JP2011061403A - Equalizer and electroacoustic transducer - Google Patents

Equalizer and electroacoustic transducer Download PDF

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JP2011061403A
JP2011061403A JP2009207818A JP2009207818A JP2011061403A JP 2011061403 A JP2011061403 A JP 2011061403A JP 2009207818 A JP2009207818 A JP 2009207818A JP 2009207818 A JP2009207818 A JP 2009207818A JP 2011061403 A JP2011061403 A JP 2011061403A
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JP5333085B2 (en
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Takao Kawasaki
隆生 川崎
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Victor Company of Japan Ltd
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Abstract

<P>PROBLEM TO BE SOLVED: To provide an equalizer which can successfully equalize a voice output of a polyhedral speaker by a comparative simple circuit configuration or calculation by equalizing based on a transfer function of the polyhedral speaker. <P>SOLUTION: An equalizer 50 prepares a model transfer function of a simplified polyhedral speaker 12 from a minimum resonant frequency f0 and a Q value (Q0) of the polyhedral speaker 12 and a virtual circumference of the polyhedral speaker 12. An equalizer 30 performs equalizing based on a transfer function of a reverse filter of the model transfer function. Thus, a circuit scale or a calculation amount can be reduced. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

本発明は、スピーカを多面体状に配設した多面体型スピーカの音声出力を等化するイコライザ装置、同イコライザ装置を備えた電気音響変換装置に関するものである。   The present invention relates to an equalizer device for equalizing sound output of a polyhedral speaker in which speakers are arranged in a polyhedron shape, and an electroacoustic conversion device including the equalizer device.

電気信号を音声として出力するスピーカの一つとして、スピーカを外側に向けて多面体状に配設した多面体型スピーカが存在する。この多面体型スピーカとは［特許文献１］に示すように例えば正５角形の振動板を正１２面体となるように設置し（ただし、１面は台座とする。）、それぞれの振動板にスピーカユニットを設置したものである。このように、多面体型スピーカは全方向にスピーカが配設されているためその音声出力は点音源、無指向性となり、理想的には全ての方向に同じ音圧の音声を出力することができる。ただし、多面体型スピーカは一般的に周波数特性が平坦ではないため、例えば［特許文献２］では、音源と多面体型スピーカとの間にイコライザ回路を設けて、多面体型スピーカからの音声出力を平坦化（等化）している。   As one of loudspeakers that output an electrical signal as sound, there is a polyhedral speaker in which the loudspeaker is arranged in a polyhedral shape with the outside facing outward. With this polyhedral speaker, as shown in [Patent Document 1], for example, a regular pentagonal diaphragm is installed to be a regular dodecahedron (however, one surface is a pedestal), and the speaker is attached to each diaphragm. A unit is installed. In this way, since the polyhedral speakers are arranged in all directions, the sound output is a point sound source and omnidirectional, and ideally, the sound of the same sound pressure can be output in all directions. . However, since the frequency characteristics of polyhedral speakers are generally not flat, for example, in [Patent Document 2], an equalizer circuit is provided between a sound source and a polyhedral speaker to flatten the sound output from the polyhedral speaker. (Equalization).

特開２００６−３１１３４９号公報Japanese Patent Laid-Open No. 2006-311349 特開２００５−０５１６９４号公報Japanese Patent Laid-Open No. 2005-05694

［特許文献２］の発明に記載されているイコライザ回路は、音声信号を比較的狭い周波数帯域に分割し、その周波数帯域毎に所定量ブースト又はカットして所望の値に近似させそれを積み重ねることで、全体として多面体型スピーカの周波数特性を補完して音声出力の等化を行う。しかしながら、多面体型スピーカの伝達関数の構成と一般的なイコライザ回路の伝達関数の構成とは大きく異なっており、その異なったイコライザ回路の伝達関数により多面体型スピーカの音声出力の等化を十分に行うためには、より狭い周波数帯で多くの周波数帯域に分割する必要がある。このため、アナログ回路の場合には回路規模が大きくなるという問題点がある。また、デジタル処理の場合には演算量が多くなるという問題点がある。さらに、等化後の位相特性の誤差が大きいという問題点がある。   The equalizer circuit described in the invention of [Patent Document 2] divides an audio signal into a relatively narrow frequency band, and boosts or cuts a predetermined amount for each frequency band to approximate a desired value and stack it. Therefore, the sound output is equalized by complementing the frequency characteristics of the polyhedral speaker as a whole. However, the configuration of the transfer function of the polyhedral speaker is greatly different from the configuration of the transfer function of a general equalizer circuit, and the sound output of the polyhedral speaker is sufficiently equalized by the transfer function of the different equalizer circuit. For this purpose, it is necessary to divide into a number of frequency bands in a narrower frequency band. For this reason, in the case of an analog circuit, there is a problem that the circuit scale becomes large. In the case of digital processing, there is a problem that the amount of calculation increases. Furthermore, there is a problem that the phase characteristic error after equalization is large.

本発明は上記事情に鑑みてなされたものであり、比較的容易な回路構成もしくは演算で多面体型スピーカの音声出力の等化を良好に行うことが可能なイコライザ装置及び電気音響変換装置を提供することを目的とする。   The present invention has been made in view of the above circumstances, and provides an equalizer device and an electroacoustic transducer capable of satisfactorily equalizing the sound output of a polyhedral speaker with a relatively easy circuit configuration or calculation. For the purpose.

