Reduced-cost combination of adaptive filters for acoustic echo cancellation

Adaptive combination of adaptive filters is an attractive approach that improves the performance attainable with individual filters. However, the computational cost associated with the operation of several filters in parallel could be unaffordable for some applications. In this paper, we propose a scheme with reduced computational cost for a combination of two adaptive filters with different step sizes, working in scenarios with a low signal-to-noise ratio and where the energy of the unknown system is concentrated at short delays. For this case, we propose to reduce the length of the fast filter, speeding up the convergence of the combination at the cost of a slight degradation on the steady-state error. We study and evaluate the performance of the combined scheme considering the length of the fast filter as a parameter. In addition, we discuss a possible application of this scheme in real-world acoustic echo cancellation for hands-free systems in cars.