Delayed adaptation for improved doubletalk resilience in adaptive echo cancellers

This paper proposes a simple modification to adaptive echo cancellers to prevent rapid divergence due to doubletalk conditions. The proposed structure introduces a delay only into the adaptation algorithm, which compensates for doubletalk detector response time at the onset of near-end speech. The structure is described and analyzed for the NLMS and cross-correlation-based doubletalk detector algorithms. The method introduces no delay into the return path, and no additional constraints on adaptation step size arise. Simulations with ITU-T Q. 168 tests confirm that the proposed structure prevents divergence at the onset of doubletalk for near-end to echo signal ratios of-26 to -6 dB.