Echo is the time delayed version of the original signal. Acoustic echo results from a feedback path set up between the speaker and the microphone in a mobile phone, hands-free phone .Echo can degrade the quality of service in telecommunication. Therefore echo cancellation is an important part of communication systems. A new approach based on the number of coefficients in an adaptive finite impulse response filter based acoustic echo cancellation setup is an important parameter, affecting the overall performance of the echo cancellation. Too few coefficients give under modeling and too many cause slow convergence and an additional echo due to the mismatch of the extra coefficients This paper focuses on the use of adaptive filtering techniques to cancel this unwanted echo thus increasing communication quality

1. Christian Schuldt a, FredricLindstromb,HaiboLic, Ingvar Claesson, elsevier 2009 Adaptive filter length selection for acoustic echo cancellation,
2. Seon Joon Park,Student Member,IEEE,Chom Gun Cho,Chungyong Lee,Member IEEE,Dae Hee Youn,senior Member,IEEE,Integrated Echo and Noise canceller for Hands –Free Applications
3. KunShi,Xiao G.TongZhou Atlanta,2009 An efficient acoustic echo cancellation design for systems with long room impulses and nonlinear loudspeakers School of Electrical and Computer Engineering, Georgia Institute of Technology
4. Andreas Mader, Henning Puder, Gerhard Uwe Schmidt,Darmstadt University of Technology, Institut fur Nachrichtentechnik, Fachgebiet Theorie der Signale, elsevier 2000 Step-size control for acoustic echo cancellation-an overview
5. Fabian Kuech_,Walter Kellermann ,University of Erlangen-Nuremberg, Erlangen, Germany elsevier 2006 Orthogonalized power filters for nonlinear acoustic echo cancellation
6. T. Nguyen-Ky, J. Leis, W. Xiang Faculty of Engineering and Surveying, University of Southern Queensland, Toowoomba Queensland , Australia, 2010 An improved new error estimation algorithm for optimal filter lengths for stereophonic acoustic echo cancellation
7. Ville Myllyla, Elsevier 2006 Residual echo filter for enhanced acoustic echo control
8. Magnus Evestedt , Alexander Medvedev, Torbjorn Wigren elsevier,2008 Windup properties of recursive parameter estimation algorithms in acoustic echo cancellation.

Echo adaptive filtering