【発明の詳細な説明】〔産業上の利用分野〕この発明は、例えば自動車室内のように室内が狭くかつ
吸音性の高い聴取環境の残響特性を改善する残響装置に
関するものである。DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a reverberation device that improves the reverberation characteristics of a listening environment with a narrow interior and high sound absorption properties, such as the interior of a car.
一般にホールなどの残響特性は第２図に示すようになっ
ている。すなわち、原音のインパルスが発生した時、あ
る時間遅れて初期反射音群が到達し、その後、後部残響
音が続いてくる。これら残響音のエネルギの減衰が一６
０ｄＢ以下になるまでの時間を残響時間と定義し、これ
を残響特性の指標としている。第３図はこの残響時間の
最適値を示したものであり、家庭では一般におよそ０．
２〜０．４秒が最適とされている。しかも、録音された
レコード、ＣＤ、テープ等はこの残響特性を見越して残
響処理をしであるのが普通である。Generally, the reverberation characteristics of a hall etc. are as shown in Figure 2. That is, when the original sound impulse is generated, the early reflection sound group arrives after a certain time delay, followed by the rear reverberation sound. The energy attenuation of these reverberating sounds is
The time it takes for the temperature to drop below 0 dB is defined as the reverberation time, and this is used as an index of reverberation characteristics. Figure 3 shows the optimum value for this reverberation time, which is generally around 0.
2 to 0.4 seconds is considered optimal. Furthermore, recorded records, CDs, tapes, etc. are usually subjected to reverberation treatment in anticipation of this reverberation characteristic.
ところが、自動車車室は通常２Ｍと狭く、残響時間は第
３図中丸印で示すように０．１秒と短い特性であるため
、前述したような一般家庭での音楽再生に適する残響処
理が施されたソースを再生する場合、自然な残響を得る
のは困難であ、た。However, since automobile cabins are usually as small as 2M, and the reverberation time is as short as 0.1 seconds, as shown by the circle in Figure 3, reverberation treatment suitable for music playback in ordinary homes, as described above, cannot be applied. It is difficult to obtain natural reverberation when playing sources that have been
また、従来の残響装置としては例えば特公昭６２−５２
８７８号公報に示されたものがあり、これは第２図に示
すような残響特性を得ようとするものであるが、残響特
性をどのように決定するかは示されていない、また、特
公昭６０−６００７２号公報にも残響付加装置が示され
ているが、人力信号に依存した残響特性を付加する装置
であって、聴取空間の残響時間に適した残響特性の設定
方法は示されていない。In addition, as a conventional reverberation device, for example,
There is a method disclosed in Publication No. 878, which attempts to obtain the reverberation characteristics shown in Figure 2, but it does not indicate how to determine the reverberation characteristics, and it does not show any special characteristics. Publication No. 60-60072 also discloses a reverberation adding device, but it is a device that adds reverberation characteristics that depend on human input signals, and does not disclose a method for setting reverberation characteristics suitable for the reverberation time of the listening space. do not have.
このように従来の残響装置は音源に依存した残響特性を
得ようとするものであって、聴を環境、特に自動車車室
のような空間特性に対応した残響特性を得ようとするも
のではなかった。In this way, conventional reverberation devices attempt to obtain reverberation characteristics that depend on the sound source, and do not attempt to obtain reverberation characteristics that correspond to the listening environment, especially spatial characteristics such as the interior of a car. Ta.
この発明は上記の問題点を解決するためになされたもの
で、聴取空間の残響特性に係わりなく自然な残響感を得
ることのできる残響装置を提供することを目的とする。The present invention was made to solve the above problems, and an object of the present invention is to provide a reverberation device that can provide a natural feeling of reverberation regardless of the reverberation characteristics of a listening space.
この発明に係わる残響装置は、聴取空間にインパルス信
号を放射して聴取空間のインパルス応答特性を測定し、
このインパルス応答特性から自己相関関数を計算し、更
にこの自己相関関数の正規化包絡線特性よりその包絡線
が所定の値になる時点に反射音が来るよう最適反射音の
位置を計算してこの最適反射音をソース信号に付加する
ようにしたものである。The reverberation device according to the present invention measures the impulse response characteristics of the listening space by emitting an impulse signal into the listening space,
An autocorrelation function is calculated from this impulse response characteristic, and the optimal position of the reflected sound is calculated based on the normalized envelope characteristic of this autocorrelation function so that the reflected sound comes at the point when the envelope reaches a predetermined value. The optimum reflected sound is added to the source signal.
この発明においては、聴取時間のインパルス応答特性か
ら最適反射音を計算するため、聴取空間の残響特性に対
応した最適反射音がソース信号に付加される。従って、
例えば自動車車室のような狭い空間でかつ吸音性の高い
聴取空間であっても自然な残響感が得られる。In this invention, in order to calculate the optimal reflected sound from the impulse response characteristics of the listening time, the optimal reflected sound corresponding to the reverberation characteristics of the listening space is added to the source signal. Therefore,
For example, a natural sense of reverberation can be obtained even in a narrow space such as a car cabin and a listening space with high sound absorption.
