I have a 20x14 room with two Nest Mini's and one Nest Hub placed around the room (one on each side of the long measure of the room and one on the interior wall). A moment ago in a completely silent room with no sound coming from anything I said "Hey Google turn off light <name here>"
Nothing happened. So my question is how do I get the system to follow commands with three devices in the room and no other sound present. Is there a hidden microphone gain I need to tweak? One would think this to be a simple task, but I find myself repeating commands to Google on a regular basis and writing it off to noise interference. Apparently I'm wrong that noise interference was the only problem.
You can adjust the "Hey Google" sensitivity level: https://support.google.com/assistant/answer/9712065?hl=en
But if you have 3 Nest devices in the same room, that might not work well. We don't have more than one device in any single room, but once in a great while a Google device in another room will respond.