JPS61281925A - Sound collecting type sound source investigator - Google Patents

Abstract

PURPOSE:To investigate and measure the position of a sound source object easily and accurately by converting the reflected sound from a sound collector to an electric signal with a microphone array and correcting the sensitivity of this signal in accordance with the arranged position of a microphone. CONSTITUTION:An object image and an acoustic image are focused. After focusing, a microphone array 8 and a camera 21 are fixed there, and sounds from a sound source object S are reflected on a reflecting face 1a and are received by each microphone and are converted to an electric signal. This signal is amplified and filtered and has the sensitivity corrected by a control part 18 and is inputted to a light emitting diode array, and the acoustic image is displayed visibly. A part of this acoustic image is transmitted through a half mirror and is formed on a focal plane, and another part is reflected there to go toward a shutter. A part of the object image of an object S is reflected and is formed on the focal plane, and another part goes to the shutter. Thus, the object image and the acoustic image are superposed on the focal plane, and the sound source position, the range, etc. of the object S are investigated and measured.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field 1] The present invention relates to a sound source detection device that searches 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 something.

[Prior art 1] 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 complex arithmetic processing equipment, and the arithmetic processing takes a large amount of time. There were some drawbacks, such as difficulty in detecting and measuring the source location of static noise and fluctuating noise.

Therefore, the present inventor has proposed a method of easily detecting the position of a sound source by using a sound collector, and the principle of this method of detecting a sound source is as shown in FIG. 9. That is, as shown in the figure, a sound source S is provided at a position P, and a reflection type sound collector having a concave curved surface shape such as a paraboloid of revolution or a concave spherical surface is placed at a distance from this position P as the sound source. When the sound source S is disposed toward S, the sound from the sound source S is reflected by the reflective surface r of this sound collector, and a sound image S' is formed at a 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 visually displaying the pressure distribution using an appropriate means, it becomes possible to detect and measure the position of the sound source.

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

First of all, as shown in Figure 9, the mirror axis x of the sound collector
The distance from the reflective surface r on -x to the focal point F, that is, the focal length, is f, and the distance from the focal point F to the sound image forming position P' is Δ
When X, Δx=−□−f, and ΔX changes depending on the distance between the position of the sound source S and the position of the sound collector, and the sound image forming position changes. Therefore, during measurement, when the sound incident on the microphone array includes complex sounds, reflected sounds, etc., it becomes extremely difficult to accurately position the microphone array at the sound image forming 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, depending on the microphone array, 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 horizontal position of the sound source, but also the distance between it and the sound collector. There are cases in which it is not possible to perform sound source detection that requires distance measurement, for example, to detect which object is the sound source among a plurality of objects arranged three-dimensionally at different positions.

Furthermore, fourthly, the sound pressure of the sound incident on the sound collector from the sound source S is attenuated as it moves away from the mirror axis x-x due to the angle of incidence on the sound collector. Since this amount of attenuation varies depending on the frequency, the reproducibility of the sound image deteriorates as the image receiving surface moves away from the mirror axis. Therefore, it is only possible to accurately measure the sound source within an extremely narrow angular range, and if the sound source to be searched for is over a wide range,
This makes it impossible to put it into practical use.

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 the position of a sound source object to be explored and measured.

Means for Solving Problem E 1 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 each other, and a microphone array formed by arranging a plurality of microphones in parallel in a matrix are arranged to face the reflective surface of the sound collector, and each microphone array An electric signal from a microphone is amplified by a sensitivity correction amplifier consisting of a plurality of amplifiers with different amplification degrees depending on the position, and a sound image of the sound source object is visually displayed on a display based on the output signal from the sensitivity correction amplifier. a sound image visualization device configured to have a sound image visualization device; and an object image forming device comprising a lens and a focus plate and forming an object image of a sound source object on the focus plate, the sound image and object image visualized and displayed by the sound image visualization device A feature of this system is that it is configured to search for the sound source position by focusing an object image formed by an imaging device and comparing these images.

[Function 1] Therefore, in order to find out from which side of a sound source object, such as a mechanical device, noise is coming from, first place the sound collector on the side of the sound source object. The object image is focused on the focus plate through the lens of the object image imaging device, and the sound image by the sound image visualization device is focused in accordance with the focusing of the object image. Position the microphone 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 effects,
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 the sound image, we can see that the source of the sound is a device, member, etc. located at the position where the focus of the object image formed on the focus plate was, and which is also displayed as a sound image. It will be detected as an object.

