WO2011001578A1 - Communication apparatus - Google Patents

Communication apparatus Download PDF

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Publication number
WO2011001578A1
WO2011001578A1 PCT/JP2010/002786 JP2010002786W WO2011001578A1 WO 2011001578 A1 WO2011001578 A1 WO 2011001578A1 JP 2010002786 W JP2010002786 W JP 2010002786W WO 2011001578 A1 WO2011001578 A1 WO 2011001578A1
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audio signal
band
level
noise
degree
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PCT/JP2010/002786
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French (fr)
Japanese (ja)
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竹田博昭
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パナソニック株式会社
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    • G—PHYSICS
    • G10—MUSICAL INSTRUMENTS; ACOUSTICS
    • G10L—SPEECH ANALYSIS TECHNIQUES OR SPEECH SYNTHESIS; SPEECH RECOGNITION; SPEECH OR VOICE PROCESSING TECHNIQUES; SPEECH OR AUDIO CODING OR DECODING
    • G10L21/00—Speech or voice signal processing techniques to produce another audible or non-audible signal, e.g. visual or tactile, in order to modify its quality or its intelligibility
    • G10L21/02—Speech enhancement, e.g. noise reduction or echo cancellation
    • G10L21/0208—Noise filtering
    • G—PHYSICS
    • G10—MUSICAL INSTRUMENTS; ACOUSTICS
    • G10L—SPEECH ANALYSIS TECHNIQUES OR SPEECH SYNTHESIS; SPEECH RECOGNITION; SPEECH OR VOICE PROCESSING TECHNIQUES; SPEECH OR AUDIO CODING OR DECODING
    • G10L21/00—Speech or voice signal processing techniques to produce another audible or non-audible signal, e.g. visual or tactile, in order to modify its quality or its intelligibility
    • G10L21/02—Speech enhancement, e.g. noise reduction or echo cancellation
    • G10L21/038—Speech enhancement, e.g. noise reduction or echo cancellation using band spreading techniques

Definitions

  • the present invention relates to a communication device, and in particular, receives a voice signal with a narrow frequency band (narrow band voice signal) in voice communication, expands the frequency band of the received narrow band voice signal, and widens the voice signal (broadband).
  • the present invention relates to a communication apparatus and a band expansion method for performing band expansion to be converted into a voice signal.
  • a voice signal whose frequency band is limited to about 300 to 3400 Hz which is called a narrowband voice signal, is transmitted on the telephone line. For this reason, voice quality is deteriorated.
  • band extension a narrowband audio signal as an input is analyzed to generate a signal in a frequency band that does not originally exist.
  • the band expansion often uses the characteristics of an audio signal such as pitch and formant.
  • noise generated around a speaker is often superimposed as noise or line noise is often superimposed.
  • Patent Document 2 since noise removal processing is performed on an audio signal whose frequency band is extended, malfunction of the band expansion processing cannot be prevented.
  • An object of the present invention is to improve a voice quality by converting a narrowband audio signal to a wideband audio signal, and to perform a band extension on a narrowband audio signal containing noise, due to a malfunction of the band extension process.
  • a communication apparatus capable of suppressing noise generation is provided.
  • the communication apparatus includes an expansion unit that performs band expansion to expand a frequency band of a narrowband audio signal and convert it to a wideband audio signal, a noise level of the narrowband audio signal, and an audio level of the narrowband audio signal And a reference table in which a relationship between the band extension effect degree of the band extension is set, and a determination unit that determines the degree of the band extension effect with reference to the reference table based on the noise level and the audio level And.
  • a narrowband audio signal is converted into a wideband audio signal to improve audio quality, and what kind of band expansion effect can be achieved when performing band extension on a narrowband audio signal containing noise. It can be set by using a reference table. For example, it is possible to simply avoid noise such as performing an operation to avoid malfunction of broadband processing due to noise or performing broadband processing even if noise generation is allowed.
  • the bandwidth extension effect can be controlled more effectively than the bandwidth extension effect is controlled in proportion to the level.
  • the figure which shows the degree of the band expansion effect which concerns on Embodiment 1 of this invention The block diagram which shows the structure of the communication apparatus which concerns on Embodiment 2 of this invention.
  • the figure which shows the degree of the band expansion effect which concerns on Embodiment 2 of this invention The figure which shows the degree of the band expansion effect which concerns on Embodiment 2 of this invention.
  • FIG. 1 shows the configuration of communication apparatus 100 according to the present embodiment.
  • the communication unit 102 establishes a call connection with the communication apparatus of the communication partner via the public network 101, and transmits / receives a digital narrowband audio signal to / from the communication partner.
  • the received narrowband audio signal is input to the noise level estimation unit 103 and the band extension unit 105.
  • the noise level estimation unit 103 estimates the level of noise included in the digital narrowband audio signal (the noise level of the narrowband audio signal), and outputs the estimation result to the band extension effect determination unit 104.
  • the noise level may be estimated using the technique disclosed in Japanese Patent No. 3244252, for example.
  • the band expansion effect determination unit 104 determines the degree (strength) of the band expansion effect when the band expansion unit 105 expands the narrowband audio signal to the wideband audio signal according to the noise level estimated by the noise level estimation unit 103. Then, the bandwidth extension unit 105 is instructed to determine the degree of the bandwidth extension effect. A method for determining the degree of the bandwidth expansion effect will be described later.
  • the band extension unit 105 adjusts the degree (strength) of the band extension effect in accordance with an instruction from the band extension effect determination unit 104, and uses the technique described in Patent Document 1, for example, to adjust the frequency band of the digital narrowband audio signal. Extends the bandwidth to be converted into a digital wideband audio signal. For example, when band extension is performed using the technique described in Patent Document 1, the adjustment of the degree of the band extension effect is performed by increasing or decreasing the addition ratio of the frequency component having a higher frequency than the original sound generated based on the original sound to the original sound. Can be performed.