第１図はこの発明の一実施例による残響装置の構成図で
ある。図において、１はインパルス発生器で、その出力
であるインパルス信号は切り換えスイッチ２を経てアン
プ３に付加され、更にアンプ３にて増幅されてスピーカ
４より自動車の車室５に放射される。このインパルス信
号による車室５内の応答は、所定位置例えば運転席に設
置されたマイクロホン６によって収音され、インパルス
応答測定器７に送出される。また、インパルス応答測定
器７には、インパルス発生器ｌの出力であるインパルス
信号もトリガ信号として印加される。FIG. 1 is a block diagram of a reverberation device according to an embodiment of the present invention. In the figure, reference numeral 1 denotes an impulse generator, and the output impulse signal is applied to an amplifier 3 via a changeover switch 2, and is further amplified by the amplifier 3 and radiated from a speaker 4 to a passenger compartment 5 of the automobile. A response within the vehicle interior 5 due to this impulse signal is collected by a microphone 6 installed at a predetermined position, for example, the driver's seat, and is sent to an impulse response measuring device 7. Further, an impulse signal output from the impulse generator 1 is also applied to the impulse response measuring device 7 as a trigger signal.
インパルス応答測定器７で測定されたインパルス応答信
号は、自己相関関数計算器８に送られる。The impulse response signal measured by the impulse response measuring device 7 is sent to an autocorrelation function calculator 8.
自己相関関数計算器８はインパルス応答特性より自己相
関関数（ＡＣＦ’）を計算し、これを最適反射音計算器
９に出力する。The autocorrelation function calculator 8 calculates an autocorrelation function (ACF') from the impulse response characteristics and outputs it to the optimal reflected sound calculator 9.
なお、上記インパルス発生器ｌおよびインパルス応答測
定器７は公知の発生器および測定器で構成され、また自
己相関関数計算器８および最適反射音計算器９はマイク
ロコンピュータなどで構成されるが、これらの構成に限
定されるものではなく、専用の測定器を用いてもよい。Note that the impulse generator 1 and the impulse response measuring device 7 are composed of known generators and measuring instruments, and the autocorrelation function calculator 8 and the optimum reflected sound calculator 9 are composed of a microcomputer or the like. The configuration is not limited to this, and a dedicated measuring device may be used.
最適反射音計算器９にて計算された最適な初期反射音の
位置のデータは、パラメータデータ記録回路１０に送ら
れ、ここに記録される。パラメータデータ記録回路１０
は、ＲＡＭ、ＲＯＭなどの記録素子で構成され、最適反
射音計算器９および後述する残響音形成回路１２と共に
残響音形成手段を形成している。１１は、音楽ソースで
あり、例えばＣＤプレーヤ、ＦＭ放送受信機、カセット
プレーヤなどの再生装置で構成される。実際の音楽が再
生される場合、ソース１１から再生された音楽信号は、
残害音形成回路１°２に印加される・。The data on the position of the optimum early reflected sound calculated by the optimum reflected sound calculator 9 is sent to the parameter data recording circuit 10 and recorded therein. Parameter data recording circuit 10
is composed of recording elements such as RAM and ROM, and together with the optimum reflected sound calculator 9 and a reverberant sound forming circuit 12 to be described later, forms a reverberant sound forming means. Reference numeral 11 denotes a music source, which is composed of, for example, a playback device such as a CD player, an FM broadcast receiver, or a cassette player. When actual music is played, the music signal played from the source 11 is
Applied to the residual sound forming circuit 1°2.
残響音形成回路１２では、パラメータデータ記録手段１
０に記録された最適な初期反射音の位置のデータに基づ
き、原音に初期反射音を加えることにより、自然な残響
を形成する。In the reverberant sound forming circuit 12, the parameter data recording means 1
Based on the data of the optimal early reflected sound position recorded in 0, a natural reverberation is created by adding the early reflected sound to the original sound.
残響音形成回路１２で自然な残響に改善された音楽信号
は、切り換えスイッチ２を経て、アンプ３に印加され、
アンプ３によって増幅されてスピーカ４より車室内に放
射される。The music signal that has been improved to have natural reverberation by the reverberation sound forming circuit 12 is applied to the amplifier 3 via the changeover switch 2.
The signal is amplified by the amplifier 3 and radiated into the vehicle interior from the speaker 4.
