JP2011053395A - Acoustic resistance measuring device of acoustic resistance material - Google Patents

Acoustic resistance measuring device of acoustic resistance material Download PDF

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JP2011053395A
JP2011053395A JP2009201361A JP2009201361A JP2011053395A JP 2011053395 A JP2011053395 A JP 2011053395A JP 2009201361 A JP2009201361 A JP 2009201361A JP 2009201361 A JP2009201361 A JP 2009201361A JP 2011053395 A JP2011053395 A JP 2011053395A
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acoustic resistance
pipe
resistance material
acoustic
speaker
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JP5398428B2 (en
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Yutaka Akino
裕 秋野
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Audio Technica KK
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Abstract

<P>PROBLEM TO BE SOLVED: To provide an acoustic resistance measuring device capable of measuring acoustic resistance of an acoustic resistance material for microphones at a desired frequency though being simple in configuration and low in cost. <P>SOLUTION: The acoustic resistance measuring device includes: a speaker 2 for generating a sound wave of predetermined frequency; a first piping 10 having one end 11 connected with the speaker 2 and the other side pipe end 12 arranged with a reference acoustic resistance material 40S, and provided with a first acoustic resistance tube 13 in the way; a second piping 20 of similar arrangement with the first piping 10, having one end 21 connected with the speaker 2 and the other side end 22 arranged with an acoustic resistance material 40X to be measured and provided with the first acoustic resistance tube 13 in the way; and a bridge pipe 30 having a bi-directional microphone 31 and coupled between the first piping 10 and the second piping 20 on the downstream side of the first acoustic resistance tube 13 and the second acoustic resistance tube 23; and a measuring means 33 for measuring whether the acoustic resistance of the acoustic resistance material 40X to be measured is larger or not, than that of the reference acoustic resistance material 40S, based on microphone output which is output from the bi-directional microphone 31. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

本発明は、マイクロホンに用いられる音響抵抗材の音響抵抗測定装置に関し、さらに詳しく言えば、音響抵抗材の音響抵抗を所望とする周波数で測定できる音響抵抗測定装置に関するものである。   The present invention relates to an acoustic resistance measurement device for an acoustic resistance material used in a microphone, and more particularly to an acoustic resistance measurement device capable of measuring the acoustic resistance of an acoustic resistance material at a desired frequency.

マイクロホンに用いられる音響抵抗材には、通常、ナイロンメッシュや連続気泡を有するスポンジ材等が用いられている。その音響抵抗の測定方法には、例えば音波の透過率や圧搾空気の透過率を測定する方法が知られている。   As an acoustic resistance material used for a microphone, a nylon mesh or a sponge material having open cells is usually used. As a method for measuring the acoustic resistance, for example, a method of measuring the transmittance of sound waves or the transmittance of compressed air is known.

しかしながら、ラインマイクロホン（ガンマイク）等に用いられる狭指向性マイクロホンユニットでは、後部音響端子の音響抵抗がきわめて高く設計される。   However, in a narrow directivity microphone unit used for a line microphone (gun microphone) or the like, the acoustic resistance of the rear acoustic terminal is designed to be extremely high.

したがって、上記の測定方法では、音響抵抗材に対して大きな音波もしくは圧搾空気を加えなければならないため、それによって音響抵抗材が破壊したり、破壊に至らなくても特性が変化してしまうことがある。   Therefore, in the above measurement method, since a large sound wave or compressed air must be applied to the acoustic resistance material, the acoustic resistance material may be destroyed thereby, or the characteristics may be changed without being destroyed. is there.

そこで、本出願人は、特許文献１で、音響抵抗材を破壊することなく、その音響抵抗値を高精度に測定し得るようにした発明を提案している。   In view of this, the present applicant has proposed an invention in which the acoustic resistance value can be measured with high accuracy in Patent Document 1 without destroying the acoustic resistance material.

すなわち、特許文献１に記載された発明は、一端が圧搾空気供給源に接続され他端側の管端に基準となる基準音響抵抗材が配置されるとともにその途中に空気絞り部を有する第１配管と、一端が圧搾空気供給源に接続され他端側の管端に被測定音響抵抗材が配置されるとともにその途中に空気絞り部を有し上記空気絞り部の空気抵抗値を含めて上記第１配管と同一構成の第２配管と、差圧計を有し上記各空気絞り部の下流側で上記第１配管と上記第２配管との間に連結されるブリッジ管とを備えていることを特徴としている。   That is, the invention described in Patent Document 1 is a first device in which one end is connected to a compressed air supply source, a reference acoustic resistance material serving as a reference is arranged at the other end of the pipe, and an air constriction portion is provided in the middle. The pipe, one end is connected to the compressed air supply source, and the acoustic resistance material to be measured is disposed at the other end of the pipe and has an air restrictor in the middle thereof, including the air resistance value of the air restrictor. A second pipe having the same configuration as the first pipe, and a bridge pipe having a differential pressure gauge and connected between the first pipe and the second pipe on the downstream side of each air restrictor. It is characterized by.

