JPH0460557B2 - - 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 microphone array was formed by arranging microphones in a matrix, and this microphone array received sound from a sound source, and a sound image based on the sound pressure level of each microphone was created using a light emitting diode, etc. The present inventors have proposed a method of searching for the position of a sound source by visualizing it by displaying it on a display device.

[Problems to be Solved by the Invention] By the way, in a sound source object, there are multiple sound sources, and it is difficult to detect and locate one of the multiple sound sources.
When making measurements, it is not possible to simply arrange microphones to form a microphone array and have the microphone array receive sound, as in the sound source detection method described above. Sound pressure distribution cannot be extracted separately from other sounds. 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 an object of the present invention is to provide a sound source detection device that can accurately recognize the sound pressure distribution at each sound source position in a sound source object that generates a complex sound. It is.

[Means for Solving the Problems] In order to solve the above-mentioned problems, the present invention has a plurality of microphones arranged in parallel in a matrix,
a microphone array that receives sound generated from a sound source object using microphones and converts it into an electrical signal corresponding to the sound pressure; an amplifier to which the electrical signals from each microphone of the microphone array are respectively input; a reference sound detector that is installed opposite to the sound source and detects the sound generated from the sound source and converts the sound pressure into an electrical signal;
The output signal from the reference sound detector is amplified, and the phase is adjusted to synchronize the amplified output signal with the sound reception signal at the sound source in the microphone array, and the signal after this phase adjustment is input to each of the amplifiers as an amplification degree 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 reference sound is separated from the others. A sound image of a specific sound is displayed based on an amplification control signal generator for extracting and amplifying the output signal from each of the amplifiers, which is selectively amplified by the amplification control signal from the amplification control signal generator. The feature is that it is composed of a display device that performs the following functions.

[Operation] Therefore, the sound at a specific sound generating part of a sound source object that generates a complex sound, such as a mechanical device that has a plurality of operating members and generates noise from each of the operating members, can be suppressed. In order to separate the pressure distribution from other sounds, the microphone array should be placed directly facing the sound source object, or if the sound source object is large, a concave reflective surface should be used to reflect the sound from it. A sound collector having a sound collector is disposed facing the sound source, a microphone array is installed facing the sound collector, and the reflected sound from the sound source object is received by the microphone array.

On the other hand, a reference sound detector consisting of a reference microphone, a vibrometer, etc. is installed opposite to the noise generating section to be sampled, and the reference sound detector measures the sound at the noise generating section and converts it into an electrical signal. Convert to The input sound pressure signal of this reference sound detector is amplified by the amplification degree control signal generator, and the amplification degree control signal is generated by adjusting the phase to synchronize with the sound reception signal at the sound generation source in the microphone array. generate. This amplification control signal is input to the control terminal of each amplifier, and the instantaneous value of the waveform of this signal is multiplied by the instantaneous value of the waveform of the output signal from each microphone, thereby selectively amplifying the signal. Sound pressure distribution information at the position where the reference sound detectors are disposed opposite to each other is obtained, and this sound pressure distribution information can be displayed as a sound image on an appropriate display device.

Here, the phase adjustment in the amplification control signal generator is performed because the distances between the sound source object and the microphone array and reference sound detector are different.
This phase adjustment is determined by the frequency of the sound from the sound generator to be sampled and the ratio of the distance between the microphone array and the sound source object and the reference sound detector. It may be calculated by calculation, but it can also be calculated by using a phase adjuster having a time delay element and controlling the time delay in this phase adjuster manually or automatically.

Then, by creating sound pressure distribution information for each sound generating section, information regarding the sound pressure distribution of each sound source in the composite sound source object can be obtained.

[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 reverse slope r of this sound collector D, and a sound image S' is formed 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. 5A, a multi-channel VCA unit 18 is connected to the microphone array 8, and the VCA unit 18 receives sound pressure signals received by each microphone 8a and converted into electrical signals. An amplifier 18a having a voltage-controlled multiplication function for amplifying the signal is provided in correspondence with each microphone 8a. Each amplifier 18a constituting this VCA unit 18 is capable of amplifying the sound pressure signal converted into an electric signal by each microphone 8a with the same amplification degree. And each amplifier 1
In order to control the amplification degree of 8a, a reference sound detector 180 consisting of a reference microphone, a vibration meter, etc. is provided, and the reference sound detector 180 faces a desired position of the sound source object S. This makes it possible to extract and receive only the sound at a specific position in the sound source object S. and,
This reference sound detector 180 is connected to an amplification control signal generator 181, which includes a control amplifier 182 and a phase adjuster 183. is connected via a resistor R, and by adjusting the value of this resistor, the output signal of the reference sound detector can be amplified to a desired degree of amplification.

