the rear end of the rod portion 11B, and a plurality of microphone elements 111, 112. A signal processing unit 2 that outputs an acoustic signal obtained by processing the acoustic signals from the acoustic beamforming technique, and a receiver 3 that receives the acoustic signal from the signal processing unit 2.

Description

Technical Field

[0001] The present disclosure relates to a sound source detection device used for identifying the position of a sound source (sound source localization).

Background Art

[0002] The sound source detection device shown in Patent Document 1 includes a microphone array in which microphone elements, which are microphone chips having a function of converting a sound signal into an electrical signal and having eight sound sensors, for example, diaphragm elements that are displaced by sound pressure, arranged in a ring shape (annular shape) on the first surface of the baffle portion at a position more than a predetermined length inward from the outer edge, a signal processing unit that performs A / D (Analog to Digital) conversion on signals output from the eight microphone elements, performs conversion processing into a time signal or a frequency domain signal, and then performs a calculation process based on the phase difference between the eight sound sensors to localize or identify the arrival direction of the sound, and a display unit that displays the processing result of the signal processing unit.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Since the sound source detection device shown in Patent Document 1 identifies the position of the sound source using the intensity (sound pressure level: strength of sound) of the sound wave from the sound source of the microphone element, it is difficult to identify the position of the sound source that generates a relatively low sound pressure abnormal sound buried in the ambient sound.

[0005] The present disclosure has been made in view of the above points, and aims to obtain a sound source exploration device used for specifying the position of a sound source that generates an abnormal sound to be detected, specifying the position of a sound source that generates a minute sound compared to ambient sound, or specifying the position of a sound source that generates an abnormal sound due to a difference in tone color among a plurality of aligned sound sources (targets).

Means for Solving the Problems

[0006] The sound source exploration device according to the present disclosure includes an acoustic acquisition unit having a rod portion on which a plurality of microphone elements arranged at intervals along a directivity direction are arranged at the tip, and a handle portion continuous from the rear end of the rod portion, a signal processing unit that outputs an acoustic signal obtained by processing acoustic signals from the plurality of microphone elements using an acoustic beamforming technique, and a receiver that receives the acoustic signal from the signal processing unit. The acoustic signal processed using the acoustic beamforming technology by the signal processing unit is an acoustic signal obtained by compensating for the delay time of the path difference of the acoustic signals of other microphone elements with respect to the acoustic signal of the reference microphone element among the acoustic signals from a plurality of microphone elements, and adding the acoustic signals from the plurality of microphone elements for which the delay time has been compensated.

Effects of the Invention

[0007] According to the present disclosure, it can be used for specifying the position of any sound source, including specifying the position of a sound source that generates an abnormal sound, specifying the position of a sound source that generates a minute sound compared to ambient sound, or specifying the position of a sound source that generates an abnormal sound due to a difference in tone color among a plurality of aligned sound sources.

Brief Description of the Drawings

[0008]

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Mode for Carrying Out the Invention

[0009] Embodiment 1. The sound source search device according to Embodiment 1 will be described with reference to FIGS. 1 to 9. The sound source search device according to Embodiment 1 is particularly used to identify the position of the source (sound source) of the target sound (e.g., abnormal sound) under noise. The sound source search device according to Embodiment 1 is particularly used to search for the source (sound source) of the abnormal sound of the product and identify the generation site of the source (sound source) of the abnormal sound.

[0010] The sound source search device according to Embodiment 1 is a portable type sound source search device that is easy to carry. The sound source search device according to Embodiment 1 is characterized in that, particularly, instead of capturing a wide area in the entire space as a search for the source (sound source) of the abnormal sound, it aims at and picks up the sound source, and can distinguish the timbre of the picked-up sound source.

[0011] As shown in FIG. 1, the sound source search device according to Embodiment 1 includes an acoustic acquisition unit 1, a signal processing unit 2, a receiver 3, and a housing 4 (shown in FIG. 7). The acoustic acquisition unit 1 is a microphone for beamforming having a plurality of microphone elements 111 and 112 with equal characteristics arranged at intervals d along the directivity direction. In Embodiment 1, the 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. The microphone element 111 will be hereinafter described as the first microphone element, and the microphone element 112 as the second microphone element.