上記特許文献１に記載された発明は、ホイートストンブリッジ回路に見立てられ、第１配管および第２配管の各空気絞り部を含む配管部分が固定辺に相当し、第１配管の空気絞り部の下流側で基準音響抵抗材が配置される配管部分が基準辺に相当し、第２配管の空気絞り部の下流側で被測定音響抵抗材が配置される配管部分が被測定辺に相当し、差圧計が検流計に相当する。したがって、差圧計の指示値により基準音響抵抗材に対する被測定音響抵抗材の音響抵抗値を測定することができる。   The invention described in Patent Document 1 is regarded as a Wheatstone bridge circuit, and a pipe part including each air throttle part of the first pipe and the second pipe corresponds to a fixed side, and is downstream of the air throttle part of the first pipe. The pipe portion where the reference acoustic resistance material is arranged on the side corresponds to the reference side, and the pipe portion where the measured acoustic resistance material is arranged on the downstream side of the air throttle part of the second pipe corresponds to the measurement side. The pressure gauge corresponds to a galvanometer. Therefore, the acoustic resistance value of the acoustic resistance material to be measured with respect to the reference acoustic resistance material can be measured based on the indication value of the differential pressure gauge.

特開２００５−３２８３４７号公報JP 2005-328347 A

ところで、マイクロホンユニットの制御方式には、質量制御（特には、単一指向性ダイナミックマイクロホン），抵抗制御（特には、無指向性ダイナミックマイクロホン，単一指向性コンデンサマイクロホン），弾性制御（特には、無指向性コンデンサマイクロホン）があるが、各制御方式ごとに測定すべき音響抵抗材の周波数が異なる。   By the way, the control method of the microphone unit includes mass control (especially unidirectional dynamic microphone), resistance control (especially omnidirectional dynamic microphone, unidirectional condenser microphone), elastic control (especially, There is an omnidirectional condenser microphone), but the frequency of the acoustic resistance material to be measured is different for each control method.

しかしながら、上記特許文献１に記載された発明では、圧搾空気を用いているため、直流成分での測定しかできない、という問題がある。   However, in the invention described in Patent Document 1, since compressed air is used, there is a problem that only measurement using a direct current component is possible.

また、コンプレッサー，エアータンク，圧力調整器等の圧搾空気を発生させ、安定化させるための設備を必要とするため、測定装置が大型であり、設備コストもかかる、という問題もある。   Moreover, since the apparatus for generating and stabilizing compressed air, such as a compressor, an air tank, and a pressure regulator, is required, there also exists a problem that a measuring apparatus is large sized and an installation cost also starts.

したがって、本発明の課題は、マイクロホンに用いられる音響抵抗材の音響抵抗測定装置において、構成が簡素かつコストが安価でありながら、音響抵抗材の音響抵抗を所望とする周波数で測定できるようにすることにある。   Accordingly, an object of the present invention is to enable an acoustic resistance measuring device for an acoustic resistance material used in a microphone to measure the acoustic resistance of the acoustic resistance material at a desired frequency while having a simple configuration and low cost. There is.

上記課題を解決するため、本発明は、マイクロホンに用いられる音響抵抗材の音響抵抗を測定する音響抵抗材の音響抵抗測定装置において、所定周波数の音波を発生するスピーカと、一端が上記スピーカに接続され他端側の管端に基準となる基準音響抵抗材が配置される第１配管および上記第１配管の途中に含まれ上記スピーカからの音波に対して所定の音響抵抗として作用する第１音響抵抗管と、一端が上記第１配管の一端とともに上記スピーカに接続され他端側の管端に被測定音響抵抗材が配置される上記第１配管とほぼ同一構成の第２配管および上記第２配管の途中に含まれ上記第１音響抵抗管とほぼ同一の音響抵抗を有する第２音響抵抗管と、双指向性マイクロホンを含み上記第１音響抵抗管および上記第２音響抵抗管の各下流側で上記第１配管と上記第２配管との間に連結されるブリッジ管と、上記双指向性マイクロホンから出力されるマイク出力に基づいて上記基準音響抵抗材に対する上記被測定音響抵抗材の音響抵抗の大小を測定する測定手段とを備えていることを特徴としている。   In order to solve the above problems, the present invention provides an acoustic resistance measurement apparatus for an acoustic resistance material that measures acoustic resistance of an acoustic resistance material used for a microphone, a speaker that generates a sound wave of a predetermined frequency, and one end connected to the speaker. A first pipe in which a reference acoustic resistance material serving as a reference is disposed at the other end of the pipe, and a first sound which is included in the middle of the first pipe and acts as a predetermined acoustic resistance against sound waves from the speaker. A resistance pipe, a second pipe having one end connected to the speaker together with one end of the first pipe, and a second pipe having substantially the same configuration as the first pipe in which the acoustic resistance material to be measured is arranged at the other end of the pipe. A second acoustic resistance tube that is included in the middle of the pipe and has substantially the same acoustic resistance as the first acoustic resistance tube; and downstream sides of the first acoustic resistance tube and the second acoustic resistance tube that include a bidirectional microphone so The bridge pipe connected between the first pipe and the second pipe, and the acoustic resistance of the acoustic resistance material to be measured with respect to the reference acoustic resistance material based on the microphone output output from the bidirectional microphone And measuring means for measuring magnitude.

