JP2006173840A - Sound output apparatus - Google Patents

Sound output apparatus Download PDF

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JP2006173840A
JP2006173840A JP2004360904A JP2004360904A JP2006173840A JP 2006173840 A JP2006173840 A JP 2006173840A JP 2004360904 A JP2004360904 A JP 2004360904A JP 2004360904 A JP2004360904 A JP 2004360904A JP 2006173840 A JP2006173840 A JP 2006173840A
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power
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microphone
audio
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JP4495581B2 (en
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Toru Marumoto
徹 丸本
Nozomi Saito
望 齊藤
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Alpine Electronics Inc
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Abstract

<P>PROBLEM TO BE SOLVED: To provide a sound output apparatus capable of suppressing deterioration in loudness compensation due to variations in frequency characteristics of lower frequencies of a microphone. <P>SOLUTION: An output sound power calculation section 15 and a second high pass filter 14 estimate a power of a guide sound signal component except its lower frequency component included in a signal outputted from the microphone 7 and use the estimated power as an output sound power. An adder 10 cancels the output sound power from the power of a guide sound signal component except its lower frequency component included in a signal outputted from the microphone 7 calculated by a first high pass filter 8 and an input sound power calculation section 9 to calculate the power of surrounding noise except its lower frequency components. A low frequency power component addition section 16 adds the power of the surrounding noise power of the surrounding noise of its lower frequency component estimated from a vehicle speed V to the power of the surrounding noise to provide the result as the noise power. A loudness compensation control section 11 adjusts a gain of a sound volume adjustment amplifier 3 according to a prescribed loudness compensation function on the basis of the power of the output sound power and the noise power. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

本発明は、音声を出力する音声出力装置において、ユーザに聞こえる音声の明瞭度を改善する技術に関するものである。   The present invention relates to a technique for improving the intelligibility of sound heard by a user in a sound output device that outputs sound.

音声を出力する音声出力装置において、ユーザに聞こえる音声の明瞭度を改善する技術としては、音声出力装置のスピーカから出力した音声と周辺騒音が混在した音声信号をマイクを用いてピックアップし、マイクから出力される音声信号中の周囲騒音成分のパワーと音声出力装置から出力された音声成分のパワーに応じて、音声出力装置から出力する音声のゲインを、人間のラウドネス特性に従って周波数帯域毎に調整するラウドネス補償の技術が知られている(たとえば、特許文献1)。   In a voice output device that outputs voice, as a technique for improving the clarity of voice heard by the user, a voice signal mixed with voice output from the speaker of the voice output device and ambient noise is picked up using a microphone, The gain of the sound output from the sound output device is adjusted for each frequency band according to the human loudness characteristic according to the power of the ambient noise component in the output sound signal and the power of the sound component output from the sound output device. A loudness compensation technique is known (for example, Patent Document 1).

なお、この技術では、音声出力装置がスピーカに出力する音声信号と、マイクから出力される音声信号とより、音声出力装置がスピーカに出力する音声信号のマイクまでの伝達関数を学習する適応フィルタを設けている。そして、この適応フィルタを用いて、音声出力装置がスピーカに出力する音声信号から、マイクから出力される音声信号中に含まれるスピーカから出力された音声成分を推定する。そして、推定した音声成分を、マイクから出力される音声信号から除いた成分を、マイクから出力される音声信号中に含まれる周囲騒音成分として推定している。
特開2001-236090号公報
In this technique, an adaptive filter that learns a transfer function from the audio signal output from the audio output device to the speaker and the audio signal output from the microphone to the microphone of the audio signal output from the audio output device to the speaker is provided. Provided. And using this adaptive filter, the audio | voice component output from the speaker contained in the audio | voice signal output from a microphone is estimated from the audio | voice signal which an audio | voice output apparatus outputs to a speaker. And the component remove | excluding the estimated audio | voice component from the audio | voice signal output from a microphone is estimated as an ambient noise component contained in the audio | voice signal output from a microphone.
JP 2001-236090 A

さて、前述したような音声出力装置では、音声信号をピックアップするためのマイクとして、人声収音用の汎用型の小型のマイクが用いられることが多い。そして、このような人声収音用の汎用の小型のマイクの、人声の周波数帯域下限付近より低域側の周波数特性は、同じ製造者の同じ製品(同型番の製品)であってもばらつきがあることが多い。   Now, in the audio output device as described above, a general-purpose small microphone for collecting human voice is often used as a microphone for picking up an audio signal. And the frequency characteristics of the low frequency side of the general-purpose small microphone for collecting human voices near the lower limit of the human voice frequency band are the same products of the same manufacturer (products of the same model number). There are often variations.

そして、このために、このような低域の周波数特性を一義的に定めることができないマイクを用いた場合には、マイクから出力される音声信号中のスピーカ出力音声成分や周囲騒音成分の推定を正しく行えず、ラウドネス補償を適正に行えないことがある。
一方で、このような問題に対処するために、マイクから出力される音声信号の低域成分をカットして、マイクから出力される音声信号中のスピーカ出力音声成分や周囲騒音成分の推定を行うようにすることも考えられるが、たとえば自動車車内環境などでは周囲騒音は低域の成分を多く含むために、このようにしても、やはりラウドネス補償は適正に行えない場合が生じる。
For this reason, when a microphone that cannot uniquely define such low frequency characteristics is used, the speaker output sound component and the ambient noise component in the sound signal output from the microphone are estimated. It may not be performed correctly and loudness compensation may not be performed properly.
On the other hand, in order to cope with such a problem, the low frequency component of the audio signal output from the microphone is cut, and the speaker output audio component and the ambient noise component in the audio signal output from the microphone are estimated. Although it is conceivable that the ambient noise includes many low-frequency components in an automobile interior environment, for example, loudness compensation may not be performed properly even in this case.

そこで、本発明は、音声を出力する音声出力装置において、マイクの低域の周波数特性のばらつきによる、ラウドネス補償の劣化を抑制することを課題とする。   Accordingly, an object of the present invention is to suppress degradation of loudness compensation due to variations in low-frequency characteristics of a microphone in an audio output device that outputs audio.

