[AmazonEchoControl] Turn mic off in unoccupied rooms

Hi there.
I have several Echos at home and sometimes, the wrong one responses. Any Idea how to catch that?
I would love to turn off/on the microphone based on motion in that room, but that seems to be not possible.
I could cut the mains from them, but it takes too long to boot to make this a “good solution”.
I have not tried to use some sort of on-the-fly-firewall … guess that this will probably not work fast enough as well…
Other Ideas?
PhiL