JP2005124031A - Sound collector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sound collector in which compatibility is established between prevention of deterioration in sound collecting performance and prevention of corruption of a microphone arranged inside a sound collecting hood. <P>SOLUTION: The sound collector is provided with the sound collecting hood and the microphone arranged inside the sound collecting hood. The sound collector is further provided with a bulkhead which is arranged further ahead than a sound receiving surface of the microphone and barrierring a rear region including at least this sound receiving region in the sound collecting hood from the sound collecting hood, and a sound absorbing material arranged so as to surround the periphery of the sound receiving surface of the microphone. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a sound collector that collects sound with a microphone disposed inside a hood.

  Conventionally, the surface to be inspected is struck with a hammer or other impacting tool, and the sound generated during the impact (hereinafter referred to as struck sound) is collected and analyzed by a microphone. A sound inspection system that detects a defect such as a cavity existing inside is known (see, for example, Non-Patent Document 1).

  In the sound-inspecting system described in Non-Patent Document 1, the sound-collecting sound is collected with a stethoscope-type sound collecting hood for blocking a surrounding sound while the microphone is arranged at the center. It is done by a vessel. Further, the inventor of the present case has also proposed a sound collector in which sound collection performance is improved by arranging a sound absorbing material so as to surround the side surface of the microphone (Patent Document 1).

  FIG. 1 shows an abnormality that occurs in a mechanical facility by collecting and analyzing a sound inspection system other than the sound inspection system described in Non-Patent Document 1 and operation sounds generated from the mechanical facility. 1 is a cross-sectional view of a sound collector that is generally employed also in a mechanical equipment diagnosis system that detects the noise.

  A sound collector 100 shown in FIG. 1 is used to fix a sound collecting hood 101, a microphone 102, and a microphone 102 inserted through a hole 101a formed in the rear end side of the sound collecting hood 101 to the sound collecting hood. The fixture 103 is configured.

  FIG. 2 is a diagram showing voltage waveforms output from the sound collector when a tone burst having a duration of 2 ms is collected by the sound collector shown in FIG.

  2A to 2C show voltage waveforms when the tone burst frequencies are 9 kHz, 11 kHz, and 13 kHz, respectively.

  By the way, the sound collectors used for these sound inspection systems and machine equipment diagnosis systems are rainy or snowy outdoors, or in the form of a mist with invisible lubricating oil even indoors. When the microphone is used in a scattered environment, the contamination of the microphone results in the contamination of the diaphragm of the microphone. Therefore, the mass of the diaphragm changes, causing fluctuations in the microphone characteristics, making accurate acoustic diagnosis impossible.

  Therefore, it is conceivable to prevent the microphone from being soiled by covering the opening of the sound collecting hood with a sheet-like material.

  3 shows the output from the sound collector when a tone burst of 2 ms duration is collected with the sound collecting hood opening of the sound collector shown in FIG. 1 covered with a 0.1 mm thick vinyl sheet. It is a figure which shows the voltage waveform performed.

  In FIGS. 3 (a) to 3 (c), as in FIGS. 2 (a) to 2 (c), the sound was output from the sound collector by the transmission of tone bursts having frequencies of 9 kHz, 11 kHz, and 13 kHz. A voltage waveform is shown. Here, a waveform having a long tail that is far from the waveforms shown in FIGS. 2A to 2C is shown.

  FIG. 4 is a diagram showing voltage waveforms obtained when a film having a thickness smaller than that of the vinyl sheet used in FIG. 3 is used.

  FIGS. 4 (a) to 4 (c) also show voltage waveforms output from the sound collector due to the transmission of tone bursts having frequencies of 9 kHz, 11 kHz, and 13 kHz. Here, FIG. From (a) to the waveform shown in FIG. 3 (c) is shown a waveform with a slightly weaker tail.

  However, the waveforms shown in FIGS. 4 (a) to 4 (c) are also far from the waveforms shown in FIGS. 2 (a) to 2 (c). This is because the sound wave incident on the hood is reflected multiple times between the inner wall of the hood and the vinyl sheet.

For this reason, this sheet-like material is usually used in a loose state rather than a tight state.
'Inspection Technology', July 2002, 41-45 (Technical Topics / Architecture / Civil Engineering) Japanese Patent No. 3223237

  However, when the sound collecting hood with the sheet-like material attached in a relaxed state as described above is used outdoors, acoustic noise occurs because the sheet-like material flutters in the wind, and the acoustic diagnosis is accurate. There is a problem that it is impossible to go to.