  • the DAC / AMP unit 106 analogizes and amplifies the digital broadband audio signal output from the band expansion unit 105 to obtain an analog broadband audio signal.
  • the output device unit 107 converts an analog broadband audio signal into sound and outputs the sound in the air.
  • the output device unit 107 includes a receiver, a speaker, a headphone, and the like.
  • the degree of the band expansion effect is determined according to the noise level of the digital narrowband audio signal. Specifically, the band expansion effect determination unit 104 determines the degree of the band expansion effect as shown in FIG.
  • the band extension effect determination unit 104 strengthens the band extension effect in order to improve the voice quality.
  • the band expansion effect determination unit 104 sets the band expansion effect to medium in order to improve voice quality.
  • the band expansion effect determination unit 104 weakens the band expansion effect in order to suppress the occurrence of noise due to the malfunction of the band expansion process in the band expansion unit 105.
  • the band expansion effect determination unit 104 determines the degree (strength) of the band expansion effect according to the noise level estimated by the noise level estimation unit 103. Then, according to the determined degree (strength), the band extension unit 105 performs band extension while adjusting the degree of the band extension effect.
  • the degree of the band expansion effect that emphasizes the voice quality is used.
  • the optimum degree of band expansion effect is determined in accordance with the degree of band expansion effect that can suppress the occurrence of noise due to the malfunction of and the noise level.
  • the narrowband audio signal is converted into the wideband audio signal to improve the audio quality, and the band extension is performed even when the band extension is performed on the narrowband audio signal including noise. Generation of noise due to processing malfunction can be suppressed.
  • FIG. 3 shows the configuration of communication apparatus 200 according to the present embodiment.
  • the same components as those in FIG. 1 (Embodiment 1) are denoted by the same reference numerals, and description thereof is omitted.
  • the narrowband audio signal received by the communication unit 102 is input to the level ratio estimation unit 201 and the band extension unit 105.
  • the level ratio estimation unit 201 estimates the noise level of the narrowband audio signal and also estimates the level of the audio signal included in the digital narrowband audio signal (the audio level of the narrowband audio signal). Then, the level ratio estimation unit 201 estimates the ratio (level ratio) between the audio level and the noise level, and outputs the estimation result to the band extension effect determination unit 202.
  • the noise level may be estimated using the technology disclosed in, for example, Japanese Patent No. 3244252 as described above.
  • the estimation of the voice level may be performed by a method such as subtracting the noise level from the level of the entire digital narrowband voice signal.
  • the band expansion effect determination unit 202 determines the degree (strength) of the band expansion effect when the band expansion unit 105 expands the narrowband audio signal to the wideband audio signal according to the level ratio estimated by the level ratio estimation unit 201. Then, the bandwidth extension unit 105 is instructed to determine the degree of the bandwidth extension effect.
  • the degree of the band expansion effect is determined according to the ratio (level ratio) between the audio level and the noise level of the digital narrowband audio signal. Specifically, the band expansion effect determination unit 202 determines the degree of the band expansion effect as shown in FIG.
  • the band extension effect determination unit 202 sets the band extension effect to a medium level in order to improve voice quality.
  • the band expansion effect determination unit 202 performs the band expansion effect in order to suppress the occurrence of noise due to the malfunction of the band expansion process in the band expansion unit 105 when the noise level is high and the sound level is medium. Weaken.
  • the band expansion effect determination unit 202 weakens the band expansion effect in order to suppress the occurrence of noise due to the malfunction of the band expansion process in the band expansion unit 105 if the noise level is large and the sound level is small.
  • the band extension effect determination unit 202 strengthens the band extension effect in order to improve the voice quality if the noise level is medium and the voice level is high.
  • the band expansion effect determination unit 202 sets the band expansion effect to medium in order to improve the voice quality if the noise level is medium and the sound level is medium.
  • the band expansion effect determination unit 202 weakens the band expansion effect in order to suppress the occurrence of noise due to the band expansion processing malfunction in the band expansion unit 105. To do.
  • the band extension effect determination unit 202 strengthens the band extension effect in order to improve voice quality if the noise level is low and the voice level is high.
  • the band extension effect determination unit 202 strengthens the band extension effect in order to improve the voice quality if the noise level is low and the voice level is medium.
  • the band extension effect determination unit 202 makes the band extension effect moderate in order to improve voice quality.
  • the band extension effect determination unit 202 determines the degree (strength) of the band extension effect according to the level ratio estimated by the level ratio estimation unit 201. Then, according to the determined degree (strength), the band extension unit 105 performs band extension while adjusting the degree of the band extension effect.
  • the present invention can also realize an operation in which the degree of the band expansion effect is not proportional to the ratio between the audio level and the noise level by replacing the contents of the reference table for determining the degree of the band expansion effect as shown in FIG. .
  • the band expansion process may malfunction, so it is desirable not to perform the band expansion process from the viewpoint of voice quality, but dare to make it easier to hear the voice
  • band expansion processing is performed while allowing noise to be generated is also conceivable.
  • the degree of bandwidth expansion effect may be determined using a reference table as shown in FIG. A case where the sound level is low will be described with reference to FIG.
  • the band extension effect determination unit 202 sets the band extension effect to a medium level in order to improve voice quality.
  • the band expansion effect determination unit 202 weakens the band expansion effect in order to suppress the occurrence of noise due to the band expansion processing malfunction in the band expansion unit 105. To do.