本発明は、
（１）音源１０からの音声信号Ｖｉｎが入力される入力端２０ａと、前記入力端２０ａに入力された音声信号Ｖｉｎを所定の伝達関数に基づいてイコライジングするイコライザ部３０と、前記イコライザ部３０でイコライジングした音声信号Ｖｏｕｔを多面体型スピーカ１２に出力する出力端２０ｂと、を有し、
前記伝達関数が第１の伝達関数の逆フィルタの伝達関数と第２の伝達関数の逆フィルタの伝達関数との積を含み、
前記第１の伝達関数は、遮断周波数が前記多面体型スピーカ１２の最低共振周波数ｆ０と略同等であり、遮断周波数でのＱ値が前記多面体型スピーカ１２の最低共振周波数ｆ０でのＱ値（Ｑ０）と略同等である２次のハイパスフィルタの伝達関数であり、
前記第２の伝達関数は、遮断周波数ｆｃが前記多面体型スピーカ１２の仮想円周と同等の波長を有する音波の周波数と略同等である１次のローパスフィルタの伝達係数であることを特徴とするイコライザ装置５０を提供することにより、上記課題を解決する。
（２）前記多面体型スピーカ１２の前記仮想円周は、前記多面体型スピーカ１２の外側に接する球の円周と内側に接する球の円周、もしくは前記多面体型スピーカ１２の体積と等しい体積を有する球の円周に基づいて取得することを特徴とする上記（１）記載のイコライザ装置５０を提供することにより、上記課題を解決する。
（３）前記伝達関数が、前記第１の伝達関数の逆フィルタの伝達関数と前記第２の伝達関数の逆フィルタの伝達関数との積に、高次のハイパスフィルタの伝達関数と１次又は高次のローパスフィルタの伝達関数の双方もしくはいずれか一方を乗じたものであることを特徴とする上記（１）又は（２）記載のイコライザ装置５０を提供することにより、上記課題を解決する。
（４）上記（１）〜（３）のいずれか１項に記載のイコライザ装置５０と、前記イコライザ装置５０から出力される音声信号Ｖｏｕｔを再生する多面体型スピーカ１２と、を備えることを特徴とする電気音響変換装置１００を提供することにより、上記課題を解決する。 The present invention
(1) The input end 20a to which the audio signal Vin from the sound source 10 is input, the equalizer unit 30 that equalizes the audio signal Vin input to the input end 20a based on a predetermined transfer function, and the equalizer unit 30 An output terminal 20b for outputting the equalized audio signal Vout to the polyhedral speaker 12;
The transfer function includes a product of an inverse filter transfer function of a first transfer function and an inverse filter transfer function of a second transfer function;
The first transfer function has a cutoff frequency substantially equal to the lowest resonance frequency f0 of the polyhedral speaker 12, and a Q value at the cutoff frequency is a Q value (Q0 at the lowest resonance frequency f0 of the polyhedral speaker 12). ) Is a transfer function of a second-order high-pass filter that is substantially equivalent to
The second transfer function is a transfer coefficient of a first-order low-pass filter whose cutoff frequency fc is substantially equal to the frequency of a sound wave having a wavelength equivalent to the virtual circumference of the polyhedral speaker 12. By providing the equalizer device 50, the above problem is solved.
(2) The virtual circumference of the polyhedral speaker 12 has a volume equal to the circumference of the sphere in contact with the outside of the polyhedral speaker 12 and the circumference of the sphere in contact with the inside, or the volume of the polyhedral speaker 12. The above problem is solved by providing the equalizer device 50 described in (1) above, which is obtained based on the circumference of a sphere.
(3) The transfer function is a product of the transfer function of the inverse filter of the first transfer function and the transfer function of the inverse filter of the second transfer function, and the transfer function of the high-order high-pass filter and the first order or The above problem is solved by providing the equalizer device 50 described in (1) or (2) above, which is obtained by multiplying both or one of the transfer functions of a high-order low-pass filter.
(4) The equalizer device 50 according to any one of (1) to (3) above and the polyhedral speaker 12 that reproduces the audio signal Vout output from the equalizer device 50 are provided. By providing an electroacoustic transducer 100 that performs the above-described problems, the above-described problems are solved.

本発明のイコライザ装置及び電気音響変換装置は、実際の多面体型スピーカの伝達関数をモデル化し、そのモデル化した伝達関数の逆フィルタの伝達関数に基づいてイコライジングするため、比較的容易な回路構成もしくは演算で多面体型スピーカの音声出力の等化を振幅、位相とも、より正確に行うことができる。   Since the equalizer device and the electroacoustic conversion device of the present invention model the transfer function of an actual polyhedral speaker and perform equalization based on the transfer function of the inverse filter of the modeled transfer function, a relatively easy circuit configuration or It is possible to perform the equalization of the sound output of the polyhedral speaker more accurately in terms of both amplitude and phase by calculation.

本発明に係るイコライザ装置及び電気音響変換装置を示すブロック図である。It is a block diagram which shows the equalizer apparatus and electroacoustic transducer which concern on this invention. 多面体型スピーカの伝達関数を説明する周波数特性図である。It is a frequency characteristic figure explaining the transfer function of a polyhedral speaker. 多面体型スピーカの実測した周波数特性と算出した伝達関数による周波数特性とを比較する図である。It is a figure which compares the measured frequency characteristic of a polyhedral speaker with the frequency characteristic by the calculated transfer function. 本発明に係るイコライザ装置の伝達関数を説明する周波数特性図である。It is a frequency characteristic figure explaining the transfer function of the equalizer apparatus concerning the present invention. 本発明に係るイコライザ装置の伝達関数を示す周波数特性図である。It is a frequency characteristic figure which shows the transfer function of the equalizer apparatus which concerns on this invention. 本発明に係るイコライザ部のアナログ回路の例を示す図である。It is a figure which shows the example of the analog circuit of the equalizer part which concerns on this invention. 本発明に係るイコライザ部のデジタル処理の構成例を示す図である。It is a figure which shows the structural example of the digital process of the equalizer part which concerns on this invention. 本発明により等化された音声出力を示す周波数特性図である。It is a frequency characteristic figure which shows the audio | voice output equalized by this invention.

