JPH0421141B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a sound source detection device for detecting and measuring the position of a sound source such as a noise source.

[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 has drawbacks such as requiring a large-scale microphone sweep device and complicated processing equipment, and the processing time required. It was hot.

Therefore, a method is used in which a microphone array is formed by arranging microphones in a matrix, the microphone array receives sound from a sound source, and the position of the sound source is detected based on the sound pressure level of each microphone. has been proposed by the present inventors.

[Problems to be Solved by the Invention] By the way, when there are multiple sound sources to be detected, it is possible to arrange microphones to form a microphone array, as in the sound source detection method described above, and have this microphone array receive sound. It is not possible to recognize the sound source position and the sound pressure distribution of a specific sound in a complex sound source object only by using this method. For example, when sampling the sound pressure distribution of each type of sound source for machinery or equipment that generates noise from multiple sound sources and using it as data for noise countermeasures, this sound source detection method cannot be used. Become.

The present invention has been made in view of the above points, and it separates the sound source position of a specific sound source from a sound source object that generates multiple sounds and the distribution of sound pressure that is correlated with that sound from other sounds. The purpose of this invention is to provide a sound source detection device that can recognize sound sources.

[Means for Solving the Problems] In order to solve the above-mentioned problems, the present invention has a plurality of microphones arranged side by side in a matrix,
a microphone array that receives sound generated from a sound source object with each microphone and converts it into an electrical signal corresponding to the sound pressure; a main amplifier to which electrical signals from each microphone of the microphone array are respectively input; and a main amplifier for each of the microphones. a microphone array signal selector for selectively extracting an electrical signal from any one of the microphones; amplifying the signal selected by the microphone array signal selector and inputting the amplified signal to each of the main amplifiers as an amplification control signal; By multiplying the instantaneous value of the waveform of this amplified signal by the instantaneous value of the waveform of the signal received by each of the microphones, the signal of a specific sound that has a correlation with the sound of the selected microphone is a control amplifier for separating, extracting, and amplifying the sound from the main amplifier; and a display device for displaying a sound image of a specific sound based on output signals from each of the main amplifiers selectively amplified by an amplification degree control signal from the control amplifier. Its distinctive feature is that it is composed of the following.

[Function] Therefore, the position and sound pressure of a specific sound source of a sound source object that generates a complex sound, such as a mechanical device that has a plurality of driving parts and generates noise from each driving part, can be determined. To sample the distribution, either place the microphone array directly facing the sound source object, or, if the sound source object is large, use a sound collector with a concave reflective surface to reflect the sound from the sound source object. A microphone array is arranged facing the sound collector, and the sound from the sound source object is received by the microphone array.

On the other hand, the microphone array signal selector manually or automatically selects a microphone at a specific position, and the input sound pressure signal of this microphone is sent via a control amplifier to the control terminal of the main amplifier connected to each microphone for amplification control. Based on this amplification degree control signal, the sound pressure signal received by each microphone in the microphone array is selectively amplified. That is, the signal selected by the microphone array signal selector is amplified and input as an amplification control signal to each main amplifier, and the instantaneous value of the waveform of this amplified signal is determined by the waveform of the signal received by each microphone. Multiply by the instantaneous value of . By this,
It is possible to obtain sound pressure distribution information that correlates with the sound at the position corresponding to the selected microphone among the microphones, and to display this sound pressure distribution information on an appropriate display device.

By creating sound pressure distribution information for each microphone, information regarding the position of each sound source and its sound pressure distribution can be obtained. Further, if each sound source position of the composite sound source is known in advance, it is sufficient to obtain sound pressure distribution information only for the microphones corresponding to each of these sound source positions.

[Example] Hereinafter, an example of the present invention will be described based on the drawings. However, in this embodiment, a configuration is shown in which the microphone array is not made to directly face the sound source object, but is configured so that the microphone array receives the reflected sound from the sound collector. By using a sound collector in this way, it becomes possible to search for the sound source of a large sound source object using a small microphone array.

First, the principle of this sound collection type sound source detection device will be explained.

That is, as shown in FIG. 10, there is a sound source S at position P.
If 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 toward the sound source S, the sound from the sound source S will be is reflected by the reflective surface r of the sound collector D, and the sound source S' is imaged at the position P'. Therefore, if a microphone array in which a large number of microphones are arranged side by side in a matrix is placed facing the reflecting surface r at this sound image forming position P', even if the sound source object is large, this sound image can be reflected in the sound pressure distribution in the microphone array. By visualizing and displaying this sound pressure distribution using an appropriate means, the position of the sound source can be detected and measured.

As shown in FIGS. 1 and 2, the sound collector 1 has a concave curved surface shape such as a paraboloid of revolution or a concave spherical surface.
A reflective surface 1a is formed on the inner surface of the sound collector 1.
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 meshes with a pinion 16 attached to the output shaft of an electric motor 15 fixed to the fixed base 12.
This rack-and-pinion mechanism allows the microphone array 8 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.
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.