  • the band extension effect determination unit 202 weakens the band extension effect in order to suppress the occurrence of noise due to the malfunction of the band extension process in the band extension unit 105 when the noise level is high and the sound level is low. It should be, however, that the voice is very difficult to hear when the voice is low and the noise level is high. In this case, the band expansion effect is strengthened for the purpose of allowing generation of noise and making it easy to hear the voice.
  • the noise level in a narrowband audio signal is sufficiently small with respect to the audio level
  • the noise level in the narrowband audio signal is reduced to the degree of the band expansion effect that emphasizes the audio quality.
  • the optimal bandwidth expansion effect is determined according to the level of the bandwidth expansion effect that can suppress the occurrence of noise due to malfunction of the bandwidth expansion process and the ratio between the audio level and the noise level. .
  • the degree of the bandwidth expansion effect using the reference table as in the embodiment of the present invention, specifically, by using a reference table that is not proportional to the ratio between the audio level and the noise level. For example, when the audio level is low and the noise level is high, the band expansion effect should be weakened, but it is not proportional to the ratio between the audio level and the noise level.
  • the degree of the bandwidth expansion effect can be determined, and a bandwidth expansion effect that makes it easier to hear the voice can be provided.
  • the narrowband audio signal is converted into the wideband audio signal to improve the audio quality, and the band extension is performed even when the band extension is performed on the narrowband audio signal including noise. It is possible to control the excellent degree of bandwidth expansion effect, which can suppress the generation of noise due to a malfunction of the process, and can set the emphasis on ease of listening even if the generation of noise is allowed.
  • the present invention can be used for all communication devices capable of narrowband voice communication.
  • the present invention can be used for a wired telephone connected to a fixed communication network and a mobile phone connected to a mobile communication network.

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  • Engineering & Computer Science (AREA)
  • Computational Linguistics (AREA)
  • Quality & Reliability (AREA)
  • Signal Processing (AREA)
  • Health & Medical Sciences (AREA)
  • Audiology, Speech & Language Pathology (AREA)
  • Human Computer Interaction (AREA)
  • Physics & Mathematics (AREA)
  • Acoustics & Sound (AREA)
  • Multimedia (AREA)
  • Noise Elimination (AREA)
  • Telephone Function (AREA)

Abstract

Provided is a communication apparatus that increases audio quality by converting a narrowband audio signal to a wideband audio signal, and can minimize noise generation due to errors in the band spreading process, even when performing band spreading on a narrowband audio signal that contains noise. In the provided communication apparatus, a noise-level estimation unit (103) estimates the level of noise in a narrowband audio signal; a band spreading effect decision unit (104) decides, in accordance with the noise level estimated by the noise-level estimation unit (103), the degree (strength) of the band spreading effect to use when a band spreading unit (105) spreads the narrowband audio signal into a wideband audio signal; and the band spreading unit (105) performs band spreading while adjusting the degree (strength) of the band spreading effect in accordance with instructions from the band spreading effect decision unit (104).

Description

通信装置Communication device
　本発明は、通信装置に関し、特に、音声通信における周波数帯域の狭い音声信号（狭帯域音声信号）を受信し、受信した狭帯域音声信号の周波数帯域を拡張して周波数帯域の広い音声信号（広帯域音声信号）に変換する帯域拡張を行う通信装置及び帯域拡張方法に関する。 The present invention relates to a communication device, and in particular, receives a voice signal with a narrow frequency band (narrow band voice signal) in voice communication, expands the frequency band of the received narrow band voice signal, and widens the voice signal (broadband). The present invention relates to a communication apparatus and a band expansion method for performing band expansion to be converted into a voice signal.
　現在運用されているほとんどの電話通信サービスでは、電話回線上において、狭帯域音声信号と呼ばれるおよそ３００～３４００Ｈｚに周波数帯域が制限された音声信号が伝達されている。このため、音声品質の劣化が生じる。 In most telephone communication services currently in operation, a voice signal whose frequency band is limited to about 300 to 3400 Hz, which is called a narrowband voice signal, is transmitted on the telephone line. For this reason, voice quality is deteriorated.
　この劣化を改善するために、受信した狭帯域音声信号の周波数帯域を例えば１００～７０００Ｈｚ程度にまで拡張する技術（帯域拡張）が提案されている（特許文献１参照）。周波数帯域が拡張された音声信号は、広帯域音声信号と呼ばれる。 In order to improve this deterioration, a technique (band extension) for extending the frequency band of the received narrowband audio signal to, for example, about 100 to 7000 Hz has been proposed (see Patent Document 1). An audio signal whose frequency band is expanded is called a wideband audio signal.
　また、信号処理により生成された３４００Ｈｚ以上の周波数帯域の音声信号は、元々存在していない信号であり、狭帯域音声信号から推測して生成されるため、その推測を誤るとノイズが発生する場合がある。このため、周波数帯域が拡張された音声信号に対して雑音除去処理を行う技術が提案されている（特許文献２参照）。 In addition, since the audio signal in the frequency band of 3400 Hz or more generated by the signal processing is a signal that does not originally exist and is generated by inferring from the narrow band audio signal, noise is generated if the estimation is incorrect. There is. For this reason, a technique for performing noise removal processing on an audio signal with an expanded frequency band has been proposed (see Patent Document 2).
特許第３２４３１７４号公報Japanese Patent No. 3243174 特許第４１３５２４０号公報Japanese Patent No. 4135240
　ここで、帯域拡張は、入力となる狭帯域音声信号を分析して元々存在していない周波数帯域の信号を生成する。帯域拡張には、ピッチやフォルマントなどの音声信号の特徴を利用していることが多い。 Here, in the band extension, a narrowband audio signal as an input is analyzed to generate a signal in a frequency band that does not originally exist. The band expansion often uses the characteristics of an audio signal such as pitch and formant.
