APPARATUS AND METHOD FOR CANCELING ACOUSTIC ECHOES INCLUDING NON-LINEAR DISTORTIONS IN LOUDSPEAKER TELEPHONES

摘要

An echo caneling loudspeaker telephone includes a loudspeaker which produces a sound pressure wave in response to an input signalwhich is applied to an audio input thereof. This sound pressure wave includes a desired linear component which is a linear function ofthe input signal, and an undesired non-linear component which is a non-linear function of the input signal, and the sound pressure wave istransmitted along an acoustic path. A microphone is positioned in the acoustic path and converts the sound pressure wave into an outputsignal. An echo filter is responsive to the input signal and generates an estimated echo signal. This echo filter includes a loudspeaker modelwhich generates an estimate of the sound pressure wave including an estimate of the linear component and an estimate of the non-linearcomponent. This echo filter also includes an acoustic path model which generates an estimate of the acoustic path from the loudspeakerto the microphone. In addition, a subtractor subtracts the estimated echo signal from the output signal thereby reducing an echo portion ofsaid sound signal.