Abstract: The invention provides a signal processor installed in a communication device. In one embodiment, the signal processor comprises a voice activity detector, a nonlinear echo processor, and a speaker attenuation module. The voice activity detector generates a control signal indicating whether both a far-end talker at a far end and a near-end talker at a near end are speaking or only the far-end talker is speaking. The nonlinear echo processor, controlled by the control signal, cancels more nonlinear echo from the near-end signal in time domain while only the far-end talker is speaking and cancels less nonlinear echo from the near-end signal in time domain while both the far-end talker and the near-end talker are speaking. The speaker attenuation module, controlled by the control signal, attenuates the far-end signal while both the far-end talker and the near-end talker are speaking.