　一般的に音声通信で送受信される音声信号には、話者の周囲で発生している騒音がノイズとして重畳されたり、回線ノイズが重畳されたりする場合が多い。 In general, in a voice signal transmitted and received by voice communication, noise generated around a speaker is often superimposed as noise or line noise is often superimposed.
　このようなノイズが重畳されている音声信号に対して帯域拡張を行うと、音声信号以外の情報によって帯域拡張の処理が誤動作しノイズが発生することが容易に想定される。 When performing band expansion on an audio signal on which such noise is superimposed, it is easily assumed that the band expansion processing malfunctions due to information other than the audio signal and noise is generated.
　上記特許文献２では、周波数帯域が拡張された音声信号に対して雑音除去処理を行うため、帯域拡張処理の誤動作を防ぐことはできない。 In Patent Document 2 described above, since noise removal processing is performed on an audio signal whose frequency band is extended, malfunction of the band expansion processing cannot be prevented.
　本発明の目的は、狭帯域音声信号を広帯域音声信号に変換して音声品質の向上を図るとともに、ノイズが含まれている狭帯域音声信号に帯域拡張を行う場合でも、帯域拡張処理の誤動作によるノイズ発生を抑えることができる通信装置を提供することである。 An object of the present invention is to improve a voice quality by converting a narrowband audio signal to a wideband audio signal, and to perform a band extension on a narrowband audio signal containing noise, due to a malfunction of the band extension process. A communication apparatus capable of suppressing noise generation is provided.
　本発明の通信装置は、　狭帯域音声信号の周波数帯域を拡張して広帯域音声信号に変換する帯域拡張を行う拡張手段と、前記狭帯域音声信号のノイズレベルと、前記狭帯域音声信号の音声レベルと、前記帯域拡張の帯域拡張効果の度合いとの関係が設定された参照テーブルと、前記ノイズレベル及び前記音声レベルを基に、前記参照テーブルを参照し前記帯域拡張効果の度合いを決定する決定手段と、を具備する。 The communication apparatus according to the present invention includes an expansion unit that performs band expansion to expand a frequency band of a narrowband audio signal and convert it to a wideband audio signal, a noise level of the narrowband audio signal, and an audio level of the narrowband audio signal And a reference table in which a relationship between the band extension effect degree of the band extension is set, and a determination unit that determines the degree of the band extension effect with reference to the reference table based on the noise level and the audio level And.
　本発明によれば、狭帯域音声信号を広帯域音声信号に変換して音声品質の向上を図るとともに、ノイズが含まれている狭帯域音声信号に帯域拡張を行う場合にどのような帯域拡張効果を付加するかを参照テーブルを用いて設定することができ、例えばノイズによる広帯域処理の誤動作を回避する動作をするか、ノイズの発生を許容しても広帯域処理を行うか等のように、単にノイズレベルに比例して帯域拡張効果を制御するよりも効果的な帯域拡張効果の制御が可能となる。 According to the present invention, a narrowband audio signal is converted into a wideband audio signal to improve audio quality, and what kind of band expansion effect can be achieved when performing band extension on a narrowband audio signal containing noise. It can be set by using a reference table. For example, it is possible to simply avoid noise such as performing an operation to avoid malfunction of broadband processing due to noise or performing broadband processing even if noise generation is allowed. The bandwidth extension effect can be controlled more effectively than the bandwidth extension effect is controlled in proportion to the level.
本発明の実施の形態１に係る通信装置の構成を示すブロック図The block diagram which shows the structure of the communication apparatus which concerns on Embodiment 1 of this invention. 本発明の実施の形態１に係る帯域拡張効果の度合いを示す図The figure which shows the degree of the band expansion effect which concerns on Embodiment 1 of this invention 本発明の実施の形態２に係る通信装置の構成を示すブロック図The block diagram which shows the structure of the communication apparatus which concerns on Embodiment 2 of this invention. 本発明の実施の形態２に係る帯域拡張効果の度合いを示す図The figure which shows the degree of the band expansion effect which concerns on Embodiment 2 of this invention 本発明の実施の形態２に係る帯域拡張効果の度合いを示す図The figure which shows the degree of the band expansion effect which concerns on Embodiment 2 of this invention
　以下、添付図面を参照して本発明の各実施の形態について説明する。 Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.
　（実施の形態１）
　本実施の形態に係る通信装置１００の構成を図１に示す。 (Embodiment 1)
FIG. 1 shows the configuration of communication apparatus 100 according to the present embodiment.
　通信装置１００において、通信部１０２は、公衆網１０１を介して、通信相手の通信装置との呼接続を確立し、その通信相手との間でディジタル狭帯域音声信号を送受信する。受信された狭帯域音声信号は、ノイズレベル推定部１０３および帯域拡張部１０５に入力される。 In the communication apparatus 100, the communication unit 102 establishes a call connection with the communication apparatus of the communication partner via the public network 101, and transmits / receives a digital narrowband audio signal to / from the communication partner. The received narrowband audio signal is input to the noise level estimation unit 103 and the band extension unit 105.
　ノイズレベル推定部１０３は、ディジタル狭帯域音声信号に含まれるノイズのレベル（狭帯域音声信号のノイズレベル）を推定し、推定結果を帯域拡張効果決定部１０４に出力する。ノイズレベルの推定は、例えば特許第３２４４２５２号公報に開示の技術を用いて行うとよい。 The noise level estimation unit 103 estimates the level of noise included in the digital narrowband audio signal (the noise level of the narrowband audio signal), and outputs the estimation result to the band extension effect determination unit 104. The noise level may be estimated using the technique disclosed in Japanese Patent No. 3244252, for example.
