Sound source search system

It is possible to simultaneously identify the sound coming direction from a sound source in all directions and estimate the sound intensity of the sound source. A plurality of microphones (11) are arranged on the surface of a baffle (10) of a shape such as a sphere and polyhedron so that sound from all directions are acquired. A calculation device (40) calculates the amplitude characteristic and the phase characteristic of acoustic signals acquired by the microphones (11). The signal information and information on sound field analysis around the baffle are integrated and calculation to emphasize a sound coming from a particular direction is performed for all the directions so as to identify the sound coming direction from a sound source. According to these calculation results and the distance input by an input device (70), it is possible to estimate the sound intensity of the sound source at a plurality of portions generated at the sound source or boundary surface.

CROSS REFERENCE TO RELATED APPLICATION

This application is a national stage of PCT/JP003/010851 filed Aug. 27, 2003 under the International Convention.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a sound-source-search system that searches for a sound source such as acoustic noise, and more particularly to a sound-source-search system in which a plurality of microphones are arranged at locations on a spherical, semi-spherical or polyhedral baffle surface and/or location separated from the surface, and processes the electrical signals from the sounds obtained from each of the microphones, and estimates the direction from which the sound comes and intensity of the sound source from all directions.

In an electric generation plant, chemical plant, factory having an assembly line, or the like, acoustical noise that is generated from various equipment and machinery such as motors, pumps, fans, transformers, etc., are combined and reach bordering areas or nearby homes. Also, inside transportation means such as automobiles, trains, airplanes, acoustical noises that are generated by the various components such as engines, gears, fans, and the like are combined and inhibit silence inside. Moreover, in normal housing areas such as apartments, and the like, silence inside is inhibited by various noises. In order to solve the problems posed by these acoustical noises, it is necessary to accurately know the direction from which the sound is coming, and the intensity of the sound source.

Conventionally, a sound source was searched for by placing a plurality of microphones over a wide area, recording the acoustical signals obtained by way of those microphones by a recording device such as a tape recorder and processing each of the recorded acoustical signals. However, in this kind of method of searching for a sound source, not only was it necessary to set up a plurality of microphones over a wide area, it was also necessary to wire each of the microphones to a recording device, so the set up work was very complicated.

Also, as a different sound-source-search method is the sound-source-search apparatus disclosed, for example, in Japanese Patent Publication No. H06-113387. This is an apparatus that faces a parabolic reflector in the direction from which the sound is coming and records the acoustic signal to make it possible to visualize the sound source. However, the disadvantage of this method is that the estimated sound source is limited to the direction in which the parabolic reflector is faced. In other words, the recording direction is limited by the location and angle at which the microphone is located, so it is impossible to search for sound sources in all directions at the same time.

In order to solve this problem, in Japanese Patent Publication No. 2003-111183 a sound-source-search system is proposed in which a first to fourth microphone are arranged on a rotating frame that is installed on a base to form a detection unit with an origin point located in the center of a square XY plane, and a fifth microphone is placed above the center of the square formed by the first to fourth microphones such that the distances between the first to fourth microphones and fifth microphone are the same, and the direction from which the sound is coming is estimated from the difference in arrival time of output signals from each microphone.

However, in Japanese Patent Publication No. 2003-111183 described above, the first to fifth microphone are located on a rotating frame, and as can be analogized from the simplified installation work and a single-mounted camera, since it is necessary to rotate the rotating frame in order to search for a sound source in all directions, it is impossible to identify the direction from which the sound is coming and estimate the intensity of the sound source in all directions at the same time. Moreover, since the microphones, camera and accompanying cables are located in a naked state in the space through which the sound propagates, the system is vulnerable to the sound reflected from the microphones, camera and cables themselves, which has a large effect on the results of the search for the sound source.

Taking into consideration the problems described above, the object of this invention is to provide a sound-source-search system that is not limited to a small space and is capable of identifying the direction from which sound is coming and the intensity of the sound source in all directions at the same time.