本発明に係るイコライザ装置及び電気音響変換装置の実施の形態について図面に基づいて説明する。図１に示す本実施の形態に係るイコライザ装置５０は、音源１０側からの音声信号Ｖｉｎが入力する入力端２０ａと、入力端２０ａから入力した音声信号Ｖｉｎを所定の伝達関数でイコライジングするイコライザ部３０と、イコライザ部３０でイコライジングした音声信号Ｖｏｕｔを多面体型スピーカ１２側に例えばアンプ１４を介して出力する出力端２０ｂと、を有している。また、本実施形態に係わる電気音響変換装置１００は、イコライザ装置５０と多面体型スピーカ１２を有している。   Embodiments of an equalizer device and an electroacoustic transducer according to the present invention will be described with reference to the drawings. An equalizer device 50 according to the present embodiment shown in FIG. 1 includes an input end 20a to which a sound signal Vin from the sound source 10 is input, and an equalizer section that equalizes the sound signal Vin input from the input end 20a with a predetermined transfer function. 30 and an output end 20b for outputting the audio signal Vout equalized by the equalizer unit 30 to the polyhedral speaker 12 side through, for example, an amplifier 14. The electroacoustic transducer 100 according to the present embodiment includes an equalizer device 50 and a polyhedral speaker 12.

ここでの多面体型スピーカ１２は、スピーカが多面体状に配設されていれば正１２面体に限らず如何なる多面体でも構わない。また、スピーカが多面体状に配設されていれば、外形に特に制限はない。さらに、理想的な多面体型スピーカ１２は球形であるため、ここでは球形スピーカも多面体型スピーカ１２に含むものとする。   The polyhedral speaker 12 here is not limited to a regular dodecahedron as long as the speakers are arranged in a polyhedron shape, and may be any polyhedron. Further, the outer shape is not particularly limited as long as the speakers are arranged in a polyhedral shape. Furthermore, since the ideal polyhedral speaker 12 has a spherical shape, a spherical speaker is also included in the polyhedral speaker 12 here.

次に、イコライザ部３０の伝達関数の基となる多面体型スピーカ１２の伝達関数に関して説明を行う。先ず、多面体型スピーカ１２には、一般的なスピーカと同様、振動系支持機構のばね定数、内部空気のばね定数、振動系質量などで決定する最低共振周波数ｆ０が存在する。そして、多面体型スピーカ１２におけるスピーカ駆動電圧（音声信号）から振動系加速度（音声出力）への伝達関数は、一般的なスピーカと同様、遮断周波数と当該遮断周波数におけるＱ値が、多面体型スピーカ１２の最低共振周波数ｆ０と当該最低共振周波数ｆ０におけるＱ値（Ｑ０）とそれぞれ同等の２次のハイパスフィルタの伝達関数（第１の伝達関数）とほぼ等しくなる。尚、２次のハイパスフィルタの遮断周波数と遮断周波数ｆ０におけるＱ値（Ｑ０）とが決定すればこの２次のハイパスフィルタのＱ値の周波数曲線（ピークの値、ピークの周波数、ピークの鋭さ等）も概ね決定する。   Next, the transfer function of the polyhedral speaker 12 that is the basis of the transfer function of the equalizer unit 30 will be described. First, the polyhedral speaker 12 has a minimum resonance frequency f0 determined by a spring constant of a vibration system support mechanism, a spring constant of internal air, a vibration system mass, and the like, as in a general speaker. The transfer function from the speaker drive voltage (audio signal) to the vibration system acceleration (audio output) in the polyhedral speaker 12 is similar to that of a general speaker in that the cutoff frequency and the Q value at the cutoff frequency are the polyhedral speaker 12. And the transfer function (first transfer function) of the second-order high-pass filter equivalent to the Q value (Q0) at the minimum resonance frequency f0 and the Q value (Q0) at the minimum resonance frequency f0. If the cut-off frequency of the secondary high-pass filter and the Q value (Q0) at the cut-off frequency f0 are determined, the frequency curve of the Q value of the secondary high-pass filter (peak value, peak frequency, peak sharpness, etc.) ) Is also largely determined.

一方、多面体型スピーカ１２の理想型は呼吸球であり、呼吸球ではその表面を入力信号（音声信号）に比例した加速度で駆動したときの音圧（音声出力）の伝達関数が、呼吸球の円周に応じた遮断周波数ｆｃの１次のローパスフィルタの伝達関数とほぼ等しくなる。ここで、この１次のローパスフィルタの遮断周波数ｆｃは、呼吸球の半径をｒとした時に呼吸球の円周（２πｒ）と波長が一致する音波の周波数とほぼ同等となる。従って、遮断周波数ｆｃは、ｃを音速とした時に
ｆｃ＝ｃ／（２πｒ） となる。 On the other hand, the ideal type of the polyhedral speaker 12 is a respiratory sphere, and the transfer function of the sound pressure (speech output) when the surface of the respiratory sphere is driven at an acceleration proportional to the input signal (speech signal) is The transfer function of the first-order low-pass filter having a cutoff frequency fc corresponding to the circumference is substantially equal. Here, the cut-off frequency fc of the first-order low-pass filter is substantially equal to the frequency of the sound wave whose wavelength matches the circumference (2πr) of the respiratory sphere when the radius of the respiratory sphere is r. Accordingly, the cutoff frequency fc is fc = c / (2πr) where c is the speed of sound.

