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JP2005249751

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This translation is machine-generated. It cannot be guaranteed that it is intelligible, accurate,
complete, reliable or fit for specific purposes. Critical decisions, such as commercially relevant or
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DESCRIPTION JP2005249751
An object of the present invention is to make it possible to effectively measure abnormal noise in
an in-vehicle abnormal noise pickup device and to easily install it in a vehicle. A vehicle abnormal
noise collecting apparatus (60) comprises a substantially hexagonal sound collecting unit (62)
having six sound collecting horns (70) arranged circumferentially, a stage (64) on which the
sound collecting unit (62) is mounted, and a stage (64). And a mounting leg 66 provided at the
bottom of the housing. Each sound collecting horn 70 has a flared shape, and the wide-mouth
side that picks up sound is directed outward, that is, in each direction inside the vehicle. Further,
the narrow end side of each sound collecting horn 70 is a portion for collecting sound, and the
nondirectional microphone 80 is inserted and provided there. By using the sound collecting horn
70, the sound pressure is increased by about 25 to 30 dB as compared to when not used, and it
is possible to efficiently detect the in-vehicle abnormal noise whose energy amount is smaller
than the background noise. [Selected figure] Figure 1
In-vehicle noise pickup device
[0001]
The present invention relates to an in-vehicle noise collecting apparatus, and more particularly to
an in-vehicle noise collecting apparatus which collects noise in each direction in a vehicle by a
microphone.
[0002]
A directional microphone can be used or a directional sound collector can be used to identify and
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measure the source of the sound generated from the vehicle.
For example, in Patent Document 1, in order to specify the sound source position in a wind
tunnel test of a vehicle, an acoustic mirror and a microphone are mounted on a traverse which is
a position moving device, and moved to the position of a sound source generated by a wind
tunnel test of the vehicle. It is disclosed that the vehicle is moved vertically and rearwardly from
the side surface of the vehicle.
[0003]
JP 2002-267569 A
[0004]
Whether using directional microphones or directional sound collectors, move them to the
position of the sound source or aim in all directions to specify the sound source and perform
measurement. It is necessary to rotate, and as shown in Patent Document 1, a complicated
mechanism is required, and the apparatus becomes larger.
[0005]
In the vehicle, there are sounds generated by interference or rubbing between parts, etc. In order
to identify and measure the sound source of abnormal noise in these vehicles, a large-sized
device like the prior art is used I can not do it.
In addition, even if recording is performed using only a microphone, the amount of energy of
noise in the vehicle to be measured and evaluated is smaller than background noise such as road
noise, and it is difficult to perform sufficient acoustic evaluation.
Moreover, since the part which generate | occur | produces is unspecified and generate | occur |
produces from various parts simultaneously, the arrival direction of sound can not be specified
from the recorded data.
[0006]
As described above, in the prior art, it is difficult to measure and evaluate noise with a small
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amount of energy by installing it in a vehicle having a limited space.
[0007]
An object of the present invention is to provide an in-vehicle noise collecting apparatus capable
of effectively measuring noise in a vehicle.
Another object is to provide an in-vehicle noise pickup device that is easy to install in a vehicle.
The invention according to the following claims contributes to at least one of the above objects.
[0008]
1. The present invention is based on the finding that noise in a vehicle having a small amount
of sound energy can be efficiently measured in an experiment using a broad sound collecting
horn. And, by devising the shape of the sound collection horn, it can be installed in a limited
space in the vehicle, and it is possible to efficiently measure the abnormal noise from each
direction in the vehicle. The course of a series of experiments will be described below.