また、上記課題を解決するため、本発明は、マイクロホンに用いられる音響抵抗材の音響抵抗を測定する音響抵抗材の音響抵抗測定装置において、所定周波数の音波を発生するスピーカと、一端が上記スピーカに接続され他端側の管端に基準となる基準音響抵抗材が配置される第１配管および上記第１配管の途中に含まれ上記スピーカからの音波に対して所定の音響抵抗として作用する第１音響抵抗管と、一端が上記第１配管の一端とともに上記スピーカに接続され他端側の管端に被測定音響抵抗材が配置される上記第１配管とほぼ同一構成の第２配管および上記第２配管の途中に含まれ上記第１音響抵抗管とほぼ同一の音響抵抗を有する第２音響抵抗管と、上記第１音響抵抗管および上記第２音響抵抗管の各下流側で上記スピーカからの音波を収音する第１および第２の無指向性マイクロホンと、上記第１および第２の無指向性マイクロホンの各マイク出力端子に接続された差動増幅器を介して上記基準音響抵抗材に対する上記被測定音響抵抗材の音響抵抗の大小を測定する測定手段とを備えていることを特徴としている。   In order to solve the above-described problems, the present invention provides an acoustic resistance measurement apparatus for an acoustic resistance material that measures the acoustic resistance of an acoustic resistance material used in a microphone. Is connected to the other end of the first pipe, and a reference acoustic resistance material serving as a reference is disposed at the other end of the pipe. The first pipe is included in the middle of the first pipe and acts as a predetermined acoustic resistance against sound waves from the speaker. A first acoustic resistance pipe, a second pipe having substantially the same configuration as the first pipe, one end of which is connected to the speaker together with one end of the first pipe, and a measured acoustic resistance material is disposed at the other end of the pipe; A second acoustic resistance tube that is included in the middle of the second pipe and has substantially the same acoustic resistance as the first acoustic resistance tube, and from the speaker at each downstream side of the first acoustic resistance tube and the second acoustic resistance tube sound of The first and second omnidirectional microphones for picking up sound and the above-mentioned reference acoustic resistance material with respect to the reference acoustic resistance material via a differential amplifier connected to each microphone output terminal of the first and second omnidirectional microphones. And a measurement means for measuring the magnitude of the acoustic resistance of the measurement acoustic resistance material.

本発明において、上記第１音響抵抗管および上記第２音響抵抗管の音響抵抗値が上記基準音響抵抗材の音響抵抗値とほぼ等しい値に設定されていることが好ましい。   In the present invention, it is preferable that the acoustic resistance values of the first acoustic resistance tube and the second acoustic resistance tube are set to be substantially equal to the acoustic resistance value of the reference acoustic resistance material.

また、本発明には、上記スピーカから発せられる音波の周波数を可変する周波数可変手段をさらに備え、上記被測定音響抵抗材が用いられるマイクロホンユニットの制御方式に応じて上記音波の周波数が選択可能である、という態様が含まれる。   Further, the present invention further includes frequency varying means for varying the frequency of the sound wave emitted from the speaker, and the sound wave frequency can be selected according to the control method of the microphone unit in which the measured acoustic resistance material is used. The aspect of being is included.

本発明によれば、スピーカから放音される所定周波数の音波をホイートストンブリッジ回路に相当する配管系を介して基準音響抵抗材と被測定音響抵抗材とに与える構成であるため、音波の周波数を可変とすることにより、音響抵抗材の音響抵抗を所望とする周波数（音響抵抗材が適用されるマイクロホンの制御方式に応じた周波数）で測定することができる。   According to the present invention, since the sound wave having a predetermined frequency emitted from the speaker is provided to the reference acoustic resistance material and the acoustic resistance material to be measured through the piping system corresponding to the Wheatstone bridge circuit, the frequency of the sound wave is set. By making it variable, the acoustic resistance of the acoustic resistance material can be measured at a desired frequency (frequency according to the control method of the microphone to which the acoustic resistance material is applied).

また、測定設備にしても、スピーカやマイクロホン等を用意するだけでよいため、装置が小型であり、設備コストも安価に済ませられる。また、外来音波が入り込んでも、音響抵抗が平衡した状態ではキャンセルされる。   Moreover, since it is only necessary to prepare a speaker, a microphone, or the like for the measurement equipment, the apparatus is small and the equipment cost can be reduced. Even if an external sound wave enters, the sound resistance is canceled in a balanced state.

本発明の第１実施形態に係る音響抵抗測定装置を示す模式図。The schematic diagram which shows the acoustic resistance measuring apparatus which concerns on 1st Embodiment of this invention. 上記第１実施形態に係る音響抵抗測定装置の等価回路図。The equivalent circuit diagram of the acoustic resistance measuring apparatus which concerns on the said 1st Embodiment. 本発明の第２実施形態に係る音響抵抗測定装置を示す模式図。The schematic diagram which shows the acoustic resistance measuring apparatus which concerns on 2nd Embodiment of this invention. 上記第２実施形態に係る音響抵抗測定装置の等価回路図。The equivalent circuit schematic of the acoustic resistance measuring apparatus which concerns on the said 2nd Embodiment.

次に、図１ないし図４により、本発明の第１および第２実施形態について説明するが、本発明はこれに限定されるものではない。   Next, the first and second embodiments of the present invention will be described with reference to FIGS. 1 to 4, but the present invention is not limited thereto.

まず、図１，図２を参照して、本発明の第１実施形態（請求項１に対応）に係る音響抵抗測定装置１Ａについて説明する。   First, an acoustic resistance measuring device 1A according to a first embodiment (corresponding to claim 1) of the present invention will be described with reference to FIGS.