Therefore, instead of visually displaying the electrical signals from each microphone that makes up the microphone array on the display as is, the electrical signals are displayed on the display via a sensitivity correction amplifier equipped with multiple amplifiers with different amplification degrees depending on the position. When connected, the sound pressure attenuation of incident sound from a sound source located far from the mirror axis is corrected by this sensitivity correction amplifier, resulting in extremely good sound image reproducibility. . Therefore, by increasing the planar spread of the microphone array placed opposite the sound collector, wide-angle sound source exploration becomes possible.

If the sound source is a complex sound with different frequencies, the amount of attenuation changes depending on the frequency, so the output signal from the microphone is passed through a variable filter to extract only a specific frequency signal, and this signal is is input to the sensitivity correction amplifier, each amplifier constituting this sensitivity correction amplifier is made into a variable amplifier, and the set frequency in the variable filter described above is used as the amplification control signal in the sensitivity correction amplifier. The amplification degree of each variable amplifier is changed based on this signal.

This makes it possible to visually display a complex sound as an extremely accurate sound image for each frequency.

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.

The sound image is focused by placing the microphone array at the sound image forming position P' shown in Fig. 9, but this position changes depending on the distance between the sound collector and the sound source object. do. 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, the sound image focal distance m that allows the microphone array to be moved along the mirror axis of the reflective surface in the sound image visualization device is provided.
Having 411 configurations makes it 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. In addition,
For example, in a case where the distance between the sound source object and the sound collector is constant, it is not necessary to provide an inter-focal S 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. I can do it. In particular, when superimposing and contrasting images, it is necessary that the object image and the sound image have the same magnification.

Furthermore, if a display device that visually displays a sound image is constructed by arranging light emitting diodes in a matrix in correspondence with each microphone in a microphone array, each light emitting diode will light up with an amount of light that corresponds to 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 compared with the object image, the position and size of multiple sound sources can be measured simultaneously. be able to. As the display device, in addition to the above-mentioned light emitting diode, liquid crystal, CRT, etc. can also be used.

[Example] Hereinafter, examples of the present invention will be described based on the drawings. First, in FIGS. 1 and 2, l is a paraboloid of revolution,
The sound collector 1 has a concave curved shape such as a concave spherical surface, and the inner surface is a reflective surface 1a. 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 l to be tilted at an arbitrary angle. In addition, it can be locked in an appropriate position by the 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 plurality of microphones 8a, 8a are arranged side by side in a matrix on a plate 8, and a sound absorbing material 10 made of, for example, glass wool is interposed between the microphones 8a to reduce the reflection of each microphone 8a and the support plate 8. Prevents the transmission of sound effects. A movable table 9a is connected to the support plate 9, and a movable rail 11.11 provided on the lower surface of the movable table 9a supports the fixed rail 13.
13 in a slidable manner. A rack 14 is formed on one movable rail lla of the movable rails 11, and the rack 14 meshes with a pinion 1B attached to the output shaft of an electric motor 15 fixed to the fixed base 12. This rack-binion mechanism allows the microphone array 8 to move on the mirror axis of the reflective surface 1a of the sound collector 1 at a distance t6-
It is configured to be moved in the direction of separation. 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 two sound collectors 1. The support arm 17 is formed from a thin plate of two pieces of wood in order to prevent interference with sound incident toward the reflecting surface 1a.

On the other hand, the microphone array 8 is provided on the pedestal 2, and the sound received by each microphone 8a is converted into an electrical signal.This electrical signal is input to the control section 18, where it is amplified and Along with filtering, sensitivity correction is performed. This control section 18 is composed of a first-order width amplifier 18a at the front stage and a sensitivity correction amplifier 18b with a variable filter,
The first-order term amplifier 18a is composed of a voltage-controlled amplifier, and an amplifier A is provided for each microphone 8a of the microphone array 8.
are connected, the power supply voltage Vcc for each amplifier A is made common, and a resistor R is connected to this power supply voltage Vcc,
By connecting each amplifier A in parallel to the gain signal line G connected to the resistor R and changing the resistance value of this resistor H, the amount of gain can be changed continuously or stepwise. There is.

Further, the sensitivity correction amplifier device 18b with a variable filter has a filter F connected to each amplifier A, and the control signal line H of each filter F is connected to a bypass type, a low-pass type, and a band-pass type, and a cut-off signal. A switching device f capable of sending a control signal that continuously controls the off frequency or center frequency in one step. and this switching device f. By appropriately switching , it is possible to pass only signals in a specific range of frequencies among the signals amplified by the first-order width amplifier 18a. After this filter F, a variable amplifier FA for sensitivity correction is installed.
The variable amplifier FA has a correction coefficient whose amplification degree is determined by the position and set frequency of each microphone 8a, and each variable amplifier FA has a switching device f. A set frequency signal is input as a control signal, and sensitivity correction is performed by changing the amplification degree of each microphone 8d according to this control signal. The structure is such that a clear electrical signal without sound pressure attenuation can be obtained even from a sound source far away.

