Limitations of handsfree acoustic echo cancellers due to nonlinear loudspeaker distortion and enclosure vibration effects

The limitations of adaptive echo cancellers (AEC) for handsfree telephony include noise, finite precision and truncation effects, undermodelling of the acoustic impulse response, vibration of the plastic enclosure, loudspeaker nonlinearities, dynamic tracking and convergence and double-talk. This paper examines the effect that the loudspeaker nonlinearity and enclosure vibration have on the steady state ERLE performance and concludes that enclosure vibration is an important limitation which, although rarely mentioned in the literature, is probably the major limitation in terms of sound quality. Experimental measurements indicate that enclosure vibration at medium to high loudspeaker volumes limits the achievable ERLE and the perceived audio quality more than any other limitation mentioned above.