　帯域拡張効果決定部１０４は、帯域拡張部１０５が狭帯域音声信号を広帯域音声信号に拡張する際の帯域拡張効果の度合い（強弱）をノイズレベル推定部１０３によって推定されたノイズレベルに応じて決定し、決定した帯域拡張効果の度合いを帯域拡張部１０５に指示する。帯域拡張効果の度合いの決定方法については後述する。 The band expansion effect determination unit 104 determines the degree (strength) of the band expansion effect when the band expansion unit 105 expands the narrowband audio signal to the wideband audio signal according to the noise level estimated by the noise level estimation unit 103. Then, the bandwidth extension unit 105 is instructed to determine the degree of the bandwidth extension effect. A method for determining the degree of the bandwidth expansion effect will be described later.
　帯域拡張部１０５は、帯域拡張効果決定部１０４からの指示に従って帯域拡張効果の度合い（強弱）を調節しながら、例えば上記特許文献１記載の技術を用いて、ディジタル狭帯域音声信号の周波数帯域を拡張してディジタル広帯域音声信号に変換する帯域拡張を行う。例えば上記特許文献１記載の技術を用いて帯域拡張を行う場合、帯域拡張効果の度合いの調節は、原音を元に生成された、原音よりも周波数が高い周波数成分の原音への加算比率を増減させることにより行うことができる。 The band extension unit 105 adjusts the degree (strength) of the band extension effect in accordance with an instruction from the band extension effect determination unit 104, and uses the technique described in Patent Document 1, for example, to adjust the frequency band of the digital narrowband audio signal. Extends the bandwidth to be converted into a digital wideband audio signal. For example, when band extension is performed using the technique described in Patent Document 1, the adjustment of the degree of the band extension effect is performed by increasing or decreasing the addition ratio of the frequency component having a higher frequency than the original sound generated based on the original sound to the original sound. Can be performed.
　ＤＡＣ／ＡＭＰ部１０６は、帯域拡張部１０５から出力されたディジタル広帯域音声信号をアナログ化および増幅してアナログ広帯域音声信号を得る。 The DAC / AMP unit 106 analogizes and amplifies the digital broadband audio signal output from the band expansion unit 105 to obtain an analog broadband audio signal.
　出力デバイス部１０７は、アナログ広帯域音声信号を音声に変換して空気中に出力する。出力デバイス部１０７は、具体的には例えばレシーバ、スピーカ、ヘッドフォンなどによって構成される。 The output device unit 107 converts an analog broadband audio signal into sound and outputs the sound in the air. Specifically, the output device unit 107 includes a receiver, a speaker, a headphone, and the like.
　次いで、帯域拡張効果の度合いの決定方法の具体例について説明する。 Next, a specific example of a method for determining the degree of bandwidth expansion effect will be described.
　本実施形態では、ディジタル狭帯域音声信号のノイズレベルに応じて帯域拡張効果の度合いを決定する。具体的には、帯域拡張効果決定部１０４は、図２に示すようにして帯域拡張効果の度合いを決定する。 In this embodiment, the degree of the band expansion effect is determined according to the noise level of the digital narrowband audio signal. Specifically, the band expansion effect determination unit 104 determines the degree of the band expansion effect as shown in FIG.
　すなわち、帯域拡張効果決定部１０４は、ノイズレベルが小さければ、音声品質を向上させるために、帯域拡張効果を強くする。 That is, if the noise level is low, the band extension effect determination unit 104 strengthens the band extension effect in order to improve the voice quality.
　また、帯域拡張効果決定部１０４は、ノイズレベルが中程度であれば、音声品質を向上させるために、帯域拡張効果を中程度にする。 Also, if the noise level is medium, the band expansion effect determination unit 104 sets the band expansion effect to medium in order to improve voice quality.
　また、帯域拡張効果決定部１０４は、ノイズレベルが大きければ、帯域拡張部１０５での帯域拡張処理の誤動作によるノイズの発生を抑えるために、帯域拡張効果を弱くする。 In addition, if the noise level is high, the band expansion effect determination unit 104 weakens the band expansion effect in order to suppress the occurrence of noise due to the malfunction of the band expansion process in the band expansion unit 105.
　このように、帯域拡張効果決定部１０４は、ノイズレベル推定部１０３によって推定されたノイズレベルに応じて、帯域拡張効果の度合い（強弱）を決定する。そして、決定された度合い（強弱）に従って、帯域拡張部１０５は、帯域拡張効果の度合いを調節しながら帯域拡張を行う。 As described above, the band expansion effect determination unit 104 determines the degree (strength) of the band expansion effect according to the noise level estimated by the noise level estimation unit 103. Then, according to the determined degree (strength), the band extension unit 105 performs band extension while adjusting the degree of the band extension effect.
　このように、本実施の形態によれば、例えば狭帯域音声信号のノイズレベルが小さい場合は音声品質を重視した帯域拡張効果の度合いに、狭帯域音声信号のノイズレベルが大きい場合は帯域拡張処理の誤動作によるノイズの発生を抑えられる帯域拡張効果の度合いにと、ノイズレベルに応じて最適な帯域拡張効果の度合いを決定する。 As described above, according to the present embodiment, for example, when the noise level of a narrowband audio signal is small, the degree of the band expansion effect that emphasizes the voice quality is used. The optimum degree of band expansion effect is determined in accordance with the degree of band expansion effect that can suppress the occurrence of noise due to the malfunction of and the noise level.