[0012] As shown in FIGS. 1 and 2, the acoustic acquisition unit 1 includes a rod 11 having a microphone unit 11A at its tip, a handle unit 12, and a wind noise prevention filter 13. The rod 11 has a cylindrical rod portion 11B in which the microphone unit 11A and the microphone unit 11A are continuous. The axes of the microphone unit 11A and the rod portion 11B are the same.

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

[0014] When a plane wave arrives from the direction of the incident angle θ with respect to the plane perpendicular to the directivity direction, for this plane wave, the second microphone element 112 has a delay time of the path difference δ (= dsinθ) with respect to the first microphone element 111 and is received.

[0015] The acoustic signal output from the second microphone element 112 is output with a delay time of the path difference δ with respect to the acoustic signal output from the first microphone element 111. The interval 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. Note that the rod portion 11B may have a telescopic structure.

[0016] The handle part 12 is formed continuously from the rear end of the rod part 11B of the rod 11. When the measurer holds the handle part 12, the microphone part 11A can be easily directed by the measurer in various directions, for example, toward a sound source where an abnormal sound is likely to occur, and it is easy to search for the sound source (sound source) of the abnormal sound. The wind noise prevention cover 13 is attached so as to cover the microphone part 11A, preventing the influence of wind noise.

[0017] Thus, since the acoustic acquisition unit 1 has a structure having the rod 11 having the microphone part 11A at the tip and the handle part 12 formed continuously from the rear end of the rod 11, it is possible to easily determine the target for the sound source to be targeted, and the tone color from the determined sound source can be picked up from the plurality of microphone elements 111, 112 arranged with an interval d along the directivity direction in the microphone part 11A, that is, 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 outputs an acoustic signal obtained by processing the acoustic signals from the first microphone element 111 and the second microphone element 112 using a directivity control technique based on an acoustic beamforming technique.

[0019] The beamforming signal processing unit 21 receives acoustic signals having a delay time of a path difference δ from the other of the first microphone element 111 and the second microphone element 112 with respect to one of them, 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, 112 for which the delay time has 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 21a 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 delayed by the delay circuit 21a from the first microphone element 111 becomes an acoustic signal with 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 delayed by the delay circuit 21a and the acoustic signal from the second microphone element 112. 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 represents the incident angle θ, the vertical axis represents the gain, the solid line represents 4 KHz, and the dashed line represents 2 KHz, respectively showing the addition output results.

[0022] As understood from Fig. 5, since the phases of the added acoustic signals are the same for the acoustic signals arriving from the incident direction θ, which is 20 degrees in this example, the signal arriving from the incident direction θ is emphasized. Signals arriving from directions other than the incident direction θ do not have the same phase as each other, so they are not as emphasized as the signal arriving from the incident direction θ.

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

[0024] Therefore, by directing the direction of the microphone unit 11A located at the tip of the pole 11 towards the highly sensitive direction, the position of the sound source can be specified. The control of the beam direction is called beam steering, and the beamforming signal processing unit 21 that handles the delayed and added 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 represents the incident angle θ, the vertical axis represents the gain, the solid line represents 4 KHz, and the dashed line represents 2 KHz, respectively showing the subtraction output results.

[0026] As can be understood from Fig. 6, the subtracted acoustic signal has a directivity with a null in the incident direction θ, where the signal arriving from the incident direction θ, in this example 20 degrees, is completely canceled, forming a low-sensitivity incident direction.

[0027] Therefore, when using the subtracted output (acoustic signal) from the beamforming signal processing unit 21, the subtracted output from the beamforming signal processing unit 21 forms a directivity with a null in the incident direction θ as a low-sensitivity incident direction. The beam in the incident direction θ indicating the null is the arrival direction of the abnormal sound source (sound source). Therefore, by turning the direction of the microphone unit 11A located at the tip of the rod 11 in the low-sensitivity direction, the position of the sound source can be specified. The control of the null direction is called null steering.

[0028] Performing beam steering and null steering simultaneously is called adaptive beamforming, and the beamforming signal processing unit 21 shown in Fig. 4 is an adaptive beamformer. Note that as the beamforming signal processing unit 21, a delay-and-sum beamformer that omits the subtractor 21c and processes the delayed and added acoustic signals may also be used.