尚、多面体型スピーカ１２は多面体であり理想的な呼吸球ではないから、正確な円周を求めることはできない。従って、実際の多面体型スピーカ１２では、上記の遮断周波数ｆｃを導くための円周の値（これを仮想円周（２πｒ’）とする）を以下のようにして取得することが好ましい。先ず、仮想円周の第一の取得方法は、多面体型スピーカ１２の外側に接する球の円周と内側に接する球の円周を求めその中間値を仮想円周とする方法である。また、仮想円周の第二の取得方法は、多面体型スピーカ１２の体積と等しい体積を有する球を求めその球の円周を仮想円周とする方法である。これら仮想円周の取得方法を比較した場合、第二の取得方法の方が呼吸球の円周により近い仮想円周を得ることができる。   In addition, since the polyhedral speaker 12 is a polyhedron and is not an ideal breathing sphere, an accurate circumference cannot be obtained. Therefore, in the actual polyhedral speaker 12, it is preferable to obtain the circumference value (this is the virtual circumference (2πr ′)) for deriving the cutoff frequency fc as follows. First, the first acquisition method of the virtual circumference is a method in which the circumference of the sphere in contact with the outer side of the polyhedral speaker 12 and the circumference of the sphere in contact with the inside are obtained, and an intermediate value thereof is set as the virtual circumference. The second method for obtaining the virtual circumference is a method for obtaining a sphere having a volume equal to the volume of the polyhedral speaker 12 and using the circumference of the sphere as the virtual circumference. When these virtual circumference acquisition methods are compared, the second acquisition method can obtain a virtual circumference closer to the circumference of the respiratory sphere.

上記のように多面体型スピーカ１２は、一般的なスピーカとしての第１の伝達関数と、呼吸球としての仮想円周に応じた遮断周波数ｆｃ（ｆｃ＝ｃ／（２πｒ’））の１次のローパスフィルタの伝達関数（第２の伝達関数）との２つの伝達関数を備えている。従って、多面体型スピーカ１２の伝達関数は、第１の伝達関数と第２の伝達関数との積に近いものとなる。   As described above, the polyhedral speaker 12 has a first-order transfer function fc (fc = c / (2πr ′)) corresponding to a first transfer function as a general speaker and a virtual circumference as a respiratory sphere. Two transfer functions including a transfer function (second transfer function) of the low-pass filter are provided. Therefore, the transfer function of the polyhedral speaker 12 is close to the product of the first transfer function and the second transfer function.

ここで、一辺が約３７ｍｍの正５角形の振動板を有するスピーカユニットで構成された正１２面体（１面は台座）の多面体型スピーカ１２を用意し、その最低共振周波数ｆ０とそのときのＱ値（Ｑ０）を測定した。その結果、最低共振周波数ｆ０＝６４０Ｈｚ、Ｑ０＝３．６であった。   Here, a regular dodecahedron (one surface is a pedestal) polyhedral speaker 12 composed of a speaker unit having a regular pentagonal diaphragm with a side of about 37 mm is prepared, and its lowest resonance frequency f0 and Q at that time are prepared. The value (Q0) was measured. As a result, the lowest resonance frequency was f0 = 640 Hz and Q0 = 3.6.

また、この多面体型スピーカ１２の体積と同等な球の直径を算出し、仮想円周を算出したところ２９７ｍｍとなった。ここで、音速を３４０ｍ／ｓとし、１次のローパスフィルタの遮断周波数ｆｃを、
ｆｃ＝３４０／（２９７×１０−３）≒１１４５（Ｈｚ）とした。 Further, the diameter of a sphere equivalent to the volume of the polyhedral speaker 12 was calculated, and the virtual circumference was calculated to be 297 mm. Here, the sound speed is 340 m / s, and the cutoff frequency fc of the first-order low-pass filter is
fc = 340 / (297 × 10 −3 ) ≈1145 (Hz).

ここで、遮断周波数がｆ０が６４０ＨｚでＱ０が３．６の２次のハイパスフィルタの周波数特性図を図２（ａ）に示す。また、遮断周波数ｆｃが１１４５Ｈｚの１次のローパスフィルタの周波数特性図を図２（ｂ）に示す。   Here, FIG. 2A shows a frequency characteristic diagram of a second-order high-pass filter having a cutoff frequency f0 of 640 Hz and Q0 of 3.6. FIG. 2B shows a frequency characteristic diagram of a first-order low-pass filter having a cutoff frequency fc of 1145 Hz.

次に、図２（ａ）に示した２次のハイパスフィルタの伝達関数（第１の伝達関数）と図２（ｂ）に示した１次のローパスフィルタの伝達関数（第２の伝達関数）とを求めそれらの積を算出した。ここで、算出した伝達関数による周波数特性図と実測した多面体型スピーカ１２の周波数特性図とを図３に示す。尚、図３中、実線Ａが算出した伝達関数による周波数特性を示し、実線Ｂ１、Ｂ２が実測（２回測定）した多面体型スピーカ１２の周波数特性である。また、実線Ａのうち領域ａが主に第１の伝達関数（図２（ａ））が大きく関与する領域であり、領域ｂが主に第２の伝達関数（図２（ｂ））が大きく関与する領域である。   Next, the transfer function (first transfer function) of the second-order high-pass filter shown in FIG. 2 (a) and the transfer function (second transfer function) of the first-order low-pass filter shown in FIG. 2 (b). And the product of them was calculated. Here, FIG. 3 shows a frequency characteristic diagram based on the calculated transfer function and an actually measured frequency characteristic diagram of the polyhedral speaker 12. In FIG. 3, the solid line A shows the frequency characteristic based on the calculated transfer function, and the solid lines B <b> 1 and B <b> 2 are the frequency characteristics of the polyhedral speaker 12 measured (measured twice). Further, in the solid line A, the region a is a region where the first transfer function (FIG. 2A) is mainly involved, and the region b is mainly the second transfer function (FIG. 2B). It is an area involved.

