JPH0321873B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is a sound source search method that searches for and measures the position of a sound source, such as a noise source, by visually displaying the position of the sound source using a sound collector. It is related to the device.

[Prior Art] The first step in noise reduction measures in machinery, factories, etc. is to accurately detect the source of the noise, and there are various methods for detecting the location of the noise source. Among the methods that have been developed and put into practical use, the most representative method is acoustic holography. This acoustic holography method can detect and measure the location of sound sources with high precision, but it requires a large-scale microphone sweep device and complicated processing equipment, and the processing requires a large amount of time. There were some difficulties, such as difficulty in detecting and measuring the source location of static noise and fluctuating noise.

Therefore, the present inventor has proposed a method for easily detecting the sound source location by using a sound collector, and this sound source location method is theoretically based on the 10th method.
It is as shown in the figure. That is, as shown in the figure, a sound source S is provided at a position P, and a reflective sound collector D having a concave curved surface shape such as a paraboloid of revolution or a concave spherical surface is placed at a distance L from this position P as the sound source. When the sound collector D is placed facing toward S, the sound from the sound source S is reflected by the reflective surface r of the sound collector D, and a sound image S' is formed at the position P'. Therefore, by arranging a microphone array in which a large number of microphones are arranged side by side in a matrix at this sound image forming position P' facing the reflecting surface r, this sound image can be extracted as a sound pressure distribution in the microphone array, and this sound By visualizing and displaying the pressure distribution using an appropriate means, the position of the sound source can be detected and measured.

[Problems to be Solved by the Invention] However, in order to put into practical use the sound source detection method based on the above-described principle, it is necessary to solve various problems as shown below.

First, as shown in FIG. 10, let f be the distance from the reflective surface r on the mirror axis XX of the sound collector D to the focal point F, that is, the focal length, and from the focal point F to the sound image forming position. When the distance to P' is ΔX, ΔX=f ² /L−f, and ΔX changes according to the distance L between the position of the sound source S and the position of the sound collector D, and the sound image forming device becomes different. Therefore, it is necessary to position the microphone array at this sound image formation position during measurement.
In cases where the sound incident on the sound collector includes complex sounds, reflected sounds, etc., it becomes extremely difficult to accurately position the microphone array at the sound image formation position.

Second, even if the sound pressure distribution in the microphone array is visually displayed, it is not possible to compare this display with the object to be measured, so the position of the sound source may not be accurately identified.

Third, with some microphone arrays, it is not possible to identify how far the sound source object is from the sound collector, so it is not only possible to determine the two-dimensional position of the sound source, but also the distance between it and the sound collector. In some cases, it may not be possible to perform a sound source search that requires measuring the distance between objects, such as detecting which object is the sound source among a plurality of objects arranged three-dimensionally at different positions.

Therefore, the present invention solves various problems when putting this sound source detection method into practical use by combining the above-mentioned sound collection type sound source detection method with an optical method. A technical object of the present invention is to enable accurate exploration and measurement of the position of a sound source object.

[Means for Solving the Problems] In order to solve the above-mentioned problems, the present invention provides a reflection surface having a concave curved shape such as a paraboloid of revolution or a concave spherical surface that reflects sound from a sound source object. A sound collector configured to face the reflective surface of the sound collector, and a microphone array formed by arranging a plurality of microphones in parallel in a matrix are arranged facing the reflective surface of the sound collector. A sound image visualization device configured to amplify electrical signals from each microphone in the array using an amplifier, and visually display a sound image of a sound source object on a display based on the output signal from the amplifier, and a lens and focus plate. and an object image forming device for forming an object image of the sound source object on the focus plate, and arranged so that the mirror axis of the sound image visualization device and the optical axis of the object image forming device substantially coincide with each other. The sound image visualized by the sound image visualization device and the object image formed by the object image forming device are focused, and the sound source position is searched by comparing these images. It is characterized by its structure.

[Operation] Therefore, in order to find out from which side of the side surface of a sound source object, such as a mechanical device, noise is being generated, first place a sound collector on the side surface of the sound source object. The microphones are arranged opposite to each other and focus the object image formed on the focus plate through the lens of the object image forming device, and the sound image visualized by the sound image visualization device is focused according to the focusing of the object image. Position the array. By comparing the sound image and object image obtained in this way, the position of the sound source can be easily and accurately detected. Here, the object image is first focused, and then the sound image is focused in accordance with this focusing, but this is because the sound from the sound source object is a complex sound or contains reflected sound. If the microphone array can be reliably positioned at the sound image formation position even with these influences,
Either focusing may be performed first.