SUMMARY OF THE INVENTION

The sound-source search system according to the first claim of the invention comprises: a spherical, semi-spherical or polyhedral baffle; a plurality of microphones that are arranged on the surface of the baffle for picking up sound in all directions; an amp that amplifies analog signals, which are electrical signals for the sounds in all directions that were picked up by the plurality of microphones; an A/D converter that converts the analog signals the were amplified by the amp to digital signals; an arithmetic-processing apparatus that performs arithmetic processing on the digital signals that were converted by the A/D converter, and analyzes the direction from which the sound from the sound source comes, and/or estimates the intensity of the sound from the sound source; a memory apparatus for storing the arithmetic-processing results from the arithmetic-processing apparatus; a display apparatus that displays the intensity distribution of the sound from the sound source based on the arithmetic-processing results from the arithmetic-processing apparatus; and an input apparatus for entering the distance to the sound source, or sound sources generated at a plurality of sites on boundary surfaces; and wherein the arithmetic-processing apparatus, by arithmetic processing, finds the amplitude characteristics and phase characteristics of the acoustic signals picked up by the plurality of microphones, after which it combines that signal information with analysis information for the sound field around the baffle, and together with performing arithmetic processing to emphasize the sound coming from a specific direction for all directions, and identifying the direction from which the sound comes, it estimates the intensity of the sound from the sound source or sound source(s) generated at one or more sites on boundary surfaces based on the arithmetic-processing results and distance(s) input from the input apparatus.

Also, it is possible for the system to be such that there are one or more directive or non-directive sound-source elements that generate sound waves arranged on the surface of the baffle; and where the arithmetic-processing apparatus, by arithmetic processing, finds the amplitude characteristics and phase characteristics of each of the reflected sounds that are picked up by the plurality of microphones, after which it combines that signal information with analysis information for the sound field around the baffle, and together with performing arithmetic processing to emphasize the sound coming from a specific direction for all directions, and identifying the direction from which the reflected sound comes, automatically measures the distance from the baffle to the sound source or sound source(s) generated at one or more sites on boundary surfaces by using the time difference from when the test sound was generated to when the reflected sound was picked up; and uses that value as information for estimating the intensity of the sound from the sound source or sound source(s) generated at one or more sites on boundary surfaces, and/or estimating the intensity of the sound reflected from that area.

It is also possible for the system to be such that one or more light-receiving elements are arranged on the surface of the baffle such that their imaging ranges overlap; and where the arithmetic-processing apparatus takes in the images from said one or more light-receiving elements that corresponds to the direction from which a specific sound comes, and combines and displays the image of the direction from which the sound comes and/or intensity of the sound found through arithmetic processing with that image or the result of image processing based on that image.

It is also possible for the system to be such that one or more light sources are arranged on the surface of the baffle; and where the arithmetic-processing apparatus automatically measures the distance from the baffle to sound sources generated at a plurality of sites on boundary surfaces by using the time from when light was generated until the reflected light was taken in; and uses that value as information for estimating the intensity of the sound from the sound source or sound source(s) generated at one or more sites on boundary surfaces.

Furthermore, the system can be such that the arithmetic-processing apparatus performs image processing on the area of the imaging range of the light-receiving elements that overlap, and automatically measures the distance to the sound source or sound source(s) generated at one or more sites on boundary surfaces.

The system can also be such that there is a plurality of baffles; and the arithmetic-processing apparatus finds: the distance from one of the baffles to the sound source or sound source(s) generated at one or more sites on boundary surfaces and/or the direction from which the sound comes; the distance from another baffle to the sound source or sound source(s) generated at one or more sites on boundary surfaces and/or the direction from which the sound comes; and the positional relationship between the baffles; after which, based on this information, uses the theory of triangulation to find the distance to the sound source or sound source(s) generated at one or more sites on boundary surfaces.

Moreover the system can be such that one or more satellite microphones are arranged at locations separated from the surface of the baffle; and where the arithmetic-processing apparatus uses the sound picked up by the plurality of satellite microphones to find the direction from which the sound comes and/or intensity of the sound from the sound source.

