JP2005091263A - Microphone and microphone array - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a simple and compact microphone array capable of accurately measuring the sound pressure distribution of sound sources distributed in three-dimensional space. <P>SOLUTION: The microphone array 2 for detecting sound emitted from the sound sources distributed in the three-dimensional space is provided with both a plurality of microphones 20 in which sensor parts for detecting sound pressure from an object to be measured 8 having the sound sources are arranged in the approximately same direction and a frame 30 for arranging the plurality of microphones 20 along a plane or a curved surface. The plurality of microphones 20 are each provided with a position adjusting means for adjusting the distances between the sound sources and the sensor parts. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a microphone array or the like, and more particularly to a microphone array or the like that arranges a plurality of microphones and detects sound at a plurality of positions.

  A technique of a microphone array that arranges a plurality of microphones along a plane or a curved surface and measures sound pressure at a plurality of positions is used in many scenes. For example, when taking noise countermeasures for equipment, it is necessary to specify the sound pressure distribution of equipment having sound sources at a plurality of positions. The technique of the microphone array is particularly effective for measuring the sound pressure distribution of such a device (see, for example, Non-Patent Document 1).

Matsushita Techno Trading, electronic measurement, SV solution, “BK product”, [online], [searched on September 12, 2003], Internet <URL: http: // www. mitc. co. jp / msm / sv / bk / stsf / stsf. html>

  By the way, the sound source of the device is distributed in a three-dimensional space, and the distance to the surface on which the microphones are arranged (hereinafter sometimes referred to as an array surface) may be different. As described above, when the sound pressure is measured in a state where the distance from the sound source to the microphone is not uniform, there is a case where the sound propagation path is different and the sound pressure distribution cannot be measured accurately. However, if the amount of attenuation simply changes due to different propagation paths, this can be corrected mathematically. However, if there is a difference in the propagation path, a change in the sound diffusion range, a problem of interference, etc. occur, making it very difficult to estimate the sound pressure distribution.

  In order to correct the difference in the distance between the sound source and the microphone due to the uneven distance from the sound source to the microphone, we have arranged a plurality of slidably mounted microphones in advance. We reported a method of measuring the sound pressure after pressing the array surface against the object whose sound pressure distribution is to be measured, adjusting the position of the slid microphone according to the shape of the object at once. 2002-369372). In this method, a plurality of microphones are slid and fixed together by a lock mechanism.

  However, as further investigation proceeds, this method adjusts the position of a plurality of slidably mounted microphones at a time, so that, for example, the microphone array can be slidable when pressed against an object diagonally or downwardly. The attached microphone may slide suddenly and damage the sensor. In addition, in the method of pressing a plurality of slidable microphones against an object, if there is a gap in the object, the microphone will be placed in the gap even if the sound leakage from the gap is virtually measured as a sound source. May get in.

  Furthermore, since the cable connected to the microphone has a structure that penetrates the inside of the slider that slides the microphone, the volume of the slider portion tends to increase. Therefore, when measuring the sound pressure of the object, the sound field may be disturbed. In addition, there is a problem that it is difficult to replace the cable when a problem occurs in the cable housed in the slider.

  The present invention has been made to solve such technical problems, and the object of the present invention is simple and compact that can accurately measure the sound pressure distribution of a sound source distributed in a three-dimensional space. An object is to provide a simple microphone array.

  In order to solve this problem, in the present invention, a lock mechanism that individually fixes the position of each microphone is attached to a plurality of microphones that are slidably attached. That is, the microphone to which the present invention is applied is a microphone used in a microphone array that detects sound emitted from a sound source distributed in a three-dimensional space, and includes a sensor unit that detects sound pressure from the sound source, a sound source, And a position adjusting means for adjusting the distance to the sensor unit.

  In the microphone to which the present invention is applied, the position adjusting means includes a rod-like member that holds the sensor portion at the tip and moves the sensor portion in the front-rear direction, and a lock mechanism portion that adjusts the operating resistance of the rod-like member. It is characterized by providing.

  Further, in the microphone to which the present invention is applied, the lock mechanism unit is in contact with the holding unit that slidably holds the rod-shaped member, the operation unit that is attached to the rear end portion of the rod-shaped member, and the holding unit. One end of the wire is connected to the sensor portion directly or via another member, and the other end is connected to the operation portion.

  Further, the microphone to which the present invention is applied includes a cable for transmitting a signal detected by the sensor unit, and this cable is wired in the longitudinal direction along the rod-shaped member. The increase in the volume of can be reduced.

