An improved new error estimation algorithm for optimal filter lengths for stereophonic acoustic echo cancellation T. Nguyen-Ky * , J. Leis, W. Xiang Faculty of Engineering and Surveying, University of Southern Queensland, Toowoomba Queensland 4350, Australia article info Article history: Available online 25 December 2008 Keywords: Adaptive filter The stereophonic acoustic echo cancellation (SAEC) The filter length The error estimate algorithm abstract In this paper, we propose an new error estimate algorithm (NEEA) for stereophonic acous- tic echo cancellation (SAEC) that is based on the error estimation algorithm (EEA) in [Ngu- yen-Ky T, Leis J, Xiang W. An improved error estimate algorithm for stereophonic acoustic echo cancellation system. In: International conference on signal processing and communi- cation systems, ICSPCS’2007, Australia; December 2007]. In the EEA and NEEA, with the minimum error signal fixed, we compute the filter lengths so that the error signal may approximate the minimum error signal. When the echo paths change, the adaptive filter automatically adjusts the filter lengths to the optimum values. We also investigate the dif- ference between the adaptive filter lengths. In contrast with the conclusions in [Khong AWH, Naylor PA. Stereophonic acoustic echo cancellation employing selective-tap adaptive algorithms. IEEE Trans Audio, Speech, Lang Process 2006;14(3):785–96, Gansler T, Benesty J. Stereophonic acoustic echo cancellation and two channel adaptive filtering: an overview. Int J Adapt Control Signal Process 2000;4:565–86, Benesty J, Gansler T. A multichannel acoustic echo canceler double-talk detector based on a normalized cross-correlation matrix. Acoust Echo Noise Control 2002;13(2):95–101, Gansler T, Benesty J. A frequency- domain double-talk detector based on a normalized cross-correlation vector. Signal Process 2001;81:1783–7, Eneroth P, Gay SL, Gansler T, Benesty J. A real-time implementation of a stereophonic acoustic echo canceler. IEEE Trans. Speech Audio Process 2001;9(5):513–23, Gansler T, Benesty J. New insights into the stereophonic acoustic echo cancellation problem and an adaptive nonlinearity solution. IEEE Trans. Speech Audio Process 2002; 10(5):257– 67, Benesty J, Gansler T, Morgan DR, Sondhi MM, Gay SL. Advances in network and acoustic echo cancellation. Berlin: Springer-Verlag; 2001], our simulation results have shown that the filter lengths can be different. Our simulation results also confirm that the NEEA is bet- ter than EEA and SM-NLMS algorithm in terms of echo return loss enhancement. Ó 2008 Elsevier Ltd. All rights reserved. 1. Introduction An echo is the phenomenon in which a delayed version of an original signal is reflected back to the source. Acoustic echo cancellers (AEC’s) are necessary in applications such as mobile phones, hands-free telephony, speakerphones, audio and vi- deo conferencing. AEC’s rely on an adaptive filter to estimate the echo signal and subsequently use this estimate to reduce the echo signal. Typical adaptive algorithms for the filter update procedure in the AEC are recursive least squares (RLS) [3], fast recursive least squares (FRLS) [6], the normalized least mean square (NLMS) [9] and affine projection (AP) [10,11]. The 0045-7906/$ - see front matter Ó 2008 Elsevier Ltd. All rights reserved. doi:10.1016/j.compeleceng.2008.11.012 * Corresponding author. E-mail addresses: nguyentk@usq.edu.au (T. Nguyen-Ky), leis@usq.edu.au (J. Leis), xiangwei@usq.edu.au (W. Xiang). Computers and Electrical Engineering 36 (2010) 664–675 Contents lists available at ScienceDirect Computers and Electrical Engineering journal homepage: www.elsevier.com/locate/compeleceng