切り換えスイッチ２は、接点２ａがアンプ３と接続され
、また接点２ｂがインパルス発生器１と、接点２Ｃが残
響音形成回路１２と接続されており、インパルス応答測
定時は接点２ａと接点２ｂとが接続され、音楽聴取時は
接点２ａと接点２ｃとが接続される。The changeover switch 2 has a contact 2a connected to the amplifier 3, a contact 2b connected to the impulse generator 1, and a contact 2C connected to the reverberation sound forming circuit 12. During impulse response measurement, the contacts 2a and 2b are connected. When listening to music, contacts 2a and 2c are connected.
第４図は、上記残響音形成回路１２の一例を示すもので
、これは初期反射音生成回路１００をデジタル回路で構
成した例である０図において、１０１はＡ／Ｄコンバー
タであり、折り返し防止用のローパスフィルタを含み、
入力端子１０２に印加されたアナログ信号をデジタル信
号に変換する。このＡ／Ｄコンバータ１０１の出力は、
遅延素子ＤＩ （１０３ａ）、Ｄ２ （１０３ｂ）、
Ｄ３（１０３ｃ）、＝・、ＤＮ（１０３ｎ）を従属接続
した遅延回路１０３に印加される。各遅延素子のＤＩ
（１０３ａ）、 ・−、ＤＮ （１０３ｎ）の出力はそ
れぞれの出力にある一定の係数Ｋｌ。FIG. 4 shows an example of the reverberant sound forming circuit 12. This is an example in which the early reflected sound generating circuit 100 is configured with a digital circuit. In FIG. Contains a low-pass filter for
The analog signal applied to the input terminal 102 is converted into a digital signal. The output of this A/D converter 101 is
Delay element DI (103a), D2 (103b),
It is applied to the delay circuit 103 in which D3 (103c), =., and DN (103n) are connected in cascade. DI of each delay element
The outputs of (103a), .
Ｋ２．に３． ・、ＫＮを乗する係数器１０４ａ。K2. 3. , a coefficient unit 104a that multiplies KN.
１０４ｂ、１０４ｃ、−＝、１０４ｎに印加される。104b, 104c, -=, 104n.
なお、ここで遅延素子と係数器の数はＮ個の場合を示し
ており、これらのそれぞれにパラメータ記録回路１０の
出力がパラメータデータとして供給されるようになって
いる。各係数器１０４ａ、・・・ｔｏａｎの出力は、加
算器１０５に印加され、加算器１０５において出力の総
和が求められる。また加算器１０５にはＡ／Ｄコンバー
タ１０１の出力信号も加えられ、これらの和がとられる
。加算器１０５の出力は、Ｄ／Ａコンバータ１０６に印
加される。Ｄ／Ａコンバータ１０６は、平滑用のローパ
スフィルタを含み、印加されたデジタル信号をアナログ
信号に変換し、出力端子１０７に出力する。ここで、遅
延素子Ｄｉ （１０３ａ）〜ＤＮ（１０３ｎ）、係数器
１０４ ａ＋・・・＋ｌ Ｏ４ｎおよび加算器１０５は
すべてデジタル演算素子で構成されている。Note that here, a case is shown in which the number of delay elements and coefficient units is N, and the output of the parameter recording circuit 10 is supplied to each of these as parameter data. The outputs of each coefficient multiplier 104a, . . . The output signal of the A/D converter 101 is also added to the adder 105, and the sum of these signals is calculated. The output of adder 105 is applied to D/A converter 106. D/A converter 106 includes a smoothing low-pass filter, converts the applied digital signal into an analog signal, and outputs the analog signal to output terminal 107. Here, the delay elements Di (103a) to DN (103n), the coefficient multipliers 104a+...+lO4n, and the adder 105 are all composed of digital arithmetic elements.
次にこのように構成された残響装置の動作について説明
する。この実施例装置では、最初に実際の自動車車室５
のインパルス応答特性を測定する必要がある。これは先
ず切り換えスイッチ２の接点２ａと接点２ｂを接続し、
インパルス発生器１よりインパルス信号を発生させる。Next, the operation of the reverberation device configured as described above will be explained. In this example device, first, an actual automobile compartment 5 is constructed.
It is necessary to measure the impulse response characteristics of To do this, first connect contact 2a and contact 2b of changeover switch 2,
An impulse generator 1 generates an impulse signal.
このインパルス信号は、切り換えスイッチ２を経てアン
プ３に印加され、アンプ３にて増幅されてスピーカ４よ
り車室５内に放射される。このインパルス信号による車
室内の応答は、マイクロホン６にて収音されインパルス
応答測定器７に送られる。インパルス応答測定器７には
、インパルス発生器１の出力であるインパルス信号がト
リガ信号として加えられるので確実にインパルス応答波
形を測定できる。This impulse signal is applied to the amplifier 3 via the changeover switch 2, is amplified by the amplifier 3, and is radiated into the vehicle interior 5 from the speaker 4. A response in the vehicle interior due to this impulse signal is collected by a microphone 6 and sent to an impulse response measuring device 7. Since the impulse signal output from the impulse generator 1 is applied as a trigger signal to the impulse response measuring device 7, the impulse response waveform can be reliably measured.