  In view of the above circumstances, an object of the present invention is to provide a sound collector that is compatible with prevention of deterioration in sound collection performance outdoors and prevention of contamination of a microphone disposed in a sound collection hood. .

To achieve the above object, the sound collector of the present invention comprises:
A sound collecting hood having an opening at the front end and a sound reflecting inner wall having a rotating surface shape having a focal point behind the opening and having an internal space at least on the opening side;
A microphone that receives sound waves incident on the sound collection hood, at least the sound reception surface is disposed in the sound collection hood with the sound reception surface facing forward;
A sound absorbing material disposed in the sound collection hood so as to surround the sound receiving surface of the microphone;
A partition wall disposed forward of the sound receiving surface and separating at least a rear region including the sound receiving surface in the internal space from the outside of the sound collecting hood is provided.

  The sound collector of the present invention includes a sound absorbing material surrounding the sound receiving surface of the microphone together with a partition located on the opening side of the sound collecting hood with respect to the sound receiving surface of the microphone, and includes only the partition. The standing wave generated by the multiple reflection of sound waves between the inner wall of the sound collecting hood and the partition wall of the conventional sound collecting device not provided with the sound absorbing material surrounding the sound receiving surface of the microphone is the present invention. Generation in the sound collector is suppressed by the presence of the sound absorbing material arranged as described above in the sound collecting hood of the sound collector of the present invention. Moreover, the partition used in the sound collector of the present invention is a sheet-like material in a tight state that has been thought to be unusable in the past, and this partition does not flutter by the wind. Therefore, according to the sound collector of the present invention, it is possible to achieve both the prevention of a decrease in sound collection performance and the prevention of contamination of the microphone.

  Here, it is preferable that the sound collecting hood further has a sound absorbing material disposed along the peripheral edge of the opening.

  In this way, when the sound absorbing material is arranged along the peripheral edge of the opening, the sound wave that has arrived from the side or rear of the hood and is diffracted by the edge of the opening of the hood and entering the hood is attenuated. Therefore, it is possible to contribute to suppressing the invasion of the sound wave between the inner wall surface of the sound collecting hood and the partition wall.

  Moreover, it is also a preferable aspect that the partition is a partition made of a sheet having sound permeability.

  Thus, the partition may be a sheet as long as it has sound permeability.

  Furthermore, it is also a preferable aspect that the partition is detachable from the sound collecting hood.

  This is convenient because the partition wall can be easily replaced when the partition wall is soiled.

  According to the sound collector of the present invention, it is possible to achieve both the prevention of a decrease in sound collection performance and the prevention of contamination of the microphone disposed in the sound collection hood.

  Hereinafter, embodiments of the present invention will be described.

  FIG. 5 is a cross-sectional view of an embodiment of the sound collector of the present invention. 5 that are the same as those shown in FIG. 1 are given the same reference numerals as those shown in FIG.

  In FIG. 5, the sound collecting hood 101, the microphone 102, the fixture 103, the vinyl chloride sheet 104 covering the opening of the sound collecting hood, and the microphone 102 that constitute the sound collector 1 of the present embodiment are arranged. In the sound collector 1 of the present embodiment, the glass wool 105 is disposed around the microphone and is 0.1 mm in comparison with the conventional sound collector 100 shown in FIG. The opening of the sound collecting hood 101 is covered with the vinyl chloride sheet 104. Note that the sound receiving surface of the microphone 102 is disposed at the focal position of the sound collecting hood 10.

  FIG. 6 is a view showing a vinyl chloride sheet attached to the sound collecting hood.

  In FIG. 6, a vinyl chloride sheet 104 cut to a size that can cover the opening of the sound collecting hood with a margin is provided to cover the opening of the sound collecting hood with the vinyl chloride sheet 104. A state is shown in which a frame 1041 having a diameter slightly longer than the diameter of the opening that can be fitted around the opening edge of the sound collecting hood while winding the end of the vinyl chloride sheet is attached to the sound collecting hood 101. In the sound collector 1 of the embodiment, the replacement of the vinyl chloride sheet 104 can be easily performed.

  Here, FIG. 7 is a figure which shows the sound collection performance of the sound collector 1 of this embodiment according to frequency.

