WO2007109949A1 - Procédé et dispositif permettant de générer un bruit supportable lors de la suppression d'échos - Google Patents

Procédé et dispositif permettant de générer un bruit supportable lors de la suppression d'échos Download PDF

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Publication number
WO2007109949A1
WO2007109949A1 PCT/CN2007/000166 CN2007000166W WO2007109949A1 WO 2007109949 A1 WO2007109949 A1 WO 2007109949A1 CN 2007000166 W CN2007000166 W CN 2007000166W WO 2007109949 A1 WO2007109949 A1 WO 2007109949A1
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WO
WIPO (PCT)
Prior art keywords
noise
amplitude
comfort noise
echo
residual echo
Prior art date
Application number
PCT/CN2007/000166
Other languages
English (en)
Chinese (zh)
Inventor
Dailin Jiang
Original Assignee
Huawei Technologies Co., Ltd.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Huawei Technologies Co., Ltd. filed Critical Huawei Technologies Co., Ltd.
Publication of WO2007109949A1 publication Critical patent/WO2007109949A1/fr

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Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B3/00—Line transmission systems
    • H04B3/02—Details
    • H04B3/20—Reducing echo effects or singing; Opening or closing transmitting path; Conditioning for transmission in one direction or the other
    • H04B3/23—Reducing echo effects or singing; Opening or closing transmitting path; Conditioning for transmission in one direction or the other using a replica of transmitted signal in the time domain, e.g. echo cancellers
    • 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
    • G10L2021/02082—Noise filtering the noise being echo, reverberation of the speech

