Acoustic Feedback Cancellation using the Variable Step Size Affine Projection Tanh Algorithm

In this paper, a new algorithm is proposed for the acoustic feedback cancellation for hearing aids. It is based on the affine projection tanh algorithm, combined with a modified practical variable step size and frequency shifting. A modified soft clipping stability detector that controls both the variable step sizes and the frequency shifting is used. It is shown that the proposed variable step size approach that considers the tanh nonlinearities applied to both the preprocessed error signal with the pre-whitening filter and the error signal is beneficial for faster recovery from howling. Dichotomous coordinate descent iterations reduce the numerical complexity of the algorithm. Our experiments indicate that the proposed algorithm outperforms competing methods for incoming speech and music signals.