図３より、実測した多面体型スピーカ１２の周波数特性と算出した伝達関数による周波数特性とはほぼ一致していることが分かる。このことから、第１の伝達関数と第２の伝達関数の積は、多面体型スピーカ１２の伝達関数とほぼ同等となることが分かる。つまり、多面体型スピーカ１２の最低共振周波数ｆ０とそのときのＱ値（Ｑ０）、及び多面体型スピーカ１２の仮想円周の値が取得できれば、多面体型スピーカ１２の伝達関数とほぼ同等の伝達関数（以後、モデル伝達関数と記述）を算出することが可能となる。   From FIG. 3, it can be seen that the actually measured frequency characteristic of the polyhedral speaker 12 and the calculated frequency characteristic of the transfer function are substantially the same. From this, it can be seen that the product of the first transfer function and the second transfer function is substantially equal to the transfer function of the polyhedral speaker 12. In other words, if the lowest resonance frequency f0 of the polyhedral speaker 12 and the Q value (Q0) at that time and the value of the virtual circumference of the polyhedral speaker 12 can be acquired, a transfer function substantially equivalent to the transfer function of the polyhedral speaker 12 ( Thereafter, the model transfer function and description) can be calculated.

尚、実際のモデル伝達関数の設定では、最低共振周波数ｆ０、Ｑ０、仮想円周の値から仮のモデル伝達関数を作成する。そして、この仮のモデル伝達関数による周波数特性と実測した実際の多面体型スピーカ１２の周波数特性とを比較しながらｆ０、Ｑ０、仮想円周の値を約±２０％程度の範囲で変化させて、伝達係数の合わせ込みを行い最終的なモデル伝達関数とする。この場合でも基本となる２次のハイパスフィルタと１次のローパスフィルタは固定であり、パラメータはｆ０、Ｑ０、仮想円周の値の３つであるから、多面体型スピーカ１２のモデル伝達関数を容易且つ迅速に求めることができる。   In setting the actual model transfer function, a temporary model transfer function is created from the values of the lowest resonance frequencies f0 and Q0 and the virtual circumference. Then, f0, Q0, and the value of the virtual circumference are changed in a range of about ± 20% while comparing the frequency characteristics of the temporary model transfer function with the actually measured frequency characteristics of the polyhedral speaker 12; The final model transfer function is obtained by fitting the transfer coefficients. Even in this case, the basic second-order high-pass filter and the first-order low-pass filter are fixed, and the parameters are three values of f0, Q0, and virtual circumference, so that the model transfer function of the polyhedral speaker 12 can be easily performed. And it can be obtained quickly.

イコライザ部３０は、上記のようにして求められたモデル伝達関数の逆フィルタの伝達関数をとるようなアナログ回路もしくはデジタルフィルタを用いことができる。尚、モデル伝達関数の逆フィルタの伝達関数は、第１の伝達関数の逆フィルタの伝達関数と第２の伝達関数の逆フィルタの伝達関数との積と同等である。ここで、図３に示したモデル伝達関数の逆フィルタの周波数特性図を図４（ａ）に示す。   The equalizer unit 30 can use an analog circuit or a digital filter that takes the transfer function of the inverse filter of the model transfer function obtained as described above. The transfer function of the inverse filter of the model transfer function is equivalent to the product of the transfer function of the inverse filter of the first transfer function and the transfer function of the inverse filter of the second transfer function. Here, a frequency characteristic diagram of the inverse filter of the model transfer function shown in FIG. 3 is shown in FIG.

図４（ａ）に示すようにモデル伝達関数の逆フィルタの周波数特性は、通常、低周波側と高周波側とが無限に上昇する。従って、イコライザ部３０には多面体型スピーカ１２側への過大な音声信号の印加防止と音質の調整のため、音声出力の再生周波数帯域以外の低周波成分と高周波成分とを減衰させる高次のハイパスフィルタと１次又は高次のローパスフィルタとを組み入れることが好ましい。この場合、イコライザ部３０全体としての伝達関数は、第１の伝達関数の逆フィルタの伝達関数と第２の伝達関数の逆フィルタの伝達関数との積に、高次のハイパスフィルタの伝達関数と１次又は高次のローパスフィルタの伝達関数とを乗じたものとなる。   As shown in FIG. 4A, the frequency characteristic of the inverse filter of the model transfer function usually increases infinitely on the low frequency side and the high frequency side. Therefore, the equalizer unit 30 has a high-order high-pass that attenuates low-frequency components and high-frequency components other than the reproduction frequency band of the audio output in order to prevent application of excessive audio signals to the polyhedral speaker 12 side and to adjust sound quality. It is preferable to incorporate a filter and a first or higher order low pass filter. In this case, the transfer function of the equalizer unit 30 as a whole is the product of the transfer function of the inverse filter of the first transfer function and the transfer function of the inverse filter of the second transfer function, and the transfer function of the high-order high-pass filter. It is multiplied by the transfer function of the first-order or higher-order low-pass filter.