この音響抵抗測定装置１Ａは、基本的な構成として、測定信号発生源としてのスピーカ２と、長さと内径がほぼ同一である第１配管１０および第２配管２０と、双指向性マイクロホン３１を含むブリッジ管３０とを備える。   The acoustic resistance measuring apparatus 1A includes, as a basic configuration, a speaker 2 as a measurement signal generation source, a first pipe 10 and a second pipe 20 having substantially the same length and inner diameter, and a bidirectional microphone 31. A bridge pipe 30.

この実施形態において、スピーカ２にはコーン型スピーカが用いられているが、例えば平面型スピーカが用いられてもよい。詳しくは図示しないが、スピーカ２を駆動する駆動回路２ａには、発音する音波の周波数を可変するための周波数可変手段が含まれている。   In this embodiment, a cone type speaker is used as the speaker 2, but a flat type speaker may be used, for example. Although not shown in detail, the drive circuit 2a for driving the speaker 2 includes frequency varying means for varying the frequency of sound waves to be generated.

第１配管１０は、その一端１１がスピーカ２に接続される。第１配管１０の他端側の管端１２は、トレー状に形成されており、その内部に音響抵抗が既知（良品）の基準音響抵抗材４０Ｓが配置される。   One end 11 of the first pipe 10 is connected to the speaker 2. The pipe end 12 on the other end side of the first pipe 10 is formed in a tray shape, and a reference acoustic resistance material 40S having a known acoustic resistance (non-defective product) is disposed therein.

第１配管１０の途中には、スピーカ２からの音波に対して所定の音響抵抗として作用する第１音響抵抗管１３が接続されている。音響抵抗管（音響管と呼ばれているものを含む）の音響抵抗Ｚは、空気の密度をρ，音速をｃ，管内の断面積をｓとして、Ｚ＝ρｃ／ｓにより求められる。   A first acoustic resistance tube 13 that acts as a predetermined acoustic resistance against sound waves from the speaker 2 is connected midway through the first pipe 10. The acoustic resistance Z of an acoustic resistance tube (including what is called an acoustic tube) is obtained by Z = ρc / s where ρ is the density of air, c is the speed of sound, and s is the cross-sectional area in the tube.

この種の音響抵抗管（音響管）は、比較的リアクタンス成分が少ないため、ホイートストンブリッジ回路の固定辺に設けられる抵抗として好ましく採用される（位相回転の問題から）。   Since this type of acoustic resistance tube (acoustic tube) has a relatively small reactance component, it is preferably employed as a resistor provided on the fixed side of the Wheatstone bridge circuit (from the problem of phase rotation).

第２配管２０は、その一端２１が第１配管１０の一端１１とともにスピーカ２に接続される。第２配管２０の他端側の管端２２は、第１配管１０と同じくトレー状に形成されており、その内部に被測定音響抵抗材４０Ｘが配置される。   One end 21 of the second pipe 20 is connected to the speaker 2 together with the one end 11 of the first pipe 10. The pipe end 22 on the other end side of the second pipe 20 is formed in a tray shape like the first pipe 10, and the acoustic resistance material 40 </ b> X to be measured is disposed therein.

第２配管２０の途中にも、スピーカ２からの音波に対して所定の音響抵抗として作用する第２音響抵抗管２３が接続されている。この第２音響抵抗管２３は、その音響抵抗値を含めて第１音響抵抗管１３と同一構成である。   A second acoustic resistance tube 23 that acts as a predetermined acoustic resistance against the sound wave from the speaker 2 is also connected in the middle of the second piping 20. The second acoustic resistance tube 23 has the same configuration as the first acoustic resistance tube 13 including its acoustic resistance value.

スピーカ２を上流側として、第１音響抵抗管１３および第２音響抵抗管２３の各下流側（管端側）で、第１配管１０と第２配管２０との間には、双指向性マイクロホン３１を含むブリッジ管３０が連結される。   A bidirectional microphone is provided between the first pipe 10 and the second pipe 20 on the downstream side (tube end side) of the first acoustic resistance tube 13 and the second acoustic resistance tube 23 with the speaker 2 as the upstream side. A bridge tube 30 including 31 is connected.

双指向性マイクロホン３１のマイク出力（音声信号）は、増幅器３２を介して測定部３３に与えられる。この実施形態において、双指向性マイクロホン３１はリボンマイクロホンであり、その振動板３１ａは、第１配管１０側の音波と第２配管２０側の音波の差圧により振動し、両側で位相が逆になる。   The microphone output (audio signal) of the bidirectional microphone 31 is given to the measurement unit 33 via the amplifier 32. In this embodiment, the bidirectional microphone 31 is a ribbon microphone, and its diaphragm 31a vibrates due to the differential pressure between the sound wave on the first pipe 10 side and the sound wave on the second pipe 20 side, and the phases are reversed on both sides. Become.

