Adaptive IIR digital filters for noise and echo reduction in speech

In this paper, two types of adaptive IIR digital filters with saturation outputs are introduced for noise and echo reduction in speech. By imposing a saturation operation at the output of an adaptive IIR digital filter, undesirable effects of any instability that may arise in the filter can be avoided. The preliminary simulation results presented indicate that these two adaptive IIR digital filters, as compared to other common adaptive algorithms, perform well in noise reduction, echo reduction, and in combined noise and echo reduction in speech.