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JP2005091272

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DESCRIPTION JP2005091272
PROBLEM TO BE SOLVED: To provide a sound pressure distribution analysis system capable of
measuring a sound pressure distribution by automatically adjusting the position of a microphone
according to the unevenness of a measurement object. SOLUTION: The microphone array 2
includes a plurality of microphones 20 in which sensor units for detecting a sound pressure from
a sound source are arranged in substantially the same direction, and a photographing means for
photographing a measurement object 8 having a sound source. A sound pressure distribution
analysis system 1 comprising: a camera pair 7; and position adjustment means for adjusting the
distance between the sensor unit and the measurement object 8 for each of the plurality of
microphones 20 based on image information captured by the camera pair 7 . The distance
between the sensor unit and the measurement object 8 is automatically adjusted by the
movement amount calculated by the controller 9 based on the difference between the image
information captured by the camera pair 7. . [Selected figure] Figure 1
Sound pressure distribution analysis system
[0001]
The present invention relates to a sound pressure distribution analysis system, and more
particularly to a sound pressure distribution analysis system using a microphone array in which
a plurality of microphones are arrayed to detect sound at a plurality of positions.
[0002]
Microphone array technology, in which multiple microphones are arranged along a flat or curved
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surface and sound pressure is measured at multiple locations, is used in many situations.
For example, when taking measures against noise of the device, it is necessary to specify the
sound pressure distribution of the device having a sound source at a plurality of positions. The
microphone array technology is particularly effective for measuring the sound pressure
distribution of such devices (see, for example, Non-Patent Document 1).
[0003]
Matsushita Techno-Trading, Electronic Measurement, SV Solution, "BK Company Products",
[online], [search on September 12, 2003], Internet <URL: http: // www. mitc. co. jp / msm / sv /
bk / stsf / stsf. html>
[0004]
By the way, the sound sources of the device are distributed in a three-dimensional space, and
may be described as a plane on which the microphones are arranged (hereinafter, referred to as
an array plane.
) The distance of the eyebrows 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 不 is uneven, a
difference may occur in the sound propagation path, and the sound pressure distribution may
not be accurately measured. However, if the attenuation amount simply changes due to the
different propagation paths, this can be corrected mathematically. However, when a difference
occurs in the propagation path, the change of the sound diffusion range, the problem of
interference, etc. occur, and the estimation of the sound pressure distribution becomes very
difficult.
[0005]
Due to the non-uniform distance between the sound source and the microphone 我 々, we have
arranged a plurality of slideably mounted microphones in order to compensate for differences in
the distance between the sound source and the microphone. Was pressed against the target
whose sound pressure distribution is to be measured, and the microphones fixed according to the
shape of the target were fixed, and then a method of measuring the sound pressure was reported
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(Japanese Patent Application No. 2002-369372) . In this method, after sliding the plurality of
microphones according to the shape of the object, the distance between the sound source and the
microphones is adjusted by manually aligning the respective microphones.
[0006]
However, in the case of measuring the sound pressure distribution for the purpose of product
evaluation or the like in the quality evaluation department of industrial products, higher accuracy
is required. In addition, in order to ensure the resolution of the sound pressure distribution, it is
necessary to use many microphones. Furthermore, the alignment of the individual microphones
must be managed with high accuracy. For this reason, in applications where such a high system
is required, it is not realistic to manually align individual microphones, but usually to perform
automatic alignment to improve reliability. Is required.
[0007]
As a method of automatically performing alignment of the microphone, for example, a method of
moving the microphone to directly contact the microphone itself or a member integrated
therewith or a distance between the microphone and the sound source using some non-contact
sensor There is a method of measuring and moving the microphone according to the
measurement result.
[0008]
In the former method, a thin film or a thin film whose function is lost due to contact with the
microphone, if the measurement target which is the sound source has portions such as various
switches or opening / closing parts that cause some operation by pressing the microphone.
When it has an optical lens portion etc., since it can not be used in reality, there is a limit in terms
of versatility.