Next, as shown in FIG. 5, on the pedestal 2 there is a voltage-controlled multiplication function that converts the sound received by each microphone 8a of the microphone array 8 into an electrical signal and amplifies this electrical signal. A main amplifier 18a having a main amplifier 18a is installed in correspondence with each of these microphones 8a. The main amplifier 18a is capable of amplifying the sound pressure signals converted into electrical signals by the respective microphones 8a with the same amplification degree. And each main amplifier 18
In order to control the amplification degree of a, the input signal of one of the microphones 8a is amplified and the input signal of each main amplifier 18 is
It is configured to be input to the control terminal at a. Here, in order to select the microphone 8a for performing this amplification control, a microphone array selector 18b is installed, and the microphone array selector 18b has terminals a, b connected to each of the microphones 8a, c,...n are provided, and by manually or automatically switching the connection between one of these terminals and the output terminal t, the input signal of one of the microphones 8a can be extracted. In order to make this signal suitable as an amplification control signal for each main amplifier 18a, a control amplifier 18c is connected to the microphone array signal selector 18b. This control amplifier 18c has a power supply voltage Vcc.
is connected through a resistor R, and by adjusting the value of this resistor, it is possible to obtain an optimal bias signal for each main amplifier 18a. By connecting the output side of this control amplifier 18c to the control terminal of each main amplifier 18a, each of these main amplifiers 18a can be amplified at the same level by the amplification control signal selected by the microphone array signal selector 18c. It is becoming more and more amplified.

Next, reference numeral 19 indicates a light emitting diode array as a display device, and the light emitting diode array 19 has a large number of light emitting diodes 19a, 19a, . . . arranged side by side in a matrix, as shown in FIGS. 6 and 7. Each of these light emitting diodes 19
a indicates each microphone 8 constituting the microphone array 8
The microphones 8a at each of these positions are connected to a light emitting diode 19a located in a corresponding position via a voltage-controlled main amplifier 18a. In the upper part of this light emitting diode array 19, aperture holes 20a, 20 are provided at the positions where each light emitting diode 19a is arranged.
A diaphragm plate 20 having holes a, ... is installed,
The visibility of the position of the lighted light emitting diode 19a can be switched to be strong or weak depending on the purpose.

Furthermore, 21 indicates a camera for forming an object image, and the camera 21 is, as shown in FIG.
Lens barrel 2 with a focus adjustment mechanism attached with a lens 22
3, and a body 24 connected to the lens barrel 23, the incident light from the lens 22 is guided into the body 24 through the aperture 25, and the optical axis of the lens 22 is A part of it is reflected by the half mirror 26 installed at an angle of 45 degrees, and an image is formed on the focus plate 27.
The object image of the sound source object formed on the focus plate 27 can be viewed from the outside through the focus plate 8. On the other hand, the light passing through the half mirror 26 is guided to a dark room 29 formed at the rear of the body 24, so that when the shutter 30 is opened, a negative film placed in the dark room 29 can be exposed. . Further, the light emitting diode array 19 is installed in a housing 31 provided at the bottom of the camera 21, and the light from the light emitting diodes 19a in the light emitting diode array 19 is diffusely reflected through a filter 32 and adjusted to make it easier to see. The light is transmitted to the body 24 through the lens 33 and the aperture 34.
The focus plate 27 is guided by the half mirror 26.
and imaged on negative film, this sound source and camera 2
The image of the object image in 1 can be superimposed. 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.

In order to explore and measure the position and sound pressure distribution of the noise generated from the complex sound source generated from 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 The microphone array is placed so as to face the sound source object S, and the object image is focused by operating the lens barrel 23 while looking through the viewfinder 28 of the camera 21. 8 to focus the sound image.

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 forming the array 8 receives sound, converts it into an electrical signal, and inputs this signal to the main amplifier 18a. At the same time, the microphone array signal selector 18
a, one of the microphones 8a is extracted as an amplification control signal, and this signal is amplified to a predetermined voltage level by the control amplifier 18c. Here, the microphone array signal selector 18a
When selecting the microphone 8a, it is preferable to select a microphone at a position corresponding to one of the noise generation positions among the plurality of sound sources. Since noise of a specific frequency is generated from this sound source position, this sound pressure signal is selected by the microphone array signal selector 18b and inputted to the control terminal of each main amplifier 18a, and this microphone array signal is Each main amplifier 1
At 8a, a signal having a different frequency and phase from the amplification control signal biased to this control terminal is removed. Therefore, by inputting the input signal of a specific microphone 8a as an amplification degree control signal to the main amplifier 18a, only the sound pressure signal having a correlation with the selected microphone 8a can be extracted in a state separated from other sounds. You will be able to do this. Then, the signals related to the sound pressure are arranged in the same manner as the microphone array 8 and input to the light emitting diode array 19, and by lighting up each of these light emitting diodes 19a with an amount of light corresponding to the sound pressure level, the sound pressure can be detected. Visualize and display the location of the target noise and its sound pressure distribution as a sound image. Here, the light emitting diode 19a may also be lit by an output signal from a microphone 8a other than the one related to the microphone 8a selected as described above, but such lighting will be in an unstable state. Therefore, if the light emitting diode is unstable during lighting, it can be treated as noise.

