Method, communication device and communication system for double-talk detection and echo cancellation

A method for double-talk detection and echo cancellation adapted to a communication device having a voice processing circuit, wherein the communication device is configured to electrically connect to a speaker and a microphone, and the method comprises: obtaining a far-end signal by the communication device, wherein the far-end signal is configured to be played by the speaker, generating a recording signal by the microphone, performing, by the voice processing circuit, a voice processing procedure according to the far-end signal and the recording signal to generate a near-end amplitude, generating, by the voice processing circuit, a determination result according to the near-end amplitude, a historic data and a threshold data at least, wherein the determination result is configured to indicate a condition of double-talk condition or single-talk, and adjusting a parameter set of a dynamic equalizer according to the determination result by the voice processing circuit.