[0009]
On the other hand, in the latter method, as a method of measuring the distance between the
microphone and the sound source, there is a method of measuring by attaching a sensor to each
microphone, or a method of measuring the distance remotely using a laser, for example.
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However, attaching a sensor to each microphone is undesirable because it increases the volume
of the microphone portion and disturbs the sound field to be measured.
Further, the measurement method using a laser is not suitable when measuring an industrial
product having a complicated component configuration, because of limitations on the surface
reflection condition to be measured.
[0010]
The present invention has been made to solve such technical problems, and the purpose thereof
is to automatically adjust the position of the microphone according to the unevenness of the
object to be measured and measure the sound pressure distribution. It is to provide a sound
pressure distribution analysis system that can
[0011]
In order to solve this problem, in the present invention, the position of the microphone is
automatically adjusted based on the video information by the plurality of imaging devices.
That is, in the sound pressure distribution analysis system to which the present invention is
applied, a measurement target having a sound source and a microphone array provided with a
plurality of microphones in which sensor units for detecting the sound pressure from the sound
source are arranged in substantially the same direction. Providing a plurality of photographing
means for photographing an object, and position adjustment means for adjusting the distance
between the sensor unit and the measurement object for each of the plurality of microphones by
the image information photographed by the plurality of photographing means; It is a feature.
[0012]
In the sound pressure distribution analysis system to which the present invention is applied, as a
plurality of photographing means, a pair of photographing in which a predetermined distance
and an angle with the measurement object are set such that the entire image of the measurement
object falls within the photographing range. It is preferably an apparatus.
[0013]
Further, in the sound pressure distribution analysis system to which the present invention is
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applied, the position adjustment means drives the drive unit by the rod-like member for moving
the sensor unit in the back and forth direction, the drive unit for driving the rod-like member,
and the image information. A controller for calculating a drive signal, and a drive cable for
transmitting the drive signal calculated by the controller to a drive unit.
[0014]
Furthermore, in the sound pressure distribution analysis system to which the present invention is
applied, the controller is characterized in that the movement amount of each of the plurality of
microphones is calculated based on the difference between the video information photographed
by each of the pair of photographing devices. .
[0015]
According to the present invention, it is possible to obtain a sound pressure distribution analysis
system capable of measuring the sound pressure distribution by automatically adjusting the
position of the microphone according to the unevenness of the measurement object.
[0016]
Hereinafter, with reference to the accompanying drawings, the best mode for carrying out the
present invention (hereinafter referred to as an embodiment of the present invention).
Will be described in detail.
FIG. 1 is a diagram for explaining a sound pressure distribution analysis system to which the
present embodiment is applied.
The sound pressure distribution analysis system 1 shown in FIG. 1 includes a microphone array 2
holding a plurality of microphones 20 in a frame 30, an amplifier 4 for amplifying a sound signal
input from the microphone array 2, and amplification by the amplifier 4 Obtained from an
analysis terminal 6 analyzing sound pressure distribution based on a sound signal, a
measurement object 8 for measuring the sound pressure distribution, a camera pair 7
photographing the surface shape of the measurement object 8, and a camera pair 7 A controller
9 that analyzes the received video information and controls the microphone array 2 is disposed.
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[0017]
The microphone array 2 has a plurality of microphones 20 and a frame 30 for holding the
microphones 20. The microphone array 2 detects the sound pressure emitted from the
measurement object 8 which is a sound source, and an electrical signal (hereinafter referred to as
a sound signal). There is a case.
Output to the amplifier 4 as
[0018]
The amplifier 4 is an amplifier capable of amplifying a multi-channel signal, amplifies the sound
signal at the amplification factor set by the analysis terminal 6, and outputs the sound signal to
the analysis terminal 6.
[0019]
The analysis terminal 6 is a computer in which sound field analysis software is installed, 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 temporally and spatially varying
sound pressure distribution based on the recorded temporal waveform. For example, the analysis
terminal 6 displays the distribution of sound at a time designated by the user or the distribution
of time averages of sound in a period designated by the user in a contour map.