  Next, the present invention is a microphone array that detects sound emitted from sound sources distributed in a three-dimensional space, and a plurality of sensor units that detect sound pressure from the sound sources are arranged in substantially the same direction. A microphone and a frame in which the plurality of microphones are arranged along a plane or a curved surface, and each of the plurality of microphones includes a position adjusting unit that adjusts a distance between the sound source and the sensor unit. It can be understood as a microphone array.

  The position adjusting means in the microphone array to which the present invention is applied is characterized in that each of the plurality of microphones is pushed out in accordance with the shape of the casing including the sound source.

  Moreover, it is preferable that the microphone in the microphone array to which the present invention is applied has a holding portion that attaches the microphone to the frame and slidably holds a rod-like member that moves the sensor portion back and forth.

  According to the present invention, a simple and compact microphone array that can accurately measure the sound pressure distribution of a sound source distributed in a three-dimensional space can be obtained.

The best mode for carrying out the present invention (hereinafter referred to as an embodiment of the present invention) will be described below in detail with reference to the accompanying drawings.
FIG. 1 is a diagram for explaining a sound pressure distribution analysis system using a microphone array to which the present embodiment is applied. The sound pressure distribution analysis system 1 shown in FIG. 1 has a microphone array 2 that holds a plurality of microphones 20 in a frame 30, an amplifier 4 that amplifies a sound signal input from the microphone array 2, and is amplified by the amplifier 4. An analysis terminal 6 for analyzing the sound pressure distribution based on the sound signal and a measurement object 8 for measuring the sound pressure distribution are arranged.

  The microphone array 2 includes a plurality of microphones 20 and a frame 30 that holds the microphones 20. The microphone array 2 detects sound pressure emitted from the measurement object 8 that is a sound source, and detects an electrical signal (hereinafter, a sound signal). Is output to the amplifier 4 as follows.

  The amplifier 4 is an amplifier capable of amplifying a multi-channel signal, amplifies the sound signal at an amplification factor set by the analysis terminal 6, and outputs it to the analysis terminal 6.

  The analysis terminal 6 is a computer in which sound field analysis software is installed, and A / D converts the sound signal input from the amplifier 4 and records it as a time waveform. Furthermore, the analysis terminal 6 displays an image of the sound pressure distribution that changes temporally and spatially based on the recorded time waveform. For example, the analysis terminal 6 displays the sound distribution at the time point designated by the user or the time average distribution of the sound during the period designated by the user in a contour map.

  In the following description, the direction of the measurement object 8 as viewed from the microphone array 2 is referred to as the front, and the direction away from the measurement object 8 is referred to as the rear.

  FIG. 2 is a diagram for explaining the frame 30. The frame 30 illustrated in FIG. 2 includes a holding frame 310 that holds the microphone 20 and a stand frame 320 that holds the holding frame 310 upright. The holding frame 310 has a lattice shape, and each microphone 20 is fixed by being fitted into a corner of each lattice of the holding frame 310.

  In the present embodiment, the lattice spacing of the holding frame 310 is about 100 mm. Since the distance between the holding frames 310 close to each other is preferably approximately three times the measurement distance from the tip of the microphone 20 to the measurement object 8 at the time of sound pressure measurement, the distance at the time of sound pressure measurement in the present embodiment. The measurement distance from the tip of the microphone 20 to the measurement object 8 is preferably between 30 mm and 40 mm.

  FIG. 3 is a diagram for explaining the microphone 20. The microphone 20 shown in FIG. 3 includes a sensor 210 that detects sound pressure, a preamplifier 220 that amplifies a sound signal input from the sensor 210, an attachment / detachment unit 230 that detachably holds the preamplifier 220, and an attachment / detachment unit 230. A slide part 240 (rod-like member) joined at the front end part, a protective member 250 joined to the attaching / detaching part 230, a signal cable 260 for transmitting a sound signal inputted from the preamplifier 220 to the amplifier 4 (FIG. 1), Connected to the operation unit 280 and the attaching / detaching unit 230, connected to the wire 270 that goes around the circumference of the holding unit 290, the operation unit 280 that is connected to the wire 270, and changes the tension of the wire 270, and the operation unit 280, The cable clip 285 that holds the cable 260 and the holding frame 310 (FIG. 2) are fitted, and the slide portion 240 is slid. Having a holding portion 290 which penetrates in a ready, a.

  In the microphone 20 shown in FIG. 3, the sensor 210 converts, for example, sound pressure into an electrical signal (sound signal) and outputs it to the preamplifier 220. The center of the sensor 210 is disposed so as to be on an extension line (sliding line) of a trajectory through which the center of the sliding portion in the sliding part 240 passes in order to avoid positional deviation due to the rotation of the sliding part 240. The preamplifier 220 amplifies the sound signal to a level that allows the sound signal to flow through the signal cable 260, and outputs the amplified signal to the amplifier 4 via the signal cable 260.