したがって、測定部３３は、少なくとも双指向性マイクロホン３１のマイク出力が「０」，「正相（＋）」，「逆相（−）」のいずれかを表示する。ここでは、説明の便宜上、振動板３１ａが第１配管１０側の音波により振動した場合を「正相（＋）」とし、第２配管２０側の音波により振動した場合を「逆相（−）」とする。   Therefore, the measurement unit 33 displays at least one of the microphone output of the bidirectional microphone 31 as “0”, “normal phase (+)”, or “reverse phase (−)”. Here, for convenience of explanation, the case where the diaphragm 31a vibrates with sound waves on the first pipe 10 side is referred to as “normal phase (+)”, and the case where vibrations are vibrated with sound waves on the second pipe 20 side is referred to as “reverse phase (−)”. "

この実施形態では、被測定音響抵抗材４０Ｘの音響抵抗を測定しながら、その音響抵抗値を基準音響抵抗材４０Ｓの音響抵抗値に合わせ込むことができるように、被測定音響抵抗材４０Ｘ，基準音響抵抗材４０Ｓともに、実際にマイクロホンユニットに組み込まれる状態で管端１２，２２の各トレー内に配置される。   In this embodiment, while measuring the acoustic resistance of the acoustic resistance material 40X to be measured, the acoustic resistance material 40X and the reference acoustic resistance material 40X can be matched with the acoustic resistance value of the reference acoustic resistance material 40S. The acoustic resistance material 40S is disposed in each tray at the tube ends 12 and 22 in a state where it is actually incorporated into the microphone unit.

この例において、被測定音響抵抗材４０Ｘは単一指向性コンデンサマイクロホンユニット用であり、被測定音響抵抗材４０Ｘ（基準音響抵抗材４０Ｓも同様）は、固定極４１を支持する絶縁座４２の背面側に装着される。   In this example, the measured acoustic resistance material 40X is for a unidirectional condenser microphone unit, and the measured acoustic resistance material 40X (same as the reference acoustic resistance material 40S) is the back surface of the insulating seat 42 that supports the fixed electrode 41. Mounted on the side.

固定極４１は金属の多孔板からなり、絶縁座４２には後部音響端子からの音波を固定極４１の孔を通して図示しない振動板の裏面に作用させるための音孔（音波導入孔）４２ａが穿設されている。   The fixed pole 41 is made of a metal porous plate, and the insulating seat 42 is provided with a sound hole (sound introduction hole) 42a for allowing sound waves from the rear acoustic terminal to act on the back surface of the diaphragm not shown through the hole of the fixed pole 41. It is installed.

被測定音響抵抗材４０Ｘには、例えばナイロンメッシュや連続気泡のスポンジ体等が用いられ、その圧縮比により音響抵抗値が変化する。被測定音響抵抗材４０Ｘは、絶縁座４２の音孔４２ａを覆うように絶縁座４２の背面側に配置される。   For example, a nylon mesh or an open-cell sponge body is used as the acoustic resistance material 40X to be measured, and the acoustic resistance value changes depending on the compression ratio. The measured acoustic resistance material 40 </ b> X is disposed on the back side of the insulating seat 42 so as to cover the sound hole 42 a of the insulating seat 42.

絶縁座４２の背面側のほぼ中央には、雄ネジを有する円筒状のボス４２ｂが突設されており、ボス４２ｂに被測定音響抵抗材４０Ｘに対して押圧力を加えるアジャストナット４３が螺合され、その締め付け具合により、被測定音響抵抗材４０Ｘの音響抵抗値の調整が行われる。   A cylindrical boss 42b having a male screw protrudes from substantially the center of the back side of the insulating seat 42, and an adjustment nut 43 that applies a pressing force to the acoustic resistance material 40X to be measured is screwed onto the boss 42b. Then, the acoustic resistance value of the acoustic resistance material to be measured 40X is adjusted according to the tightening condition.

スピーカ２から発生された所定周波数の音波は、第１配管１０および第２配管２０内を通ってそれぞれ基準音響抵抗材４０Ｓと被測定音響抵抗材４０Ｘとに加えられる。   A sound wave of a predetermined frequency generated from the speaker 2 passes through the first pipe 10 and the second pipe 20 and is applied to the reference acoustic resistance material 40S and the measured acoustic resistance material 40X, respectively.

基準音響抵抗材４０Ｓと被測定音響抵抗材４０Ｘの各音響抵抗値が等しければ、第１配管１０と第２配管２０内の音波は同相かつ同じ圧力となるため、振動板３１ａは振動しない。したがって、測定部３３にはマイク出力が「０」と表示される。これにより、被測定音響抵抗材４０Ｘの音響抵抗値が適正と判断される。   If the acoustic resistance values of the reference acoustic resistance material 40S and the measured acoustic resistance material 40X are equal, the sound waves in the first pipe 10 and the second pipe 20 have the same pressure and the same pressure, so the diaphragm 31a does not vibrate. Therefore, the microphone output is displayed on the measurement unit 33 as “0”. Thereby, it is determined that the acoustic resistance value of the acoustic resistance material 40X to be measured is appropriate.

これに対して、測定部３３にマイク出力が「正相（＋）」と表示された場合には、基準音響抵抗材４０Ｓの音響抵抗値に対して被測定音響抵抗材４０Ｘの音響抵抗値が小さいことを意味するため、被測定音響抵抗材４０Ｘ側のアジャストナット４３を締め付ける方向に回して、マイク出力が「０」となるようにする。   On the other hand, when the microphone output is displayed as “positive phase (+)” on the measurement unit 33, the acoustic resistance value of the acoustic resistance material to be measured 40X with respect to the acoustic resistance value of the reference acoustic resistance material 40S. In order to mean small, the microphone output is set to “0” by turning the adjusting nut 43 on the acoustic resistance material 40X side to be measured in the tightening direction.