On the other hand, when searching for a sound source object whose position cannot be specified three-dimensionally, such as when detecting a noise-generating object inside a factory where a large number of various devices and parts are arranged in three-dimensionally different positions. First, the sound image is focused by the sound image visualization device, and the object image in the object image forming device is focused in accordance with the focusing of the sound image. Comparing this object image and sound image, we can see that the sound source is a device, member, etc. located at the focused position of the object image formed on the focus plate and also in the part displayed as a sound image. It will be detected as an object.

Furthermore, in the case where sounds are generated from multiple three-dimensionally different positions, in order to identify the source of any of the sounds, first move the microphone array that makes up the sound image visualization device. Focusing is performed at the generation position of any sound captured by the sound image visualization device. Thereafter, the object image of the object image forming device is focused on the area where the sound image is focused. This makes it possible to search for a sound source occurring at a certain position. If the sound image and the object image are sequentially focused for each sound generation position captured by the sound image visualization device, all the sound images of the target sound source or multiple sound sources can be focused. The sound image of can be detected.

In addition, when the sound source object has been specified to some extent, the object image forming device is first focused on the target object image, and the sound image visualization device focuses the sound image according to the focusing of the object image. By repeating this operation, it is possible to obtain sound image information for each of a plurality of sound source objects at different three-dimensional positions.

Here, focusing of the object image can be performed by changing the distance between the lens of the object image forming device and the focus plate in relation to the distance between the lens and the object using a normal optical method. For this purpose, it is preferable that the object image forming device is equipped with an object image focusing mechanism.

In addition, to focus the sound image, the microphone array is
This is done by placing the sound image at the sound image forming position P' shown in FIG. 0, but this position changes depending on the distance between the sound collector and the sound source object. Therefore, focusing of the sound image can be performed by detecting the distance between this sound collector and the sound source object, but also by moving the microphone array along the mirror axis of the reflective surface of the sound collector. The sound image can also be focused by detecting the position where the visually displayed sound image is the clearest. Therefore, if the sound image visualization device is provided with a sound image focusing mechanism that allows the microphone array to be moved along the mirror axis of the reflecting surface, it is convenient to focus the sound image.

As mentioned above, by providing focus adjustment mechanisms for both the object image and the sound image, and making these focus adjustment mechanisms interlock with each other, the focus adjustment functions of both will complement each other and focus can be achieved with extremely high precision. can be combined. Note that, for example, when the distance between the sound source object and the sound collector is constant, it is not necessary to provide a focus adjustment mechanism for both the object image forming device and the sound image visualization device.

The object image and sound image obtained in this way can be compared by placing these images side by side, but if these two images are superimposed and compared, the location of the sound source can be more easily detected. Can be done. In particular, when superimposing and contrasting images, it is necessary that the object image and the sound image have the same magnification.

Furthermore, as a display device for visually displaying sound images, if light emitting diodes are arranged in parallel in a matrix to correspond to each microphone in a microphone array, each light emitting diode will light up with an amount of light depending on the sound pressure level. , it is possible to measure not only the position of the sound source but also its intensity, which is convenient for focusing the sound image, and when comparing this with the object image, it is possible to measure the position and size of multiple sound sources simultaneously. can do. As the display device, in addition to the above-mentioned light emitting diode, liquid crystal, CRT, etc. can also be used.

Furthermore, if the amplifier constituting the sound image visualization device is equipped with a variable filter, and the variable filter selectively extracts signals of specific frequencies, it is possible to identify the type of sound at the sound source at the same time. become.

[Example] Hereinafter, examples of the present invention will be described based on the drawings. First, in FIGS. 1 and 2, 1
indicates a sound collector having a concave curved shape such as a paraboloid of revolution or a concave spherical surface, and whose inner surface is a reflective surface 1a, and the sound collector 1 is fixed to a mounting bracket 3 fixed on a pedestal 2. The reflective surface 1a is arranged to face the sound source object S. A support leg 4 is vertically installed on the lower surface of the pedestal 2, and the support leg 4 is connected to a tripod 6 via a joint 5, which allows the sound collector 1 to be tilted at any angle. It can be locked at an appropriate position by means of a lever 7.