Definitions

  • the present invention relates to a background noise control method in a communication device, and more particularly to a method and apparatus for generating comfort noise in echo cancellation.
  • Echo is a phenomenon that occurs in the telephone system when the energy of a portion of the transmitted speech signal is reflected back to the transmitter. These reflections are caused by impedance mismatch in the analog portion of the telephone network, for example, in public switched telephones.
  • PSTN network
  • the 4-wire is converted into a 2-wire hybrid circuit, or the acoustic crosstalk in a mobile radiotelephone.
  • the echo generally includes electrical echoes and acoustic echoes, and electrical echoes often occur in long-distance signal transmission. In applications where long-distance signal transmissions involve excessive propagation delays (due to the incompleteness of the hybrid line that converts the twisted pair connections to a four-wire system).
  • the "signal leakage" or cause of the incompleteness of such hybrid lines Signal reflection caused by impedance mismatch, known as network electrical echo.
  • Sound waves from the receiver (headphones) reflected by a solid object located on the sound path into the microphone (microphone) of the phone, or in the speakerphone, An acoustic echo is formed.
  • the echo accompanying the basic delay can severely degrade the quality of the processed speech signal.
  • Fig. 1 a schematic diagram of an echo canceller in the ITU G.168 standard is shown.
  • Rin/Rout is the far-end input/output signal
  • Sin/Sout is the near-end input/output signal
  • the far-end output signal (Rout) to the near-end input signal (Sin) is the echo path
  • the near-end input signal (Sin) contains echo signals
  • linear convolution processing (subtraction) is performed with the near-end input signal (Sin) and the estimated echo to obtain residual echoes.
  • the residual echoes are in the residual echoes.
  • the echo component is very small, which can improve the call effect; but for some reason, when the cancellation effect is not good, the echo component in the residual echo is large, and the call effect is not good (or worse), then usually
  • the residual echo is nonlinearly processed by a nonlinear processor (LP) to further reduce the echo component.
  • LP nonlinear processor
  • CN comfort noise
  • the standard definition of comfort noise pseudo noise or background noise or idle channel inserted during silence when NLP is working Noise, the purpose of which is to prevent the effects of mute on background noise, where background noise is part of the speech.
  • comfort noise Two methods are now used to generate comfort noise: One is to use white noise (or HOTH noise) as comfort noise, and its amplitude is comparable to background noise. This method is easy to implement, but when the background noise is large, the background noise is The comfort noise switching is obvious, the call is unnatural; the other method is to use complex algorithms to simulate the background noise. This method works well, that is, the background noise and the comfort noise are also very close when the background noise is large. Naturally, but this method is complicated in algorithm and costly to implement.
  • white noise or HOTH noise
  • One embodiment of the present invention provides a method of generating comfort noise in echo cancellation, the method comprising the steps of:
  • the amplitude of the residual echo is greater than the absolute value of the amplitude of the background noise, limiting the amplitude of the residual echo such that the amplitude of the residual echo is equal to the amplitude of the background noise or the residual echo.
  • the amplitude difference between the amplitude and the background noise is less than a set threshold, making the residual echo a comfort noise.
  • An embodiment of the apparatus for generating comfort noise in echo cancellation comprising: a signal input unit for obtaining an absolute value of a magnitude of a residual echo and a magnitude of a background noise;
  • a comparison unit configured to compare an amplitude of the residual echo and an absolute value of a magnitude of the background noise; and if the amplitude of the residual echo is greater than an absolute value of the amplitude of the background noise, output the comparison result to the comfort noise Generating unit;
  • a comfort noise generating unit configured to limit an amplitude of the residual echo according to an indication of the comparing unit, such that an amplitude of the residual echo is equal to an amplitude of the background noise or a magnitude of the residual echo
  • the amplitude difference of the background noise is less than a set threshold, making the residual echo a comfort noise.
  • the amplitude of the residual echo is equal to the amplitude of the background noise or the amplitude difference between the amplitude of the residual echo and the background noise is less than a set threshold, making the residual echo a comfort noise , thus providing natural comfort noise with background noise switching.
  • 1 is a schematic diagram of a model of a conventional echo canceler
  • FIG. 3 is a block diagram of an embodiment of the apparatus of the present invention.
  • the present invention provides a method of generating comfort noise in echo cancellation.
  • echoes include, but are not limited to, electrical echoes and acoustic echoes.
  • the invention utilizes the obtained near-end background noise to limit the residual echo, and then appropriately processes the clipped echo as comfort noise (the definition reference background technology), that is, when the nonlinear processor works, the background is utilized.
  • comfort noise the definition reference background technology
  • the noise amplitude limits the residual echo, and then the residual echo after clipping can be filtered to reduce the low frequency component of the speech to achieve comfort noise.
  • the nonlinear processor is not working, the residual echo is not performed. deal with.
  • FIG. 2 is a flow chart of a method of generating comfort noise in echo cancellation in accordance with the present invention.
  • the method for estimating the amplitude of the background noise and the specific implementation of the condition for judging whether the nonlinear processor is working or not are explained (can be realized by many prior art), but by using the prior art amplitude estimation
  • the method, the amplitude of the comfort noise produced by the present invention should be comparable to the background noise amplitude, as in the ITU G.168 standard, the required difference between the two does not exceed ⁇ 2 dB.