反対に、測定部３３にマイク出力が「逆相（−）」と表示された場合には、基準音響抵抗材４０Ｓの音響抵抗値に対して被測定音響抵抗材４０Ｘの音響抵抗値が大きいことを意味するため、被測定音響抵抗材４０Ｘ側のアジャストナット４３を緩める方向に回して、マイク出力が「０」となるようにする。   On the other hand, when the microphone output is displayed as “reverse phase (−)” on the measurement unit 33, the acoustic resistance value of the measured acoustic resistance material 40X is larger than the acoustic resistance value of the reference acoustic resistance material 40S. Therefore, the adjustment nut 43 on the acoustic resistance material 40X side to be measured is turned in the loosening direction so that the microphone output becomes “0”.

このようにして、本発明によれば、測定信号発生源として所定周波数の音波を発生し得るスピーカ２を用いていることから、被測定音響抵抗材４０Ｘの音響抵抗値を所望とする周波数の音波で測定することができる。また、その測定結果に応じて、被測定音響抵抗材４０Ｘの音響抵抗値を調整することもできる。   Thus, according to the present invention, since the speaker 2 capable of generating a sound wave having a predetermined frequency is used as the measurement signal generation source, the sound wave having a desired frequency as the acoustic resistance value of the acoustic resistance material 40X to be measured is used. Can be measured. Moreover, according to the measurement result, the acoustic resistance value of the acoustic resistance material 40X to be measured can be adjusted.

例えば、被測定音響抵抗材４０Ｘが用いられるマイクロホンユニットの制御方式が質量制御（特には、単一指向性ダイナミックマイクロホン）の場合には１００〜２００Ｈｚ程度の低い周波数、抵抗制御（特には、無指向性ダイナミックマイクロホン，単一指向性コンデンサマイクロホン）の場合には１ｋＨｚ程度の周波数、弾性制御（特には、無指向性コンデンサマイクロホン）の場合には１０〜２０ｋＨｚ程度の高い周波数を選択することが好ましい。   For example, when the control method of the microphone unit using the acoustic resistance material to be measured 40X is mass control (especially unidirectional dynamic microphone), the frequency and resistance control (especially omnidirectional) is as low as about 100 to 200 Hz. It is preferable to select a frequency of about 1 kHz in the case of a directional dynamic microphone and a unidirectional condenser microphone) and a high frequency of about 10 to 20 kHz in the case of elastic control (particularly an omnidirectional condenser microphone).

本発明によれば、この周波数の選択（切り替え）は、駆動回路２ａに設けられている周波数可変手段により容易に行うことができる。   According to the present invention, the selection (switching) of the frequency can be easily performed by the frequency variable means provided in the drive circuit 2a.

次に、図３，図４により、本発明の第２実施形態（請求項２に対応）に係る音響抵抗測定装置１Ｂについて説明する。上記第１実施形態と変更を要しない構成要素については同じ参照符号付し、その説明は省略する。   Next, an acoustic resistance measuring device 1B according to a second embodiment (corresponding to claim 2) of the present invention will be described with reference to FIGS. Components that do not need to be changed from those in the first embodiment are denoted by the same reference numerals, and description thereof is omitted.

この第２実施形態に係る音響抵抗測定装置１Ｂでは、上記第１実施形態における双指向性マイクロホン３１に代えて、第１および第２の２つの無指向性マイクロホン５１，５２を用いる。無指向性マイクロホン５１，５２は、コンデンサマイクロホンが好ましい。   In the acoustic resistance measuring apparatus 1B according to the second embodiment, the first and second omnidirectional microphones 51 and 52 are used in place of the bidirectional microphone 31 in the first embodiment. The omnidirectional microphones 51 and 52 are preferably condenser microphones.

すなわち、第１無指向性マイクロホン５１を第１配管１０の第１音響抵抗管１３の下流側（管端１２側）に配置して、第１配管１０内の音波を収音する。同様に、第２無指向性マイクロホン５２を第２配管２０の第２音響抵抗管２３の下流側（管端１２側）に配置して、第２配管２０内の音波を収音する。   That is, the first omnidirectional microphone 51 is disposed on the downstream side (the pipe end 12 side) of the first acoustic resistance pipe 13 of the first pipe 10 to collect sound waves in the first pipe 10. Similarly, the second omnidirectional microphone 52 is arranged on the downstream side (tube end 12 side) of the second acoustic resistance pipe 23 of the second pipe 20 to collect sound waves in the second pipe 20.

ただし、この２つの無指向性マイクロホン５１，５２は、感度および周波数応答がともに揃っていることを条件とする。この点に関しては、上記第１実施形態の双指向性マイクロホン３１の方が有利である。   However, the two omnidirectional microphones 51 and 52 are required to have both sensitivity and frequency response. In this regard, the bidirectional microphone 31 of the first embodiment is more advantageous.

無指向性マイクロホン５１，５２の各マイク出力によって、基準音響抵抗材４０Ｓと被測定音響抵抗材４０Ｘの各音響抵抗値の相対的な大小関係を判別するため、この実施形態では差動増幅器５３を用いている。   In this embodiment, the differential amplifier 53 is used to determine the relative magnitude relationship between the acoustic resistance values of the reference acoustic resistance material 40S and the measured acoustic resistance material 40X based on the microphone outputs of the omnidirectional microphones 51 and 52. Used.

