The two-path algorithm for line echo cancellation

The two-path algorithm is an algorithm for line echo cancellation based on two parallel filters. This paper proposes a modification of the two-path algorithm that improves its performance. In the two-path algorithm a background filter is used for continuously adaptive estimation of the line echo, while a foreground filter is used for the actual cancellation. The coefficients of the background filter are copied into the foreground filter when the background filter is proven to perform better. A robust algorithm for line echo cancellation is thereby achieved. In this paper, the benefits and the drawbacks of the two-path algorithm are evaluated and demonstrated through simulations. A modification is proposed that reduces the negative effects of the two-path algorithm. This modification is compared to the original two-path algorithm. Simulations using real speech signals indicate that the proposed modification can improve the performance of the two-path algorithm.