[0009]
First, a conical sound collecting horn was made, and the case where the sound collecting horn
and the omnidirectional microphone were used in combination was compared with the case
where only the omnidirectional microphone was used. The sound collection horn used has a cone
length of 100 mm and a cone apex angle of 40 degrees. An omnidirectional microphone is
located at the narrow end of the cone. Figure 1 shows the experimental results, in which (a) is a
combination of the sound collection horn and the omnidirectional microphone, (b) is the case of
only the omnidirectional microphone, and in each figure, the horizontal axis represents the
frequency of sound, Sound pressure is taken on the vertical axis. The experiments were
conducted with and without abnormal noise in the vehicle, and the results are shown in FIGS. 1
(a) and 1 (b). As can be seen from FIG. 1 (b), in the case where only the nondirectional
microphone is used, the sound pressure 20 measured when there is an abnormal noise in the
vehicle almost overlaps the sound pressure 22 when there is no abnormal noise, Sound detection
is difficult. In FIG. 1 (a), a difference of about 15 dB is detected in the abnormal noise portion as
shown by the solid pressure in the vehicle when there is an abnormal noise in the vehicle and by
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the broken line when the acoustic pressure 12 when there is no abnormal noise. Be done. In FIG.
1 (a), a resonance portion 14 is shown by using a sound collecting horn.
[0010]
As described above, it is understood that, by using the wide-spreading sound collecting horn, it is
possible to efficiently measure the in-vehicle abnormal noise which is difficult to detect when
using only the microphone and has a small amount of sound energy.
[0011]
FIG. 2 shows the difference in sound pressure collected when the cone shape is changed
variously.
Here, for the four types of sound collecting horns when the cone length L of the sound collecting
horn is 190 mm and 100 mm and the apex angle θ of the cone is 40 degrees and 20 degrees,
the vertical axis and horizontal axis similar to FIG. 1 Shows the frequency characteristics of the
sound pressure. Note that the sound pressure 22 of the nondirectional microphone is shown by a
broken line for easy comparison. FIG. 2 (a) shows the sound pressure 30 of the largest type of
sound collecting horn, and FIG. 2 (d) shows the sound pressure 34 of the smallest sound
collecting horn. FIG. 2 (c) is the same as that described in FIG. 1 (a).
[0012]
As can be seen from FIGS. 2 (a) to 2 (d), although the four types of sound collecting horns have
resonance characteristics, efficiently detect in-vehicle noise which is difficult to identify with all
non-directional microphones. Can. It can also be seen that there is a difference in the degree of
detection depending on the shape of the sound collection horn. For example, among the four
types in FIG. 2, L = 100 mm and θ = 40 degrees in FIG.
[0013]
Next, the types of sound collecting horns were increased, and the frequency characteristics and
directivity characteristics and the size of the entire shape were evaluated. FIG. 3 is a list of shapes
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of sound collecting horns used in the experiment. The types of sizes were five types of TYPE1TYPE5, and two types of cone shapes and square pyramid shapes were prepared for each, and a
total of 10 types of sound collecting horns were used. In addition, as the maximum outer
diameter, a size obtained by adding 20 mm to the diameter d of the mouth that picks up the
sound on the wide mouth side is the vertical size and the horizontal size, and a size obtained by
adding 10 mm to the length L of the cone or square pyramid is the length size I am representing
you.
[0014]
FIG. 4 is a diagram showing a method of measuring the directivity characteristic. A sound
collecting device 50 combining a sound collecting horn and a nondirectional microphone is
disposed at a predetermined distance from the sound source 40, and a line connecting the sound
source 40 and the sound collecting device 50 is used as a reference axis, The sound device 50 is
tilted. The directivity characteristic can be evaluated by the degree of the sound pressure
reduction amount with respect to the inclination angle φ. For example, based on the angle φ = 0
°, the directivity characteristic can be represented by the inclination angle φ at which the
sound pressure decreases by −3 dB.