この例では、第１配管１０側の第１無指向性マイクロホン５１のマイク出力を差動増幅器５３の＋側入力端子に入力し、第２配管２０側の第２無指向性マイクロホン５２のマイク出力を差動増幅器５３の−側入力端子に入力し、その出力を測定部５４に与えるようにしている。   In this example, the microphone output of the first omnidirectional microphone 51 on the first pipe 10 side is input to the + side input terminal of the differential amplifier 53, and the microphone output of the second omnidirectional microphone 52 on the second pipe 20 side is input. Is input to the negative input terminal of the differential amplifier 53, and the output is given to the measurement unit 54.

無指向性マイクロホン５１，５２のマイク出力は、配管１０，２０内の音圧に比例するため、基準音響抵抗材４０Ｓと被測定音響抵抗材４０Ｘの各音響抵抗値が等しければ、無指向性マイクロホン５１，５２のマイク出力が同一値となる。   Since the microphone outputs of the omnidirectional microphones 51 and 52 are proportional to the sound pressure in the pipes 10 and 20, if the respective acoustic resistance values of the reference acoustic resistance material 40S and the measured acoustic resistance material 40X are equal, the omnidirectional microphone is used. The microphone outputs 51 and 52 have the same value.

これにより、差動増幅器５３の出力は０、したがって測定部５４には例えば「０」と表示され、被測定音響抵抗材４０Ｘの音響抵抗値が適正と判断される。   As a result, the output of the differential amplifier 53 is displayed as 0, and thus, for example, “0” is displayed on the measurement unit 54, and it is determined that the acoustic resistance value of the measured acoustic resistance material 40 </ b> X is appropriate.

これに対して、基準音響抵抗材４０Ｓの音響抵抗値に対して被測定音響抵抗材４０Ｘの音響抵抗値が小さい場合には、第１無指向性マイクロホン５１のマイク出力が第２無指向性マイクロホン５２のマイク出力よりも大きくなるため、測定部５４には例えば「＋（正）」と表示される。   On the other hand, when the acoustic resistance value of the measured acoustic resistance material 40X is smaller than the acoustic resistance value of the reference acoustic resistance material 40S, the microphone output of the first omnidirectional microphone 51 is the second omnidirectional microphone. For example, “+ (positive)” is displayed on the measurement unit 54 because it is larger than the microphone output of 52.

反対に、基準音響抵抗材４０Ｓの音響抵抗値に対して被測定音響抵抗材４０Ｘの音響抵抗値が大きい場合には、第２無指向性マイクロホン５２のマイク出力が第１無指向性マイクロホン５１のマイク出力よりも大きくなるため、測定部５４には例えば「−（負）」と表示される。   On the contrary, when the acoustic resistance value of the acoustic resistance material to be measured 40 </ b> X is larger than the acoustic resistance value of the reference acoustic resistance material 40 </ b> S, the microphone output of the second omnidirectional microphone 52 is that of the first omnidirectional microphone 51. Since it becomes larger than the microphone output, for example, “− (negative)” is displayed on the measurement unit 54.

このように、第２実施形態に係る音響抵抗測定装置においても、第１実施形態形態と同じく、測定信号発生源として所定周波数の音波を発生し得るスピーカ２を用いていることから、被測定音響抵抗材４０Ｘの音響抵抗値を所望とする周波数の音波で測定することができる。また、その測定結果に応じて、被測定音響抵抗材４０Ｘの音響抵抗値を調整することもできる。   As described above, in the acoustic resistance measurement apparatus according to the second embodiment, the speaker 2 that can generate a sound wave of a predetermined frequency is used as the measurement signal generation source, as in the first embodiment. The acoustic resistance value of the resistance material 40X can be measured with a sound wave having a desired frequency. Moreover, according to the measurement result, the acoustic resistance value of the acoustic resistance material 40X to be measured can be adjusted.

なお、上記第１実施形態および第２実施形態での測定部３３，５４の表示形態はあくまで一例であって、他の表示形態に任意に変更されてよい。   In addition, the display form of the measurement parts 33 and 54 in the said 1st Embodiment and 2nd Embodiment is an example to the last, Comprising: You may change arbitrarily to another display form.

１Ａ，１Ｂ 音響抵抗測定装置
２ スピーカ
２ａ スピーカの駆動回路
１０ 第１配管
１２ 管端（第１配管の他端）
１３ 第１音響抵抗管
２０ 第２配管
２２ 管端（第２配管の他端）
２３ 第２音響抵抗管
３０ ブリッジ管
３１ 双指向性マイクロホン
３３ 測定部
４０Ｓ 基準音響抵抗材
４０Ｘ 被測定音響抵抗材
５１，５２ 無指向性マイクロホン
５３ 差動増幅器
５４ 測定部 1A, 1B Acoustic resistance measuring device 2 Speaker 2a Speaker drive circuit 10 First piping 12 Tube end (the other end of the first piping)
13 First acoustic resistance pipe 20 Second pipe 22 Pipe end (the other end of the second pipe)
23 Second acoustic resistance tube 30 Bridge tube 31 Bidirectional microphone 33 Measurement unit 40S Reference acoustic resistance material 40X Acoustic resistance material to be measured 51, 52 Omnidirectional microphone 53 Differential amplifier 54 Measurement unit

Claims (4)