前記課題達成のために、本発明は、ラウドネス補償を施した音声を出力する音声出力装置を、前記出力する音声を表す音声信号である出力音声信号を生成する音声信号生成手段と、音声信号生成手段が生成した出力音声信号のラウドネス補償を行うラウドネス補償手段と前記ラウドネス補償手段がラウドネス補償を行った前記出力音声信号に基づき音声を出力するスピーカと、周辺音をピックアップするマイクと、前記マイクが出力する信号であるマイク出力信号と前記出力音声信号とに基づき、前記マイク出力信号中の前記出力音声の成分のパワーを算出する出力音声成分パワー算出手段と、前記マイクが出力するマイク出力信号のパワーと、前記出力音声成分パワー算出手段が算出した前記出力音声の成分のパワーとに基づき、前記マイク出力信号中の周囲騒音の成分のパワーを、当該周囲音の成分の低域側の所定周波数領域のパワーが無いものとして算出する周囲騒音成分パワー算出手段と、前記周囲騒音成分パワー算出手段が算出した周囲騒音成分のパワーに、所定のパワーを加算したパワーを騒音パワーとして算出する騒音パワー算出手段とを含めて構成し、前記ラウドネス補償手段において、前記出力音声成分パワー算出手段が算出した前記出力音声の成分のパワーと、前記騒音パワー算出手段が算出した前記騒音パワーとに基づいて、スピーカに出力する出力音声信号のゲインの調整を、所定のラウドネス補償関数に従って行うようにしたものである。   In order to achieve the above object, the present invention provides an audio output device that outputs a sound subjected to loudness compensation, an audio signal generation unit that generates an output audio signal that is an audio signal representing the output audio, and an audio signal generation Loudness compensation means for performing loudness compensation of the output audio signal generated by the means; a speaker for outputting sound based on the output audio signal for which the loudness compensation means has performed loudness compensation; a microphone for picking up ambient sound; and the microphone Based on a microphone output signal that is an output signal and the output audio signal, output audio component power calculating means for calculating the power of the component of the output audio in the microphone output signal, and an output of the microphone output signal output by the microphone Based on the power and the power of the output audio component calculated by the output audio component power calculation means, Ambient noise component power calculating means for calculating the power of the ambient noise component in the output signal as having no power in a predetermined frequency region on the low frequency side of the ambient sound component, and the ambient noise component power calculating means calculating Noise power calculating means for calculating a power obtained by adding a predetermined power to the power of the ambient noise component, and calculating the output calculated by the output sound component power calculating means in the loudness compensating means. Based on the power of the sound component and the noise power calculated by the noise power calculation means, the gain of the output sound signal output to the speaker is adjusted according to a predetermined loudness compensation function.

このような音声出力装置によれば、前記低域側の所定周波数領域をマイクの周波数特性にばらつきが生じる周波数領域とし、騒音パワー算出手段が加算する所定のパワーを、発生が推定される周囲音に対して、当該周囲音が発生した場合にマイク出力信号中に発生するとラウドネス補償手段において想定する周囲音成分の前記周波数領域のパワーとすることにより、個々のマイクの周波数特性に依存せずに適当なラウドネス補償が行われるように騒音パワーを算出することができる。   According to such an audio output device, the predetermined frequency region on the low frequency side is a frequency region in which the frequency characteristics of the microphone vary, and the predetermined power added by the noise power calculation means is used as the ambient sound whose occurrence is estimated. On the other hand, when the ambient sound is generated, if it occurs in the microphone output signal, the power in the frequency domain of the ambient sound component assumed in the loudness compensation means is used without depending on the frequency characteristics of the individual microphones. Noise power can be calculated so that appropriate loudness compensation is performed.

ただし、このような音声出力装置は、前記周囲音成分パワー算出手段において、前記マイクが出力するマイク出力信号のパワーと、前記出力音声成分パワー算出手段が算出した前記出力音声の成分のパワーとに基づき、前記マイク出力信号中の周囲騒音の成分のパワーを、当該周囲騒音の成分の前記低域側の前記所定周波数領域のパワーに代えて当該周囲騒音の成分の前記低域側の前記所定周波数領域のパワーを減衰させたパワーを用いて算出するようにしてもよい。   However, in such an audio output device, in the ambient sound component power calculation means, the power of the microphone output signal output by the microphone and the power of the component of the output sound calculated by the output sound component power calculation means The power of the ambient noise component in the microphone output signal is replaced with the power of the predetermined frequency region on the low frequency side of the ambient noise component, and the predetermined frequency on the low frequency side of the ambient noise component You may make it calculate using the power which attenuate | damped the power of the area | region.

このようにすることにより、低域側の前記所定周波数領域をマイクの周波数特性にばらつきが生じる周波数領域とし、騒音パワー算出手段が加算する所定のパワーを、発生が推定される周囲音に対して、当該周囲音が発生した場合にマイク出力信号中に発生するとラウドネス補償手段において想定する周囲音成分のパワーに、騒音パワーがなるように設定することにより、ラウドネス補償の個々のマイクの周波数特性に対する依存性を低めつつ、現実の周囲音の発生状況を加味して、騒音パワーの算出が行えるようになる。よって、より現実の周囲音の発生状況に応じたラウドネス補償が行えるようになる。   By doing so, the predetermined frequency region on the low frequency side is set as a frequency region in which the frequency characteristics of the microphone vary, and the predetermined power added by the noise power calculation means is set to the ambient sound that is estimated to be generated. If the ambient sound is generated in the microphone output signal when the ambient sound is generated, by setting the power of the ambient sound component assumed by the loudness compensation means to be the noise power, the frequency characteristics of the individual microphones of the loudness compensation The noise power can be calculated in consideration of the actual situation of ambient sounds while reducing the dependency. Therefore, it becomes possible to perform loudness compensation according to the actual situation of ambient sound generation.