Furthermore, the system can be such that the baffle is installed at the top of a long member such that it is held at a specified height above the ground.

In the sound-source search system of this invention, a plurality of microphones are arranged on the surface of a spherical, semi-spherical or polyhedral baffle to pick up sound from all directions, and after an arithmetic-processing apparatus finds through arithmetic processing the amplitude characteristics and phase characteristics of the acoustic signals picked up by the plurality of microphones, it combines that signal information with analysis information for the sound field around the baffle, and together with performing arithmetic processing for emphasizing sound coming from a specific direction for all directions, and identifying the direction from which the sound from the sound source comes, based on the arithmetic processing results and distances input from the input apparatus, it is able to estimate the intensity of the sound from the sound source or sound sources generated at a plurality of sites on boundary surfaces.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The preferred embodiments of the invention will be explained below.

First Embodiment

FIG. 1is a drawing for explaining the basic construction of a first embodiment of the sound-source-search system of this invention;FIG. 2andFIG. 3are drawings for explaining the sound-source-search method by the sound-source-search system shown inFIG. 1; andFIG. 4is a drawing showing an example of the sound intensity distribution that is displayed on the display apparatus shown inFIG. 1.

The sound-source-search system shown inFIG. 1comprises a baffle10, microphones11, amp20, A/D converter30, arithmetic-processing apparatus40, memory apparatus50, display apparatus60, and input apparatus70. It is possible for the arithmetic-processing apparatus40, memory apparatus50, display apparatus60and input apparatus70to be constructed using an electronic device such as a notebook computer or desktop computer.

The baffle10is spherical. Also, the baffle10is installed at the top of a long member (not shown in the figure) such as a pole such that it is kept at a specified height from the ground plane.

A plurality of microphones11is arranged on the surface of the baffle10. It is possible to use dynamic microphones or condenser microphones as the microphones11.

By placing the plurality of microphones11on the spherical baffle10in this way, it becomes possible to pick up sound uniformly in all directions. The built-in main unit (not shown in the figure) such as the pre-amp (not shown in the figure) for the microphones11, and the microphone cables11athat are connected to the main unit are installed inside the baffle10.

The radius of the baffle10shown inFIG. 1is about 130 mm. Also, in this embodiment, the number of microphones11placed on the baffle10is 17. However, the number of microphones11can be the minimum number necessary to correspond to the dimensions for searching for a sound source, and it is possible to use 2 microphones when searching for a sound source in one dimension, 3 microphones when searching for a sound source in two dimensions, and 4 microphones when searching for a sound source in 3 dimensions. In this embodiment, in order to improve precision and stability of the results of the sound-source search, 17 microphones are used.

By installing the built-in main unit (not shown in the figure) such as the pre-amp (not shown in the figure) for the microphones11, and the microphone cables11athat are connected to the main unit on the inside of the spherical baffle10in this way, it is possible to suppress disturbances in the sound field around the baffle10, and thus it becomes possible to accurately pick up sound from the sound source.

Also, coordinates that indicate the position of each microphone11on the baffle10in three dimensions (x, y, z) are set, and they are used when the arithmetic-processing apparatus40performs arithmetic operations in the sound-source search. By doing so, it becomes possible to identify from which microphone11a picked up sound is coming from.

The amp20is an amplifier that amplifies the analog signals that are electrical signals of the sounds obtained in all directions by each of the microphones11. The microphone cables11afrom each of the microphones11are connected to the amp20. Here, there is an insert port corresponding to the coordinates of each of the microphones11described above, so when connecting the microphone cables11aof the microphones11, the microphone cables11aare inserted into and connected to the respective insert ports. The A/D converter30converts the analog signal that was amplified by the amp20to a digital signal.

The arithmetic-processing apparatus40performs operations on the digital signal converted by the A/D converter30, and searches for the sound source by processing sound information picked up by each of the microphones11inclusively and as a whole. Here, the sound-source search is analyzing the direction from which the sound arrives from the sound source, and estimating the intensity of the sound from the sound source. The sound-source search will be explained in detail later.