  • the background noise amplitude obtained by the prior art amplitude estimation method is a non-negative value, expressed by AMP; suitable comfort noise can ensure the comfort noise and background output when the nonlinear processor operates.
  • the connection of the noise is natural, the voice heard at the far end has no switching sense (or is not obvious), the comfort noise is represented by CN; the residual echo is represented by RES.
  • step S20 the amplitude of the residual echo (RES) and the amplitude of the background noise are obtained in step S20, and the process of obtaining the residual echo (RES) can be referred to the description of the background art, the background noise
  • the magnitude (AMP) can be obtained using the amplitude estimation method of prior art background noise.
  • step S21 it is determined in step S21 whether the current non-linear processor is working. If the non-linear processor needs to work at this time (that is, the remote party is unilaterally talking at this time), the flow goes to step S22; When the device does not need to work (that is, the call is not unilaterally unilaterally), the flow goes to step S29, and the remote output signal (Sout) is a residual echo (RES), that is, no residual echo (RES) is needed.
  • RES residual echo
  • RES residual echo
  • step S22 it is necessary to compare the amplitude of the residual echo and the amplitude of the background noise to determine whether the amplitude of the residual echo (RES) exceeds the background noise amplitude (AMP), if the amplitude of the residual echo (RES) is smaller than the background.
  • RES residual echo
  • AMP background noise amplitude
  • the amplitude of the residual echo is equal to the negative value of the background noise amplitude (-AMP) by clipping processing, thereby generating comfort noise (CN),
  • the amplitude of the comfort noise (CN) is equal to the negative value of the background noise amplitude (-AMP); in this embodiment, the "equal to” is relative, which has two meanings of exact equality and ambiguity, the fuzzy Equivalence is both "equal, or substantially equal” as described above.
  • the "less than” or “exceeded” means that the difference is not equal or the difference is large;
  • the amplitude of the echo (RES) is greater than the positive value (AMP) of the background noise amplitude, and in step S24, the amplitude of the residual echo is equal to the positive value (AMP) of the background noise amplitude by clipping processing, thereby Residual
  • the residual echo becomes comfort noise (CN), and the amplitude of the comfort noise (CN) is equal to the positive value of the background noise amplitude (AMP).
  • the residual echo (RES) is within the background noise amplitude ( - AMP ⁇ RES ⁇ AMP), that is, when the amplitude of the residual echo is less than or equal to the absolute value of the amplitude of the background noise, then in step S25, the residual echo (RES) is not limited, then the residual echo (RES) Directly as comfort noise (CN), ie the amplitude of the comfort noise is equal to the amplitude of the residual echo.
  • CN comfort noise
  • step S23, S24 or S25 The output processed by step S23, S24 or S25 is comfort noise (CN); in step S26, Comfort noise (CN) performs filtering, such as high-pass filtering, to filter out components with low frequency components or relatively low frequencies to improve residual echo effects; and in step S27, moderate amount in comfort noise (CN) Mixed with white noise or HOTH noise, the mixing ratio can be adjusted, and can start from a preset ratio, where white noise is filtered to remove white noise of high frequency components, and the filtering process can be 4th pass filtering. Li, so that more natural conversation. No fixed order between the steps S26 and S27, wherein, in other embodiments, the step can also be omitted S26 and/or step S27. After the above processing, the final comfort noise is obtained; then in step S29, the far-end output signal (Sout) is the comfort noise (CN); this completes the processing of the comfort noise, which is heard from the far end. Voice is more natural than pure HOTH noise.
  • the residual echo is limited by the background noise amplitude, thereby providing a natural comfort noise when the background noise is large;
  • the residual echo is limited by the obtained background noise amplitude to achieve comfort noise; when the nonlinear processor is not working, the residual echo is not processed,
  • the invention solves the problem that the white noise (or HOTH noise) is used as the comfort noise (ie, the noise during the call) when the background noise is large, and the switching is obvious and the call is unnatural, and the prior art utilizes complicated
  • the algorithm to simulate background noise has complex algorithms and high cost, and achieves the purpose of natural call, small amount of calculation, easy implementation and low cost.
  • the filtering process is used to filter out the low-frequency components of the residual echo, which can reduce the influence of the residual echo; and the residual echo after clipping can be mixed with white noise that is filtered to remove high-frequency components, so that the call is made. More natural.
  • the apparatus for generating comfort noise in echo cancellation includes: a signal input unit 31 for obtaining the absolute value of the amplitude of the residual echo and the amplitude of the background noise, and a comparison unit 32, For comparing the amplitude of the residual echo and the absolute value of the amplitude of the background noise; if the amplitude of the residual echo is greater than the absolute value of the amplitude of the background noise, the comparison result is output to the comfort noise generating unit 33;
  • a comfort noise generating unit 33 configured to limit an amplitude of the residual echo according to an indication of the comparing unit 32, such that an amplitude of the residual echo is equal to an amplitude of the background noise or a magnitude of the residual echo
  • the amplitude difference from the background noise is less than a set threshold, making the residual echo a comfort noise.
  • a filtering unit 35 is further provided for filtering the comfort noise output by the comfort noise generating unit.
  • a noise mixing unit 34 is further provided for mixing a predetermined proportion of white noise or noise in the comfort noise output from the comfort noise generating unit 33. In the comfort noise described, the comfort noise mixed with white noise or HOTH noise is filtered by the filtering unit 35. This embodiment refers to FIG. 3.
  • the comparison unit 32 employs a non-linear processor.
  • the noise mixing unit 34 may also be used to mix a predetermined proportion of white noise or HOTH noise into the comfort noise in the filtered comfort noise output by the filtering unit. in.