また、以上の音声出力装置は、前記騒音パワー算出手段において、前記自動車の車速を取得し、取得した車速に対して定まるパワーを、前記周囲騒音成分パワー算出手段が算出した周囲騒音成分のパワーに加算したパワーを騒音パワーとして算出するようにしてもよい。または、前記騒音パワー算出手段において、前記周囲騒音成分パワー算出手段が算出した周囲騒音成分のパワーに応じて定まるパワーを、前記周囲騒音成分パワー算出手段が算出した周囲騒音成分のパワーに加算したパワーを騒音パワーとして算出するようにしてもよい。   Further, the sound output device described above acquires the vehicle speed of the automobile in the noise power calculation means, and sets the power determined for the acquired vehicle speed to the power of the ambient noise component calculated by the ambient noise component power calculation means. The added power may be calculated as noise power. Alternatively, in the noise power calculation means, a power determined according to the power of the ambient noise component calculated by the ambient noise component power calculation means is added to the power of the ambient noise component calculated by the ambient noise component power calculation means May be calculated as noise power.

これらのようにすることにより、騒音パワー算出手段が加算する所定のパワーを、各時点の状況に応じて、当該状況下で発生が推定される周囲音に対して、当該周囲音が発生している場合にマイク出力信号中に発生するとラウドネス補償手段において想定する周囲音成分のパワーに、騒音パワーがなるように設定することができるようになる。したがって、騒音パワーを、より正確なラウドネス補償が行われるように算出することができるようになる。   By doing so, the ambient power is generated with respect to the ambient sound that is estimated to be generated under the situation according to the situation at each point of time. If this occurs in the microphone output signal, the power of the ambient sound component assumed by the loudness compensation means can be set to be the noise power. Therefore, the noise power can be calculated so that more accurate loudness compensation is performed.

以上のように、本発明によれば、音声を出力する音声出力装置において、マイクの低域の周波数特性のばらつきによる、ラウドネス補償の劣化を抑制することができる。   As described above, according to the present invention, in an audio output device that outputs audio, it is possible to suppress degradation of loudness compensation due to variations in the low-frequency characteristics of the microphone.

以下、本発明に係る音声出力装置の実施形態について、自動車に搭載される車載装置への適用を例にとり説明する。
図1に、車載装置の構成を示す。
図示するように車載装置は、ユーザに対して現在位置や目的地までの経路案内を行うナビゲーション装置1、ラジオ受信機やCDプレイヤなどであるオーディオ機器2、音量調整アンプ3、出力音声加算器4、出力アンプ5、スピーカ6、マイク7、第1ハイパスフィルタ8、入力音パワー算出部9、加算器10、ラウドネス補償制御部11、フィルタ12、係数更新部13、第2ハイパスフィルタ14、出力音声パワー算出部15、低域パワー成分加算部16とを備えている。ここで、ナビゲーション装置1は、ユーザに対して経路や操作を案内する案内音声を表す案内音声信号を音量調整アンプ3に出力する。
Hereinafter, embodiments of an audio output device according to the present invention will be described taking application to an in-vehicle device mounted in an automobile as an example.
FIG. 1 shows the configuration of the in-vehicle device.
As shown in the figure, the in-vehicle device includes a navigation device 1 that provides route guidance to the user to the current position and destination, an audio device 2 such as a radio receiver and a CD player, a volume adjustment amplifier 3, and an output audio adder 4. , Output amplifier 5, speaker 6, microphone 7, first high-pass filter 8, input sound power calculation unit 9, adder 10, loudness compensation control unit 11, filter 12, coefficient update unit 13, second high-pass filter 14, output sound A power calculation unit 15 and a low frequency power component addition unit 16 are provided. Here, the navigation device 1 outputs to the volume adjustment amplifier 3 a guidance voice signal representing a guidance voice for guiding the route and operation to the user.

このような構成において、ナビゲーション装置1から出力された案内音声信号は、音量調整アンプ3で全体のゲインが調整された後に、出力音声加算器4に入力する。出力音声加算器4は、音量調整アンプ3から入力する案内音声信号とオーディオ機器2から入力するオーディオ信号を加算し、出力音声信号として出力アンプ5に出力する。そして、出力アンプ5は、入力する出力音声信号を増幅し、スピーカ6から出力する。そして、スピーカ6から出力された出力音(案内音声Sとオーディオ音Aの合成音)と、カーノイズなどの周囲のノイズNは、マイク7によってピックアップされ、電気信号として第1ハイパスフィルタ8に入力する。ここで、以下では説明の便宜上、このマイク7が出力する信号を「マイク出力信号」と称す。さて、マイク出力信号は、第1ハイパスフィルタ8で低域成分が減衰された後に入力音パワー算出部9に入力する。入力音パワー算出部9は低域成分が減衰されたマイク出力信号の単位時間当たりのパワーを算出し、加算器10に入力する。   In such a configuration, the guidance voice signal output from the navigation device 1 is input to the output voice adder 4 after the overall gain is adjusted by the volume adjustment amplifier 3. The output voice adder 4 adds the guidance voice signal input from the volume adjustment amplifier 3 and the audio signal input from the audio device 2 and outputs the result to the output amplifier 5 as an output voice signal. The output amplifier 5 amplifies the input output audio signal and outputs it from the speaker 6. The output sound (synthesized sound of the guidance sound S and the audio sound A) output from the speaker 6 and the ambient noise N such as car noise are picked up by the microphone 7 and input to the first high-pass filter 8 as an electric signal. . Hereinafter, for convenience of explanation, a signal output from the microphone 7 is referred to as a “microphone output signal”. The microphone output signal is input to the input sound power calculation unit 9 after the low frequency component is attenuated by the first high pass filter 8. The input sound power calculation unit 9 calculates the power per unit time of the microphone output signal in which the low frequency component is attenuated, and inputs the power to the adder 10.