The memory apparatus50stores the results of the arithmetic processing by the arithmetic-processing apparatus40. As the memory apparatus50, it is possible to use a magnetic-tape memory apparatus that uses magnetic tape as the recording medium, or an optical-disk memory apparatus that uses an optical disk as the recording medium. The display apparatus60displays the sound intensity distribution of the sound from the sound source based on the arithmetic processing results from the arithmetic-processing apparatus40. The input apparatus70is used for entering the distance to the sound source or to sound sources generated at a plurality of sites on boundary surfaces such as walls in a room. It is possible to use a keyboard, touch panel or the like as the input apparatus. However, in the case where the purpose is to analyze the direction from which the sound comes, and calculate the acoustical contribution on the location of the baffle, and is not to estimate the intensity of the sound, it is possible to eliminate the input apparatus70.

Next, the method for performing the sound-source search will be explained.

The search for a sound source can be performed in either a large space or a small space. In a large space, it is preferable that there be no obstacles between the baffle10and the sound source being searched for; for example, in a location where a large number of people may congregate, the baffle10should be set at a high location where it overlooks the entire space; or in a location such as an airport, the baffle10should be set in a location where no buildings or structures will become obstacles. On the other hand, in a small space such as indoors or inside a vehicle, the baffle10should be placed in a location where it can overlook the entire space.

Also, as shown inFIG. 2, in the case of analyzing the direction from which the sound arrives from the sound source, analysis information for the sound field, which includes direct or diffracted sound around the baffle10, is entered into the arithmetic-processing apparatus40. In this state, each of the microphones11picks up the sound from the sound source. Here, when picking up the sound from the sound source, sound is basically picked up by each of the microphones11at the same time. Also, with a specified microphone as a reference, it is possible to pick up the sound in the order of the coordinates mentioned above, or to pick up the sound with a plurality of microphones together, or to pick up the sound randomly at the same time as the reference microphone. However, the condition when not recording the sounds from all of the microphones at the same time is that the sound from the sound source must not change over time.

At this time, the sound from all directions obtained by way of each of the microphones11enters the amp20as analog signals, and those signals are amplified by the amp20and output. The analog signals that are amplified by the amp20are converted to digital signals by the A/D converter30and then taken in by the arithmetic-processing apparatus40.

In the arithmetic-processing apparatus40, analysis of the sound picked up by each of the microphones11is performed by arithmetic processing. In this case, the amplitude characteristics and phase characteristics of each of the acoustic signals picked up by each of the microphones11are found by arithmetic processing. Also, after these amplitude characteristics and phase characteristics have been found, analysis information for the sound field around the baffle10described above is added, and arithmetic processing, which emphasizes the sound coming from a specified direction, is performed in all directions, making it possible to identify through arithmetic processing the direction from which the sound from the sound source comes.

Next, when estimating the intensity of the sound from the sound source, the distance d to the sound source shown inFIG. 2is entered into the arithmetic-processing apparatus40from the input apparatus70. At this time, the direction from which the sound from the sound source comes and the sound pressure are identified by the arithmetic-processing apparatus40as described above, so it is possible to estimate the intensity of the sound from the sound source through arithmetic processing from these arithmetic processing results and the distance d to the sound source. When estimating the intensity of the sound from the sound source, by adding the distance d to the sound source to the conventional frequency domain beam forming method, it is possible to more accurately estimate the intensity of the sound from the sound source.

In this example, the case was explained in which, after analysis of the direction from which the sound from the sound from the sound source comes is finished, the distance d to the sound source used for estimating the intensity of the sound from the sound source is input to the arithmetic-processing apparatus40from the input apparatus70, however, of course it is also possible to enter the distance d to the sound source into the arithmetic-processing apparatus40from the input apparatus70before starting the sound-source search.

Also, in this example, as shown inFIG. 2, the case of analyzing the direction from which the sound from one sound source comes, and estimation of the intensity of the sound from one sound source was explained, however, as shown inFIG. 3, in the case of analyzing the directions from which sound comes from a plurality of sound sources generated at sites on boundary surfaces such as walls in a room, and estimating the intensity of the sound sources at each of these sites, it is possible to enter distances d1to d4to the sound sources a to d at these sites.

