JP5372529B2 - Soundproof box - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sound isolation box detecting noise in an inner space in which a condenser microphone to be measured is arranged and offsetting external noise of a low band. <P>SOLUTION: The sound isolation box includes: a measuring side space 22 which includes a non-directional microphone M<SB>1</SB>for detecting noise and is formed so that the condenser microphone M<SB>2</SB>to be measured can be taken out therefrom and put therein; and an output side space 32 including a noise offset control means 33 for offset-controlling external noise of a low band in the measuring side space 22 by adjusting a frequency response with respect to a noise output level detected by the non-directional microphone M<SB>1</SB>. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

The present invention relates to a soundproof box used when measuring the intrinsic noise of a condenser microphone.

It is necessary to measure the intrinsic noise of all the condenser microphones that are required to have low noise characteristics. Usually, the measurement is performed by accommodating the microphones in an anechoic chamber.

In this case, in the anechoic room, the inherent noise of each condenser microphone can be measured, but each time a measurement is made, the condenser microphone must be installed and removed from the anechoic room, and the measurement operator can It was inconvenient because I had to move each time.

For this reason, if the condenser microphone assembled on the assembly line can be stored in a soundproof box immediately after that and the inherent noise can be measured and confirmed, the working efficiency can be improved.

However, although this type of soundproof box is excellent in sound insulation in the middle and high range, it is extremely difficult to insulate the low range external sound. The reason for this is that, in addition to the long wave length of sound waves at low frequencies, large noise during operation due to movement of people in the assembly line and fluctuations in noise level due to the vibration of the building floor itself, etc. As a result, the entire soundproof box vibrates.

On the other hand, for an anechoic room where people enter and exit, for example, there is a silencer disclosed in Patent Document 1 below.

Japanese Patent Laid-Open No. 7-281647

The silencer of Patent Document 1 is an active silencer in which a sound insulation wall is disposed in front of an open surface portion of an anechoic chamber, and a sound having a phase opposite to that of a low-frequency component is output to the periphery of the sound insulation wall. By installing it, the anechoic chamber can be sufficiently silenced.

However, the prior art disclosed in the above-mentioned Patent Document 1 only discloses a soundproofing technique related to an anechoic room where people enter and exit, and cannot be applied to a soundproof box installed in an assembly line.

On the other hand, a condenser microphone with a wide frequency response is also excellent in low-frequency frequency response. Therefore, even if an attempt is made to measure inherent noise using a conventional soundproof box as described above, a low-frequency response is contained in the soundproof box. There was an inconvenience that it was difficult to measure if there was a foreign sound.

In other words, depending on the conventional soundproof box, the entire soundproof box may be affected by the generation of large noise during operation and the fluctuation of the noise level due to the vibration of the building floor itself. Since it vibrates, there is a problem that it is difficult to measure the intrinsic noise of a condenser microphone having a wide frequency response.

SUMMARY OF THE INVENTION The present invention provides a soundproof box capable of detecting noise in an internal space where a condenser microphone for measurement is arranged and canceling out low-frequency external noise in view of the above-described problems found in conventional soundproof boxes. There is a purpose.

The present invention has been made to achieve the above object, the first invention of which, measured side formed to allow entry and exit of the condenser microphone under test comprises a non-directional microphone for detecting noise An output side space provided with a noise cancellation control means for adjusting a frequency response between the space portion and a noise output level detected by the omnidirectional microphone to cancel out a low frequency external sound in the measurement side space portion In the soundproof box provided with a portion, among the measurement-side space portion and the output-side space portion that are partitioned through an immovable partition wall portion in which a plurality of acoustic resistance holes are formed in the plate thickness direction, The output side space portion is further partitioned into two chambers, an air chamber portion and a speaker space portion, through a branch wall portion, and a sound passage hole provided in the branch wall portion is provided in the speaker space portion. The air chamber and the acoustic resistance hole; A speaker that transmits low-frequency sound to the measurement-side space portion is disposed, and the noise cancellation control means is configured by the acoustic resistance hole and the speaker, and the measurement-side output by the sound output from the speaker The main feature is to cancel and control low-frequency external sounds in the space .

In addition, the second invention includes a measurement-side space portion that is provided with a noise-detecting omnidirectional microphone so that the condenser microphone for measurement can be put in and out, and a noise output level detected by the omnidirectional microphone. In the soundproof box, the noise canceling control means comprises an output side space portion provided with a noise canceling control means for adjusting a frequency response between them and canceling and controlling a low frequency external sound in the measurement side space portion. A movable partition wall partitioning the measurement-side space portion, a drive coil attached to the output-side space portion side of the partition wall portion, and a magnetism generating unit for driving the partition wall through the drive coil The most important feature is that the low-frequency external sound in the measurement-side space is canceled and controlled by the volume change of the measurement-side space when the partition is driven.

