Real-time implementation of an IIR acoustic echo canceller on ADSP21020

A practical IIR (pole-zero) lattice adaptive acoustic echo canceller (AEC) for teleconferencing application is proposed. The proposed algorithm consists in two parts: a forward lattice and an inverse lattice. Collectively, they are referred to as the LATIN (lattice and inverse lattice) configuration. While the forward lattice is responsible for acoustic echo cancellation, the inverse lattice is employed in the double-talk (DT) mode only as to undo the distortion of the near-end speech brought about by forward lattice when suppressing the acoustic echo. Assuming M poles and M zeros for the proposed AEC, the complexity of the proposed algorithm is approximately twice the complexity of an M-tap FIR gradient lattice algorithm. Real-time experimentation conducted on an ADSP21020 floating-point DSP chip attests to the stability and fast convergence of proposed IIR algorithm