ここで例えば、イコライザ部３０に、図４（ｂ）に示す周波数特性の１次のローパスフィルタと図４（ｃ）に示す周波数特性の３次のハイパスフィルタを組み入れれば、これらのフィルタが組み入れられたイコライザ部３０の周波数特性は図５のようになる。そして、イコライザ部３０の伝達関数は、第１の伝達関数の逆フィルタの伝達関数と第２の伝達関数の逆フィルタの伝達関数との積に、３次のハイパスフィルタの伝達関数と１次のローパスフィルタの伝達関数とを乗じたものとなる。尚、図５の領域ａ’が主に第１の伝達関数の逆フィルタの伝達関数が大きく関与する領域であり、領域ｂ’が主に第２の伝達関数の逆フィルタの伝達関数が大きく関与する領域であり、領域ｃが主に３次のハイパスフィルタの伝達関数が大きく関与する領域であり、領域ｄが主に１次のローパスフィルタの伝達関数が大きく関与する領域である。   Here, for example, if a first-order low-pass filter having a frequency characteristic shown in FIG. 4B and a third-order high-pass filter having a frequency characteristic shown in FIG. 4C are incorporated in the equalizer unit 30, these filters are incorporated. The frequency characteristic of the equalizer unit 30 is as shown in FIG. The transfer function of the equalizer unit 30 is the product of the transfer function of the inverse filter of the first transfer function and the transfer function of the inverse filter of the second transfer function, and the transfer function of the third-order high-pass filter and the first-order transfer function. Multiplyed by the transfer function of the low-pass filter. Note that the region a ′ in FIG. 5 is a region where the transfer function of the inverse filter of the first transfer function is mainly involved, and the region b ′ is mainly related to the transfer function of the inverse filter of the second transfer function. The region c is a region mainly involving the transfer function of the third-order high-pass filter, and the region d is a region mainly involving the transfer function of the first-order low-pass filter.

尚、モデル伝達関数や回路構成により低周波成分もしくは高周波成分の減衰が不要な場合には、高次のハイパスフィルタもしくは１次又は高次のローパスフィルタのいずれか一方を組み入れれば良い。この場合、イコライザ部３０全体の伝達関数は、第１の伝達関数の逆フィルタの伝達関数と第２の伝達関数の逆フィルタの伝達関数との積に、組み入れた高次のハイパスフィルタの伝達関数もしくは１次又は高次のローパスフィルタの伝達関数を乗じたものとなる。   If attenuation of the low-frequency component or high-frequency component is unnecessary due to the model transfer function or the circuit configuration, either a high-order high-pass filter or a primary or high-order low-pass filter may be incorporated. In this case, the transfer function of the entire equalizer unit 30 is the product of the transfer function of the inverse filter of the first transfer function and the transfer function of the inverse filter of the second transfer function. Alternatively, it is multiplied by the transfer function of a first-order or higher-order low-pass filter.

また、モデル伝達関数を多面体型スピーカ１２の伝達関数により近似させるために、イコライザ部３０に双２次型フィルタをさらに組み入れても良い。この場合、イコライザ部３０全体の伝達関数は、組み入れた双２次型フィルタの双２次型伝達関数をさらに乗じたものとなる。   Further, in order to approximate the model transfer function by the transfer function of the polyhedral speaker 12, a biquadratic filter may be further incorporated in the equalizer unit 30. In this case, the transfer function of the entire equalizer unit 30 is further multiplied by the biquadratic transfer function of the incorporated biquadratic filter.

ここで、図５の周波数特性を有するイコライザ部３０を、アナログ回路で構成した例を図６に示す。尚、イコライザ部３０はモデル伝達関数の逆フィルタの伝達関数に基づいてイコライジングすればよいから、第１の伝達関数の逆フィルタ、第２の伝達関数の逆フィルタ、その他のフィルタが明確に区別されたイコライザでなくてもよい。   Here, FIG. 6 shows an example in which the equalizer section 30 having the frequency characteristics of FIG. 5 is configured by an analog circuit. Since the equalizer unit 30 may perform equalization based on the transfer function of the inverse filter of the model transfer function, the inverse filter of the first transfer function, the inverse filter of the second transfer function, and other filters are clearly distinguished. It does not have to be an equalizer.

図６に示すイコライザ部３０は、部分的に重複しながら大きく分けて３つの回路で構成されている。回路３０ｂは低周波成分を減衰させる３次のハイパスフィルタの一部である１次のハイパスフィルタを主に構成している。回路３０ａは双２次のシェルビングイコライザであり、３次のハイパスフィルタの一部である２次のハイパスフィルタと第１の伝達関数の逆フィルタとを主に構成している。回路３０ｃは１次のシェルビングイコライザであり、第２の伝達関数の逆フィルタと高周波成分を減衰させる１次のローパスフィルタとを主に構成している。図６に示すように、本実施の形態に係るイコライザ装置５０によれば、イコライザ部３０を比較的容易なアナログ回路で構成することができる。   The equalizer unit 30 shown in FIG. 6 is roughly composed of three circuits while being partially overlapped. The circuit 30b mainly constitutes a first-order high-pass filter that is a part of a third-order high-pass filter that attenuates low-frequency components. The circuit 30a is a bi-secondary shelving equalizer, and mainly includes a second-order high-pass filter that is a part of the third-order high-pass filter and an inverse filter of the first transfer function. The circuit 30c is a first-order shelving equalizer, and mainly includes an inverse filter of the second transfer function and a first-order low-pass filter that attenuates high-frequency components. As shown in FIG. 6, according to the equalizer device 50 according to the present embodiment, the equalizer unit 30 can be configured with a relatively easy analog circuit.

