Step-size control for acoustic echo cancellation filters -- an overview. (Q1575747)

We present an overview about several approaches for controlling the step size for adaptive echo cancellation filters in hands-free telephones. First an optimal step size is derived. For the determination of this step size the power of a non-measurable signal has to be estimated. Detection and estimation methods for the determination of this power and for the determination of the optimal step size can be grouped into four classes. For each class, several principles, which differ in their reliability and in their complexity, are presented. Possibilities for combining elements from each class to create an entire step size control unit are also described. An outlook on detector combinations based on neural networks concludes this paper.