[0029] The beamforming signal processing unit 21 may include an analog-to-digital (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 the digitized acoustic signal from the first microphone element 111 and the digitized acoustic signal from the second microphone element 112 are configured by a beamforming processor implemented by a microprocessor having the functions of a delay circuit (delay unit) 21a, an adder (addition unit) 21b, and a subtractor (subtraction unit).

[0030] The headphone amplifier 22 amplifies the added or subtracted acoustic signal from the beamforming signal processing unit 21 and outputs it 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, the headphone amplifier 22 mounted on the printed circuit board, and the mobile battery 23 are housed in the housing 4 shown in FIG. 7. Although not shown, the housing 4 is provided with a jack for electrically connecting to 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, a power switch for the beamforming signal processing unit 21 and the headphone amplifier 22, and a volume switch for the headphone amplifier 22, etc.

[0032] Also, a shoulder belt 41 is attached to the housing 4. The outer shape of the housing 4 is 240 mm in width, 165 mm in length, and 60 mm in thickness. Therefore, by the measurer putting on the shoulder belt 41 on the shoulder, the housing 4 can be carried, and by attaching the plug of the acoustic acquisition unit 1 and the plug of the receiver 3 to the respective jacks provided on the housing 4, the search for the abnormal sound generation source (sound source) and the identification of the generation site of the abnormal sound generation source (sound source) can be carried out with good mobility.

[0033] As shown in FIG. 8, the receiver 3 is a highly sealed headphone with a noise canceling function. By the measurer wearing the headphones which are the receiver 3, external noise is blocked (reduced), and only the acoustic signal input from the headphone amplifier 22 from the beamforming signal processing unit 21 can be selectively listened to.

[0034] The added output from the beamforming signal processing unit 21 is such that the sound intensity, that is, the highly sensitive incident direction shown in FIG. 5 is easy to hear, and since it is being heard as sound, the timbre in the sound can also be heard, and it is easy to find the sound source which is the abnormal sound generation source due to the difference in timbre among a plurality of sound sources arranged side by side. Note that as the receiver 3, an inner ear type with a high sealing degree and a noise canceling function may also be used.

[0035] Next, the operation of the sound source exploration device according to Embodiment 1 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 in which the beamforming signal processing unit 21, the headphone amplifier 22, and the mobile battery 23 are housed. The measurer puts the housing 4 on the shoulder with the shoulder belt 41, wears the headphones which are the receiver 3 on the ears, and holds the handle portion 12 of the acoustic acquisition unit 11.

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

[0037] Now, as an example, when the beamforming signal processing unit 21 in the signal processing unit 2 receives the acoustic signal from the first microphone element 111 and the 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 processed by addition by the beamforming signal processing unit 21 is input to the headphones which are the receiver 3 via the headphone amplifier 22, and the measurer can listen to the acoustic signal obtained by adding 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 having the characteristics shown in FIG. 5 without being affected by external noise. Therefore, the measurer can know the direction in which the sound intensity is strong, that is, the incident direction with high sensitivity, and can know the arrival direction of the abnormal sound source (sound source).

[0039] Moreover, since the measurer listens to the added acoustic signal through the headphones, the timbre is also added as a judgment factor for the abnormal sound. Therefore, it is easy to specify the generation location of the abnormal sound to be discovered, the generation position of a minute sound compared to the surrounding sound, and the abnormal sound source (sound source) due to the difference in timbre among a plurality of individuals (targets: sound sources) lined up.

[0040] In short, the sound source exploration device according to the first embodiment can be used by the measurer holding the handle portion 12 of the acoustic acquisition unit 11, wearing the headphones on the ears, and hanging the housing 4 in which the signal processing unit 2 is housed on the shoulder. By aiming the microphone unit 11A in the acoustic acquisition unit 1 at the target (sound source) and listening to the sound intensity and timbre from the sound source through the headphones, the abnormal sound source (sound source) can be specified with high accuracy.

[0041] The sound source detection device according to Embodiment 1 includes an acoustic acquisition unit 1 having a rod portion 11 on which a plurality of microphone elements 111 and 112 are arranged at intervals along the directivity direction at the tip, and a handle portion 12 continuous from the rear end of the rod portion 11, a signal processing unit 2 that outputs an acoustic signal obtained by processing acoustic signals from the 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. Therefore, the acoustic signal processed using the acoustic beamforming technique can be heard by the receiver 3, and the source (sound source) of abnormal sound with high accuracy can be specified.