  The slide part 240 penetrates the holding part 290 in a slidable state, and the operating resistance with the holding part 290 is adjusted by a lock mechanism constituted by the wire 270 and the operation part 280.

  As shown in FIG. 3, the signal cable 260 is routed rearward out of the sliding line from the rear part of the preamplifier 220. At this time, the signal cable 260 can be prevented from sagging by gripping the signal cable 260 with the cable clip 285 connected to the operation portion 280 at the rear of the slide portion 240. With such a configuration, it is possible to avoid an increase in the volume of the slide portion 240 caused by passing the signal cable 260 through the slide portion 240. Further, since the access to the signal cable 260 is easy, the signal cable 260 can be easily replaced even when the signal cable 260 is defective.

  FIG. 4 is a diagram illustrating the holding unit 290. 4A is an overall view of the holding portion 290, and FIG. 4B is a cross-sectional view and a side view of the holding portion 290. The holding part 290 shown in FIG. 4 has a wire winding groove 291, a frame attachment groove 292, and a slide hole 293.

  As shown in FIG. 4, the slide portion 240 (FIG. 3) passes through the slide hole 293, and the friction between the inside of the slide hole 293 and the slide portion 240 (FIG. 3) is smooth surface finish or lubrication. It can be easily slid by application of the agent. The wire 270 (FIG. 3) is wound once along the wire winding groove 291, and an operating resistance is generated in the slide portion 240 (FIG. 3) due to this winding and tension on the wire 270 (FIG. 3). The tension of the wire 270 (FIG. 3) is loosened by the operation of the operation unit 280. When this operation is performed, the tightening force by the wire 270 (FIG. 3) is reduced and the operating resistance of the slide unit 240 (FIG. 3) is reduced. Decrease.

  As shown in the cross-sectional view of FIG. 4B, the frame attachment groove 292 is formed on one side surface and the lower side of the holding portion 290 so as to attach the holding portion 290 to the frame 30 (FIG. 2). When the holding portion 290 is fixed to the frame 30 (FIG. 2), the frame attaching groove 292 is fitted into the corner of each lattice of the holding frame 310 (FIG. 2), and the holding portion 290 is fixed. The holding portion 290 is formed of, for example, a thermoplastic resin, and the width of the frame attachment groove 292 is slightly narrower than the diameter of the holding frame 310 (FIG. 2), so that it is sufficient to withstand its own weight or unexpected contact. A fixing force can be obtained.

  FIG. 5 is a diagram illustrating a method of fixing the holding portion 290 with a leaf spring. FIG. 5 shows one of the holding frames 310, a holding portion 290 fixed to the holding frame 310, and a leaf spring 330 for reinforcing the fixing of the holding portion 290.

  As shown in FIG. 5, the leaf spring 330 has a bifurcated portion that contacts the side surface of the holding portion 290. When fixing the holding part 290 to the holding frame 310, the bifurcated portion of the leaf spring 330 is brought into contact with the side surface of the holding part 290, and one side of the leaf spring 330 is fixed to the holding part 290 of the holding frame 310. The holding portion 290 is pressed against the holding frame 310 using the elasticity of the spring against the corner opposite to the side. By using the leaf spring 330, it is possible to enhance the fixing force when the holding portion 290 is fixed to the holding frame 310.

  FIG. 6 is a diagram illustrating the operation unit 280. FIG. 6A is an overall view of the operation unit 280, and FIG. 6B is a cross-sectional view of the operation unit 280. The operation unit 280 illustrated in FIG. 6 includes a stopper 281, an operation button 282, a finger hook 283, a wire 270 coupled to the operation button 282, and a spring 284 provided between the stopper 281 and the operation button 282. Have.

  As shown in FIG. 6, the stopper 281 is connected to the end of the slide portion 240 and serves as a base for preventing the slide portion 240 from falling off and attaching the components of the operation portion 280. The operation button 282 passes through the stopper 281 and is connected to the stopper 281 through a spring 284. Since the operation button 282 is connected via the spring 284, the tension automatically returns to the high state after the operation. Therefore, the user only has to press the operation button 282 when the user wants to slide the slide portion 240. Also, it can be performed well when operating a large number of microphones 20 (FIG. 1). The finger hook 283 is connected to the stopper 281 and facilitates the user to press the operation button 282. By adopting such a configuration, the user can adjust the operating resistance of the slide portion 240 at hand, and the positioning of the multiple microphones 20 (FIG. 1) can be performed smoothly one after another. It becomes possible.