[0015]
FIG. 5 is a table summarizing the evaluation results. The evaluation items are three items of size,
frequency characteristics and directivity, and the evaluation points are four-step evaluation. The
size of the maximum outer shape described in FIG. 3 is small and ◎ = 3 that can be sufficiently
disposed in a general passenger car, and x = 0 that is difficult to be disposed in a vehicle. The
frequency characteristics are based on the sound pressure-frequency characteristics as described
in FIG. 1 and FIG. 2, and based on the sound pressure-frequency characteristics of the
nondirectional microphone, the evaluation point is improved as the sound pressure increase is
larger. . At this time, as described in FIG. 4, the inclination angle φ is changed and evaluated. The
directivity is a balance between the sound collection characteristic and the sound insulation
characteristic, but the smaller the sound pressure reduction amount at the inclination angle φ =
30 °, the better the sound collection characteristic, and the sound pressure from the inclination
angle φ = 40 ° As the amount of decrease is larger, the sound insulation characteristic is better,
and the portion where the amount of decrease in sound pressure is −3 dB is evaluated as a
standard.
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[0016]
From the results of FIG. 5, it can be understood that the conical evaluations of TYPE 1 and TYPE
2 have high overall evaluation. Data of frequency characteristics and directivity characteristics
for conical shapes TYPE1 and TYPE2 are shown in FIG.
[0017]
6 and 7 show data of frequency characteristics, and FIG. 6 shows the results for the conical
shape TYPE 1 and FIG. 7 shows the results for the conical shape TYPE 2. 6 (a) and 7 (a) are
vertical and horizontal axes similar to FIGS. 1 and 2, and when the inclination angle φ described
in FIG. 4 is 0 °, 30 °, 60 °, 90 ° The sound pressure-frequency characteristics of are shown
in the same graph. The sound pressure 22 of the nondirectional microphone is shown as a
reference of comparison. In FIGS. 6B and 7B, the vertical axis represents the increase in sound
pressure, that is, the increase from the sound pressure 22 of the nondirectional microphone. As
described above, a sound pressure increase of up to about 20 dB or about 30% is observed in
TYPE 1 of conical shape, and a sound pressure increase of up to about 25 dB or about 35% is
observed in TYPE 2 of conical shape.
[0018]
Fig. 8 is data showing sound collection characteristics among directivity characteristics. Fig. 8 (a)
is the one with conical shape TYPE1, and Fig. 8 (b) is the one with conical shape TYPE2. The
sound pressure drop from 0 ° is taken. The parameter is the frequency f of the sound source.
Thus, as the frequency f of the sound source increases, the sound pressure drop becomes more
pronounced. Since the frequency f of the sound source is about 1-5 kHz in the vehicle interior,
the frequency in this range is finely taken. Now, looking at the data in FIG. 8 with a sound
pressure drop (−) of 3 dB as a guide, in TYPE 1 the sound pressure drop of f = 5 kHz is (−) 3 dB
at an inclination angle of φ = 30 °. On the other hand, in the case of TYPE 2, the sound
pressure reduction amount of f = 5 kHz is (−) 5 dB at the inclination angle φ = 30 °. Therefore,
it is preferable that the sound pressure decrease amount at the angle is small when the
inclination angle φ = 30 ° is used as the sound collection characteristic, and therefore, TYPE 1
is a better evaluation.
[0019]
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FIG. 9 is data showing sound insulation characteristics among the directivity characteristics. FIG.
9 (a) is an inclination angle of 30 °, and (b) is a sound pressure decrease amount at an
inclination angle φ = 40 ° and the frequency f of the sound source. It shows the relationship.
The conical shape TYPE1 is shown by an open bar, and the conical shape TYPE2 is shown by a
hatched bar. Now, looking at the data in FIG. 9 with a sound pressure drop (−) of 3 dB as a
guide, the degree of sound pressure drop is within (−) 3 dB in the range of 1 to 4 kHz with TYPE
1 at inclination angle φ = 40 ° . On the other hand, in TYPE 2 the degree of sound pressure
drop is within (-) 3 dB in the range of 1-2 kHz, but at 2.5-5 kHz the degree of sound pressure
drop exceeds (-) 3 dB. As the sound insulation characteristic, it is desirable that the unnecessary
sound be isolated, that is, it is preferable that the amount of decrease in sound pressure be large,
so TYPE 2 is a better evaluation.