一方、フィルタ12は、ナビゲーション装置1の出力からマイク7の出力までの案内音声信号の伝達系のインパルス応答(伝達関数)を模擬するフィルタであり、このフィルタ12のインパルス応答を算出、更新するのが係数更新部13であり、フィルタ12と係数更新部13で適応フィルタを構成している。そして、第2ハイパスフィルタ14はフィルタ12の出力する音声信号の低域成分を減衰して、出力音声パワー算出部15に出力する。ここで、第1ハイパスフィルタ8と第2ハイパスフィルタ14の周波数特性は等しく設定されている。   On the other hand, the filter 12 is a filter that simulates the impulse response (transfer function) of the guidance voice signal transmission system from the output of the navigation device 1 to the output of the microphone 7, and calculates and updates the impulse response of the filter 12. Is the coefficient updating unit 13, and the filter 12 and the coefficient updating unit 13 constitute an adaptive filter. The second high-pass filter 14 attenuates the low frequency component of the audio signal output from the filter 12 and outputs the attenuated component to the output audio power calculation unit 15. Here, the frequency characteristics of the first high-pass filter 8 and the second high-pass filter 14 are set to be equal.

次に、出力音声パワー算出部15は、第2ハイパスフィルタ14の出力する低域成分が減衰された音声信号の単位時間当たりのパワーを算出し、係数更新部13は、LMS(平均二乗誤差)アルゴリズムやNLMS(正規化平均二乗誤差)アルゴリズムなどにより、加算器10が出力する入力音パワー算出部9の出力と、出力音声パワー算出部15の出力の差分が最小となるようにフィルタ12のフィルタ係数を算出し、フィルタ12に設定する処理を繰り返し行う。   Next, the output audio power calculation unit 15 calculates the power per unit time of the audio signal in which the low-frequency component output from the second high-pass filter 14 is attenuated, and the coefficient update unit 13 performs LMS (mean square error). By using an algorithm, an NLMS (normalized mean square error) algorithm, or the like, the filter of the filter 12 so that the difference between the output of the input sound power calculation unit 9 output from the adder 10 and the output of the output sound power calculation unit 15 is minimized. The process of calculating the coefficient and setting it in the filter 12 is repeated.

ここで、フィルタ12のインパルス応答が、ナビゲーション装置1の出力からマイク7の出力までの案内音声信号の伝達系のインパルス応答を正確に模擬している場合、フィルタ12の出力は、マイク7が出力する信号中の案内音声信号成分を表し、出力音声パワー算出部15の出力は、マイク7が出力する信号中の案内音声信号成分のうちの第2ハイパスフィルタ14で減衰された低域成分を除く部分の単位時間当たりのパワーとなる。また、加算器10の出力は、マイク7が出力する信号中の、オーディオ信号成分とカーノイズなどの周囲のノイズ成分とが合成された周囲騒音成分の、第1ハイパスフィルタ8で減衰された低域成分を除く部分のパワーとなる。   Here, when the impulse response of the filter 12 accurately simulates the impulse response of the transmission system of the guidance voice signal from the output of the navigation device 1 to the output of the microphone 7, the output of the filter 12 is output by the microphone 7. The output of the output voice power calculation unit 15 excludes a low-frequency component attenuated by the second high-pass filter 14 among the guide voice signal components in the signal output from the microphone 7. It becomes the power per unit time of the part. Further, the output of the adder 10 is a low-frequency band attenuated by the first high-pass filter 8 of the ambient noise component in which the audio signal component and the ambient noise component such as car noise in the signal output from the microphone 7 are combined. It is the power of the part excluding components.

さて、出力音声パワー算出部15は、フィルタ12から出力された案内音声信号成分の第2ハイパスフィルタ14で減衰された低域成分を除く部分の単位時間当たりのパワーを、出力音声パワーとして、ラウドネス補償制御部11にも出力する。
一方、加算器10の出力する周囲騒音成分の第1ハイパスフィルタ8で減衰された低域成分を除く部分の単位時間当たりのパワーは、低域パワー成分加算部16に出力される。低域パワー成分加算部16は、後述する低域パワー加算処理により、周囲騒音低域成分パワーを定め、定めた周囲騒音低域成分パワーを加算器10が出力したパワーに加算し、騒音パワーとしてラウドネス補償制御部11に出力する。
The output voice power calculation unit 15 uses the power per unit time of the part of the guidance voice signal component output from the filter 12 excluding the low frequency component attenuated by the second high-pass filter 14 as the output voice power. Also output to the compensation controller 11.
On the other hand, the power per unit time of the portion excluding the low frequency component attenuated by the first high pass filter 8 of the ambient noise component output from the adder 10 is output to the low frequency power component adding unit 16. The low-frequency power component adding unit 16 determines the ambient noise low-frequency component power by low-frequency power addition processing, which will be described later, and adds the determined ambient noise low-frequency component power to the power output from the adder 10 as noise power. Output to the loudness compensation controller 11.

そして、ラウドネス補償制御部11は、入力する出力音声パワーと騒音パワーとに基づいて、音量調整アンプ3のゲインを、所定のラウドネス補償関数に従って、案内音声がユーザに明瞭に聞こえるように調整する。
ただし、出力音声パワー算出部15とは別に、フィルタ12から出力された第2ハイパスフィルタ14で低域成分の減衰が行われる前の案内音声信号成分の単位時間当たりのパワーを第2出力音声パワーとして算出する第2出力パワー算出部を設け、ラウドネス補償制御部11において、この第2出力音声パワーと騒音パワーとに基づいて、音量調整アンプ3のゲインを、所定のラウドネス補償関数に従って、案内音声がユーザに明瞭に聞こえるように調整するようにしてもよい。
Then, the loudness compensation control unit 11 adjusts the gain of the volume adjustment amplifier 3 based on the input output voice power and noise power so that the guidance voice can be clearly heard by the user according to a predetermined loudness compensation function.
However, separately from the output sound power calculation unit 15, the power per unit time of the guidance sound signal component before the low-frequency component is attenuated by the second high-pass filter 14 output from the filter 12 is the second output sound power. The loudness compensation control unit 11 calculates the gain of the volume adjustment amplifier 3 based on the second output sound power and the noise power according to a predetermined loudness compensation function. May be adjusted so that it can be clearly heard by the user.

