A Howling Suppressor Using Adaptive Notch Filter and its DSP Realization

Abstract

It is well known that the suppression of howling is one of the most important problems in the realization of a teleconference system. Usually, acoustic echo cancellers have been employed in order to cancel the howling. Due to the extremely long impulse response of the acoustic system, however, this kind of howling canceller requires a large hardware and a lot of computation. This paper considers a new type of howling suppressor. Namely, noting that howling signal can be well approximated by the sinusoids, we propose a howling canceller using an adaptive notch filter. The proposed howling suppressor has following two special features: (i) It is realized by a very small hardware and requires less computation compared to the conventional cancellers. (ii) It does not require any special training period. Finally, by implementing the suppressor on a DSP (Digital Signal Processor), the effectiveness of the proposed suppressor is confirmed.