  FIG. 7 shows the voltage waveform output from the sound collector 1 when the sound collector 1 collects the same tone burst as that used to obtain the voltage waveforms shown in FIGS. ing.

  On the other hand, FIG. 8 is a figure which shows the sound collection performance of the sound collector of this embodiment according to frequency in the state which removed the vinyl chloride sheet which covers opening. In this case as well, the same tone burst as that collected in FIG. 7 is collected.

  FIG. 8 shows that the sound collector 1 with the vinyl chloride sheet removed from the opening of the sound collecting hood has no glass wool around the microphone in addition to the vinyl chloride sheet covering the opening of the sound collecting hood. It is shown that a voltage waveform substantially the same as the voltage waveform output from the type sound collector 100 is output. However, the change in voltage amplitude due to frequency is small compared to the conventional type.

  From FIG. 7, although compared with FIG. 8, the conventional collection which does not have glass wool around the microphone as shown in FIG. It can be seen that a much better sound pressure waveform is obtained compared to the voltage waveform output from the sounder.

  FIG. 9 is a diagram showing the sound collection performance of the sound collector of the present embodiment by frequency, in which the opening is replaced with a film that is thinner than the vinyl chloride sheet instead of the vinyl chloride sheet. In this case as well, the same tone burst as that collected in FIG. 7 is collected.

  FIG. 9 shows a better waveform than the voltage waveform shown in FIG.

  That is, FIG. 3 showing the voltage waveform output from the conventional sound collector 100 when collecting the same tone burst and FIG. 7 showing the voltage waveform output from the sound collector 1 of the present embodiment are compared. As can be clearly seen, in the sound collector 1 of the present embodiment, even if the opening of the sound collecting hood is covered with vinyl chloride, the glass wool disposed around the sound receiving surface of the microphone in the sound collecting hood. Therefore, the standing wave generated between the inner wall of the sound collecting hood of the conventional sound collector and the bulkhead, which has only the bulkhead and does not have a sound absorbing material surrounding the sound receiving surface of the microphone, is generated. Therefore, the voltage waveform output from the sound collector 1 of the present embodiment is prevented from lowering the sound collection performance than the voltage waveform output from the conventional sound collector 100. Therefore, according to the sound collector 1 of the present embodiment, it is possible to achieve both the prevention of the deterioration of the sound collecting performance and the prevention of the contamination of the microphone disposed in the sound collecting hood. This effect is not diminished even if the thing covering the opening of the sound collecting hood is replaced with a film having a thickness smaller than that of vinyl chloride.

  In the embodiment described above, the case where the sound absorbing material is arranged around the microphone in the sound collecting hood of the sound collector is described as an example, but the sound absorbing material is a peripheral portion of the opening of the sound collecting hood. In addition, by using the sound collector placed in the hood, the sound collected from the side or rear of the hood is attenuated by the sound waves that enter the hood after being diffracted by the edge of the hood opening. The sound wave itself that enters between the inner wall surface and the partition wall can be suppressed. Thereby, it can contribute to prevention of the fall of sound collection performance.

  Here, FIG. 10 is a cross-sectional view of an example of the sound collecting hood in which the sound absorbing material is also disposed at the peripheral edge of the opening of the sound collecting hood. In addition, what is shown here and the same kind as what is used in the said embodiment is attached | subjected the same code | symbol as the code | symbol attached | subjected in the said embodiment.

  In the sound collecting hood 101 shown in FIG. 10, as described above, the glass wool 106 that is a sound absorbing material is arranged on the entire periphery of the periphery of the opening in addition to the periphery of the microphone 102. The glass wool 106 at the peripheral edge of the opening is not limited to the one arranged on the entire circumference as shown in FIG. 10, and may be detachable.

  Further, in this way, in addition to the periphery of the microphone 102, the glass wool 105 is arranged at the peripheral portion of the sound collecting hood opening 104, and the sound wave diffracted at the edge of the hood opening and entering the hood is attenuated. By doing so, deterioration of directivity is also suppressed.

  FIG. 11 is a graph showing the directivity characteristics of the sound collector.

  FIG. 11A shows the directivity characteristics of the sound collector in which the sound absorbing material is disposed only around the microphone, and FIG. 11B shows the periphery of the opening of the sound collecting hood in addition to the microphone. In addition, the directivity characteristics of the sound collector which is an aspect of the above-described embodiment in which the sound absorbing material is disposed are shown for each frequency.

