In this paper, a method for the suppression of acoustic howling is developed, based on adaptive notch filters (ANF) with regulariza-tion (RANF). The method features three RANFs working in parallel to achieve frequency tracking, howling detection and suppression. The ANF-based approach to howling suppression introduces minimal processing delay and minimal complexity, in contrast to non-parametric frame-based methods featuring a non-parametric frequency analysis. Compared to existing ANF-based howling suppression methods, the proposed method allows for a more advanced howling detection such that tonal components in the source signal are not affected. The RANFs proposed in this paper are implemented in direct form and are updated using a gradient descent type algorithm. Results show that, under certain conditions, the level of suppression and sound quality are similar to what is obtained with frame-based methods.
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