ここで、マイク7の周波数特性と、第1ハイパスフィルタ8と第2ハイパスフィルタ14の周波数特性について説明する。
いま、マイク7として使用する製品が、個々のマイク7によって図2aに示す周波数特性や、図2bに示す周波数特性を示すものであるとする。すなわち、この製品は、所定の周波数fco(たとえば、250Hz)より大きい周波数帯域の周波数特性はおよそ等しいが、周波数fco以下の周波数帯域では個々のマイク毎に異なる周波数特性を示す製品、すなわち、周波数fco以下の周波数帯域の周波数特性に無視できないばらつきがある製品であるものとする。
Here, the frequency characteristics of the microphone 7 and the frequency characteristics of the first high-pass filter 8 and the second high-pass filter 14 will be described.
Now, it is assumed that the product used as the microphone 7 exhibits the frequency characteristics shown in FIG. 2a or the frequency characteristics shown in FIG. That is, this product has approximately the same frequency characteristics in a frequency band greater than a predetermined frequency fco (for example, 250 Hz), but shows a different frequency characteristic for each microphone in a frequency band below the frequency fco, that is, the frequency fco. It is assumed that the product has a non-negligible variation in the frequency characteristics of the following frequency bands.

そして、このような場合、第1ハイパスフィルタ8と第2ハイパスフィルタ14の周波数特性は、図2cに示すように、マイク7の周波数のばらつきがある周波数帯域の上限fco以下の周波数帯域の成分を大きく減衰させてカットするものとする。すなわち、第1ハイパスフィルタ8と第2ハイパスフィルタ14として、周波数帯域の上限fcoを超える周波数帯域の成分のみを、ほぼ減衰させずに通過させる周波数特性を備えたものを用いる。   In such a case, as shown in FIG. 2c, the frequency characteristics of the first high-pass filter 8 and the second high-pass filter 14 include components in a frequency band that is less than or equal to the upper limit fco of the frequency band in which the frequency of the microphone 7 varies. It shall be cut with a large attenuation. That is, as the first high-pass filter 8 and the second high-pass filter 14, filters having frequency characteristics that allow only the components in the frequency band exceeding the upper limit fco of the frequency band to pass without being attenuated are used.

次に、低域パワー成分加算部16が行う低域パワー加算処理について説明する。
低域パワー成分加算部16には、車両のECUなどから車両の車速信号Vが入力している。また、あらかじめ低域パワー成分加算部16には、車速と、加算器10が出力したパワーに加算すべき周囲騒音低域成分パワーの値との対応が設定されている。そして、低域パワー成分加算部16は、入力する車速信号Vが示す車速との対応が設定されている周囲騒音低域成分パワーの値を求め、求めたる周囲騒音低域成分パワーの値を加算器10が出力したパワーに加算し、ラウドネス補償制御部11に騒音パワーとして出力する。
Next, the low frequency power addition process performed by the low frequency power component adding unit 16 will be described.
A vehicle speed signal V of the vehicle is input to the low frequency power component adding unit 16 from the ECU of the vehicle. The low frequency power component adding unit 16 is set in advance with a correspondence between the vehicle speed and the value of the ambient noise low frequency component power to be added to the power output from the adder 10. Then, the low frequency power component adding unit 16 obtains the value of the ambient noise low frequency component power for which the correspondence with the vehicle speed indicated by the input vehicle speed signal V is set, and adds the obtained value of the ambient noise low frequency component power. Is added to the power output by the device 10 and output to the loudness compensation control unit 11 as noise power.

ここで、この車速と、加算器10が出力したパワーに加算すべき周囲騒音低域成分パワーの値との対応は、あらかじめ次のようにして求めて低域パワー成分加算部16に設定する。
すなわち、あらかじめ、図2dに示すように、各車速V(図ではa、b、c:a>b>C)におけるカーノイズの単位時間当たりのパワー周波数分布を測定または計算などにより求める。ここで、この測定または計算は、マイクの取り得る周波数特性のうちの特定の周波数特性を持つマイク7の使用を前提として行う。また、ラウドネス補償制御部11に設定するラウドネス補償関数は、この特定の周波数特性と等しい周波数特性を持つマイク7を使用した場合に最適なラウドネス補償が行われるよう設定する。
Here, the correspondence between the vehicle speed and the value of the ambient noise low-frequency component power to be added to the power output from the adder 10 is determined in advance as follows and set in the low-frequency power component adding unit 16.
That is, as shown in FIG. 2d, the power frequency distribution per unit time of car noise at each vehicle speed V (a, b, c: a>b> C in the figure) is obtained in advance by measurement or calculation. Here, this measurement or calculation is performed on the assumption that the microphone 7 having a specific frequency characteristic among the frequency characteristics that can be taken by the microphone is used. The loudness compensation function set in the loudness compensation control unit 11 is set so that optimum loudness compensation is performed when the microphone 7 having a frequency characteristic equal to the specific frequency characteristic is used.

さて、次に、各車速Vについて、当該車速Vに対して求めたカーノイズの単位時間当たりのパワーのうちの、図2eに示すマイク7の周波数のばらつきがある周波数帯域の上限fco以下の周波数以下の成分を抽出し、抽出した成分全体のパワーを算出する。そして、求めたfco以下の周波数以下の成分全体のパワーの値を、当該パワーを求めた車速Vに対応する周囲騒音低域成分パワーの値として、低域パワー成分加算部16に設定する。   Now, for each vehicle speed V, out of the power per unit time of the car noise obtained for the vehicle speed V, the frequency is equal to or lower than the upper limit fco of the frequency band in which the frequency of the microphone 7 shown in FIG. Are extracted, and the power of the whole extracted component is calculated. Then, the power value of the entire component below the frequency equal to or less than the obtained fco is set in the low frequency power component adding unit 16 as the value of the ambient noise low frequency component power corresponding to the vehicle speed V for which the power is obtained.

