莊世昌(Shih-chang Chuang


基本資料


  
台北市

   
國立華僑實驗高級中學
南台科技大學資管系
國立台灣科技大學資訊工程所

   
音樂,游泳,登山,電影



論文研究

l           指導教授:古鴻炎老師

l           中文題目用於網路電話之多頻帶聲學迴音消除研究

l           英文題目A Study on Multiband Acoustic-Echo-Cancellation for Voice over Internet Protocol

l           中文摘要本論文研究多頻帶聲學迴音消除的方法, 並且製作成軟體模組, 然後把先人的雜訊刪減模組及我們的迴音消除模組整合到Linphone網路電話軟體裡, 用以提升網路電話的語音品質。關於多頻帶迴音消除的方法, 我們基於多速率信號處理的理論, 研究了樹狀式分級串連之非均勻頻帶的濾波方法與均勻頻帶之DFT濾波方法, 然後拿這二個方法和正規化最小均方(NLMS)準則之單頻帶濾波方法作效能比較。 依據實驗量測到的誤差收斂曲線與主觀聽測的平均評分, 顯示我們研究的多頻帶聲學迴音消除方法比起NLSM單頻帶濾波方法,讓迴音衰減得更多一些, 而使網路電話語音品質獲得進一步的提升。

l           英文摘要 In this thesis, the problem of acoustic echo cancellation is studied, and multiband based methods are adopted and programmed into software modules. Then, the noise reduction module developed by others and the echo cancellation modules by us are integrated into the internet telephony software package, Linphone, in order to improve the voice quality over IP network. As to multiband based acoustic echo cancellation, we first review the theory of multirate signal processing. Then, we study tree structured nonuniform subband adaptive filter and uniform DFT subband adaptive filter. Next, we compare the two filtering methods with normalized least mean square (NLMS) single-band filtering method in their performances. According to the error convergence curves measured and the average scores obtained from subjective perception tests, one of the multiband based acoustic echo cancellation methods is better than NLMS method. Thus, the quality of transmitted voice can be increased.