　よって、本実施の形態によれば、狭帯域音声信号を広帯域音声信号に変換して音声品質の向上を図るとともに、ノイズが含まれている狭帯域音声信号に帯域拡張を行う場合でも、帯域拡張処理の誤動作によるノイズ発生を抑えることができる。 Therefore, according to the present embodiment, the narrowband audio signal is converted into the wideband audio signal to improve the audio quality, and the band extension is performed even when the band extension is performed on the narrowband audio signal including noise. Generation of noise due to processing malfunction can be suppressed.
　（実施の形態２）
　本実施の形態に係る通信装置２００の構成を図３に示す。なお、図３において図１（実施の形態１）と同一の構成部分には同一の符号を付して説明を省略する。 (Embodiment 2)
FIG. 3 shows the configuration of communication apparatus 200 according to the present embodiment. In FIG. 3, the same components as those in FIG. 1 (Embodiment 1) are denoted by the same reference numerals, and description thereof is omitted.
　通信装置２００において、通信部１０２によって受信された狭帯域音声信号は、レベル比率推定部２０１および帯域拡張部１０５に入力される。 In the communication apparatus 200, the narrowband audio signal received by the communication unit 102 is input to the level ratio estimation unit 201 and the band extension unit 105.
　レベル比率推定部２０１は、狭帯域音声信号のノイズレベルを推定するとともに、ディジタル狭帯域音声信号に含まれる音声信号のレベル（狭帯域音声信号の音声レベル）を推定する。そして、レベル比率推定部２０１は、音声レベルとノイズレベルとの比率（レベル比率）を推定し、推定結果を帯域拡張効果決定部２０２に出力する。ノイズレベルの推定は、上記同様、例えば特許第３２４４２５２号公報に開示の技術を用いて行うとよい。また、音声レベルの推定は、ディジタル狭帯域音声信号全体のレベルからノイズレベルを減算する等の方法により行うとよい。 The level ratio estimation unit 201 estimates the noise level of the narrowband audio signal and also estimates the level of the audio signal included in the digital narrowband audio signal (the audio level of the narrowband audio signal). Then, the level ratio estimation unit 201 estimates the ratio (level ratio) between the audio level and the noise level, and outputs the estimation result to the band extension effect determination unit 202. The noise level may be estimated using the technology disclosed in, for example, Japanese Patent No. 3244252 as described above. The estimation of the voice level may be performed by a method such as subtracting the noise level from the level of the entire digital narrowband voice signal.
　帯域拡張効果決定部２０２は、帯域拡張部１０５が狭帯域音声信号を広帯域音声信号に拡張する際の帯域拡張効果の度合い（強弱）をレベル比率推定部２０１によって推定されたレベル比率に応じて決定し、決定した帯域拡張効果の度合いを帯域拡張部１０５に指示する。 The band expansion effect determination unit 202 determines the degree (strength) of the band expansion effect when the band expansion unit 105 expands the narrowband audio signal to the wideband audio signal according to the level ratio estimated by the level ratio estimation unit 201. Then, the bandwidth extension unit 105 is instructed to determine the degree of the bandwidth extension effect.
　以下、帯域拡張効果の度合いの決定方法の具体例について説明する。 Hereinafter, a specific example of a method for determining the degree of the bandwidth expansion effect will be described.
　音声レベルがノイズレベルに対して十分に大きい場合は、ディジタル狭帯域音声信号には十分に音声信号の特徴が含まれているため、帯域拡張処理の誤動作が発生しにくい。そこで、本実施形態では、ディジタル狭帯域音声信号の音声レベルとノイズレベルとの比率（レベル比率）に応じて帯域拡張効果の度合いを決定する。具体的には、帯域拡張効果決定部２０２は、図４に示すようにして帯域拡張効果の度合いを決定する。 When the audio level is sufficiently high with respect to the noise level, the digital narrowband audio signal sufficiently includes the characteristics of the audio signal, so that the malfunction of the band expansion process is unlikely to occur. Therefore, in the present embodiment, the degree of the band expansion effect is determined according to the ratio (level ratio) between the audio level and the noise level of the digital narrowband audio signal. Specifically, the band expansion effect determination unit 202 determines the degree of the band expansion effect as shown in FIG.
　すなわち、帯域拡張効果決定部２０２は、ノイズレベルが大きく、かつ、音声レベルが大きければ、音声品質を向上させるために、帯域拡張効果を中程度にする。 That is, if the noise level is high and the voice level is high, the band extension effect determination unit 202 sets the band extension effect to a medium level in order to improve voice quality.
　また、帯域拡張効果決定部２０２は、ノイズレベルが大きく、かつ、音声レベルが中程度であれば、帯域拡張部１０５での帯域拡張処理の誤動作によるノイズの発生を抑えるために、帯域拡張効果を弱くする。 Further, the band expansion effect determination unit 202 performs the band expansion effect in order to suppress the occurrence of noise due to the malfunction of the band expansion process in the band expansion unit 105 when the noise level is high and the sound level is medium. Weaken.
　また、帯域拡張効果決定部２０２は、ノイズレベルが大きく、かつ、音声レベルが小さければ帯域拡張部１０５での帯域拡張処理の誤動作によるノイズの発生を抑えるために、帯域拡張効果を弱くする。 Also, the band expansion effect determination unit 202 weakens the band expansion effect in order to suppress the occurrence of noise due to the malfunction of the band expansion process in the band expansion unit 105 if the noise level is large and the sound level is small.
　また、帯域拡張効果決定部２０２は、ノイズレベルが中程度で、かつ、音声レベルが大きければ、音声品質を向上させるために、帯域拡張効果を強くする。 Also, the band extension effect determination unit 202 strengthens the band extension effect in order to improve the voice quality if the noise level is medium and the voice level is high.