[0020]
Although the characteristics of the conical shapes TYPE1 and TYPE2 are as described above, it
can be considered that there is no significant difference between the two abilities. Therefore, the
conical shape TYPE1 will be representatively considered to be installed inside the vehicle. From
the directivity data, the range in which the sound pressure drop of one sound collecting horn
falls within (−) 3 dB is about the inclination angle φ = 30 °. That is, the conical shape TYPE 1
can reduce the sound pressure drop to (−) 3 dB within a range of ± 30 ° from the central axis
of the cone. Therefore, it can be understood that when the cone shape type 1 is arranged on the
circumference with the wide-mouthed pick-up side facing each direction of the vehicle interior at
every 60 °, it is possible to collect the vehicle interior noise in all directions. That is, it is
understood that it is preferable to arrange the sound collecting horns of conical shape type 1
circumferentially at a pitch of 60 ° with six sound collecting horns centered on the sound
collecting side of the narrow mouth to constitute the entire sound collecting device.
[0021]
2. An in-vehicle noise collecting apparatus according to the present invention is an in-vehicle
noise collecting apparatus for collecting noise in each direction in the vehicle with a microphone,
and separating noise in each direction in the vehicle from each other. A plurality of sound
collecting horns having wide-spreading shapes, the wide mouth side for picking up the sound
being on each of the plurality of sound collecting horns arranged toward each direction in the
vehicle and the narrow mouth side collecting the sounds of each sound collecting horn And a
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plurality of omnidirectional microphones disposed.
[0022]
In addition, the sound collecting horn preferably has a conical shape or a quadrangular pyramid
shape. In addition, it is preferable that the sound collection horn has an opening angle of
approximately 40 degrees.
[0023]
Further, it is preferable that a plurality of sound collecting horns be arranged circumferentially at
intervals of approximately 60 degrees, with each narrow end side as the center side.
[0024]
Further, in the vehicle noise collecting apparatus according to the present invention, it is
preferable to have an attachment portion attachable to a headrest of a driver's seat of the vehicle.
[0025]
As described above, according to the noise suppressing device for a vehicle according to the
present invention, noise in the vehicle can be measured effectively.
In addition, according to the vehicle abnormal noise collector according to the present invention,
installation in the vehicle is easy.
[0026]
Hereinafter, embodiments of the present invention will be described in detail with reference to
the drawings.
FIG. 10 is a perspective view of the vehicle abnormal noise collector 60. The all-sounds noise
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collecting apparatus 60 for a vehicle is provided under a substantially hexagonal sound
collecting section 62 in which six sound collecting horns 70 are arranged circumferentially, a
stage 64 on which the sound collecting section 62 is mounted, and a lower part of the stage 64
Mounting feet 66 are included. The size of the substantially hexagonal shape of the sound
collection unit 62 is about 20 cm, and its height is about 10 cm.
[0027]
FIG. 11 (a) is a front view of the vehicle abnormal noise collection device 60, and FIG. 11 (b) is a
side view thereof. Below the stage 64, a microphone insertion hole (not shown) is provided, and
the omnidirectional microphone 80 is inserted into the narrow end portion of each of the six
sound collecting horns 70 using it. Further, a fixing hole 68 such as a screw hole for positioning
and fixing the nondirectional microphone 80 to be inserted is provided in the stage 64. The
mounting leg 66 can be properly tilted as shown in FIG. 11 (b).
[0028]
FIG. 12 is a bottom view of the abnormal noise collection device 60 for a vehicle. Each of the six
sound collecting horns 70 is separated and arranged circumferentially at an interval of 60
degrees. Each sound collecting horn 70 has a flared shape, and the wide-mouth side that picks up
sound is directed outward, that is, in each direction inside the vehicle. Further, the narrow end
side of each sound collecting horn 70 is a portion for collecting sound, and the nondirectional
microphone 80 is inserted and provided there. Each sound collecting horn 70 is provided with a
nondirectional microphone 80 one by one. The nondirectional microphone 80 is connected to a
vehicle acoustic analysis device or the like (not shown).