以上、本発明の実施形態について説明した。
ところで、以上の実施形態では、車速に応じて、低域パワー成分加算部16で、加算器10が出力したパワーに加算する周囲騒音低域成分パワーの値を変化させたが、この低域パワー成分加算部16で加算する周囲騒音低域成分パワーの値は固定値としてもよい。この場合には、あらかじめ、平均的な車速Vに対してカーノイズの単位時間当たりのパワーの周波数特性を求め、求めたカーノイズの単位時間当たりのパワーのうちの、マイク7の周波数のばらつきがある周波数帯域の上限fco以下の周波数以下の成分を抽出し、抽出した成分全体のパワーを算出する。そして、算出したパワーの値を、低域パワー成分加算部16で加算する周囲騒音低域成分パワーの値として低域パワー成分加算部16に設定する。
The embodiment of the present invention has been described above.
In the above embodiment, the value of the ambient noise low frequency component power added to the power output by the adder 10 is changed by the low frequency power component adding unit 16 according to the vehicle speed. The value of the ambient noise low-frequency component power added by the component adding unit 16 may be a fixed value. In this case, the frequency characteristic of the power per unit time of the car noise is obtained in advance with respect to the average vehicle speed V, and the frequency at which the frequency of the microphone 7 varies among the obtained power per unit time of the car noise. The component below the frequency below the upper limit fco of the band is extracted, and the power of the entire extracted component is calculated. Then, the calculated power value is set in the low frequency power component adding unit 16 as the value of the ambient noise low frequency component power added by the low frequency power component adding unit 16.

このように本実施形態によれば、個々のマイク7の周波数特性に依存して変動する周囲音成分のfco以下の周波数領域の成分のパワーとして、推定される周囲音に対して、周囲音成分のfco以下の周波数領域の成分のパワーとして発生すべきパワーであるとして予め定めたパワーを用いて騒音パワーを求めるので、個々のマイク7の周波数特性に依存せずに、適当なラウドネス補償を行うことができる。また、車速に応じて、加算器10が出力したパワーに加算する周囲騒音低域成分パワーを変化させることにより、現実の周囲音の発生状況に応じた騒音パワーの算出及びラウドネス補償を行えるようになる。   As described above, according to the present embodiment, the ambient sound component is estimated with respect to the estimated ambient sound as the power of the component in the frequency region below fco of the ambient sound component that varies depending on the frequency characteristics of the individual microphones 7. The noise power is obtained by using a predetermined power that is to be generated as the power of the frequency region component below fco, so that appropriate loudness compensation is performed without depending on the frequency characteristics of the individual microphones 7. be able to. Further, by changing the ambient noise low-frequency component power added to the power output from the adder 10 according to the vehicle speed, the calculation of the noise power and the loudness compensation according to the actual situation of the ambient sound can be performed. Become.

さて、以上の実施形態で用いる第1ハイパスフィルタ8と第2ハイパスフィルタ14との周波数特性としては、たとえば、図3aに示すように、マイク7の周波数のばらつきがある周波数帯域の上限fco以下の周波数以下の成分を、低域側に向かって徐々に減衰量が大きくなる周波数特性を用いるようにしてもよい。なお、この場合には、低域パワー成分加算部16に各車速に対応させて設定する周囲騒音低域成分パワーの値は、図2eに示した当該車速Vに対して求めたカーノイズの単位時間当たりのパワーのうちのマイク7の周波数のばらつきがある周波数帯域の上限fco以下の周波数以下の成分に対して、第1ハイパスフィルタ8と第2ハイパスフィルタ14との周波数関数の減衰特性の逆数として与えられるゲイン特性を与えて得られる図3bに示すfco以下の周波数以下の成分の全体のパワーの値とするようにしてもよい。   Now, as frequency characteristics of the first high-pass filter 8 and the second high-pass filter 14 used in the above embodiment, for example, as shown in FIG. A frequency characteristic in which the amount of attenuation gradually increases toward the low frequency side may be used for components below the frequency. In this case, the value of the ambient noise low-frequency component power set in the low-frequency power component adding unit 16 corresponding to each vehicle speed is the unit time of the car noise obtained with respect to the vehicle speed V shown in FIG. As a reciprocal of the attenuation characteristic of the frequency function of the first high-pass filter 8 and the second high-pass filter 14 with respect to a component having a frequency less than or equal to the upper limit fco of the frequency band in which the frequency of the microphone 7 varies in the per unit power You may make it set it as the value of the whole power of the component below the frequency below fco shown in FIG. 3b obtained by giving the given gain characteristic.

このようにすることにより、個々のマイク7の周波数特性への依存性を低めつつ、実際の周囲音成分のfco以下の周波数以下の成分のパワーも反映した騒音パワーを算出することができるので、より現実の周囲音の発生状況に応じたラウドネス補償を行えるようになる。
また、以上の実施形態では、ラウドネス補償を、音量調整アンプ3での案内音声の全体的なゲイン調整のみにより行うようにしたが、これはスピーカ6に出力される案内音声信号の周波数帯域毎のゲイン調整を行うイコライザを設け、周波数帯域毎のゲイン調整をも行うラウドネス補償を行うようにしてもよい。なお、この場合には、入力音パワー算出部9や出力音声パワー算出部部では、周波数帯域毎にパワーを算出するようにする。また、この場合には、低域パワー成分加算部16において、マイク7の周波数のばらつきがある周波数帯域の上限fco以下の各周波数帯域についてパワーを加算するようにする。
By doing so, it is possible to calculate the noise power reflecting the power of the component below the frequency fco of the actual ambient sound component while reducing the dependency on the frequency characteristics of the individual microphones 7. It becomes possible to perform loudness compensation according to the actual situation of ambient sound generation.
Further, in the above embodiment, the loudness compensation is performed only by the overall gain adjustment of the guidance voice by the volume adjustment amplifier 3, but this is performed for each frequency band of the guidance voice signal output to the speaker 6. An equalizer for performing gain adjustment may be provided, and loudness compensation for performing gain adjustment for each frequency band may be performed. In this case, the input sound power calculation unit 9 and the output sound power calculation unit calculate power for each frequency band. In this case, the low frequency power component adding unit 16 adds power for each frequency band below the upper limit fco of the frequency band in which the frequency of the microphone 7 varies.