[0020]
The camera pairs 7 are respectively installed at positions (e.g., 1 m) sufficiently away from the
measurement object 8, and their positions and angles are adjusted so that the entire
measurement object 8 falls within the imaging range. The video information taken by the camera
pair 7 is both sent to the controller 9.
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[0021]
The controller 9 calculates the amount of unevenness of each part of the measurement object 8
based on the image information from the camera pair 7, determines the amount of movement of
each microphone 20 according to the calculated amount of unevenness, and accordingly the
microphones A drive signal for 20 is sent. The calculation method of the unevenness amount of
the measurement object 8 by the controller 9 will be described later.
[0022]
In the following description, the direction of the measurement object 8 is referred to as the front,
and the direction away from the measurement object 8 as the rear as viewed from the
microphone array 2.
[0023]
FIG. 2 is a diagram for explaining the frame 30. As shown in FIG.
The frame 30 shown in FIG. 2 has a holding frame 310 for holding the microphone 20 and a
stand frame 320 for holding the holding frame 310 upright. The holding frame 310 has a lattice
shape, and the microphones 20 are detachably held by the holding frame 310 by attachment or
the like. By holding the microphones 20 detachably on the holding frame 310, for example, when
a failure occurs in the microphones 20, they can be removed for repair / replacement.
[0024]
In the present embodiment, the lattice spacing of the holding frame 310 is about 100 mm. Since
it is desirable that the distance between the holding frames 310 in close proximity to each other
is 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 sound pressure
measurement in this embodiment is performed. The measuring distance from the tip of the
microphone 20 to the measuring object 8 is preferably between 30 mm and 40 mm.
[0025]
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FIG. 3 is a diagram for explaining the microphone 20. As shown in FIG. The microphone 20
shown in FIG. 3 includes a sensor 210 for detecting a sound pressure, a preamplifier 220 for
amplifying a sound signal input from the sensor 210, an attachment / detachment unit 230 for
detachably holding the preamplifier 220, an attachment / detachment unit 230 and a front end
The slide part 240 (rod-like member) joined in one part and having a row of teeth connected in a
row, the signal cable 250 for transmitting the sound signal inputted from the preamplifier 220 to
the amplifier 4, and the slide part 240 A cable clip 260 for gripping the cable 250, a holder 270
for passing the slide 240 inward, a driver 280 connected to the holder 270 and transmitting
power by meshing with the teeth of the slide 240, and a driver And 280 a drive cable 290 for
supplying power and drive signals.
[0026]
The sensor 210, for example, converts sound pressure into an electrical signal (sound signal) and
outputs the signal to the preamplifier 220. The center of the sensor 210 is disposed on an
extension line (sliding line) of a locus through which the center of the sliding portion in the slide
portion 240 passes in order to avoid positional deviation due to the rotation of the slide portion
240. The preamplifier 220 amplifies the sound signal to a level that can flow through the signal
cable 250, and outputs the sound signal to the amplifier 4 via the signal cable 250.
[0027]
In the holding portion 270, frame attachment grooves (not shown) are formed on one side
surface and the lower side of the holding portion 270 for attaching to the frame 30 (see FIG. 2).
When the holding portion 270 is fixed to the frame 30 (see FIG. 2), the frame mounting groove is
fitted into the holding frame 310 (see FIG. 2), and the holding portion 270 is fixed. In addition, in
order to reinforce fixation to the flame | frame 30 (refer FIG. 2) of the holding | maintenance part
270, you may use together a leaf spring etc., for example.
[0028]
FIG. 4 is a diagram for explaining the drive unit 280. As shown in FIG. 4 (a) is a side view of the
drive unit 280, and FIG. 4 (b) is a front view of the drive unit 280. FIG. The drive unit 280 shown
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in FIG. 4A includes a gear 282 that meshes with the row of teeth of the slide unit 240, and a
motor 281 that drives the gear 282.
