Hello, I am getting started with MCE with MSFS 2020 and I have the following question:
-when the copilot handles the radio, I have both the MCE copilot and the MSFS ai answering the radio; can the MSFS ai voice be muted such that only the MCE copilot answers the radio ?
Yes.
In the Options menu from the welcome screen.
Assistance Options, Piloting.
Turn off AI Radio Communications (ATC)
Thank you, would that cut also the controller’s voice ?
No, it will not.
It just shuts off your AI copilot from contacting ATC.
Hi, I tested a bit more: I turned off AI Radio Communications (ATC) but when I ask my MCE copilot to request touch and go, I first hear two voices: the request is made only by the MCE copilot but the answer to ATC is given by both the MCE and the MSFS copilot voice. So I am a bit surprised. Do you have the same behavior or am I missing something ? Thank you 
If you turned off the AI radio comm in the main options menu, confirm in the in flight screen toolbar that the same command is off there as well.
If it is off in both locations, what you are hearing is probably your voice, not the co-pilot.
I do not know of any way to turn the pilot voice.