無限脈衝響應之迴音消除的研究

The Study of Infinite Impluse Response In Acoustic Echo Cancellation

張育傑(Yu-Chieh Chang)

指導教授 ： 李仲溪

元智大學/工程學院/電機工程學系/碩士(2003年)

摘要

免手持通訊系統可以應用在免手持聽筒電話、視訊會議、遠距教學及遠端醫療等系統。而此種通訊系統必需解決聲學迴音之問題。可適性濾波器提供這個問題的有效解決方法，這些方法可概分為LMS家族及RLS家族演算法，而使用這些演算法的架構又可分為FIR和IIR架構。本論文針對這兩種架構來進行比較分析，發現使用IIR架構相對於FIR架構僅需較少的係數就可達到迴音消除，且對於噪音有抑制的效果，實驗的結果也驗證了我們的分析。
在真實通訊中，噪音也是我們要面對的一大問題，本論文也討論如何設計一噪音降低機制，並配合聲學迴音消除，完成一舒適的通訊系統。

關鍵字

無限脈衝響應 ； 聲學迴音消除 ； 有限脈衝響應 ； 噪音降低機制

並列摘要

Hands-free communications system finds several applications such as speaker-phone, tele-video conferencing systems, distance learning and medicine systems. A major problem in hands-free system is that of acoustic echo. Adaptive filtering has been considered as a promising way in solving this problem. These algorithms including LMS family and RLS family employed by FIR and IIR systems. This thesis studies the performance of equation-error adaptive IIR echo canceller. Analysis shows that the equation-error IIR canceller outperforms its FIR counterpart with much smaller number of coefficients. Extensive simulation and experiments validate our analysis.
The noise is also the problem we should overcome in the hands-free communications. Our analysis as well as experiments show the IIR echo canceller is capable of reducing the colored noise. We also present a scheme that deals with acoustic echo and noise.

並列關鍵字

Iifinite impluse response ； acoustic echo canceller ； finite impluse response ； noise reduction

參考文獻

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[3] B. Widrow, et al., “Adaptive noise canceling: principles and applications,” Proc. IEEE, Vol.63, pp.1692-1716

[5] E. Hansler, “The hands-free telephone problem — An annotated bibliography,” Proc. 3rd International Workshop on Acoustic Echo Control, pp. 5-18, Sep. 1993.

[6] E. O. Moulies, A. Amrane and Y. Grenier, “The generalized multidelay adaptive filter: structure and convergence analysis,” IEEE Transactions on Signal Processing, Vol. 43, No. 1, pp. 14-28, Jan. 1995.