On the other hand, the phase adjuster 183 has a configuration as shown in FIG. 5B. That is, the control amplifier 1
The signal from 82 is converted into a digital signal by an A-D converter 183a, and the clock pulse generator 183b
By controlling the sampling timing and shift timing of this signal by generating clock pulses every moment at a predetermined time interval (t), the above-mentioned input signal can be changed to a delay time corresponding to the number of clock pulses (N). (txN) and are sequentially stored in each memory a, b, c, . . . n. And these memories a, b, c,...n
A memory switch selector 183c is connected to the memory switch selector 183c, and a memory switch selector 183c is connected to any memory by a memory switch selector signal generator 183d to generate a signal from the reference sound detector 180 with a predetermined time delay. By causing this, the phase of the reference sound signal can be adjusted so as to be synchronized with the signal received by each microphone 8a. Furthermore, the digital signal whose phase has been adjusted in this way is converted into an analog value by the D-A converter 183e, and the signal from the reference sound detector 180 is used as an amplification degree control signal to be transmitted to each amplifier of the VCA unit 18. It is configured so that it can be input as a bias signal to the control terminal of each of these amplifiers 18a.
a is amplified by the same amplification degree by the amplification degree control signal outputted from this amplification degree control signal generator 181.

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 an amplifier 18a. A diaphragm plate 20 having aperture holes 20a, 20a, . It is now possible to display the intensity by switching it to a stronger or weaker level 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 29 through the aperture 25, and the lens 22 is introduced into the body 29.
A part of the light is reflected by a half mirror 26 installed at an angle of 45 degrees with respect to the optical axis of the lens 2, and an image is formed on a focus plate 27 via a finder 28. It is now possible to see the object image of the sound source object from the outside. 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 29, 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 guided into the body 29 via the lens 33 and the aperture 34, and is imaged by the half mirror 26 on the focus plate 27 and negative film, and this sound image and the camera 21
It is now possible to superimpose images of the object image in the image. Further, 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, and the sound collector 1
A through hole 35 is bored in the hole 35 so that the camera 21 can see through the sound source object.

In order to explore and measure the sound pressure distribution of noise at a specific position among the noise generated from a complex sound source in the sound source object S using the sound source detection device configured as described above, first, the reflective surface of the sound collector 1 is 1a so as to face the sound source object S, and by operating the lens barrel 23 while looking through the viewfinder 28 of the camera 21, the object image is focused, and in this focusing, the image distance is adjusted. Microphone array 8
to focus the sound image. and,
At the same time, the reference sound detector 180 is installed so as to face the position of the sound source to be measured.

When the focusing of the object image and the sound image is completed and the reference sound detector 180 is installed at a position that accurately faces the sound generating section, the microphone array 8, camera 21, and reference sound detector sound detector 180
is fixed, and the sound generated from the sound source object S is collected by the sound collector 1.
The sound is reflected by the reflecting surface 1a and received by each microphone 8a constituting the microphone array 8, which is converted into an electrical signal and input to the amplifier 18a. At the same time, the reference sound detector 180 receives the sound of the sound generator, converts it into an electrical signal, and the control amplifier 182 that constitutes this signal amplifies it to a predetermined voltage level. The output signal from the control amplifier 182 is input to a phase adjuster 183 to control its phase. This phase adjuster 1
83 is input as an amplification control signal to each amplifier 18a to the control terminal of each amplifier 18a, and the instantaneous value of the signal waveform of this amplification control signal is input to each microphone 8 constituting the microphone array 8.
By multiplying the instantaneous value of the waveform of the received sound signal of a, only the sound pressure signal that has a correlation with the sound of a specific frequency that corresponds to the sound generation position of one of the multiple sound sources is transmitted to the other sound pressure signals. Take it out separately from the sound. A signal related to this sound pressure is transmitted by a light emitting diode array 19 arranged similarly to the microphone array 8.
By lighting up each light emitting diode 19a with an amount of light corresponding to the sound pressure level, the sound pressure distribution at the location where the sound to be searched for is generated is visualized and displayed as a sound image. Here, the sound image consists of a specific sound generation part of the sound generated from the sound source object S, the spread of the sound generated due to the influence from this sound generation part, and the loudness of the sound.

By the way, as mentioned above, in order to extract only sounds that are correlated with the sound at a specific sound source position, the phase of the amplification control signal is changed from the microphone array 8 to the amplifier 1.
It must match the phase of the signal input to 8a. In order to adjust the phase of this amplification control signal, the amplification control signal generator 181 is provided with a phase adjuster 183, and a memory switch selection signal generator 183c of the phase adjuster 183 is provided.
may be adjusted manually or automatically to cause a delay in the signal from the reference sound detector 180 so that it matches the frequency in the signal from the microphone array 8. This phase adjustment is performed by adjusting the light emitting diode 1 at the sound source position in the light emitting diode array 19.
This can be easily done by adjusting the memory switch selection signal generator 183c so that the amount of light of the light source 9a is maximized.