[0042] Furthermore, since the sound source detection device according to Embodiment 1 arranges the plurality of microphone elements 111 and 112 at the tip of the rod portion 11 as the acoustic acquisition unit 1, it can receive acoustic signals from sound sources located in relatively narrow places. Also, since the sound source detection device according to Embodiment 1 houses the signal processing unit 2 in a housing, the signal processing unit 2 can be carried, and the search for sound sources can be performed with good mobility.

[0043] Note that, regarding the number of the microphone elements 111 and 112 arranged at the tip of the rod portion 11 in the acoustic acquisition unit 1 of the sound source detection device according to Embodiment 1, mainly two cases have been described. However, M (a natural number of 3 or more) microphone elements 111 to 11 M having the same characteristics at equal intervals d along the directivity direction may be arranged at the tip.

[0044] For the acoustic acquisition unit 1 in which M microphone elements 111 to 11 M are arranged, the beamforming signal processing unit 21A in the signal processing unit 2 has the configuration shown in FIG. 9. The beamforming signal processing unit 21A is a delay-and-sum beamformer that handles acoustic signals obtained by delaying and adding. The beamforming signal processing unit 21A corresponds to the first delay circuit 21a1 from the first microphone element 111 to the M - 1th microphone element 11 M-1 to the M - 1th delay circuit 21a M-1and has an adder 21bA.

[0045] From the first delay circuit 21a1 to the M-th delay circuit 21a M-1 The delay time in each is based on a reference microphone element, for example, the M-th microphone element 11 M The delay times δ1 to δ of the path difference with respect to the acoustic signal from M-1 are set to.

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

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

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

[0049] For the acoustic acquisition unit 1 in which M microphone elements 111 to 11 M are arranged, the beamforming signal processing unit 21B in the signal processing unit 2 may be a filter-and-sum beamformer in which the acoustic signal is added after filtering. M microphone elements 111 to 11M When the beamforming signal processing unit 21B is configured as a filter and sum beamformer using this, in addition to having the same effects as the embodiment using the two microphone elements 111 and 112 described above, by adopting a filter, the relationship between frequency and directivity can be changed.

[0050] In the embodiment, it is possible to modify any component of the embodiment or omit any component of the embodiment.

Industrial Applicability

[0051] The sound source exploration device according to the present disclosure is applied to a sound source exploration device used for exploring the generation source (sound source) of abnormal sounds, specifying the position of the sound source (sound source localization), and specifying the generation site of the generation source (sound source) of abnormal sounds.

Explanation of Signs

[0052] 1 Acoustic acquisition unit, 11 Rod, 11A Microphone unit, 111 First microphone element, 112 Second microphone element, 11B Rod part, 12 Handle part, 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 a directivity direction, and a handle portion continuing from the rear end of the rod; a signal processing unit that processes the acoustic signals from the plurality of microphone elements using an acoustic beamforming technique and outputs the processed acoustic signals; A receiver for receiving an acoustic signal from the signal processing unit, The acoustic signal processed by the signal processing unit using the acoustic beamforming technique is an acoustic signal obtained by compensating for delay times of the acoustic signals from the plurality of microphone elements due to path differences between the acoustic signal from a reference microphone element and the acoustic signals from the other microphone elements and adding up the acoustic signals from the plurality of microphone elements whose delay times have been compensated for. Sound source detection device.

2. The sound source exploration device according to claim 1, wherein the rod has a microphone portion having a flat surface and the plurality of microphone elements are arranged in an axial direction on the flat surface, and a cylindrical rod portion having a common axis with 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 interval at which the plurality of microphone elements are arranged is equal to or less than half the wavelength of the highest frequency component of the target sound source.

5. 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 outputs an acoustic signal processed using an acoustic beamforming technique in which the acoustic signals from the plurality of microphone elements are compensated for a delay time of a path difference of the acoustic signals of the other microphone elements relative to the acoustic signal from a reference microphone element, and the acoustic signals from the plurality of microphone elements whose delay times have been compensated are added; a receiver that is a headphone with a noise canceling function for receiving an acoustic signal from the signal processing unit; A sound source localization device comprising:

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

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