Particular embodiments provide for attenuating one or more microphone signals in a teleconferencing system upon detecting a non-audible signal. A far end voice signal is received from a sound source. A non-audible signal is added to the far end voice signal to create a composite signal, which is provided to one or more speakers. The speakers output the composite signal and the non-audible signal are detected in the composite signal after the composite signal is received at one or more microphones. The non-audible signal allows an attenuator to attenuate a microphone signal including the composite signal from a particular microphone in response to the detected non-audible signal to reduce far end echo.