After analyzing the direction from which the sound from the sound source comes and estimating the intensity of the sound from the sound source by arithmetic processing by the arithmetic-processing apparatus40as described above, the results of the arithmetic process are displayed in color by the display apparatus60as the sound-intensity distribution.FIG. 4shows an example of the sound-intensity distribution that is displayed by the display apparatus60. InFIG. 4, the size of the sound intensity is indicated, for example, by a to f(a>f>c>d>e>f).

In this first embodiment, a plurality of microphones11are arranged on the surface of a spherical baffle10and sound is picked up from all directions in this way, and after the amplitude characteristics and phase characteristics of each of the acoustic signals picked up by the plurality of microphones11are found through arithmetic processing by the arithmetic-processing apparatus40, that signal information is combined with the analysis information for the sound field around the baffle, and arithmetic processing to emphasize the sound coming from a specific direction is performed for all directions, and together with identifying the direction from which sound from the sound source comes through arithmetic processing, the intensity of the sound from the sound source or from sound sources generated at a plurality of sites on boundaries is estimated from the arithmetic processing results and the distance entered from the input apparatus70, so regardless of whether or not the space is small, it is possible to identify the direction from which the sound from the sound source comes, and estimate the intensity of the sound from the sound source at the same time in all directions.

Also, in this first embodiment, set up work is very easy since it requires just setting a baffle10having a plurality of microphones11installed in place, and then connecting the microphone cables11afrom the microphones11to the amp20.

In this first embodiment, the case where the baffle10was spherical was explained, however, the invention is not limited to this example, and it is possible for the baffle10to be semi-spherical or polyhedral. Any one of the cases is possible as long as analysis information for the diffracted sound around the baffle10can be obtained in some form. In this way, even when the baffle10is semi-spherical or polyhedral, the microphones11are built-in the baffle, so it is possible to suppress distortion in the sound field around the baffle10, and thus it is possible to perform the sound-source search accurately.

Also, the material used for the baffle10can be any material, such as stainless steel, aluminum alloy, copper alloy or the like, that retains sufficient strength after a plurality of microphones11has been built in. It is possible to perform polishing or roughing of the surface of the baffle10, and it is also possible to attach sound absorption material. In any case, as long as it is possible to obtain analysis information for diffracted sound around the baffle10due to the shape or material of the baffle10, it is possible to accurately analyze the direction from which the sound from the sound source comes, and estimate the intensity of the sound source even though the shape and material of the baffle10may differ.

Second Embodiment

FIG. 5is a drawing showing a second embodiment in which one or more sound source elements for measuring distance are added to the baffle10shown inFIG. 1. In the drawing explained below, the same reference numbers are used for parts that are in common with those ofFIG. 1toFIG. 3, and any redundant explanation will be omitted.

In this second embodiment shown inFIG. 5, there are one or more sound-source elements12for measuring distance placed on the surface of the baffle10and they generate sound waves. It is possible to use directive or non-directive acoustical speakers or ultrasonic speakers as the sound-source elements12for measuring distance.

With this kind of construction, sound waves are generated from the sound-source elements12for measuring distance, and the reflected waves of those waves are picked up by each of the microphones11, and then after the amplitude characteristics and phase characteristics of each of the reflected waves picked up by each of the microphones11have been found through arithmetic processing by the arithmetic-processing apparatus40, that signal information is combined with the analysis information for the sound field around the baffle10, and by adding the time from when the sound waves are generated until the reflected waves are picked up together with performing arithmetic processing to emphasize the sound coming from a specified direction in all directions, and identifying the direction from which sound from the boundary surfaces comes from through arithmetic processing, it is possible to automatically measure the distance to the sound source or to sound sources generated at a plurality of sites on the boundary surfaces.

By automatically measuring the distance to the sound source or one or more sound sources generated at a plurality sites on boundary surfaces in this way, not only is it possible to more accurately analyze the direction from which the sound from the sound source comes and estimate the intensity of the sound from the sound source, but it is also possible to gain a better understanding beforehand of buildings, obstacles, mountains near the observed area, or the shape and location inside a vehicle or room.