第５図に、２０００ｃｃセダンタイプの乗用車で測定し
た運転席におけるインパルス応答波形を示す。FIG. 5 shows an impulse response waveform at the driver's seat measured in a 2000cc sedan type passenger car.
インパルス応答測定器７で測定されたインパルス応答は
、自己相関関数計算器８に送られる。自己相関関数計算
器８は、インパルス応答特性より自己相関関数（ＡＣＦ
）Φ（τ）を次式にしたがって計算する。The impulse response measured by the impulse response measuring device 7 is sent to an autocorrelation function calculator 8. The autocorrelation function calculator 8 calculates an autocorrelation function (ACF) from the impulse response characteristics.
)Φ(τ) is calculated according to the following formula.
第６図は、第５図のインパルス応答波形の自己相関関数
（ＡＣＦ）を計算し、正規化後対数表示したものである
。ここで正規化自己相関関数は、φ（τ）＝Φ（τ）／
Φ（０）で計算する。FIG. 6 shows the calculated autocorrelation function (ACF) of the impulse response waveform of FIG. 5, and the normalized logarithmic representation. Here, the normalized autocorrelation function is φ(τ) = Φ(τ)/
Calculate with Φ(0).
インパルス応答特性より計算された自己相関関数（ＡＣ
Ｆ）は、自己相関関数計算器８より最適反射音計算器９
に送られる。最適反射音計算器９では、自己相関関数（
ＡＣＦ）特性より、正規化自己相関関数の包絡線が所定
の値以下になる時点に反射音が来るように初期反射音の
位置を計算する。例えば、この値は正規化自己相関関数
（ＡＣＦ）波形の包絡線が一２０ｄＢ以下になるときが
選ばれる。なお〔従来の技術〕で述べた特公昭６０−６
００７２号公報は入力信号に応じた最適反射音の位置を
述べたものであるが、これにも自己相関関数と反射音の
位置との間には相関があることが記載されている。レコ
ード、ＣＤ１テープなどの音楽ソースには入力信号に応
した残響音があらかじめ含まれているので、同様の考え
方を聴取空間の残響を補正する為に適用できる。Autocorrelation function (AC
F) is calculated by the optimal reflected sound calculator 9 from the autocorrelation function calculator 8.
sent to. The optimal reflected sound calculator 9 calculates the autocorrelation function (
Based on the ACF) characteristic, the position of the early reflected sound is calculated so that the reflected sound arrives at the point where the envelope of the normalized autocorrelation function becomes less than or equal to a predetermined value. For example, this value is selected when the envelope of the normalized autocorrelation function (ACF) waveform is 120 dB or less. In addition, the special public interest public corporation 1986-6 mentioned in [Prior art]
Publication No. 0072 describes the optimum position of reflected sound according to an input signal, and it also states that there is a correlation between the autocorrelation function and the position of reflected sound. Since music sources such as records and CD1 tapes already contain reverberant sound corresponding to the input signal, a similar idea can be applied to correct the reverberation in the listening space.
第６図によれば、およそ１０＋ｍＳの時間遅れを持った
第１次反射音が最適だといえる。初期反射音のレベルは
、残響時間を延ばすため、二度打ち感のない範囲で自己
相関値が０．８以下になるように選ぶ必要がある。これ
はおよそ＋６ｄＢ〜−１２ｄＢの範囲である。第１次反
射音が決まれば、第１次反射音を加えたパルスをインパ
ルス発生器１から発生させ同様に第２次反射音の位置を
決めることができる。以下同様にその他の反射音も決め
られる。そして改善後の残響時間が０．２〜０．４秒に
なればこの手順を打ちきる。According to FIG. 6, it can be said that the first reflected sound with a time delay of approximately 10+mS is optimal. In order to extend the reverberation time, the level of the early reflected sound must be selected so that the autocorrelation value is 0.8 or less without causing a feeling of double hitting. This ranges from approximately +6 dB to -12 dB. Once the first reflected sound is determined, a pulse to which the first reflected sound is added is generated from the impulse generator 1, and the position of the second reflected sound can be similarly determined. Other reflected sounds can be determined in the same manner. This procedure is completed when the improved reverberation time reaches 0.2 to 0.4 seconds.