　また、帯域拡張効果決定部２０２は、ノイズレベルが中程度で、かつ、音声レベルが中程度であれば、音声品質を向上させるために、帯域拡張効果を中程度にする。 Also, the band expansion effect determination unit 202 sets the band expansion effect to medium in order to improve the voice quality if the noise level is medium and the sound level is medium.
　また、帯域拡張効果決定部２０２は、ノイズレベルが中程度で、かつ、音声レベルが小さければ、帯域拡張部１０５での帯域拡張処理の誤動作によるノイズの発生を抑えるために、帯域拡張効果を弱くする。 Further, if the noise level is medium and the sound level is low, the band expansion effect determination unit 202 weakens the band expansion effect in order to suppress the occurrence of noise due to the band expansion processing malfunction in the band expansion unit 105. To do.
　また、帯域拡張効果決定部２０２は、ノイズレベルが小さく、かつ、音声レベルが大きければ、音声品質を向上させるために、帯域拡張効果を強くする。 Also, the band extension effect determination unit 202 strengthens the band extension effect in order to improve voice quality if the noise level is low and the voice level is high.
　また、帯域拡張効果決定部２０２は、ノイズレベルが小さく、かつ、音声レベルが中程度であれば、音声品質を向上させるために、帯域拡張効果を強くする。 Also, the band extension effect determination unit 202 strengthens the band extension effect in order to improve the voice quality if the noise level is low and the voice level is medium.
　また、帯域拡張効果決定部２０２は、ノイズレベルが小さく、かつ、音声レベルが小さければ、音声品質を向上させるために、帯域拡張効果を中程度にする。 Further, if the noise level is low and the voice level is low, the band extension effect determination unit 202 makes the band extension effect moderate in order to improve voice quality.
　このように、帯域拡張効果決定部２０２は、レベル比率推定部２０１によって推定されたレベル比率に応じて、帯域拡張効果の度合い（強弱）を決定する。そして、決定された度合い（強弱）に従って、帯域拡張部１０５は、帯域拡張効果の度合いを調節しながら帯域拡張を行う。 Thus, the band extension effect determination unit 202 determines the degree (strength) of the band extension effect according to the level ratio estimated by the level ratio estimation unit 201. Then, according to the determined degree (strength), the band extension unit 105 performs band extension while adjusting the degree of the band extension effect.
　また、本発明は図４に示したような帯域拡張効果の度合いを決定する参照テーブルの内容を差し替えることにより、帯域拡張効果の度合いを音声レベルとノイズレベルの比率に比例しない動作も具現化できる。 In addition, the present invention can also realize an operation in which the degree of the band expansion effect is not proportional to the ratio between the audio level and the noise level by replacing the contents of the reference table for determining the degree of the band expansion effect as shown in FIG. .
　例えば狭帯域音声信号にノイズが含まれている場合、帯域拡張処理は誤動作する可能性があるので音声品質の観点からは帯域拡張処理を行わないことが望ましいが、音声を聞き取り易くするために敢えてノイズの発生を許容して帯域拡張処理を行う場合も考えられる。 For example, when noise is included in a narrowband audio signal, the band expansion process may malfunction, so it is desirable not to perform the band expansion process from the viewpoint of voice quality, but dare to make it easier to hear the voice A case where band expansion processing is performed while allowing noise to be generated is also conceivable.
　この場合、例えば図５に示したような参照テーブルを用いて帯域拡張効果度合いを決定すればよい。図５を用いて、音声レベルが小さい場合について説明する。 In this case, for example, the degree of bandwidth expansion effect may be determined using a reference table as shown in FIG. A case where the sound level is low will be described with reference to FIG.
　まず、帯域拡張効果決定部２０２は、ノイズレベルが小さく、かつ、音声レベルが小さければ、音声品質を向上させるために、帯域拡張効果を中程度にする。 First, if the noise level is low and the voice level is low, the band extension effect determination unit 202 sets the band extension effect to a medium level in order to improve voice quality.
　また、帯域拡張効果決定部２０２は、ノイズレベルが中程度で、かつ、音声レベルが小さければ、帯域拡張部１０５での帯域拡張処理の誤動作によるノイズの発生を抑えるために、帯域拡張効果を弱くする。 Further, if the noise level is medium and the sound level is low, the band expansion effect determination unit 202 weakens the band expansion effect in order to suppress the occurrence of noise due to the band expansion processing malfunction in the band expansion unit 105. To do.
　最後に、帯域拡張効果決定部２０２は、ノイズレベルが大きく、かつ、音声レベルが小さければ本来は帯域拡張部１０５での帯域拡張処理の誤動作によるノイズの発生を抑えるために、帯域拡張効果を弱くすべきだが、音声が小さくかつノイズレベルが大きいという状態は非常に音声が聞き取りづらいと考えられる。この場合は、ノイズの発生を許容して音声を聞き取り易くする目的で帯域拡張効果を強くする。 Finally, the band extension effect determination unit 202 weakens the band extension effect in order to suppress the occurrence of noise due to the malfunction of the band extension process in the band extension unit 105 when the noise level is high and the sound level is low. It should be, however, that the voice is very difficult to hear when the voice is low and the noise level is high. In this case, the band expansion effect is strengthened for the purpose of allowing generation of noise and making it easy to hear the voice.