[0029]
As shown in FIG. 4, the drive unit 280 receives power from the drive cable 290 (see FIG. 3) and
rotates the motor 281. The motor 281 is connected to a gear 282 which meshes with the teeth of
the slide 240 on the microphone 20 (see FIG. 3). As a result, the slide portion 240 slides and
moves, and the microphone 20 (see FIG. 3) can be moved back and forth.
[0030]
Next, a method of reading the unevenness of the object to be measured 8 by the controller 9
based on the video information from the camera pair 7 will be described. FIG. 5 is a view for
explaining a method in which the controller 9 (see FIG. 1) reads the unevenness of the
measurement object 8 based on the imaging information of the camera pair 7 (see FIG. 1). FIG. 5
(a) is a first example, and FIG. 5 (b) is a second example. FIG. 5 shows two photographed objects
(A and B) of the measurement object 8 (see FIG. 1), and a left camera image and a right camera
image by the camera pair 7. In the case of the first example of FIG. 5 (a), the two imaging objects
(A and B) are separated by the distance d1, and in the case of the second example of FIG. 5 (b),
the two objects are The imaging subjects (A and B) exist at a distance d2 apart (d1> d2).
[0031]
Assuming that the camera pair 7 is equidistant from the measurement object 8 as shown in FIG.
5A, the positional relationship on the image of the two objects (A and B) photographed by the
camera pair 7 Depends on the distance between the subject (A and B) and the camera pair 7. For
example, considering the subject B as a reference, when the two subjects (A and B) are separated
by a distance d1, the image of the subject A is a left camera image and a right camera. It will be
shifted by Δ1 with the image. Similarly, in the case of the second example shown in FIG. 5B, the
image of the subject A is obtained when the two subjects (A and B) are separated by the distance
d2 The left camera image and the right camera image are shifted by Δ2.
[0032]
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Such a shift amount (Δ1 or Δ2) generated between the left camera image and the right camera
image corresponds to the distance between the object to be photographed (A and B) and the
camera pair 7 one to one, The amount of shift (Δ1 or Δ2) can be used to measure the distance
between the subject (A and B) and the camera pair 7. In order to examine the shift amount (Δ1
or Δ2) generated between the left camera image and the right camera image, the image of the
left camera and the image of the right camera may be shifted little by little and the location with
high correlation may be searched each time. It can be determined that the portion where the
correlation is high is a portion having a distance corresponding to the amount of deviation.
[0033]
According to this method, the movement distance of the microphone 20 is calculated by the
controller 9 according to the unevenness of the measurement object 8, and the amount of
electric power sent to the drive unit 280 of the microphone 20 is adjusted based on the
calculation result. When each component of the microphone array 2 is relatively large and
interferes with imaging, the microphone array 2 may be moved out of the imaging range
manually or automatically.
[0034]
The present invention can be applied to, for example, measurement of sound pressure
distribution of an image forming apparatus having a plurality of vibration sources and noise
generation sources.
[0035]
It is a figure explaining a sound pressure distribution analysis system.
It is a figure explaining a frame. It is a figure explaining a microphone. It is a figure explaining a
drive part. Fig.4 (a) is a side view of a drive part, and FIG.4 (b) is a front view of a drive part. It is
a figure explaining the method to which a controller reads the unevenness | corrugation of a
measurement object based on the imaging information of a camera pair. FIG. 5 (a) is a first
example, and FIG. 5 (b) is a second example.
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Explanation of sign
[0036]
Reference Signs List 1 sound pressure distribution analysis system 2 microphone array 4
amplifier 6 analysis terminal 7 camera pair 8 measurement object 9 controller 20 microphone
30 frame 210 sensor 220 ... Preamplifier, 230 ... Detachable part, 240 ... Slide part, 250 ... Signal
cable, 260 ... Cable clip, 270 ... Holding part, 280 ... Drive part, 281 ... Motor, 282 ... Gear, 290 ...
Drive cable, 310 ... Holding frame , 320 ... stand frame
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