According to the present invention, the condenser microphone immediately after being assembled in the assembly line is housed in the measurement side space of the soundproof box so as to be measurable as the condenser microphone for measurement, and is sealed, and is also disposed in the measurement side space. By driving the noise cancellation output means based on the noise detected by the omnidirectional microphone, it is possible to cancel the low frequency external sound in the measurement side space. Therefore, the low-frequency external sound that enters the measurement side space is canceled by the noise canceling control means, while the mid-high frequency external sound is shielded by the soundproof box itself. Can be measured accurately and stably.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a longitudinal sectional view showing an example of a first invention of the present invention. The longitudinal cross-sectional view which shows an example of 2nd invention among this invention.

FIG. 1 is a longitudinal sectional view showing an example of the first invention of the present invention, and FIG. 2 is a longitudinal sectional view showing an example of the second invention of the present invention. According to these figures, the soundproof box 11 is provided with a noise detecting omnidirectional microphone M1 with an output code C1, and a measurement microphone formed with an output code C2 to enable measurement of the condenser microphone M2 to be measured. Noise cancellation control means 33 for adjusting the frequency response between the side space 22 and the noise output level detected by the omnidirectional microphone M1 to cancel out low-frequency external sound in the measurement side space 22 is provided. The output side space 32 is provided.

If this is concretely demonstrated based on FIG. 1 which shows 1st invention , the soundproof box 11 will cover the side plate part 12 which covers the circumference | surroundings from four sides, the top plate part 13 which covers an upper surface opening, and a lower surface opening. The bottom plate portion 14 is formed in a substantially rectangular parallelepiped shape with an appropriate volume formed by providing sound insulation against external noise in the middle and high frequency bands.

The soundproof box 11 includes a measurement side space portion 22 positioned on the upper side and an output side space positioned on the lower side via a stationary partition wall portion 34 that is horizontally fixed to an inner surface at an appropriate position of the side plate portion 12. It is partitioned into a part 32.

In addition, in the soundproof box 11, a condenser microphone M2 to be measured with an output cord C2 connected to an external measuring device is taken in and out of an appropriate part of the side plate part 12 at the position on the measurement side space part 22 side. An opening 15 is provided, and the opening 15 can be tightly closed by an opening / closing lid 16.

Furthermore, a plurality of acoustic resistance holes 35 are formed in the partition wall portion 34 that partitions the measurement-side space portion 22 and the output-side space portion 32 in the thickness direction, and measurement is performed through the acoustic resistance holes 35. The side space portion 22 communicates with the output side space portion 32.

Moreover, the soundproof box 11 is fixed at an appropriate position on the inner surface of the side plate portion 12 so as to partition the output side space portion 32 in the horizontal direction, and the air chamber portion 32a is placed between the partition wall portion 34 and the bottom plate. A supporting wall portion 37 is provided between the portion 14 and the space portion 32b for the speaker.

In addition, the branch wall portion 37 having the sound passage hole 37a having an appropriate diameter at the substantially central portion is provided with an output cord under the arrangement relationship in which the cone side is directed to the sound passage hole 37a in the speaker space portion 32b. A speaker S connected to the C1 side is attached.

Further, the noise canceling control means 33 includes an acoustic resistance hole 35 provided in an immovable partition wall portion 34 that partitions the measurement side space portion 22, and a low frequency band on the measurement side space portion side through the acoustic resistance hole 35. And a speaker S for transmitting the sound of

In this case, the low-frequency sound emitted from the speaker S adjusts the frequency response through a low-pass filter (not shown) and a power amplifier that detect noise detected by the omnidirectional microphone M1 disposed in the measurement-side space 22. Then, the output is fed back to the speaker S so that the low-frequency external sound in the measurement-side space 22 can be canceled.

On the other hand, if the 2nd invention is concretely demonstrated based on FIG. 2, the soundproof box 11 will be substantially the same as the example shown in FIG. 1, the side-plate part 12 which covers the surrounding four sides, and the top plate which covers an upper surface opening. The part 13 and the bottom plate part 14 covering the lower surface opening are formed to have a substantially rectangular parallelepiped shape with an appropriate volume formed by providing sound insulation against external noise in the middle and high frequency bands.

And the inside of the soundproof box 11 is the measurement side space part 22 located on the lower side and the output side space part located on the upper side through the movable partition wall part 44 horizontally disposed on the inner surface at an appropriate position of the side plate part 12. 32.

In this case, the partition wall portion 44 includes an elastic body 45 made of a rubber material such as silicone rubber disposed on the inner side surface at an appropriate position of the side plate portion 12 and a peripheral edge portion 46 a of the elastic body 45. It is formed with a partition material 46 made of a relatively lightweight paper material and the like that are integrally supported, and is provided with mobility in the vertical direction through an elastic body 45.