[0029]
FIG. 13 is a partial cross-sectional view of the abnormal noise collection device 60 for a vehicle,
showing the arrangement of the collection horn 70 and the nondirectional microphone 80. As
shown in FIG. The sound collecting horn 70 has a conical shape, and its length L can be 80 mm,
and the apex angle θ of the cone can be 40 degrees. Alternatively, as described in FIG. 3 and the
like, a quadrangular pyramid shape may be used. Also, as in TYPE 2 of FIG. 3, one having a
length L = 120 mm and an apex angle θ = 40 degrees can also be used. The omnidirectional
microphone 80 is omnidirectional because there is no need to use a directional microphone
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intentionally, but of course, if the directivity is ± 30 ° or more, the directional axis is the center
of the sound collecting horn 70. You may use according to the axis.
[0030]
FIG. 14 is a view showing a state in which the vehicle abnormal noise collector 60 is set in the
headrest portion 92 of the vehicle 90. As shown in FIG. In order to do this, the mounting foot 66
is preferably sized to fit into the headrest mounting hole of the vehicle 90.
[0031]
As described above with reference to FIGS. 8 and 9, since the vehicle abnormal sound collector
60 is set in this manner, each of the six sound collecting horns has directivity characteristics in
the range of ± 30 °, so In all directions, noise in the vehicle can be collected without omission.
In addition, the combination of the sound collecting horn 70 and the omnidirectional microphone
80 increases the sound pressure by approximately 25 to 30 dB as compared with the case where
the sound collecting horn 70 is not used as described in FIG. In-vehicle noise can be detected
efficiently with a smaller amount of energy than noise. Further, as described above, the size of
the all-around of the vehicle abnormal noise collection device 60 is about 20 cm and the height is
about 10 cm, and can be easily installed in the vehicle.
[0032]
It is a figure which shows the data which compare the case where it combines and uses only a
nondirectional microphone, and the case where it combines and uses a sound collecting horn and
a nondirectional microphone in experiment of the sound collecting horn which becomes the
foundation of this invention. It is a figure which shows the difference data of the sound pressure
collected when various cone shapes are changed in experiment of the sound collection horn
which is the foundation of this invention. It is a figure which shows the shape list of the sound
collection horn used for experiment in experiment of the sound collection horn used as the
foundation of this invention. It is a figure which shows the method of measuring directivity
characteristics in experiment of the sound collection horn which becomes the foundation of this
invention. It is a figure which shows the table | surface which put together the result of
evaluation in the experiment of the sound collection horn which becomes the foundation of this
invention. It is a figure which shows the example of the data of a frequency characteristic in
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experiment of the sound-collection horn which becomes the foundation of this invention. It is a
figure which shows the other example of the data of a frequency characteristic in experiment of
the sound collection horn which becomes the foundation of this invention. It is a figure which
shows the sound-collection characteristic data of directivity characteristics in experiment of the
sound-collection horn which becomes the foundation of this invention. It is a figure which shows
the sound-insulation characteristic data among directivity characteristics in experiment of the
sound collection horn used as the foundation of this invention. BRIEF DESCRIPTION OF THE
DRAWINGS It is a perspective view of the noise abnormal sound collection device for vehicles in
an embodiment concerning the present invention. FIG. 1A is a front view and a side view of a
noise abnormal sound collector for a vehicle according to an embodiment of the present
invention. FIG. 1 is a bottom view of an all-noise collecting apparatus for a vehicle according to
an embodiment of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS It is a partial
cross section figure of the noise abnormal sound collection device for vehicles in an embodiment
concerning the invention. BRIEF DESCRIPTION OF THE DRAWINGS It is a figure which shows the
mode of the vehicle in which the noise-sound-collection apparatus for vehicles in embodiment
which concerns on this invention is set.
Explanation of sign
[0033]
10,12,14,20,22,30,32,34 Sound pressure data, 40 sound sources, 50 sound collectors, 60 noise
suppressors for vehicles, 62 sound collectors, 64 stages, 66 mounting legs, 68 fixed Holes, 70
sound collecting horns, 80 omnidirectional microphones, 90 vehicles, 92 headrests.
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