第７図は改善後のインパルス応答波形の一例である。こ
の例では１０１１Ｓに第１次反射音、２０ｍ５に第２次
反射音、２５ｗ５に第３次反射音を加えている。第８図
にこのインパルス応答より計算した正規化自己相関関数
の波形を示す０反射音の自己相関関数値も０．８以下で
あり、自己相関関数の包絡線が一２０ｄＢになる時間も
およそ２５＋ｍＳと改善前の２．５倍となり、残響時間
もそれに比例して延びていることがわかる。FIG. 7 is an example of an impulse response waveform after improvement. In this example, the first reflected sound is added to 1011S, the second reflected sound is added to 20m5, and the third reflected sound is added to 25w5. Figure 8 shows the waveform of the normalized autocorrelation function calculated from this impulse response.The autocorrelation function value of the zero reflected sound is also less than 0.8, and the time for the envelope of the autocorrelation function to reach 120dB is approximately 25+mS. It is 2.5 times as long as before the improvement, and it can be seen that the reverberation time has increased proportionally.
最適反射音計算器９で計算された、この最適な初期反射
音の位置のデータは、パラメータデータ記録回路１０に
送られ記録される。第４図の初期反射音生成回路１００
では、遅延素子Ｄ ｌ （１０３ａ）。Data on the position of the optimum early reflected sound calculated by the optimum reflected sound calculator 9 is sent to the parameter data recording circuit 10 and recorded. Early reflected sound generation circuit 100 in FIG.
Now, the delay element D l (103a).
・・・、 ＤＮ （１０３ｎ）の遅延時間と係数器に１
（１０４ａ） 、−、ＫＮ （１０４ｎ）の乗算係数と
がパラメータデータとなる。..., 1 for the delay time and coefficient unit of DN (103n)
(104a), -, and the multiplication coefficient of KN (104n) become parameter data.
パラメータデータの設定が終わると、次に実際に音楽を
聞く段階となる。音楽聴取時、切り換えスイッチ２は接
点２ａと接点２Ｃとが接続される。After setting the parameter data, the next step is to actually listen to the music. When listening to music, the changeover switch 2 has its contacts 2a and 2C connected.
音楽はソース１１から再生され、その音楽信号は残響音
形成回路１２に印加される。残響音形成回路１２では、
パラメータデータ記録回路１０に記録された最適な初期
反射音のデータに基づき、原音に初期反射音を加えるこ
とにより、自然な残響を作成する。Music is played from a source 11 and the music signal is applied to a reverberation sound forming circuit 12. In the reverberation sound forming circuit 12,
Based on the optimal early reflected sound data recorded in the parameter data recording circuit 10, natural reverberation is created by adding the early reflected sound to the original sound.
残響音形成回路１２で自然な残響に改善された音楽信号
は、切り換えスイッチ２を経てアンプ３に印加され、ア
ンプ３によって増幅されてスピーカ４より車室５内に放
射され、聴取者は自然な残響をもった音楽を聞くことが
できる。The music signal, which has been improved into a natural reverberation by the reverberation sound forming circuit 12, is applied to the amplifier 3 via the changeover switch 2, is amplified by the amplifier 3, and is radiated into the passenger compartment 5 from the speaker 4, so that the listener can hear the natural reverberation. You can hear music with reverberation.
次に第４図の初期反射音生成回路１００の動作について
具体的に説明する。入力端子１０２より入力された音楽
信号は、Ａ／Ｄコンバータｌｏｔでアナログ信号からデ
ジタル信号に変換される。Next, the operation of the early reflected sound generation circuit 100 shown in FIG. 4 will be specifically explained. A music signal inputted from the input terminal 102 is converted from an analog signal to a digital signal by an A/D converter lot.
このＡ／Ｄコンバータ１０１では、例えば４４．１ｋｔ
ｌｚのサンプリング周波数を用い１６ｂｉｔの量子化幅
でデジタル化を行う。Ａ／Ｄコンバータ１０１の出力は
各遅延素子ＤＩ （１０３ａ）、・・・ ＤＮ（１０
３ｎ）と加算器１０５に印加される。各遅延素子の出力
は係数器１０４ａ、・・・、１０４ｎに印加され、出力
に所定の係数Ｋｌ、に２．に３゜ＫＮを乗するデジタル
乗算が行われる。各係数器の出力とＡ／Ｄコンバータ１
０１の出力信号は加算器１０５に印加され、この加算器
１０５でデジタル加算が行われて出力の総和が求められ
る。加算器１０５の出力はＤ／Ａコンバータ１０６に印
加され、Ｄ／Ａコンバータ１０６は印加されたデジタル
信号をアナログ信号に変換し、出力端子１０７に出力す
る。In this A/D converter 101, for example, 44.1kt
Digitization is performed using a sampling frequency of lz and a quantization width of 16 bits. The output of the A/D converter 101 is connected to each delay element DI (103a), ... DN (10
3n) and is applied to the adder 105. The output of each delay element is applied to coefficient multipliers 104a, . . . , 104n, and predetermined coefficients Kl, 2. A digital multiplication is performed by multiplying by 3°KN. Output of each coefficient unit and A/D converter 1
The output signal of 01 is applied to an adder 105, which performs digital addition to obtain the sum of the outputs. The output of adder 105 is applied to D/A converter 106 , which converts the applied digital signal into an analog signal and outputs it to output terminal 107 .