次に、図７にイコライザ部３０をデジタルフィルタで構成した例を示す。図７に示すイコライザ部３０はバイクワッドフィルタ（Biquad Filter）としてのデジタルフィルタ３２ａ、３２ｂが２段縦続して構成されている。尚、図７中、Ｚ−１は遅延器、ａ１０、ａ１１、ａ１２、ａ２０、ａ２１、ａ２２、ｂ１１、ｂ１２、ｂ２１、ｂ２２は乗算器、“＋”は加算器を示す。 Next, FIG. 7 shows an example in which the equalizer unit 30 is configured with a digital filter. The equalizer unit 30 shown in FIG. 7 is configured by cascading two stages of digital filters 32a and 32b as Biquad Filters. In FIG. 7, Z- 1 is a delay unit, a10, a11, a12, a20, a21, a22, b11, b12, b21, b22 are multipliers, and "+" is an adder.

デジタルフィルタ３２ａ、３２ｂの遅延器、乗算器、加算器は、現在及び過去の入力値と過去の出力値に各乗算器に設定された係数を乗じてそれぞれ加算することを繰り返し、各々が双２次の伝達関数を有するフィルタとしての動作を行う。そして、例えばデジタルフィルタ３２ａの乗算器の係数を図７に示すようにすれば、デジタルフィルタ３２ａは図６中の回路３０ａと同様の伝達関数を備え回路３０ａと同様に機能する。また、デジタルフィルタ３２ｂの乗算器の係数を図７に示すようにすれば、デジタルフィルタ３２ｂは図６中の回路３０ｂ及び回路３０ｃとが合わさった伝達関数を備え回路３０ｂ及び回路３０ｃと同様に機能する。これにより、イコライザ部３０は図５と同様の周波数特性を示す伝達関数を有する。   The delay units, multipliers, and adders of the digital filters 32a and 32b repeatedly multiply the current and past input values and past output values by the coefficients set in the multipliers, respectively, and add each of them. Operation as a filter having the following transfer function is performed. For example, if the coefficients of the multiplier of the digital filter 32a are as shown in FIG. 7, the digital filter 32a has the same transfer function as the circuit 30a in FIG. 6 and functions in the same way as the circuit 30a. Further, if the coefficients of the multiplier of the digital filter 32b are as shown in FIG. 7, the digital filter 32b has a transfer function in which the circuit 30b and the circuit 30c in FIG. 6 are combined, and functions similarly to the circuit 30b and the circuit 30c. To do. As a result, the equalizer unit 30 has a transfer function showing the same frequency characteristics as in FIG.

図７に示すように、本実施の形態に係るイコライザ装置５０によれば、イコライザ部３０を比較的容易な演算処理のデジタルフィルタで構成することができる。尚、各乗算器の係数はイコライザ部３０に要求される伝達係数に対し、双一次変換を行うことにより容易に求めることができる。また、上記のデジタルフィルタ３２ａ、３２ｂの構成は一例であり、さらにイコライザ部３０の伝達関数を２つの双２次の伝達関数に分割する手法及び組み合わせに関しても特に限定はない。   As shown in FIG. 7, according to the equalizer device 50 according to the present embodiment, the equalizer unit 30 can be configured with a digital filter that is relatively easy to perform arithmetic processing. The coefficient of each multiplier can be easily obtained by performing bilinear transformation on the transfer coefficient required for the equalizer unit 30. Further, the configuration of the digital filters 32a and 32b is merely an example, and there is no particular limitation on the method and combination for dividing the transfer function of the equalizer unit 30 into two biquadratic transfer functions.

次に、本実施の形態に係るイコライザ装置５０の動作を説明する。先ず、音源１０側からの音声信号Ｖｉｎが入力端２０ａからイコライザ部３０に入力する。イコライザ部３０は入力した音声信号Ｖｉｎに対しイコライジングを施す。このときのイコライジングは、前述のようにして求められた多面体型スピーカ１２の逆フィルタの伝達関数と略同等の伝達関数を含む伝達関数により行われる。よって、イコライザ部３０の出力端２０ｂから出力する音声信号Ｖｏｕｔは例えば図５に示すようにイコライジングされる。出力した音声信号Ｖｏｕｔはアンプ１４で増幅され、多面体型スピーカ１２に出力される。そして、多面体型スピーカ１２は音声信号Ｖｏｕｔを音声として出力する。このとき、多面体型スピーカ１２はイコライザ部３０の伝達関数とほぼ逆の図３に相当する周波数特性（伝達関数）を有している。従って、多面体型スピーカ１２のほぼ逆の伝達関数でイコライジングされた音声信号Ｖｏｕｔ（図５）が多面体型スピーカ１２で出力されると、その音声出力は相互に補完、補償され結果として図８に示すように等化された平坦な音声出力となる。   Next, the operation of the equalizer device 50 according to the present embodiment will be described. First, the audio signal Vin from the sound source 10 side is input to the equalizer unit 30 from the input end 20a. The equalizer unit 30 performs equalization on the input audio signal Vin. The equalizing at this time is performed by a transfer function including a transfer function substantially equal to the transfer function of the inverse filter of the polyhedral speaker 12 obtained as described above. Therefore, the audio signal Vout output from the output end 20b of the equalizer unit 30 is equalized as shown in FIG. 5, for example. The output audio signal Vout is amplified by the amplifier 14 and output to the polyhedral speaker 12. The polyhedral speaker 12 outputs the audio signal Vout as audio. At this time, the polyhedral speaker 12 has a frequency characteristic (transfer function) corresponding to FIG. 3 which is substantially opposite to the transfer function of the equalizer section 30. Therefore, when the audio signal Vout (FIG. 5) equalized with a transfer function almost opposite to that of the polyhedral speaker 12 is output from the polyhedral speaker 12, the audio outputs are complemented and compensated for each other, and the result is shown in FIG. Thus, a flat audio output is equalized.

