Nonlinear acoustic echo control using an accelerometer

A typical echo canceller uses an FIR adaptive filter to estimate the impulse response of the near-end echo path. However nonlinear echo components due to the loudspeaker and driving amplifier are not captured by such an arrangement. We propose a novel scheme for nonlinear acoustic echo cancellation where an accelerometer sensor captures loudspeaker vibration and this sensor signal is used along with the error signal to adapt the adaptive filter coefficients. The accelerometer sensor is used in lieu of explicit nonlinear modeling in the echo cancelling loop and hence it is compatible with typical NLMS and RLS echo cancellation algorithms. Experiments with an accelerometer mounted on the magnet of a hands-free kit show an echo reduction improvement by as much as 15 dB in situations of nonlinear loudspeaker distortion.