![]() There are many approaches to determining when a double-talk scenario occurs, but all follow the same general procedure. ![]() ![]() Therefore, adaptation of the filter must be prevented during this double-talk (DT) scenario via a double-talk detector. The presence of the near-end talker during far-end speech is a source of disruption in the adaptation of the filter. Ambient noise provides a theoretical bound on the achievable cancellation of the system. In a full-duplex conversation, the presence of signals other than the far-end signal convolved with the echo path, inhibit the ability of the adaptive algorithm to model the system. The difference between the near-end signal and the filter output is used as the criteria for updating the filter coefficients. An adaptive algorithm modifies the filters coefficients, so when it is convolved with the excitation signal, it’s output matches that of the microphone signal. In this situation the microphone signal is considered the desired signal and the loudspeaker signal is the excitation signal. Cancellation of these echoes is a system identification signal processing problem. AECs are used to remove the unwanted echoes from the microphone signal. Acoustic echo cancellers (AEC) are used in full-duplex hands-free communication systems in which the far-end (loudspeaker) signal is coupled with the near-end (microphone) signal.
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