回音消除與噪音抑制聯合架構用於免持式網路電話之研究

INTEGRATED ECHO CANCELLER WITH NOISE REDUCTION FOR HANDS-FREE WEB PHONE

賴嘉宏(Chia-Hung Lai)

指導教授 ： 李清坤

大同大學/電機資訊學院/通訊工程研究所/博士(2009年)

摘要

由於網路通訊系統的普及與使用者及使用場所的多樣化，但當使用者在使用免持式網路電話時便發現回音與噪音嚴重造成使用者溝通上的不便。本論文便針對免持式網路電話提出一聲學回音消除與噪音抑制之聯合架構用以改善其通訊品質。此架構包含聲學回音消除(Acoustic Echo Cancellation，AEC)機制與一個有效偵測雙方通話的偵測機制(Double-Talk Detection，DTD)最後再加上噪音抑制(Noise Reduction，NR)系統。
在聲學回音消除這部分是利用可適應性濾波器並以正規化最小均方演算法(Normalized Least Mean Square，NLMS)為基礎進而將聲學回音加以消除。在雙邊通話這部分則使用相關函數法做為偵測方法，此方法可有效偵測雙邊通話發生時機並給予相對應之處理。最後再加上噪音抑制系統來消除殘餘噪音。並透過MATLAB軟體模擬並從結果驗證出此聯合架構可有效消除干擾以提供一個舒適的通訊系統。

關鍵字

聲學回音消除 ； 可適應性濾波器 ； 雙邊通話偵測

並列摘要

The internet communication system has been widely adapted by users and implemented in a variety of locations. It was found that echo and noise could appear whilst using hands-free web phone and that has caused serious interference to communication between users. The thesis proposed an acoustic echo and noise reduction based system to improve the communication quality of wireless internet phone systems. The solution includes three techniques, acoustic echo cancellation (ACE), double-talk detection (DTD) and noise reduction (NR).
First, in AEC technique, the acoustic echo is eliminated with an adaptive filter based on the normalized least mean square (NLMS) algorithm. The DTD technique adopts coherence function method as the means of detection. This technique could detect the timing of communication efficiently and provide corresponding response. Finally, the residual noise would be dissipated by the noise reduction system. The results of simulation have presented that this system could efficiently reduce interference and provide a comfortable communication system.

並列關鍵字

Acoustic Echo Cancellation ； Adaptive Filter ； Double Talk Detector

參考文獻

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