第９図は、この実施例におけるインパルス応答波形であ
る０図において入力インパルス信号のレベルは１に正規
化されている。初期反射音は、ＤＩの時間遅れでに１の
レベヘルの反射音があり、次にＤ２の時間遅れでに２の
レベルの反射音があり、次にＤ３の時間遅れでに３のレ
ベルの反射音があり、順次Ｎ個の反射音がある。FIG. 9 shows an impulse response waveform in this embodiment, in which the level of the input impulse signal is normalized to 1. The early reflection sound has a level 1 reflection at the time delay of DI, then a level 2 reflection at the time delay D2, and then a level 3 reflection at the time delay D3. There is a sound, and in turn there are N reflected sounds.
なお、上記実施例において、インパルス応答よりの最適
反射音の測定は、聴取毎に行えばより的確な改善が得ら
れ、また聴取空間が決定された時に最初の一度だけに行
うことにすれば測定部分の装置は実装する必要がないの
で装置を小型にすることができる。In the above example, if the measurement of the optimal reflected sound from the impulse response is performed for each listening session, a more accurate improvement can be obtained, and if the measurement is performed only once when the listening space is determined, the measurement will be more accurate. Since there is no need to mount some devices, the device can be made smaller.
更に、上記実施例によれば残響改善効果は十分に得るこ
とができるが、−Ｉｎに自動車車室内の残響特性は周波
数によって異なることが多いため周波数帯域毎に残響特
性を改善すれば一層良好な改善効果が得られる。Further, according to the above embodiment, a sufficient reverberation improvement effect can be obtained, but since the reverberation characteristics inside an automobile cabin often differ depending on the frequency, it is possible to improve the reverberation characteristics by improving the reverberation characteristics for each frequency band. An improvement effect can be obtained.
例えば第１０図は自動車車室の周波数毎の残響特性の一
例である。自動車車室における残響特性は、低い周波数
で０．３秒以上の残響時間があるが周波数が高くなるに
従って残響時間が短くなり、５００Ｈｚ以上の周波数で
は０．１秒以下になることがわかる。これは低い周波数
帯域では共鳴現象によるためであり、高い周波数帯域で
は内装材、シートなどの吸音によるためであると考えら
れる。For example, FIG. 10 shows an example of the reverberation characteristics of an automobile cabin for each frequency. It can be seen that the reverberation characteristics in an automobile cabin have a reverberation time of 0.3 seconds or more at low frequencies, but as the frequency increases, the reverberation time becomes shorter, and becomes 0.1 seconds or less at frequencies of 500 Hz or more. This is thought to be due to a resonance phenomenon in low frequency bands, and to sound absorption by interior materials, sheets, etc. in high frequency bands.
第１０図に普通の家庭の部屋の残響特性も示す。Figure 10 also shows the reverberation characteristics of a normal household room.
この例によればこれらの残響時間の差は周波数によって
異なっており、１２５Ｈｚ〜２５０Ｈｚ以下の周波数帯
域では残響時間は０．１秒はどの改善でよいが、５００
Ｈｚ以上の周波数帯域では０．３秒もの改善が必要であ
ることがわかる。According to this example, the difference in reverberation time varies depending on the frequency, and in the frequency band from 125Hz to 250Hz or less, the reverberation time can be improved by 0.1 seconds, but it can be improved by 500 seconds.
It can be seen that an improvement of as much as 0.3 seconds is required in the frequency band above Hz.
次に他の実施例による残響音形成回路１３の構成を第１
１図に示す０図において２０１はローパスフィルタ、２
０２ａ、・・・、２０２ｎはＮ個のバンドパスフィルタ
、２０３はバイパスフィルタであり、これらは電子回路
で構成され、その入力が入力端子２０４にそれぞれ接続
され、入力端子２０４より入力されたアナログ信号を所
定の周波数帯域のみをろ波する。これらのフィルタはお
互いにオーバーランプしないように構成され、全てのフ
ィルタで全周波数帯域をカバーしている。Next, the configuration of the reverberation sound forming circuit 13 according to another embodiment will be explained as follows.
In figure 0 shown in figure 1, 201 is a low-pass filter;
02a, . . . , 202n are N band-pass filters, and 203 is a bypass filter. These are composed of electronic circuits, and their inputs are connected to the input terminal 204, respectively, and the analog signal input from the input terminal 204 is connected to the input terminal 204. filters only a predetermined frequency band. These filters are constructed so that they do not overlap each other, and all filters cover the entire frequency band.