  In order for the microphone 20 not to disturb the sound field, it is necessary that there is no portion having a size that can prevent the sound from passing in the direction in which the sound travels. Usually, the frequency measured by the sound pressure meter is about 12 kHz, and the wavelength in this case is about 28 mm. Therefore, when viewed from the front, which is the traveling direction of the sound source, if the shape of the microphone 20 does not include a circle having a diameter of 28 mm, sound pressure can be measured without disturbing the sound field.

  Next, a method for deforming the microphone array 2 according to the shape of the measurement object 8 will be described. First, for all the microphones 20, the operation unit 280 is adjusted to loosen the wires 270, and then the microphones 20 are pulled backward. Next, the microphone array 2 is brought close to the object. For each microphone 20, the operation unit 280 is adjusted to loosen the wire 270, and the slide unit 240 is pushed forward as much as necessary. When each microphone 20 is desired to be closest to the measurement object 8, the protection member 250 provided at the tip of the microphone 20 pushes the slide portion 240 to a position where it abuts on the measurement object 8. If there is a possibility that unnecessary chatter or the like may occur with the protective member 250 kept in contact with the measurement object 8, the entire microphone array 2 is finally pulled backward.

  When the microphone array 2 is deformed in this way, the distance from each microphone 20 to the measurement object 8 can be made substantially uniform according to the unevenness of the measurement object 8. For this reason, the sound pressure distribution analysis system 1 using the microphone array 2 can accurately analyze the sound pressure distribution even when the measurement object 8 has an uneven shape.

  As an application example of the present invention, for example, the present invention can be applied to measurement of sound pressure distribution of an image forming apparatus having a plurality of vibration sources and noise generation sources.

It is a figure explaining the sound pressure distribution analysis system using a microphone array. It is a figure explaining a frame. It is a figure explaining a microphone. It is a figure explaining a holding part. FIG. 4A is an overall view of the holding portion, and FIG. 4B is a cross-sectional view and a side view of the holding portion. It is a figure explaining the fixing method of the holding | maintenance part by a leaf | plate spring. It is a figure explaining an operation part. 6A is an overall view of the operation unit, and FIG. 6B is a cross-sectional view of the operation unit.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Sound pressure distribution analysis system, 2 ... Microphone array, 4 ... Amplifier, 6 ... Analysis terminal, 8 ... Measurement object, 20 ... Microphone, 30 ... Frame, 210 ... Sensor, 220 ... Preamplifier, 230 ... Detachable part, 240 ... Slide part, 250 ... Protection member, 260 ... Signal cable, 270 ... Wire, 280 ... Operation part, 281 ... Stopper, 282 ... Operation button, 283 ... Finger hook, 284 ... Spring, 285 ... Cable clip, 290 ... Holding part 291: Wire winding groove, 292 ... Frame mounting groove, 293 ... Slide hole, 310 ... Holding frame, 320 ... Stand frame, 330 ... Leaf spring

Claims (7)

A microphone used in a microphone array for detecting sound emitted from a sound source distributed in a three-dimensional space,
A sensor unit for detecting sound pressure from the sound source;
Position adjusting means for adjusting the distance between the sound source and the sensor unit;
A microphone, comprising: The position adjusting means includes
A rod-shaped member that holds the sensor part at the tip and moves the sensor part in the front-rear direction;
The microphone according to claim 1, further comprising: a lock mechanism unit that adjusts an operating resistance of the rod-shaped member. The locking mechanism is
A holding portion for slidably holding the rod-shaped member;
An operation unit attached to a rear end of the rod-shaped member;
The wire according to claim 2, further comprising: a wire that contacts the holding unit, has one end connected to the sensor unit directly or through another member, and the other end connected to the operation unit. Microphone.   The microphone according to claim 2, further comprising a cable that transmits a signal detected by the sensor unit, wherein the cable is wired in a longitudinal direction along the rod-shaped member. A microphone array that detects sound emitted from sound sources distributed in a three-dimensional space,
A plurality of microphones arranged with sensor portions for detecting sound pressure from the sound source oriented in substantially the same direction;
A frame that arranges the plurality of microphones along a plane or a curved surface, and
Each of the plurality of microphones includes a position adjusting unit that adjusts a distance between the sound source and the sensor unit.   The microphone array according to claim 5, wherein the position adjusting unit pushes out the microphone according to a shape of a casing including the sound source.   The microphone array according to claim 6, wherein the microphone includes a holding portion that slidably holds a rod-like member that attaches the microphone to the frame and moves the sensor portion back and forth.

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