Moreover, by analyzing the reflected sound characteristics such as the direction from which a test sound generated by a sound-source element12for measuring distance and its reflected sound comes for every direction, intensity, and phase, it becomes possible to also investigate the acoustics such as the reverberation time at that place and the echo time pattern.

It is also possible to use a test wave having a specific frequency as the sound wave from the sound-source element12for measuring distance, and it is also possible to use random noise, pseudo random noise, an M-sequence signal, a frequency-sweep signal, or the like to perform arithmetic processing and automatically measure the distance to sound sources at one or more sites. After measuring the distance to the sound source or sound sources generated at a plurality of sites on the boundary surfaces in this way, it is possible to more accurately analyze the direction from which sound from the sound source comes, and estimate the intensity of the sound from the sound source.

Third Embodiment

FIG. 6is a drawing showing a third embodiment in which one or more light-receiving elements are added to the baffle10shown inFIG. 5.

In this third embodiment shown inFIG. 6, one or more light-receiving elements13are arranged on the surface of the baffle10. It is possible to use a camera such as a CCD camera comprising a CCD (Charge Coupled Device) and lens, a laser-receiving element, infrared-ray-receiving element or the like as the light-receiving element13.

In the case of a camera as the light-receiving element13, it is preferred that each light-receiving element13be placed such that its imaging range overlaps that of the adjacent light-receiving elements. In other words, as shown inFIG. 7, by having the light-receiving element13take an image of the image range X and Y, and the other adjacent light-receiving element13take an image of the image range Y and Z, the image ranges Y overlap.

With this kind of construction, since a plurality of light-receiving elements13are arranged on the surface of the baffle10such that the image ranges overlap, it is possible to automatically take in an image of around the sound source or sound sources generated at a plurality of sites on the boundary surfaces that correspond to the direction from which a specific sound comes, and to display that obtained image in color by the display apparatus60.FIG. 8shows an example of the image displayed by the display apparatus60.

Moreover, it is possible to combine and display the image of the sound-intensity distribution shown inFIG. 4with the image shown inFIG. 8. In that case, by selecting the area indicated by the dotted line in the image shown inFIG. 9Acorresponds to the image shown inFIG. 4, the image corresponding to that selected area is obtained as shown inFIG. 9B, and the sound-intensity distribution of the area selected inFIG. 9Ais combined with the image shown inFIG. 9Bas shown inFIG. 9Cand displayed.

By automatically taking images with the light-receiving elements13in this way, in addition to the effects described above, it is possible to display the direction from which the sound comes and/or the sound-intensity distribution, and thus it becomes easy to visually grasp those distributions.

When a laser-receiving element, infrared-ray-receiving element or the like is used as the light-receiving element13, they are effectively used in a fourth embodiment described below.

Fourth Embodiment

FIG. 10is a drawing showing a fourth embodiment in which a plurality of light sources is added to the baffle10shown inFIG. 6.

In this fourth embodiment shown inFIG. 10, a plurality of light sources14is arranged on the surface of the baffle10. It is possible to use CCD-camera lighting, a laser pointer, a laser range finder, strobe or the like as the light source14.

When a light source having sharp directivity such as a laser pointer is used in this kind of construction, it is possible to accurately set the installation location of the baffle even when installing the baffle in difficult locations.

When a range finder such as a laser range finder is used in this kind of construction, light is emitted from the light source14, and the reflected light of that light is received by the light-receiving unit13, making it possible to automatically measure the distance to the boundary surface, which can be the baffle or sound source.

Also, by using the light generated by the light source14, it is possible to light up the area of the sound source or sound sources generated at a plurality of sites on the boundary surfaces, so even in an area with dim lighting, it is possible to take good images with the light-receiving elements13.