Next, reference numeral 8 denotes a microphone array disposed on the mirror axis of the reflective surface 1a of the sound collector 1, facing the reflective surface 1a, and the microphone array 8 is supported as shown in FIGS. 3 and 4. A large number of microphones 8a, 8 are mounted on the board 9.
A sound absorbing material 10 made of, for example, glass wool is interposed between each microphone 8a, and each microphone 8a is arranged in parallel in a matrix.
This prevents the influence of sound reflected from the support plate 9 and the support plate 9 from being transmitted. A movable table 9a is connected to the support plate 9, and movable rails 11, 11 provided on the lower surface of the movable table 9a can freely slide on fixed rails 13, 13 provided on a fixed table 12 that supports the movable rails 11, 11. is engaged in. A rack 14 is formed on one movable rail 11a of the movable rails 11, and the rack 14 is connected to an electric motor 1 fixed to a fixed base 12.
The rack-pinion mechanism engages the pinion 16 attached to the output shaft of the microphone array 8.
is configured to be moved on the mirror axis of the reflective surface 1a of the sound collector 1 in directions toward and away from it. A support arm 17 is attached to the fixed base 12, and the support arm 17 is bent into a substantially V shape and is attached to the lower surface of the pedestal 2 so as to avoid the sound collector 1. The support arm 17 is formed of two thin plates in order to prevent interference with sound incident toward the reflecting surface 1a.

On the other hand, on the pedestal 2 is a voltage-controlled amplifier 1 that converts the sound received by each microphone 8a of the microphone array 8 into an electrical signal and amplifies this electrical signal.
8 is installed. This voltage controlled amplifier 18
has the circuit configuration shown in FIG. 5, for example. That is, as shown in the figure, each microphone 8a of the microphone array 8 is provided with an amplifier A.
are connected, the power supply voltage Vcc for each amplifier A is common, a resistor R is connected to this power supply voltage Vcc, and each amplifier A is connected in parallel to the gain signal line G connected to the resistor R. By changing the resistance value of R, the gain amount can be changed continuously or stepwise.

Next, 19 indicates a light emitting diode array as a display section, and this light emitting diode array 19 is the sixth light emitting diode array.
As shown in FIG. 7 and FIG. 7, a large number of light emitting diodes 19a, 19a, . The microphones 8a at each position are connected via a voltage-controlled amplifier 18 to a light emitting diode 19a in a corresponding positional relationship. Each light emitting diode 19 is placed above the light emitting diode array 19.
A diaphragm plate 20 having aperture holes 20a, 20a, . I'm starting to be able to do it. Here, the aperture hole 20a is formed parallel to the thickness direction of the aperture plate 20, or the aperture hole 20a is formed at a predetermined angle so that the light flux of each light emitting diode 19a is directed to the center. It may also be an inclined hole. As described above, the microphone array 8, the voltage-controlled amplifier 18, the light emitting diode array 19, etc. constitute the sound image visualization device.
The rack-and-pinion mechanism that moves the microphone array 8 forms a sound image focusing mechanism.

Further, 21 indicates a camera as an object image forming device, and the camera 21 is, as shown in FIG.
It has a lens barrel 23 to which a lens 22 is attached, and a body 24 connected to the lens barrel 23. Incident light from the lens 22 is guided into the body 24 via a diaphragm 25, and the light enters the body 24. With respect to the optical axis of the lens 22
Half mirror 2 installed at a 45° angle
A portion of the sound is reflected by the focus plate 27 and is imaged on the focus plate 27, and the object image of the sound source object formed on the focus plate 27 can be seen from the outside through the viewfinder 28. On the other hand, the light passing through the half mirror 26 is guided into a dark room 29 formed at the rear of the body 24 when the shutter 30 is opened, and a negative film placed in the dark room 29 can be exposed. There is. Further, the light emitting diode array 19 is installed in a housing 31 provided at the bottom of the camera 21, and the light emitting diode 19a in this light emitting diode array 19 is
The light is diffusely reflected through a filter 32 and is dimmed to make it easier to see.
The light is guided into the body 24 through a diaphragm 34, and a half mirror 26 allows the focusing plate 27 and the image of the object on the negative film to be superimposed. For this reason, the magnification of the sound image by the sound collector 1 and the lens 33 is made equal to the magnification of the object image by the lens 22. Moreover, the lens barrel 23
lens 2 by forming it into a telescope shape.
The distance between the focus plate 27 and the focus plate 27 can be adjusted, thereby forming an object image focus adjustment mechanism. The camera 21 is placed as close to the mirror axis of the reflective surface 1a as possible within the range where the microphone array 8 does not obstruct the view of the sound source object S. A through hole 35 is bored in order to be able to see through.