各フィルタでろ波されたアナログ信号はそれぞれ初期反
射音生成回路２０５，２０６ａ、・・・２０６ｎ、２０
７に印加される。この初期反射音生成回路２０５，２０
６ａ、−，２０６ｎ。The analog signals filtered by the respective filters are output to early reflected sound generation circuits 205, 206a, . . . 206n, 20, respectively.
7. These early reflected sound generation circuits 205, 20
6a, -, 206n.
２０７には第４図に示した初期反射音生成回路ｌＯＯと
同様の回路が用いられる。初期反射音生成回路２０５，
２０６ａ、・・・、２０６ｎ、２０７の出力はアナログ
加算器２０８に印加される。アナログ加算器２０８は、
電子回路で構成され、初期反射音生成回路の出力を加算
し出力端子２０９に出力する。For 207, a circuit similar to the early reflected sound generation circuit lOO shown in FIG. 4 is used. Early reflected sound generation circuit 205,
The outputs of 206a, . . . , 206n, 207 are applied to an analog adder 208. The analog adder 208 is
It is composed of an electronic circuit, and adds the outputs of the early reflected sound generation circuit and outputs the result to the output terminal 209.
次にこのように構成された残響音形成回路１３の動作を
説明する。先ず、入力端子２０４より入力された音楽信
号が、ローパスフィルタ２０１゜バンドパスフィルタ２
０２ ａ、・・・、’２０２ ｎ ％バイパスフィルタ
２０３にそれぞれ印加され、これらのフィルタで所定の
周波数帯域のみの信号をろ波される。そして、ろ波され
た所定の周波数帯域の音楽信号は、それぞれ初期反射音
生成回路２０５．２０６ａ、・・・、２０６ｎ、２０７
に印加され、それぞれの周波数帯域毎に最適の反射音特
性が付加される。この反射音のデータは上記実施例と同
様に周波数毎の自己相関関数（ＡＣＦ）から求められる
。この場合、周波数毎の自己相関関数（ＡＣＦ）を求め
る方法は、インパルス発生器１の出力側にフィルタを設
ける等により車室５内に放射するインパルス信号を周波
数毎とし、それぞれの周波数に関してインパルス応答特
性を測定するか、または放射するインパルス信号を周波
数毎に分割せず、マイクロホン６での収音後に信号処理
して周波数毎に分割して自己相関関数を計算するように
しても良い、初期反射音生成回路２０５．２０６ａ、・
・・、２０６ｎ、２０７で最適の反射音を付加された所
定の周波数帯域毎の音楽信号は、アナログ加算器２０８
に印加される。Next, the operation of the reverberation sound forming circuit 13 configured as described above will be explained. First, a music signal inputted from the input terminal 204 is passed through the low-pass filter 201 and the band-pass filter 2.
02 a, . . . , '202 n % are applied to bypass filters 203, and these filters filter signals only in predetermined frequency bands. Then, the filtered music signals in a predetermined frequency band are transmitted to early reflection sound generation circuits 205, 206a, . . . , 206n, 207, respectively.
is applied to each frequency band, and the optimum reflected sound characteristics are added for each frequency band. This reflected sound data is obtained from the autocorrelation function (ACF) for each frequency, as in the above embodiment. In this case, the method of determining the autocorrelation function (ACF) for each frequency is to set the impulse signal radiated into the passenger compartment 5 for each frequency by providing a filter on the output side of the impulse generator 1, etc., and to calculate the impulse response for each frequency. It is also possible to measure the characteristics or to calculate the autocorrelation function by processing the radiated impulse signal by signal processing and dividing by frequency after the sound is collected by the microphone 6, instead of dividing the radiated impulse signal by frequency. Sound generation circuit 205.206a,・
. . , 206n, 207, the music signals for each predetermined frequency band to which the optimal reflected sound has been added are sent to the analog adder 208.
is applied to
アナログ加算器２０８は、初期反射音生成回路２０５．
２０６ａ、 ・、２０６ｎ、２０７の出力である音楽信
号を加算し、全周波数帯域の音楽信号として出力端子２
０９に出力する。The analog adder 208 is connected to the early reflected sound generation circuit 205.
The music signals output from the output terminals 206a, .
Output on 09.
第１０図の例によれば１２５Ｈｚ〜２５０Ｈｚ以下の周
波数帯域と、それ以上の周波数帯域とに分けるのが一番
簡単な分は方（バンドパスフィルタの個数Ｎ＝Ｏの場合
）であるが、１２５Ｈ２以下１２５Ｈｚ〜５００８２．
５００Ｈ２以上と３つの周波数帯域に分ける方法（Ｎ
＝１の場合）もある、また分割する周波数帯域を更に多
くすればより残響改善効果が向上することは言うまでも
ない。According to the example shown in Fig. 10, it is easiest to divide the frequency band into the frequency band below 125Hz to 250Hz and the frequency band above it (when the number of bandpass filters N=O). 125H2 or less 125Hz ~ 50082.
