免持式語音通訊之聲學回音與雜音消除

ACOUSTIC ECHO CANCELLATION AND NOISE SUPPRESSION FOR HANDS-FREE SPEECH COMMUNICATION

葉國楨(Kuo-Chen Yeh)

指導教授 ： 李清坤

大同大學/電機資訊學院/通訊工程研究所/碩士(2009年)

摘要

在免持聽筒的語音通訊系統中，藉由回音與噪音的消除，來提升語音的品質是很重要的。本論文主要針對免持式通訊系統中的聲學回音及周遭噪音問題，以一個聯合聲學回音消除及噪音降低的架構處理，此架構包含一個聲學回音消除(Acoustic Echo Cancellation，AEC)機制與一個有效計算雙方談話偵測方法(Double-Talk Detection, DTD)與殘餘雜音消除(Residual Noise Reduction)演算法。在聲學回音消除部份利用適應性濾波器以正規化最小均方 (Normalized Least Mean Square, NLMS) 演算法估測回音並調整濾波器係數進而將聲學回音消除。在雙方談話的部分我們使用二個相關函數的雙方談話偵測方法，此法可有效解決雙方談話問題。
而在殘餘回音消除方面我們使用聲音偵測器(Voice Activity Detector, VAD)來判斷語音與非語音，再利用頻域演算法偵測殘存回音，使噪音抑制器(Noise Suppression, NS)消除殘餘回音上發生之短關聯回音與背景雜音。從模擬結果驗證了我們的分析並且呈現出此聯合架構可以提供了一個舒適的通訊系統。

關鍵字

回音消除器 ； 可適性濾波器 ； 雙邊談話偵測

並列摘要

In hands-free communication systems, the enhancement of speech signals by canceling the acoustic echo and the residual noise is particularly important. In this thesis, the fundamental problems and techniques of echo and noise cancellation are introduced. The main purpose of this thesis is to combine acoustic echo cancellation and residual noise reduction to solve acoustic echo and residual noise problems in hands-free telecommunications.
The proposed system includes Acoustic Echo Canceller (AEC) and computationally efficient Double Talk Detector (DTD) and a residual noise cancellation algorithm. The AEC utilizes an adaptive filter with the Normalized Least Mean Square (NLMS) algorithm to estimate echo and adjust the factor of the wave filter to eliminate the acoustics echo. The DTD method uses the Geigel Algorithm. In the Noise Suppression (NS) approach, using a voice active detection (VAD) algorithm to removes the residual noise signal, used in order to reduce the noise and to eliminate the echo in the telecommunication systems such as hands free telephone. The results verify our analysis and show that the structure we propose is suitable to provide a comfortable communication system.

並列關鍵字

Acoustic Echo Cancel ； Adaptive Filters ； Double Talk Detection

參考文獻

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