なお、この低域パワー成分加算部16で加算するfco以下の各周波数帯域のパワーは、図2eや図3bに示した各車速Vに対して求めたカーノイズの単位時間当たりのパワーのうちのfco以下の周波数成分のパワー分布に従って、予め低域パワー成分加算部16に設定する。   The power of each frequency band below fco added by the low frequency power component adding unit 16 is fco of the power per unit time of the car noise obtained for each vehicle speed V shown in FIGS. 2e and 3b. The low frequency power component adding unit 16 is set in advance in accordance with the following power distribution of frequency components.

ただし、このように周波数帯域毎のゲイン調整をも行うラウドネス補償を行う場合には、低域パワー成分加算部16で加算するfco以下の各周波数帯域のパワーは以下のように定めるようにしてもよい。
すなわち、図3cに示すように予め設定したfco以下の周波数帯域のパワー分布300にオフセットOSを与えたパワー分布311、312が、図3dや図3eに示すように、加算器10が出力したfcoを超える周波数帯域のパワー分布301、302と、周波数fcoにおいて連続するように、当該オフセットOSを求める。そして、図3cに示すパワー分布300に求めたオフセットOSを加えたパワー分布311、312に従って、低域パワー成分加算部16で加算するfco以下の周波数帯域のパワーを算出する。このようにすることにより、周波数帯域毎のゲイン調整を含むラウドネス補償を行う場合に、周波数fco付近で不連続なゲイン調整が行われ不自然な案内音声が出力されてしまうことを抑制することができる。なお、前述のような全体的なゲイン調整のみによりラウドネス補償を行う場合であっても、このようにして求めたパワー分布311、312に従って、低域パワー成分加算部16で加算するパワーを定めるようにしてもよい。
However, when performing loudness compensation that also performs gain adjustment for each frequency band in this way, the power in each frequency band below fco to be added by the low frequency power component adding unit 16 may be determined as follows. Good.
That is, the power distributions 311 and 312 obtained by adding the offset OS to the power distribution 300 in the frequency band equal to or lower than fco set in advance as shown in FIG. 3C are the fcos output from the adder 10 as shown in FIGS. The offset OS is obtained so as to be continuous with the power distributions 301 and 302 in the frequency band exceeding the frequency fco. Then, in the power distributions 311 and 312 obtained by adding the offset OS to the power distribution 300 shown in FIG. In this way, when performing loudness compensation including gain adjustment for each frequency band, it is possible to suppress discontinuous gain adjustment near the frequency fco and output an unnatural guidance voice. it can. Even when the loudness compensation is performed only by the overall gain adjustment as described above, the power to be added by the low frequency power component adding unit 16 is determined according to the power distributions 311 and 312 thus obtained. It may be.

このようにすることにより、より現実の周囲音の発生状況に応じた騒音パワーの算出及びラウドネス補償を行えるようになる。
なお、以上の実施形態では、ナビゲーション装置1が出力する案内音声に対してラウドネス補償を行う場合について説明したが、本実施形態に係る音声明瞭化の技術は、任意の装置が出力する音声の明瞭化のために適用可能である。
By doing so, it becomes possible to perform noise power calculation and loudness compensation in accordance with the actual situation of ambient sound generation.
In the above embodiment, the case where the loudness compensation is performed on the guidance voice output from the navigation apparatus 1 has been described. However, the voice clarification technique according to the present embodiment is the clarity of the voice output from any apparatus. It can be applied for

本発明の実施形態に係る車載装置の構成を示すブロック図である。It is a block diagram which shows the structure of the vehicle-mounted apparatus which concerns on embodiment of this invention. 本発明の実施形態に係る音声出力装置が行う処理を示す図である。It is a figure which shows the process which the audio | voice output apparatus which concerns on embodiment of this invention performs. 本発明の実施形態に係る音声出力装置が行う処理を示す図である。It is a figure which shows the process which the audio | voice output apparatus which concerns on embodiment of this invention performs.

符号の説明Explanation of symbols

1…ナビゲーション装置、2…オーディオ機器、3…音量調整アンプ、4…出力音声加算器、5…出力アンプ、6…スピーカ、7…マイク、8…第1ハイパスフィルタ、9…入力音パワー算出部、10…加算器、11…ラウドネス補償制御部、12…フィルタ、13…係数更新部、14…第2ハイパスフィルタ、15…出力音声パワー算出部、16…低域パワー成分加算部。   DESCRIPTION OF SYMBOLS 1 ... Navigation apparatus, 2 ... Audio equipment, 3 ... Volume adjustment amplifier, 4 ... Output audio adder, 5 ... Output amplifier, 6 ... Speaker, 7 ... Microphone, 8 ... 1st high pass filter, 9 ... Input sound power calculation part DESCRIPTION OF SYMBOLS 10 ... Adder, 11 ... Loudness compensation control part, 12 ... Filter, 13 ... Coefficient update part, 14 ... 2nd high pass filter, 15 ... Output audio | voice power calculation part, 16 ... Low frequency power component addition part

Claims (4)