以上のように、本実施の形態に係るイコライザ装置５０は、多面体型スピーカ１２の最低共振周波数ｆ０と当該最低共振周波数ｆ０におけるＱ値（Ｑ０）及び多面体型スピーカ１２の仮想円周とから、簡略化した多面体型スピーカ１２のモデル伝達関数の逆フィルタの伝達関数に基づいてイコライジングする。このため周波数帯域を分割してイコライジングを行う従来のイコライザ装置と比較して回路規模もしくは演算量を減らすことができる。   As described above, the equalizer device 50 according to the present embodiment is simplified from the lowest resonance frequency f0 of the polyhedral speaker 12, the Q value (Q0) at the lowest resonance frequency f0, and the virtual circumference of the polyhedral speaker 12. Equalizing is performed based on the transfer function of the inverse filter of the model transfer function of the polyhedral loudspeaker 12. Therefore, the circuit scale or the amount of calculation can be reduced as compared with a conventional equalizer device that performs equalization by dividing a frequency band.

また、本実施の形態に係るイコライザ装置５０は、多面体型スピーカ１２の伝達関数に基づいてイコライジングするため、多面体型スピーカ１２の音声出力の等化をより正確に行うことができる。さらに、音声出力の位相特性に大きな誤差が生じることもない。   Moreover, since the equalizer device 50 according to the present embodiment performs equalization based on the transfer function of the polyhedral speaker 12, it is possible to more accurately equalize the sound output of the polyhedral speaker 12. Furthermore, no large error occurs in the phase characteristics of the audio output.

尚、上記のイコライザ装置５０は一例であるから、アナログ回路の構成、デジタル回路の構成は無論のこと、本発明は本発明の要旨を逸脱しない範囲で変更して実施することが可能である。   Since the equalizer device 50 is an example, the configuration of the analog circuit and the configuration of the digital circuit can of course be changed, and the present invention can be implemented without departing from the scope of the present invention.

１０ 音源
１２ 多面体型スピーカ
２０ａ 入力端
２０ｂ 出力端
３０ イコライザ部
５０ イコライザ装置
１００ 電気音響変換装置
Ｖｉｎ 音声信号（入力）
Ｖｏｕｔ 音声信号（出力） 10 sound sources
12 Polyhedral speakers
20a input terminal
20b output terminal
30 Equalizer section
50 Equalizer device
100 Electroacoustic transducer
Vin audio signal (input)
Vout audio signal (output)

Claims (4)

音源からの音声信号が入力される入力端と、
前記入力端に入力された音声信号を所定の伝達関数に基づいてイコライジングするイコライザ部と、
前記イコライザ部でイコライジングした音声信号を多面体型スピーカに出力する出力端と、
を有し、
前記伝達関数が第１の伝達関数の逆フィルタの伝達関数と第２の伝達関数の逆フィルタの伝達関数との積を含み、
前記第１の伝達関数は、遮断周波数が前記多面体型スピーカの最低共振周波数と略同等であり、遮断周波数でのＱ値が前記多面体型スピーカの最低共振周波数でのＱ値と略同等である２次のハイパスフィルタの伝達関数であり、
前記第２の伝達関数は、遮断周波数が前記多面体型スピーカの仮想円周と同等の波長を有する音波の周波数と略同等である１次のローパスフィルタの伝達係数であることを特徴とするイコライザ装置。 An input terminal to which an audio signal from a sound source is input;
An equalizer for equalizing the audio signal input to the input terminal based on a predetermined transfer function;
An output terminal for outputting an audio signal equalized by the equalizer unit to a polyhedral speaker;
Have
The transfer function includes a product of an inverse filter transfer function of a first transfer function and a transfer function of an inverse filter of a second transfer function;
In the first transfer function, the cutoff frequency is substantially equal to the lowest resonance frequency of the polyhedral speaker, and the Q value at the cutoff frequency is substantially equivalent to the Q value at the lowest resonance frequency of the polyhedral speaker 2. Is the transfer function of the high-pass filter
The equalizer is characterized in that the second transfer function is a transfer coefficient of a first-order low-pass filter whose cutoff frequency is substantially equal to the frequency of a sound wave having a wavelength equivalent to the virtual circumference of the polyhedral speaker. . 前記多面体型スピーカの前記仮想円周は、前記多面体型スピーカの外側に接する球の円周と内側に接する球の円周、もしくは前記多面体型スピーカの体積と等しい体積を有する球の円周に基づいて取得することを特徴とする請求項１記載のイコライザ装置。 The virtual circumference of the polyhedral speaker is based on the circumference of a sphere in contact with the outside of the polyhedral speaker and the circumference of a sphere in contact with the inside, or the circumference of a sphere having a volume equal to the volume of the polyhedral speaker. The equalizer device according to claim 1, wherein the equalizer device is acquired. 前記伝達関数が、前記第１の伝達関数の逆フィルタの伝達関数と前記第２の伝達関数の逆フィルタの伝達関数との積に、高次のハイパスフィルタの伝達関数と１次又は高次のローパスフィルタの伝達関数の双方もしくはいずれか一方を乗じたものであることを特徴とする請求項１又は請求項２記載のイコライザ装置。 The transfer function is the product of the transfer function of the inverse filter of the first transfer function and the transfer function of the inverse filter of the second transfer function, and the transfer function of the high-order high-pass filter and the first order or higher order 3. The equalizer device according to claim 1, wherein the equalizer device is obtained by multiplying both or one of the transfer functions of the low-pass filter. 請求項１〜３のいずれか１項に記載のイコライザ装置と、
前記イコライザ装置から出力される音声信号を再生する多面体型スピーカと、
を備えることを特徴とする電気音響変換装置。 The equalizer device according to any one of claims 1 to 3,
A polyhedral speaker for reproducing an audio signal output from the equalizer device;
An electroacoustic transducer characterized by comprising:
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