The sound image visualized in this manner is formed on the focus plate 27, and a part of it is reflected and travels toward the shutter 32, and the object image of the sound source object S is transmitted through the lens 22 and the half mirror 26. Proceed toward shutter 32. As a result, the focus plate 27
The object image and the sound source are superimposed on the sound source object S, and the sound pressure distribution such as the position, range, and intensity of the sound source in the sound source object S can be accurately and easily probed and measured. Furthermore, if the shutter 32 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. At this time, by adjusting the exposure time, it is possible to remove the unstable component caused by the blinking of the light emitting diode, making it possible to accurately display the sound image.

Therefore, the selection of each microphone 8a by the microphone array signal selector 18b is changed as appropriate.
If one of these microphones 8a facing each sound source in the sound source object S is sequentially selected and its sound pressure distribution is sampled, the sound pressure distribution of each sound source in the sound source object S, that is, the spread and loudness of the sound etc. can be visualized and displayed as a sound image.

Furthermore, as shown in FIG.
By disposing a variable filter 36 on the output side of the sound source object S, only the sound of a specific frequency from the sound source object S can be extracted. That is, in the same figure, each amplifier A and the light emitting diode 19a connected thereto.
and a switching device _f0 for switching each filter F to a high-pass type, low-pass type, and band-pass type and controlling the cut-off frequency or center frequency continuously and stepwise,
If this switching device _f0 is switched appropriately, only signals with frequencies in a specific range will pass through, so the sound pressure distribution of only the sound of a specific frequency from a specific sound source in a sound source object that generates a complex sound can be adjusted. Can be visualized.

In this embodiment, the microphone array 8 is arranged to face the sound collector 1, but it goes without saying that the microphone array 8 may be arranged to face the sound source object S directly. In addition, the sound image display device is not limited to the above-mentioned light emitting diode array, but various display devices that display sound pressure levels using liquid crystals, cathode ray tubes, etc. can be used.Moreover, the sound image display is based on the amount of light from the light emitting diodes. In addition to this, it is also possible to use means such as digitization and color coding. Further, although this sound image may be displayed alone, if this sound image is superimposed on the object image as shown in the above embodiment, the sound pressure distribution will be displayed accurately. In addition to the above-mentioned means, a video camera or the like can also be used as means for displaying this object image.

[Effects of the Invention] As explained in detail above, the sound source detection device according to the present invention converts a signal input from a sound source object into a microphone array into an input signal from one of the microphones constituting this microphone array. Since this is selectively amplified as an amplification control signal, a sound image consisting of the position, size, and spread of the sound source that is correlated with the input signal of the selected microphone is displayed separately from other sounds. It is possible to easily and accurately explore and measure each sound source position and sound pressure distribution in a sound source object of a complex sound.

[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 main amplifier, Fig. 6 is a partial plan view of the light emitting diode array with the aperture plate attached, and Fig. 7 is the same as Fig. 6. - A sectional view, FIG. 8 is a structural explanatory diagram of a camera as a sound image forming position detection device, FIG. 9 is a circuit diagram of a variable filter, and FIG. 10 is an explanatory diagram of the principle of a sound collection type sound source detection method. 8...Microphone array, 8a...Microphone,
18a... Main amplifier, 18b... Microphone array signal selector, 18c... Control amplifier, 19... Light emitting diode array, 19a... Light emitting diode,
21...Camera, 36...Variable filter, f ₀ ...
Switching device, S...Sound source object.

Claims (1)

[Claims] 1. A microphone array in which a plurality of microphones are arranged side by side in a matrix, and each microphone receives sound generated from a sound source object and converts it into an electrical signal corresponding to the sound pressure, and the microphone array a main amplifier into which electrical signals from each of the microphones are respectively input; a microphone array signal selector for selectively extracting electrical signals from any one of the microphones; The signal is amplified and input as an amplification degree control signal to each of the main amplifiers, and the instantaneous value of the waveform of this amplified signal is multiplied by the instantaneous value of the waveform of the signal received by each of the microphones. a control amplifier for separating, extracting and amplifying a specific sound signal having a correlation with the sound of the selected microphone; A sound source searching device comprising: a display device that displays a sound image of a specific sound based on output signals from each of the main amplifiers. 2. The sound source searching device according to claim 1, wherein the microphone array is arranged opposite to a sound collector provided facing a sound source object. 3. Claim 1, characterized in that the display device is formed of any one of a light emitting diode array, a liquid crystal display, and a display device using a cathode ray tube.
Sound source detection device as described in section.