To probe and measure the position of noise generated on one side of the sound source object S using the sound source detection device configured as described above, first, the reflective surface 1a of the sound collector 1 is made to face the sound source object S. Place it like this,
While looking through the viewfinder 28 of the camera 21,
3, the object image is focused, and during this focusing, the microphone array 8 is moved by the amount that the image distance is adjusted, and the sound image is focused. The object image and the sound image may be focused independently or in conjunction with each other.

When the focusing of the object image and the sound image is completed, the microphone array 8 and the camera 21 are fixed at that position, and the sound generated from the sound source object S is reflected by the reflective surface 1a of the sound collector 1, and the microphone array 8 and the camera 21 are fixed at that position. Each microphone 8a constituting the array 8 receives sound and converts it into an electrical signal. This signal is amplified by a voltage-controlled amplifier 18, and each light-emitting diode 19a of a light-emitting diode array 19 arranged in the same manner as the microphone array 8 is turned on in accordance with this amplified signal with an amount of light corresponding to its sound pressure level. The sound image is visualized and displayed. The sound image visualized in this way is guided into the body 24 via the lens 33 and the diaphragm 34, a part of it is transmitted by the half mirror 26 and is imaged on the focus plate 27, and a part of it is reflected. Proceed toward shutter 30. On the other hand, a part of the object image of the sound source object S is reflected through the lens 22 and the half mirror 26 to form an image on the focus plate 27, and a part is transmitted through the half mirror 26 and is directed to the shutter 30. proceed towards. As a result, the object image and the sound image are superimposed on the focus plate 27, and the position, range, intensity, etc. of the sound source in the sound source object S can be accurately and easily probed and measured. Furthermore, if the shutter 30 is opened in this state and the negative film is exposed, a superimposed image of the object image and the sound image can be photographed.

Furthermore, when there are multiple sound source objects at different three-dimensional positions, the sound collector 1 is directed toward the sound source and the microphone array 8 receives the sound. As a result, the light emitting diodes at a plurality of positions in the light emitting diode array 19 emit light. Therefore, when the microphone array 8 is moved along the mirror axis of the reflective surface 1a, a position is reached where one of the light emitting diodes emits light with the maximum amount of light. At this position, the sound source object is in focus. Then, the camera 21 is focused on the object at the position where the light emitting diode emits the maximum amount of light. As a result, a sound image of one sound source object can be obtained. After that, the microphone array 8 is moved to focus on the position where the light intensity of the part where the other light emitting diodes emit light is maximum, and then the camera 21 is focused on the position of this light emitting diode. Sound images of other sound source objects can be obtained. By sequentially repeating this operation, sound image information for each of a plurality of sound source objects can be obtained.

If the number of sound source objects is limited to a certain extent, first focus the object image by the camera 21 on one of the objects, and then focus the sound image on the position corresponding to this object image on the light emitting diode array 19. It is also possible to match them. and,
By sequentially repeating the focusing of the camera 21 on an object that may be a sound source and the focusing of the corresponding sound image, sound image information for each of a plurality of sound source objects can be obtained as described above. In this case, if the sound image is out of focus at a position corresponding to a certain object image, it is confirmed that no sound is generated from the object.

On the other hand, when searching for a sound source object in a factory where a large number of various devices and members are arranged at different three-dimensional positions, the microphone array 8 is used with the sound collector 1 facing the direction of the sound source. The microphone array 8 is moved along the mirror axis of the reflecting surface 1a to focus the sound image. This sound image is focused when the light emitting diode array 19 is placed at a position where the amount of light from the light emitting diodes 19a is maximum. Then, the object image in the camera 21 is focused in accordance with this focusing, and the object image and sound image thus obtained are superimposed on the focus plate 27. From this superimposed image, it is possible to easily and accurately search for the sound source object by detecting the focused device or member of the object image that is emitting light as a sound image. . Also,
Of course, this superimposed image can be photographed by exposing the negative film.