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  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Cable Transmission Systems, Equalization Of Radio And Reduction Of Echo (AREA)
  • Noise Elimination (AREA)

Abstract

La présente invention concerne un procédé et un dispositif qui assurent un bruit supportable lors de la suppression d'échos, le procédé comprenant les étapes suivantes: l'obtention de l'amplitude de l'écho résiduel et de la valeur absolue de l'amplitude du bruit de fond (S20); la comparaison de l'amplitude de l'écho résiduel et de la valeur absolue de l'amplitude du bruit de fond (S22); si l'amplitude de l'écho résiduel est supérieure à la valeur absolue de l'amplitude du bruit de fond, l'écrêtage de l'amplitude de l'écho résiduel de sorte que l'amplitude de l'écho résiduel soit égale à l'amplitude du bruit de fond (S23,S24) ou de sorte que la différence entre l'amplitude de l'écho résiduel et l'amplitude du bruit de fond soit inférieure à une valeur de seuil prédéfinie (S25) ceci établissant l'écho résiduel comme bruit supportable.
PCT/CN2007/000166 2006-03-27 2007-01-17 Procédé et dispositif permettant de générer un bruit supportable lors de la suppression d'échos WO2007109949A1 (fr)

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CN 200610034737 CN101046965B (zh) 2006-03-27 2006-03-27 一种在回波消除中产生舒适噪声的方法
CN200610034737.0 2006-03-27

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Cited By (1)

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CN113746494A (zh) * 2020-05-15 2021-12-03 华为技术有限公司 一种回波抵消方法及收发机

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CN1286862A (zh) * 1998-01-09 2001-03-07 艾利森公司 用于在通信系统中提供舒适噪声的方法和设备
WO2001019062A1 (fr) * 1999-09-07 2001-03-15 D.S.P.C. Technologies Ltd. Suppression d'un echo acoustique residuel
US6545985B1 (en) * 1997-04-18 2003-04-08 Nokia Corporation Echo cancellation mechanism
US6622030B1 (en) * 2000-06-29 2003-09-16 Ericsson Inc. Echo suppression using adaptive gain based on residual echo energy
US6766020B1 (en) * 2001-02-23 2004-07-20 3Com Corporation System and method for comfort noise generation
US20040204934A1 (en) * 2003-04-08 2004-10-14 Motorola, Inc. Low-complexity comfort noise generator
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Publication number Priority date Publication date Assignee Title
CN1187271A (zh) * 1995-06-08 1998-07-08 诺基亚电信公司 数字移动通信系统中的回声消除
US6545985B1 (en) * 1997-04-18 2003-04-08 Nokia Corporation Echo cancellation mechanism
CN1286862A (zh) * 1998-01-09 2001-03-07 艾利森公司 用于在通信系统中提供舒适噪声的方法和设备
WO2001019062A1 (fr) * 1999-09-07 2001-03-15 D.S.P.C. Technologies Ltd. Suppression d'un echo acoustique residuel
US6622030B1 (en) * 2000-06-29 2003-09-16 Ericsson Inc. Echo suppression using adaptive gain based on residual echo energy
US6766020B1 (en) * 2001-02-23 2004-07-20 3Com Corporation System and method for comfort noise generation
CN1706174A (zh) * 2002-10-16 2005-12-07 艾利森公司 综合噪声消除及残余回波抑制
US20040204934A1 (en) * 2003-04-08 2004-10-14 Motorola, Inc. Low-complexity comfort noise generator

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN113746494A (zh) * 2020-05-15 2021-12-03 华为技术有限公司 一种回波抵消方法及收发机
CN113746494B (zh) * 2020-05-15 2022-10-18 华为技术有限公司 一种回波抵消方法及收发机

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