Further, an opening 15 for taking in and out the condenser microphone M2 to be measured is provided at an appropriate portion of the side plate 12 at the position on the measurement side space 22 in the soundproof box 11, and the opening 15 can be tightly closed by the opening / closing lid 16.

The noise cancellation control means 33 is a cylindrical drive connected to the movable partition wall 44 and an appropriate position on the surface of the partition wall 44 facing the output side space 32 of the partition wall material 46 and connected to the output cord C1 side. The coil 47 and a magnetic generation unit 48 that drives the partition wall 44 side through the drive coil 47 are configured.

In this case, the drive coil 47 is formed by attaching a conductive wire 47b to the outer peripheral surface of the insulating cylindrical portion 47a. The magnetism generating unit 48 has a gap G interposed between a bottomed cylindrical yoke portion 49 having a U-shaped cross section disposed on the inner surface of the top plate portion 13 and the inner surface of the yoke portion 49. The cylindrical permanent magnet 50 and the pole piece 51 are arranged in combination. The drive coil 47 is disposed via a gap G secured between the superimposed permanent magnet 50, pole piece 51, and yoke portion 49.

Moreover, the drive control of the partition wall 44 is performed after adjusting the frequency response through a low-pass filter and a power amplifier (not shown) for noise detected by the omnidirectional microphone M1 disposed in the measurement-side space 22. The output voltage is fed back to the drive coil 47.

That is, the omnidirectional microphone M1 detects a pressure change (sound pressure) in the measurement-side space 22 and cancels the pressure change by the partition material 46 that can drive the partition 44 and change its volume. By doing so, the low-frequency extraneous sound in the measurement side space part 22 can be canceled.

For this reason, according to the present invention, the condenser microphone immediately after being assembled on the assembly line is housed in the measurement side space 22 of the soundproof box 11 so as to be measurable as the condenser microphone M2 to be measured, and is sealed. By driving the noise cancellation control means 33 based on the noise detected by the omnidirectional microphone M1 disposed in the measurement side space 22, the low frequency external sound in the measurement side space 22 is controlled to cancel. be able to.

Therefore, even if the noise state fluctuates during operation of the assembly line, the external sound in the middle and high range is always sound-insulated by the soundproof box 11 itself, and the low frequency external sound entering the measurement side space 22 is omnidirectional. It is possible to accurately and stably measure the inherent noise of a condenser microphone having a wide frequency response by canceling with the noise canceling control means 33 driven according to the noise of the time detected by the microphone M1. become.

11 Soundproof box 12 Side plate portion 13 Top plate portion 14 Bottom plate portion 15 Opening portion 16 Opening / closing lid 22 Measurement side space portion 32 Output side space portion 32a Air chamber portion 32b Speaker space portion 33 Noise canceling control means 34 Partition portion (non-moving)
35 Acoustic resistance hole 37 Branch wall part 37a Sound passage hole 44 Bulkhead part (movable)
45 Elastic body 46 Bulkhead material 46a Peripheral part 47 Drive coil 48 Magnetic generating unit 49 Yoke part 50 Permanent magnet 51 Pole piece M1 Omnidirectional microphone C1 Output code M2 Capacitor microphone C2 to be measured Output code S Speaker G Gap

Claims (2)

The frequency response is adjusted between the measurement side space provided with a non-directional microphone for noise detection and capable of entering and exiting the condenser microphone for measurement and the noise output level detected by the non-directional microphone. In the soundproof box provided with the output side space portion provided with the noise cancellation control means for canceling and controlling the low frequency external sound in the measurement side space portion ,
Of the measurement-side space portion and the output-side space portion partitioned through an immovable partition wall portion in which a plurality of acoustic resistance holes are formed in the plate thickness direction, the output-side space portion is a supporting wall portion Is further divided into two chambers, an air chamber portion and a speaker space portion,
In the speaker space portion, a speaker is disposed that sends low-frequency sound from a sound passage hole provided in the support wall portion to the measurement-side space portion through the air chamber portion and the acoustic resistance hole. ,
The noise canceling control means is constituted by the acoustic resistance hole and the speaker, and cancels and controls the low-frequency external sound in the measurement-side space by the sound output from the speaker . The frequency response is adjusted between the measurement side space provided with a non-directional microphone for noise detection and capable of entering and exiting the condenser microphone for measurement and the noise output level detected by the non-directional microphone. In the soundproof box provided with the output side space portion provided with the noise cancellation control means for canceling and controlling the low frequency external sound in the measurement side space portion,
The noise cancellation control means includes a partition wall portion of the variable dynamic partitioning between the measurement-side space, and a drive coil is attached to the output side space side of the partition wall portion, wherein through the drive coil bulkhead parts constituted by the magnetic field generators to drive the, characterized in that to offset controls the low-frequency foreign sound of the partition wall the measurement side space portion by the volume change of the measuring-side space at the time of driving the Soundproof box.

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