  From FIG. 11, by arranging the sound absorbing material in the periphery of the opening of the sound collecting hood in addition to the periphery of the microphone, the directivity characteristics with respect to the side and the rear of the sound collector are improved for 1 kHz. It can be seen that the improvement of the directivity with respect to the direction is remarkable, and for 10 kHz, the directivity in the direction close to the front of the sound collector is improved.

  Furthermore, by arranging the sound absorbing material also at the peripheral edge of the opening of the sound collecting hood, it is possible to reduce the impact when the opening of the sound collecting device comes into contact with the object to be inspected and to prevent the damage of both. .

  Furthermore, by arranging the sound absorbing material also at the peripheral edge of the opening of the sound collecting hood, it is possible to reduce the impact when the opening of the sound collecting device comes into contact with the object to be inspected and to prevent the damage of both. .

  In this embodiment, the case where a sheet-like material such as vinyl chloride or a film is employed as the partition has been described as an example. However, the present invention is not limited to this as long as it is sound-transmitting. The position of the partition wall in the sound collection hood is not limited to the opening surface as long as it is on the front side of the sound receiving surface of the microphone. Further, the case where the partition wall is detachably attached to the sound collection hood has been described as an example, but the present invention is not limited to this, and even if the partition wall is fixed to the sound collection hood, the present invention is not limited thereto. The effect is not reduced, and further, an example in which glass wool is used as the sound absorbing material has been described. However, the present invention is not limited to this as long as it has a sound absorbing function. Further, the partition wall is not limited to a flat surface but may be a curved surface or the like.

  Further, a net-like or lattice-like guard that prevents the partition wall from being damaged may be provided on the surface of the partition wall or on the front side of the partition wall.

  Further, in the present embodiment, the case where the sound absorbing material is disposed also on the outer peripheral portion of the opening of the sound collecting hood has been described as an example. It may be arranged.

It is sectional drawing of the sound collector generally employ | adopted. It is a figure which shows the voltage waveform output from a sound collector when the tone burst of 2 ms duration is collected with the sound collector shown in FIG. It is a figure which shows the voltage waveform output from a sound collector, when the sound burst of 2 ms duration is collected. It is a figure which shows the voltage waveform obtained when the film thinner than the vinyl sheet used in FIG. 3 is used. It is sectional drawing of one Embodiment of the sound collector of this invention. It is a figure which shows the vinyl chloride sheet attached to the sound collection hood. It is a figure which shows the voltage waveform output from the sound collector of this embodiment in the state which removed the vinyl chloride sheet which covers opening of a sound collection hood. It is a figure which shows the voltage waveform output from the sound collector of this embodiment with which the opening of the sound collection hood was covered with the vinyl chloride sheet. It is a figure which shows the voltage waveform output from the sound collector of this embodiment by which the vinyl chloride which covers a sound collection hood was replaced | exchanged for the film thinner than this vinyl chloride. It is sectional drawing of an example of the sound collection hood by which a sound absorption material is arrange | positioned also in the peripheral part of opening of the sound collection hood. It is a graph which shows the directivity characteristic of a sound collector.

Explanation of symbols

1, 100 sound collector 101 sound collecting hood 101a
102 Microphone 102a Sound receiving surface 103 Fixing fixture 104 Vinyl chloride 105, 106 Glass wool

Claims (4)

A sound collecting hood having an opening on the front end and a sound reflection inner wall in the shape of a rotating surface having a focal point behind the opening and having an internal space at least on the opening side;
A microphone that receives at least the sound receiving surface in the sound collecting hood, the sound receiving surface facing forward, and receiving a sound wave incident on the sound collecting hood;
A sound absorbing material disposed in the sound collecting hood so as to surround the sound receiving surface of the microphone;
A sound collector comprising: a partition wall disposed in front of the sound receiving surface and separating at least a rear region including the sound receiving surface in the internal space from the outside of the sound collecting hood. The sound collector according to claim 1, wherein the sound collecting hood further includes a sound absorbing material disposed along a peripheral edge portion of the opening. The sound collector according to claim 1, wherein the partition is a partition made of a sheet having sound permeability. 4. The sound collector according to claim 1, wherein the partition wall is detachable from the sound collection hood.

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