When a strobe light source is used as the light from the light source14, by shining a light onto a rotating body and keeping the flashing period of the light from the light source14constant, then by measuring the period when the rotating flashing period and rotation cycle match and the rotating body appears to be still, it is possible to remotely measure the speed of the rotating body. Also, similarly, when the flashing period of the light is constant and it is shown onto a vibrating surface, using the theory of the stroboscope, it becomes possible for the light-receiving elements13to observe the vibration state of a boundary surface, which is the sound source.

Fifth Embodiment

FIG. 11is a drawing explaining a fifth embodiment in which the light-receiving elements13shown inFIG. 6automatically measure the distance to the sound source or sound sources generated at a plurality of sites on the boundary surfaces.

In this fifth embodiment shown inFIG. 11, similar to as was explained above, after images have been automatically taken by the light-receiving elements13, the images where the imaging range of adjacent light-receiving elements13overlap are processed, and the distance to the sound source or sound sources generated at a plurality of sites on the boundary surfaces is automatically measured. By having the light-receiving elements13automatically take images in this way and then having the arithmetic-processing apparatus40process the image of the overlapping area, and automatically measure the distance to the sound source, then similar to as was described above, it becomes possible to accurately estimate the intensity of the sound from the sound source or sound sources generated at a plurality of sites on the boundary surfaces.

Sixth Embodiment

FIG. 12is a drawing showing a sixth embodiment in which, as an example of having a plurality of the baffles10shown inFIG. 6, two baffles10are used.

In this sixth embodiment shown inFIG. 12, by having two baffles10, through arithmetic processing by the arithmetic-processing apparatus40, it is possible to obtain the distance from one baffle10to the sound source and/or the direction from which the sound comes, the distance from the other baffle10to the sound source and/or direction from which the sound comes, and the positional relationship between the pair of baffles10. Also, based on that information, the distance to the sound source is even more accurately measured according to the theory of triangulation, and of course, it is possible to more accurately measure the intensity of the sound from the sound source; and compared with the case of using only one baffle, when the number of microphones used is increased, the range of received sound is expanded, and it becomes possible to greatly improve the precision of the sound-source search.

Seventh Embodiment

FIG. 13is a drawing showing a seventh embodiment in which a plurality of satellite microphones is located on the baffle10shown inFIG. 1.

In this seventh embodiment shown inFIG. 13, a plurality of satellite microphones11A is arranged on the baffle10.

By arranging a plurality of satellite microphones11A on the baffle10in this way, in addition to the built-in microphones on the baffle10, the arithmetic-processing apparatus40is able to use acoustic information from the satellite microphones in the sound-source search. As in the case of the microphones arranged on the baffle10, it is preferred that the acoustic information from the satellite microphones11A be used in a form in which analysis information about the diffracted sound around the baffle10has been added. The satellite microphones11A are located further outside than the baffle10, and have the effect of virtually increasing the size of the baffle10without having to change the size of the baffle10. Since the number of microphones that can be used in the sound-source search is increased, it becomes possible to greatly increase the precision of the sound-source search.

In this seventh embodiment, the case of placing a plurality of satellite microphones11A around the baffle10shown inFIG. 1was explained, however, the invention is not limited to this example, and of course it is also possible to place a plurality of satellite microphones11A around the baffle10shown inFIG. 5,FIG. 6,FIG. 10orFIG. 12. Naturally, it is also possible to replace the microphones on the baffle completely with satellite microphones.

INDUSTRIAL APPLICABILITY

With the sound-source search system of this invention as described above, one or more microphones are arranged on and/or near the surface of a spherical, semi-spherical or polyhedral baffle to pick up sound from all directions, and after an arithmetic-processing apparatus identifies the direction from which sound comes through arithmetic processing that focuses on the amplitude characteristics and phase characteristics of the acoustic signals picked up by the plurality of microphones, the intensity of the sound from the sound source or sound sources generated at a plurality of sites on boundary surfaces is estimated from the arithmetic processing results and distances entered from an input apparatus or measured by sound-source, light-source or image processing, so regardless of whether or not the space is small, it is possible to identify the direction from which sound from the sound source comes, and to estimate the intensity of the sound source in all directions at the same time.