マイクロホンに用いられる音響抵抗材の音響抵抗を測定する音響抵抗材の音響抵抗測定装置において、
所定周波数の音波を発生するスピーカと、
一端が上記スピーカに接続され他端側の管端に基準となる基準音響抵抗材が配置される第１配管および上記第１配管の途中に含まれ上記スピーカからの音波に対して所定の音響抵抗として作用する第１音響抵抗管と、
一端が上記第１配管の一端とともに上記スピーカに接続され他端側の管端に被測定音響抵抗材が配置される上記第１配管とほぼ同一構成の第２配管および上記第２配管の途中に含まれ上記第１音響抵抗管とほぼ同一の音響抵抗を有する第２音響抵抗管と、
双指向性マイクロホンを含み上記第１音響抵抗管および上記第２音響抵抗管の各下流側で上記第１配管と上記第２配管との間に連結されるブリッジ管と、
上記双指向性マイクロホンから出力されるマイク出力に基づいて上記基準音響抵抗材に対する上記被測定音響抵抗材の音響抵抗の大小を測定する測定手段とを備えていることを特徴とする音響抵抗材の音響抵抗測定装置。 In the acoustic resistance measurement device for an acoustic resistance material for measuring the acoustic resistance of the acoustic resistance material used for the microphone,
A speaker that generates sound waves of a predetermined frequency;
A first acoustic pipe having one end connected to the speaker and a reference acoustic resistance material arranged as a reference at the other end of the pipe, and a predetermined acoustic resistance against sound waves from the speaker included in the middle of the first pipe. A first acoustic resistance tube acting as
One end of the second pipe is connected to the speaker together with one end of the first pipe, and the acoustic resistance material to be measured is disposed at the other end of the pipe. A second acoustic resistance tube included and having substantially the same acoustic resistance as the first acoustic resistance tube;
A bridge pipe including a bidirectional microphone and connected between the first pipe and the second pipe on each downstream side of the first acoustic resistance pipe and the second acoustic resistance pipe;
A measuring means for measuring the magnitude of the acoustic resistance of the measured acoustic resistance material with respect to the reference acoustic resistance material based on a microphone output output from the bidirectional microphone. Acoustic resistance measuring device. マイクロホンに用いられる音響抵抗材の音響抵抗を測定する音響抵抗材の音響抵抗測定装置において、
所定周波数の音波を発生するスピーカと、
一端が上記スピーカに接続され他端側の管端に基準となる基準音響抵抗材が配置される第１配管および上記第１配管の途中に含まれ上記スピーカからの音波に対して所定の音響抵抗として作用する第１音響抵抗管と、
一端が上記第１配管の一端とともに上記スピーカに接続され他端側の管端に被測定音響抵抗材が配置される上記第１配管とほぼ同一構成の第２配管および上記第２配管の途中に含まれ上記第１音響抵抗管とほぼ同一の音響抵抗を有する第２音響抵抗管と、
上記第１音響抵抗管および上記第２音響抵抗管の各下流側で上記スピーカからの音波を収音する第１および第２の無指向性マイクロホンと、
上記第１および第２の無指向性マイクロホンの各マイク出力端子に接続された差動増幅器を介して上記基準音響抵抗材に対する上記被測定音響抵抗材の音響抵抗の大小を測定する測定手段とを備えていることを特徴とする音響抵抗材の音響抵抗測定装置。 In the acoustic resistance measurement device for an acoustic resistance material for measuring the acoustic resistance of the acoustic resistance material used for the microphone,
A speaker that generates sound waves of a predetermined frequency;
A first acoustic pipe having one end connected to the speaker and a reference acoustic resistance material arranged as a reference at the other end of the pipe, and a predetermined acoustic resistance against sound waves from the speaker included in the middle of the first pipe. A first acoustic resistance tube acting as
One end of the second pipe is connected to the speaker together with one end of the first pipe, and the acoustic resistance material to be measured is disposed at the other end of the pipe. A second acoustic resistance tube included and having substantially the same acoustic resistance as the first acoustic resistance tube;
First and second omnidirectional microphones that collect sound waves from the speaker on the downstream sides of the first acoustic resistance tube and the second acoustic resistance tube;
Measuring means for measuring the magnitude of the acoustic resistance of the acoustic resistance material to be measured relative to the reference acoustic resistance material via a differential amplifier connected to each microphone output terminal of the first and second omnidirectional microphones; An acoustic resistance measuring device for an acoustic resistance material, comprising: 上記第１音響抵抗管および上記第２音響抵抗管の音響抵抗値が上記基準音響抵抗材の音響抵抗値とほぼ等しい値に設定されていることを特徴とする請求項１または２に記載の音響抵抗材の音響抵抗測定装置。   The acoustic resistance value according to claim 1 or 2, wherein acoustic resistance values of the first acoustic resistance tube and the second acoustic resistance tube are set to be substantially equal to an acoustic resistance value of the reference acoustic resistance material. An acoustic resistance measurement device for resistance materials. 上記スピーカから発せられる音波の周波数を可変する周波数可変手段をさらに備え、上記被測定音響抵抗材が用いられるマイクロホンユニットの制御方式に応じて上記音波の周波数が選択可能であることを特徴とする請求項１ないし３のいずれか１項に記載の音響抵抗材の音響抵抗測定装置。   A frequency varying means for varying the frequency of the sound wave emitted from the speaker is further provided, and the frequency of the sound wave can be selected according to a control method of a microphone unit in which the acoustic resistance material to be measured is used. Item 4. The acoustic resistance measurement device for an acoustic resistance material according to any one of Items 1 to 3.
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US10582298B2 (en) 2015-03-31 2020-03-03 Bose Corporation Directional acoustic device and method of manufacturing a directional acoustic device

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