Here, the light-emitting diode 19a may also be turned on by a sound pressure signal related to a sound other than the sound received by the reference sound detector 180, but the light-emitting diode 19a blinks 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 way is formed on the focusing plate 27, and a part of it is reflected and travels toward the shutter 30, and the object image of the sound source object S is transmitted through the lens 22 and the half mirror 26. Proceed toward shutter 30. As a result, the focus plate 27
The object image and the sound image 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 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. 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, and it is possible to accurately display the sound image.

Therefore, by making the reference sound detector 180 face each noise generation position in the sound source object S, the sound pressure distribution for each of these sound sources can be sampled, and the sound pressure distribution of each sound source in the sound source object S can be sampled. It is possible to visually display the sound pressure distribution, that is, the spread and loudness of the sound.

Furthermore, if a variable filter 36 is provided on the output side of the amplifier 18a as shown in FIG. 9, only the sound of a specific frequency 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 If a switching device f ₀ is provided to control the frequency continuously and stepwise, and if this switching device f ₀ is switched appropriately, only signals in a specific range of frequencies will pass, so that the sound source object that generates the complex sound can be It is possible to visualize and display the sound pressure distribution of only the sound of a specific frequency from a specific sound source.

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. Furthermore, although the phase adjuster 183 has been shown to adjust the phase by converting the input signal of the reference sound detector 180 into a digital signal, for example, if an analog memory such as a charge-coupled device is used, A-D, D-A
Phase adjustment can be performed without conversion. Furthermore, the sound image display device is not limited to the above-mentioned light emitting diode array, and various display devices that display sound pressure levels using liquid crystals, cathode ray tubes, etc. can be used, and the sound image display method is not limited to the above-mentioned ones. Alternatively, the information may be displayed using numerical values, color coding, contour lines, or the like. Furthermore, although this sound image may be displayed alone, if the 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 above in detail, the sound source detection device according to the present invention detects the input signal from the reference sound detector provided facing the specific sound source position by inputting the signal input from the sound source object to the microphone array. Since this is selectively amplified as an amplification control signal, the size, spread, etc. of the sound source that has a correlation with the sound reception signal of the reference sound detector at this specific sound source position can be separated from other sounds. The sound pressure distribution of each sound source in the sound source object of a complex sound can be easily and accurately detected and displayed.
can be measured.

[Brief explanation of the drawing]

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 a front view and a side view of the microphone array, respectively. Figure 5A is the circuit diagram of the amplifier, Figure 5B is the circuit diagram of the phase adjuster, and Figure 6 is the light emitting diode array with the aperture plate attached. A partial plan view, FIG. 7 is a cross-sectional view of FIG. 6, 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 a sound collection diagram. FIG. 2 is an explanatory diagram of the principle of a sound source search method. 8...Microphone array, 8a...Microphone,
18...Multi-channel VCA unit, 18a...
...Amplifier, 18t...Control terminal, 19...Light emitting diode array, 19a...Light emitting diode, 2
1...Camera, 36...Variable filter, 180...
... Reference sound detector, 181 ... Amplification control signal generator, 182 ... Control amplifier, 183 ... Phase adjuster, f ₀ ... Switching device, S ... Sound source object.

Claims (1)

[Scope of Claims] 1. A microphone array in which a plurality of microphones are arranged in parallel in a matrix, each of which receives sound generated from a sound source object and converts it into an electrical signal corresponding to the sound pressure; and the microphone array. an amplifier into which electrical signals from each microphone are input, and an amplifier that is installed opposite to a specific sound source in the sound source object, detects the sound generated from the sound source, and converts the sound pressure into an electrical signal. a reference sound detector; amplifying the output signal from the reference sound detector; and adjusting the phase of the amplified output signal to synchronize it with the sound reception signal at the sound source in the microphone array; This phase-adjusted signal is input to each of the amplifiers as an amplification degree control signal, 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. Therefore, an amplification control signal generator is provided for separating and amplifying a specific sound signal having a correlation with a reference sound, and an amplification control signal from the amplification control signal generator is used. and a display device that displays a sound image of a specific sound based on the amplified output signals from each of the amplifiers. 2. The sound source detection device according to claim 1, wherein the microphone array is provided facing a sound collector disposed to face a sound source object. 3. The sound source searching device according to claim 1, wherein the reference sound detector is either a reference microphone or a reference vibrometer. 4. 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. 5. A variable filter is provided on the output side of each of the amplifiers, the reference sound detector receives a reference sound consisting of a composite sound, and the reference sound is used as an amplification degree control signal to be transmitted to each of the microphones by each of the amplifiers. By filtering the signal after selectively amplifying the received sound signal using the variable filter, and performing amplification control based on the set frequency signal of the variable filter, the sound related to a specific frequency is determined from the composite reference sound. The sound source searching device according to claim 1, characterized in that it is configured to form a sound image.