Next, reference numeral 19 indicates a light emitting diode array as a display, and the light emitting diode array 1!3 includes a large number of light emitting diodes 19a, 1, as shown in FIGS. 6 and 7.
9a and +10 are arranged in parallel in a matrix, and each of these light emitting diodes lea is connected to the microphone array 8.
The microphones 8a at each position are arranged in a positional relationship corresponding to each microphone 8a constituting the control unit 18, and the microphone 8a at each position is arranged in a positional relationship corresponding to the light emitting diode 19a and the control unit 18.
connected via. A diaphragm plate 20 having aperture holes 2Qa, 20a, .
The visibility of the position 9a can be switched to be strong or weak depending on the purpose. Here, aperture hole 2
0a may be formed parallel to the thickness direction of the aperture plate 20, or may be an inclined hole having a predetermined angle to the aperture hole 20a so that the light beams of each light emitting diode 19a are directed to the center. Good, as mentioned above, microphone array 8
, a control unit 18, a light emitting diode array 19, and the like constitute a sound image visualization device. The rack-pinion mechanism that moves the microphone array 8 forms a sound image focusing mechanism.

Furthermore, 21 indicates a camera as an object image forming device,
As shown in FIG. 8, the camera 21 has a lens barrel 23 to which a lens 22 is attached, and a body 24 connected to the lens barrel 23, and the incident light from the lens 22 passes through an aperture 25. is guided into the body 24, a part of which is reflected by a half mirror 26 installed in the body 24 at an angle of 45° with respect to the optical axis of the lens 22, and is imaged on the focus plate 27, This focus plate 27 through the finder 28
The object image of the sound source object formed in the image can be seen from the outside.

On the other hand, the light passing through the half mirror 2B is guided into a dark room 29 formed at the rear of the body 24 when the shutter 3o 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 this light emitting diode array I
The light from the light-emitting diode 19a at 8 is diffusely reflected through a filter 32 and adjusted to make it easier to see.The light is then guided into the body 24 through a lens 33 and an aperture 34, and is then passed through a focusing plate 27 and a negative film by a half mirror 2B. It is now possible to superimpose the image of the object image above.

For this reason, the magnification of the sound image by the sound collector l and the lens 33 is equal to the magnification of the object image by the lens 22.

Furthermore, the lens barrel 23 is formed into a telescopic shape so that the distance between the lens 22 and the focusing plate 27 can be adjusted, thereby forming an object image focusing mechanism.

Further, the camera 21 is mounted on the reflective surface 1 as much as possible within the range where the microphone array 8 does not obstruct the view of the sound source object S.
The sound collector l has a through hole 35 in order to allow the camera 21 to see through the sound source object.

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 l is made to face the sound source object S. The viewfinder 28 of the camera 21
The object image is focused by operating the lens barrel 23 while looking into the camera, and the microphone array 8 is moved by the amount corresponding to the image distance adjusted during this focusing, 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, filtered, and sensitivity corrected by the control unit 18, and is inputted to the light emitting diode array 19 arranged in the same manner as the microphone array 8, so that each light emitting diode 19a
The sound image is visualized and displayed by lighting it with an amount of light corresponding to the sound pressure level. The sound image visualized in this way is guided into the body 24 via the lens 33 and the diaphragm 34, a part of which is transmitted through the half mirror 26 and is imaged on the focus plate 27, and a part of which is reflected. shutter 3
Progress towards 0. On the other hand, a part of the object image of the sound source object S passes through the lens 22 and the half mirror 26 and is reflected onto the focus plate 27, and a part of it passes through the half mirror 2B and is directed to the shutter 30. proceed towards As a result, the object image and the sound image are superimposed on the focusing plate 27, and the position, range, intensity, frequency, etc. of the sound source in the sound source object S can be investigated and measured. Further, 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.

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.
It will be in focus when placed at the position where the amount of light 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,
By detecting a device or member that is in focus in the object image and is emitting light as a sound image, it is possible to search for the sound source object. Of course, this superimposed image can be photographed by exposing a negative film.

Here, the sound incident on the sound collector l is reflected by its reflection surface! The amount of attenuation differs depending on the angle of incidence with respect to a. That is, on the tangent to the reflecting surface 1a, the amount of attenuation is greater at the peripheral edge where the light is incident at a smaller angle than at a position on the mirror axis where the light is incident at a right angle. Furthermore, the attenuation rate differs depending on the frequency, and the attenuation rate is larger for low frequency components than for high frequency components. For this reason, in the wooden embodiment, the sensitivity of the microphones 8a constituting the microphone array 8 is corrected via the control unit 18, thereby correcting the attenuation of the incident sound described above.