Furthermore, if a variable filter 36 is provided on the output side of the voltage-controlled amplifier 18 as shown in FIG. 9, only a specific type of sound from the sound source object S can be extracted. That is, in the figure, a filter F is interposed between each amplifier A and the light emitting diode 19a connected thereto, and each filter F is switched to a high-pass type, a low-pass type, and a band-pass type, and the cutoff frequency or center Switching device _that controls frequency continuously and stepwise0
If this switching device ₀ is properly switched, only signals in a specific range of frequencies will pass through, so it is possible to visually display only a specific sound from a complex sound source, and it is also possible to identify the type of sound source at the same time. Can be done. Therefore, when there are a plurality of sound sources three-dimensionally located at different positions and each having a different frequency, information for each sound source can be obtained.

In this embodiment, the moving mechanism of the microphone array 8 is constructed of a rack-pinion, but a pulley belt (or wire), ball screw, etc.
It may be composed of a nut (bearing) and a cylinder. Furthermore, although the support arm 17 is made up of two thin plates, it may have any structure as long as it does not interfere with the sound that is incident on the reflective surface 1a of the sound collector 1.
It is also possible to configure it with a pipe (tubular member) or the like.

[Effects of the Invention] As explained in detail above, the sound collection type sound source detection device according to the present invention has a sound collector that combines an optical object image forming device consisting of a lens and a focusing plate. With a simple configuration, it is possible to easily and accurately locate and measure the position of a sound source.

[Brief explanation of drawings]

FIG. 1 is a partially cutaway front view showing one embodiment of the present invention, FIG. 2 is a right side view of FIG. 1, and FIGS.
The figures are respectively a front view and a side view of the microphone array, Fig. 5 is a circuit diagram of the voltage-controlled amplifier, Fig. 6 is a partial plan view of the light emitting diode array with the aperture plate attached, and Fig. 7 is the circuit diagram of the voltage-controlled amplifier. Figure 8 is a structural explanatory diagram of a camera as a sound image forming position detection device, Figure 9 is a circuit diagram of a variable filter,
Figure 0 is an explanatory diagram of the principle of the sound collection type sound source detection method. 1... Sound collector, 1a... Reflective surface, 8... Microphone array, 8a... Microphone, 9... Support plate,
9a...Moving table, 11...Movable rail, 12...
Fixed stand, 13...Fixed rail, 14...Rack,
15...Electric motor, 16...Pinion, 18...
... Voltage controlled amplifier, 19 ... Light emitting diode array, 19a ... Light emitting diode, 21 ... Camera, 22 ... Lens, 23 ... Lens barrel, 24 ... Body, 27 ... Focusing plate, 36 ... Variable filter,
A...Amplifier, F...Filter, ₀ ...Switching device, S...Sound source object.

Claims (1)

[Scope of Claims] 1. A sound collector having a concave-curved reflecting surface that reflects sound from a sound source object and facing the sound source object, and a plurality of microphones arranged side by side in a matrix. A microphone array formed by the method is arranged opposite to the reflective surface of the sound collector, and an electric signal from each microphone of this microphone array is amplified by an amplifier, and a sound image of the sound source object is generated based on the output signal from the amplifier. It consists of a sound image visualization device configured to display on a display, a lens and a focus plate,
an object image forming device for forming an object image of the sound source object on the focus plate, and arranged so that the mirror axis of the sound image visualization device and the optical axis of the object image forming device substantially coincide; The sound image visualized by the sound image visualization device and the object image formed by the object image forming device are focused, and the sound source position is searched by comparing these images. A sound collection type sound source detection device featuring: 2. The sound image visualization device is characterized by being equipped with a sound image focusing mechanism that focuses the sound image by making the microphone array movable along the mirror axis of the reflective surface of the sound collector. A sound collection type sound source searching device according to claim 1. 3. A patent claim characterized in that the object image forming device is equipped with an object image focusing mechanism that focuses the object image by adjusting the distance between the lens and the focus plate. The sound collection type sound source detection device according to item 2. 4. The sound collection type sound source detection device according to claim 1, wherein the amplifier is an amplifier equipped with a variable filter capable of extracting only a signal of a specific frequency.