ラウドネス補償を施した音声を出力する音声出力装置であって、
前記出力する音声を表す音声信号である出力音声信号を生成する音声信号生成手段と、
音声信号生成手段が生成した出力音声信号のラウドネス補償を行うラウドネス補償手段と
前記ラウドネス補償手段がラウドネス補償を行った前記出力音声信号に基づき音声を出力するスピーカと、
周辺音をピックアップするマイクと、
前記マイクが出力する信号であるマイク出力信号と前記出力音声信号とに基づき、前記マイク出力信号中の前記出力音声の成分のパワーを算出する出力音声成分パワー算出手段と、
前記マイクが出力するマイク出力信号のパワーと、前記出力音声成分パワー算出手段が算出した前記出力音声の成分のパワーとに基づき、前記マイク出力信号中の周囲騒音の成分のパワーを、当該周囲音の成分の低域側の所定周波数領域のパワーが無いものとして算出する周囲騒音成分パワー算出手段と、
前記周囲騒音成分パワー算出手段が算出した周囲騒音成分のパワーに、所定のパワーを加算したパワーを騒音パワーとして算出する騒音パワー算出手段とを有し、
前記ラウドネス補償手段は、前記出力音声成分パワー算出手段が算出した前記出力音声の成分のパワーと、前記騒音パワー算出手段が算出した前記騒音パワーとに基づいて、スピーカに出力する出力音声信号のゲインの調整を、所定のラウドネス補償関数に従って行うことを特徴とする音声出力装置。
An audio output device that outputs audio with loudness compensation,
Audio signal generating means for generating an output audio signal that is an audio signal representing the output audio;
A loudness compensation unit that performs loudness compensation of an output audio signal generated by the audio signal generation unit; and a speaker that outputs audio based on the output audio signal that the loudness compensation unit performs loudness compensation;
A microphone that picks up ambient sounds,
Output sound component power calculating means for calculating the power of the component of the output sound in the microphone output signal based on the microphone output signal which is a signal output from the microphone and the output sound signal;
Based on the power of the microphone output signal output from the microphone and the power of the component of the output sound calculated by the output sound component power calculation means, the power of the ambient noise component in the microphone output signal is determined as the ambient sound. Ambient noise component power calculation means for calculating that there is no power in a predetermined frequency region on the low frequency side of the component,
Noise power calculation means for calculating, as noise power, a power obtained by adding a predetermined power to the power of the ambient noise component calculated by the ambient noise component power calculation means;
The loudness compensation means is a gain of an output sound signal output to a speaker based on the power of the output sound component calculated by the output sound component power calculation means and the noise power calculated by the noise power calculation means. Is adjusted according to a predetermined loudness compensation function.
ラウドネス補償を施した音声を出力する音声出力装置であって、
前記出力する音声を表す音声信号である出力音声信号を生成する音声信号生成手段と、
音声信号生成手段が生成した出力音声信号のラウドネス補償を行うラウドネス補償手段と
前記ラウドネス補償手段がラウドネス補償を行った前記出力音声信号に基づき音声を出力するスピーカと、
周辺音をピックアップするマイクと、
前記マイクが出力する信号であるマイク出力信号と前記出力音声信号とに基づき、前記マイク出力信号中の前記出力音声の成分のパワーを算出する出力音声成分パワー算出手段と、
前記マイクが出力するマイク出力信号のパワーと、前記出力音声成分パワー算出手段が算出した前記出力音声の成分のパワーとに基づき、前記マイク出力信号中の周囲騒音の成分のパワーを、当該周囲騒音の成分の低域側の所定周波数領域のパワーに代えて当該周囲騒音の成分の前記低域側の前記所定周波数領域のパワーを減衰させたパワーを用いて算出する周囲騒音成分パワー算出手段と、
前記周囲騒音成分パワー算出手段が算出した周囲騒音成分のパワーに、所定のパワーを加算したパワーを騒音パワーとして算出する騒音パワー算出手段とを有し、
前記ラウドネス補償手段は、前記出力音声成分パワー算出手段が算出した前記出力音声の成分のパワーと、前記騒音パワー算出手段が算出した前記騒音パワーとに基づいて、スピーカに出力する出力音声信号のゲインの調整を、所定のラウドネス補償関数に従って行うことを特徴とする音声出力装置。
An audio output device that outputs audio with loudness compensation,
Audio signal generating means for generating an output audio signal that is an audio signal representing the output audio;
A loudness compensation unit that performs loudness compensation of an output audio signal generated by the audio signal generation unit; and a speaker that outputs audio based on the output audio signal that the loudness compensation unit performs loudness compensation;
A microphone that picks up ambient sounds,
Output sound component power calculating means for calculating the power of the component of the output sound in the microphone output signal based on the microphone output signal which is a signal output from the microphone and the output sound signal;
Based on the power of the microphone output signal output from the microphone and the power of the component of the output sound calculated by the output sound component power calculation means, the power of the ambient noise component in the microphone output signal is determined as the ambient noise. Ambient noise component power calculating means for calculating using the power obtained by attenuating the power of the predetermined frequency region on the low frequency side of the ambient noise component instead of the power of the predetermined frequency region on the low frequency side of the component of
Noise power calculation means for calculating, as noise power, a power obtained by adding a predetermined power to the power of the ambient noise component calculated by the ambient noise component power calculation means;
The loudness compensation means is a gain of an output sound signal output to a speaker based on the power of the output sound component calculated by the output sound component power calculation means and the noise power calculated by the noise power calculation means. Is adjusted according to a predetermined loudness compensation function.
請求項1または2記載の音声出力装置であって、
当該音声出力装置は、自動車に搭載される音声出力装置であって、
前記騒音パワー算出手段は、前記自動車の車速を取得し、取得した車速に対して定まるパワーを、前記周囲騒音成分パワー算出手段が算出した周囲騒音成分のパワーに加算したパワーを騒音パワーとして算出することを特徴とする音声出力装置。
The audio output device according to claim 1 or 2,
The audio output device is an audio output device mounted on an automobile,
The noise power calculation means acquires a vehicle speed of the automobile, and calculates a power obtained by adding the power determined for the acquired vehicle speed to the power of the ambient noise component calculated by the ambient noise component power calculation means as a noise power. An audio output device characterized by that.
請求項1または2記載の音声出力装置であって、
前記騒音パワー算出手段は、前記周囲騒音成分パワー算出手段が算出した周囲騒音成分のパワーに応じて定まるパワーを、前記周囲騒音成分パワー算出手段が算出した周囲騒音成分のパワーに加算したパワーを騒音パワーとして算出することを特徴とする音声出力装置。
The audio output device according to claim 1 or 2,
The noise power calculation means adds a power determined according to the power of the ambient noise component calculated by the ambient noise component power calculation means to the power of the ambient noise component calculated by the ambient noise component power calculation means. An audio output device that calculates power.
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