Therefore, in the sensitivity correction amplifier 18a, the variable amplifier FA connected to the microphone 8a located on the mirror axis is set to the smallest amplification factor, and each variable By making the amplification degrees of the amplifiers FA different, it becomes possible to correct the attenuation of the incident sound as described above. For this reason, the microphone array 8 can be formed to have a wide area, and sound source detection from a wide angle can be performed accurately.

Moreover, by providing the sensitivity correction amplifier 18a with a variable filter, by appropriately switching the switching device f0, it is possible to sample and visually display any frequency of the complex sound. It becomes possible to locate the source of the sound. In this case, the attenuation rate of the incident sound changes depending on its frequency, but each variable amplifier FA is configured so that its amplification degree changes using the set frequency signal from the switching device f0 as a control signal. , it becomes possible to visualize and display the sound source extremely accurately at each frequency.

In this embodiment, the moving mechanism for the microphone array 8 is composed of a rack-binion, but a pulley belt (
or wire), pole screw-nut (bearing)
Although the support arm 17 is constructed from two thin plates, it may be constructed as long as it does not interfere with the sound incident toward the reflective surface 1a of the sound collector 1. It is also possible to configure it with a pipe (tubular member) or the like.

Furthermore, when searching for a sound source of a sound of a specific frequency, a configuration may be provided in which only r-1, an amplifier set to different amplification degrees depending on the position, is provided as the control unit. moreover,
Although the variable amplifier FA has been configured to be provided after the filter F, it may also serve as the amplifier A of the first-order width amplifier 18a provided before the filter F.

[Advantageous Effects of the Invention 1] As explained in detail above, the sound collection type sound source detection device according to the present invention converts the reflected sound from the sound collector into an electric signal using a microphone array, and converts this signal into an electric signal using a sensitivity correction amplifier. The structure is simple because it combines a sound image visualization device that performs sensitivity correction according to the placement position of the microphone and then visually displays the sound image, and an optical object image forming device. , the position of the sound source can be easily and accurately probed and measured at a wide angle. Furthermore, the sensitivity correction amplifier is equipped with a variable filter, and each amplifier constituting the amplifier is a variable amplifier whose amplification degree changes using a set frequency signal in the variable filter as a control signal. Sound can be visualized and displayed extremely accurately.

[Brief explanation of drawings]

FIG. 1 is a partially cutaway front view showing one embodiment of the present invention, and FIG.
The figure is the right side view of Figure 1, Figures 3 and 4 are the front and side views of the microphone array, respectively, Figure 5 is the circuit diagram of the control device, and Figure 6 shows the aperture plate installed. A partial plan view of the light emitting diode array, Fig. 7 is a sectional view taken along the line ■-■ of Fig. 6, Fig. 8 is an explanatory diagram of the structure of a camera as a sound image forming position detection device, and Fig. 9 is a sound collection type sound source detection method. FIG. 1. ψ sound collector, 1a..Reflecting surface, 80 microphone array 4.8Bmm microphone, 9..Support plate, 9
a...Moving table! 1. Life movable rail, 12.. Fixed stand, 13. Φ fixed rail, 14.. Rack, 15..
Electric motor, 18--pinion, 18...control unit,
18a...first-order term amplifier, lab...sensitivity correction amplifier, 19--light emitting diode array, 19a...light emitting diode, 21...camera, 22...lens. 23φ・lens barrel, 24・O body, 27・focus plate, FLL・variable filter, A-φ amplifier,
fo...Switching device, S--Sound source object,
FA--variable amplifier.

Claims (5)

[Claims] (1) A sound collector in which a concave-curved reflecting surface that reflects sound from a sound source object is disposed opposite to the sound source object;
A microphone array formed by arranging a plurality of microphones side by side in a matrix is arranged opposite to the reflective surface of the sound collector, and electrical signals from each microphone of the microphone array are transmitted to a plurality of amplifiers whose amplification degree differs depending on the position. a sound image visualization device configured to amplify the sound image of the sound source object on a display based on the output signal from the sensitivity correction amplifier, and a lens and a focus plate; an object image forming device that forms an object image of the sound source object on the focus plate, and focuses the sound image visually displayed by the sound image visualization device and the object image formed by the object image forming device; A sound collection type sound source searching device characterized in that it is configured to search for a sound source position by comparing these images. (2) Signals from each microphone of the microphone array are filtered by a variable filter, and the amplification degree of each amplifier in the sensitivity correction amplifier is controlled based on a set frequency signal of the variable filter. A sound collection type sound source searching device according to claim 1. (3) 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. (4) 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 3. (5) The sound collection type sound source detection device according to claim 4, wherein the sound image focus adjustment mechanism and the object image focus adjustment mechanism are configured to be linked.