Multi-band structure self-adaptive filter switching method for AEC (acoustic echo cancellation)

An adaptive filter and acoustic echo cancellation technology, applied in the field of signal processing, can solve the problem of compromise between convergence speed and steady-state imbalance, and achieve the effect of improving system noise cancellation ability

Active Publication Date: 2017-05-31
CHONGQING UNIV OF POSTS & TELECOMM
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Problems solved by technology

The currently used algorithms generally have a trade-off between convergence speed and steady-state imbalance. It is necessary to distinguish different states of the signal, and use different adaptive algorithms for different states.

Method used

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  • Multi-band structure self-adaptive filter switching method for AEC (acoustic echo cancellation)
  • Multi-band structure self-adaptive filter switching method for AEC (acoustic echo cancellation)
  • Multi-band structure self-adaptive filter switching method for AEC (acoustic echo cancellation)

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Embodiment 1

[0041] As shown in the figure, the specific steps of the multi-band structure adaptive filter switching method for echo cancellation provided in this embodiment are as follows: acquire the voice signal, then detect the voice endpoint, and output the VAD flag and the improved envelope decision threshold ;The speech signal is sent to the lithosphere as the desired signal, and is input to the adaptive filter at the same time; the adaptive filter adopts a switchable multi-band structure and a corresponding adaptive algorithm, and adjusts the filtering parameters according to the feedback information and the least mean square criterion , to obtain the optimal solution; the sub-band output signal through adaptive filtering; and compare with the expected signal to obtain the error signal, output the error signal and feed it back to the adaptive filter.

[0042] The multi-band structure adaptive filter switching method for echo cancellation provided in this embodiment includes the foll...

Embodiment 2

[0065] The adaptive filter provided in this embodiment adopts subband adaptive filtering based on subband and multi-rate, and the subband algorithm uses an analysis filter bank to divide an input signal and a desired signal into multiple frequency subbands. The sub-band signal is extracted to obtain a sampled signal, and finally the sampled signal is processed by an adaptive filter. The length of each sub-filter is usually shorter than that of the full-band filter, and the calculation amount is low, so the convergence speed is fast. But this subband structure will produce aliasing components at the output of the filter, resulting in high steady-state offset of the subband adaptive filter. Can utilize multi-band structure to solve this problem; Considering the high correlation characteristic of input voice signal, present embodiment will have the VAD (VoiceActivity Detection) technology that has important correlation with voice signal to introduce algorithm, adopt new switching...

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Abstract

The invention discloses a multi-band structure self-adaptive filter switching method for AEC (acoustic echo cancellation). Firstly, a far-end voice signal is acquired; a voice endpoint is detected, and a VAD (voice activity detection) flag bit and an improved envelope decision threshold are output; the voice signal is fed into a loudspeaker to serve as a desired signal and also input into a self-adaptive filter; the self-adaptive filter adopts a switchable multi-band structure and a corresponding self-adaptive algorithm, parameters of the filter are adjusted by use of the least mean square criterion according to feedback information, and the optimal solution is obtained. According to the provided switching method, voice characteristics are considered sufficiently under the condition that steady maladjustment is guaranteed, and optimized configuration of the convergence rate and the algorithm complexity is realized while advantages of the algorithm in the convergence rate are utilized. During actual application of echo cancellation, a single algorithm does not easily meet various variable demands. The variable switching algorithm provides more probability for a user and has great significance in application of self-adaptive echo cancellation.

Description

technical field [0001] The invention relates to the technical field of signal processing, in particular to a multi-band structure adaptive filter switching method for echo cancellation. Background technique [0002] Acoustic Echo Cancellation (AEC) is an important research topic that widely exists in communication fields such as in-vehicle systems, teleconferencing and hearing aids due to the coupling between microphones and speakers. It is mainly realized by adaptive filtering algorithm. Commonly used adaptive algorithms include least mean square (Least Mean Square, LMS) algorithm, least square (Recursive Least Square, RLS) method and affine projection algorithm (Affine Projection Algorithm, APA), etc. . [0003] Adaptive echo cancellation is to send the signal processed by the system to the speaker and also to the adaptive filter. The output signal is compared with the microphone input signal to obtain an error signal, and then the adaptive filter coefficient is calculate...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G10L21/0208G10L21/0232G10L21/0264G10L21/034G10L25/18G10L25/78
Inventor 周翊魏丹丹师黎明刘宏清
Owner CHONGQING UNIV OF POSTS & TELECOMM
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