　このように、本実施の形態によれば、例えば狭帯域音声信号においてノイズレベルが音声レベルに対して十分に小さい場合は音声品質を重視した帯域拡張効果の度合いに、狭帯域音声信号においてノイズレベルが音声レベルに対して大きい場合は帯域拡張処理の誤動作によるノイズの発生を抑えられる帯域拡張効果の度合いにと、音声レベルとノイズレベルとの比率に応じて最適な帯域拡張効果の度合いを決定する。 As described above, according to the present embodiment, for example, when the noise level in a narrowband audio signal is sufficiently small with respect to the audio level, the noise level in the narrowband audio signal is reduced to the degree of the band expansion effect that emphasizes the audio quality. Is greater than the audio level, the optimal bandwidth expansion effect is determined according to the level of the bandwidth expansion effect that can suppress the occurrence of noise due to malfunction of the bandwidth expansion process and the ratio between the audio level and the noise level. .
　また、本発明の実施の形態のように参照テーブルを用いて帯域拡張効果の度合いを決定することにより、具体的には音声レベルとノイズレベルとの比率に比例しないような参照テーブルを用いることにより、例えば音声レベルが小さくかつノイズレベルが大きい場合、本来は帯域拡張効果を弱くすべきところを、聞き取り易さを重視して帯域拡張効果を強くする、という音声レベルとノイズレベルの比率に比例しない帯域拡張効果の度合い決定が可能となり、より音声が聞き取り易い帯域拡張効果をもたらすことが可能である。 Further, by determining the degree of the bandwidth expansion effect using the reference table as in the embodiment of the present invention, specifically, by using a reference table that is not proportional to the ratio between the audio level and the noise level. For example, when the audio level is low and the noise level is high, the band expansion effect should be weakened, but it is not proportional to the ratio between the audio level and the noise level. The degree of the bandwidth expansion effect can be determined, and a bandwidth expansion effect that makes it easier to hear the voice can be provided.
　よって、本実施の形態によれば、狭帯域音声信号を広帯域音声信号に変換して音声品質の向上を図るとともに、ノイズが含まれている狭帯域音声信号に帯域拡張を行う場合でも、帯域拡張処理の誤動作によるノイズ発生を抑えることも可能で、かつノイズの発生を許容してでも聞き取り易さを重視する設定も可能な、優れた帯域拡張効果度合いの制御が可能である。 Therefore, according to the present embodiment, the narrowband audio signal is converted into the wideband audio signal to improve the audio quality, and the band extension is performed even when the band extension is performed on the narrowband audio signal including noise. It is possible to control the excellent degree of bandwidth expansion effect, which can suppress the generation of noise due to a malfunction of the process, and can set the emphasis on ease of listening even if the generation of noise is allowed.
　２００９年６月２９日出願の特願２００９－１５４０５６の日本出願に含まれる明細書、図面および要約書の開示内容は、すべて本願に援用される。 The disclosure of the specification, drawings, and abstract included in the Japanese application of Japanese Patent Application No. 2009-154056 filed on June 29, 2009 is incorporated herein by reference.
　本発明は、狭帯域音声通信が可能な通信装置のすべてに利用することができる。例えば、本発明は、固定通信網に接続される有線電話、および、移動通信網に接続される携帯電話にも利用可能である。 The present invention can be used for all communication devices capable of narrowband voice communication. For example, the present invention can be used for a wired telephone connected to a fixed communication network and a mobile phone connected to a mobile communication network.
１００，２００　通信装置
１０１　公衆網
１０２　通信部
１０３　ノイズレベル推定部
１０４，２０２　帯域拡張効果決定部
１０５　帯域拡張部
１０６　ＤＡＣ／ＡＭＰ部
１０７　出力デバイス部
２０１　レベル比率推定部 DESCRIPTION OF SYMBOLS 100,200 Communication apparatus 101 Public network 102 Communication part 103 Noise level estimation part 104,202 Band extension effect determination part 105 Band extension part 106 DAC / AMP part 107 Output device part 201 Level ratio estimation part

Claims (2)

  1. 　狭帯域音声信号の周波数帯域を拡張して広帯域音声信号に変換する帯域拡張を行う拡張手段と、
    　前記狭帯域音声信号のノイズレベルと、前記狭帯域音声信号の音声レベルと、前記帯域拡張の帯域拡張効果の度合いとの関係が設定された参照テーブルと、
    　前記ノイズレベル及び前記音声レベルを基に、前記参照テーブルを参照し前記帯域拡張効果の度合いを決定する決定手段と、
    　を具備する通信装置。     Expansion means for extending the frequency band of the narrowband audio signal and converting it to a wideband audio signal;
    A reference table in which a relationship between the noise level of the narrowband audio signal, the audio level of the narrowband audio signal, and the degree of the band extension effect of the band extension is set;
    Determining means for determining a degree of the bandwidth extension effect with reference to the reference table based on the noise level and the audio level;
    A communication apparatus comprising:
  2. 　狭帯域音声信号の周波数帯域を拡張して広帯域音声信号に変換する帯域拡張を行う拡張工程と、
    　前記狭帯域音声信号のノイズレベルと、前記狭帯域音声信号の音声レベルと、前記帯域拡張の帯域拡張効果の度合いとの関係を参照テーブルに設定する設定工程と、
    　前記ノイズレベル及び前記音声レベルを基に、前記参照テーブルを参照し前記帯域拡張効果の度合いを決定する決定工程と、
    　を具備する帯域拡張方法。
          An expansion process for expanding the frequency band of the narrowband audio signal and converting it to a wideband audio signal;
    A setting step for setting a relationship between the noise level of the narrowband audio signal, the audio level of the narrowband audio signal, and the degree of the band extension effect of the band extension in a reference table;
    A determination step of determining a degree of the bandwidth extension effect with reference to the reference table based on the noise level and the audio level;
    A bandwidth expansion method comprising:
PCT/JP2010/002786 2009-06-29 2010-04-16 Communication apparatus WO2011001578A1 (en)

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