Method of dividing into 500H2 or more and 3 frequency bands (N
= 1), and it goes without saying that the reverberation improvement effect will be further improved if the number of frequency bands to be divided is further increased.
なお上記各実施例では、初期反射音生成回路１００、２
０５． ２０６ ａ、・・・、２０６ｎ、２０７におい
て各遅延素子は従属接続の場合を示したが、並列接続で
もよく、また従属並列接続でもよい。Note that in each of the above embodiments, the early reflected sound generation circuits 100 and 2
05. Although the delay elements 206a, . . . , 206n, and 207 are connected in a cascade manner, they may be connected in parallel or in cascade parallel connection.
更にデジタル回路の構成例を示しているが、アナログ回
路でもよい。Furthermore, although an example of the configuration of a digital circuit is shown, an analog circuit may also be used.
また、上記各実施例で２０００ｃｃセダンタイプの乗用
車の場合について説明したがこれに限定されるものでは
なく、バスなどの車両やヨツトの室内等に用いても良く
、特に、室内空間が狭くかつ吸音性の高い聴取環境にお
いて高い効果を奏するものである。Further, in each of the above embodiments, the case of a 2000cc sedan type passenger car has been described, but the invention is not limited to this, and may be used in the interior of a vehicle such as a bus or a yacht. This is highly effective in highly sensitive listening environments.
以上のようにこの発明によれば、聴取空間のインパルス
応答特性を測定し、この測定値に基づいて計算した反射
音をソース信号に付加するようにしたので、聴取空間に
係わりなく、例えば聴取空間が狭くかつ吸音性の高い聴
取環境であっても自然な残響感が得られる効果がある。As described above, according to the present invention, the impulse response characteristic of the listening space is measured, and the reflected sound calculated based on the measured value is added to the source signal. This has the effect of providing a natural sense of reverberation even in a narrow and highly sound-absorbing listening environment.
第１図はこの発明の一実施例による残響装置を示す構成
図、第２図は一般的な残響波形を示す模式図、第３図は
種々の聴取環境の残響時間を示す図、第４図はこの発明
の残響装置における残響音形成回路の一実施例を示す構
成図、第５図は自動車車室のインパルス応答の一例を示
す波形図、第６図は自己相関関数の波形図、第７図は改
善後の自動車車室のインパルス応答の一例を示す波形図
、第８図は改善後の自己相関関数の波形図、第９図はこ
の発明の初期反射音生成回路のインパルス応答を示す波
形図、第１０図は周波数毎の残響特性図、第１１図はこ
の発明の残響装置における残響音形成回路の他の実施例
を示す構成図である。１・・・インパルス発生器、４・・・スピーカ、５・・
・車室、６・・・マイクロホン、７・・・インパルス応
答測定器、８・・・自己相関関数計算器、９・・・最適
反射音計算器、１０・・・パラメータデータ記録回路、
１１・・・ソース、１２．１３・・・残響音形成回路。なお、図中、同一符号は同一部分を示す。FIG. 1 is a block diagram showing a reverberation device according to an embodiment of the present invention, FIG. 2 is a schematic diagram showing a general reverberation waveform, FIG. 3 is a diagram showing reverberation times in various listening environments, and FIG. 4 5 is a configuration diagram showing an example of a reverberant sound forming circuit in a reverberation device of the present invention, FIG. 5 is a waveform diagram showing an example of an impulse response of an automobile cabin, FIG. The figure is a waveform diagram showing an example of the impulse response of the automobile cabin after the improvement, Figure 8 is the waveform diagram of the autocorrelation function after the improvement, and Figure 9 is the waveform diagram showing the impulse response of the early reflected sound generation circuit of the present invention. 10 is a reverberation characteristic diagram for each frequency, and FIG. 11 is a configuration diagram showing another embodiment of the reverberation sound forming circuit in the reverberation apparatus of the present invention. 1... Impulse generator, 4... Speaker, 5...
- Vehicle interior, 6...Microphone, 7...Impulse response measuring device, 8...Autocorrelation function calculator, 9...Optimum reflected sound calculator, 10...Parameter data recording circuit,
11... Source, 12.13... Reverberant sound forming circuit. In addition, in the figures, the same reference numerals indicate the same parts.
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP1102203AJPH02280199A (en) | 1989-04-20 | 1989-04-20 | reverberation device |
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP1102203AJPH02280199A (en) | 1989-04-20 | 1989-04-20 | reverberation device |
| Publication Number | Publication Date |
|---|---|
| JPH02280199Atrue JPH02280199A (en) | 1990-11-16 |
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP1102203APendingJPH02280199A (en) | 1989-04-20 | 1989-04-20 | reverberation device |
| Country | Link |
|---|---|
| JP (1) | JPH02280199A (en) |
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