Once, I told DD1 that I needed five minutes with no noise, otherwise my head would explode. Cue lots of graphic descriptions from her about how there will be blood everywhere ...
I reckon I'll just stop talking entirely once DD2 learns to talk, because there will just not be enough time for all three of us to have our say.
The only genuine discovery I have made is that I have to stay quiet myself in order to have any hope of persuading DD1 to be quieter. So I tell her, very calmly and quietly, that she doesn't need to shout when I'm sitting right next to her. And DD2 has learned what Sshhh! means and thinks it's a very funny game. I blank her when she's too noisy and give her lots of attention when she tries again quietly, in the vain hope that it might become a habit ...
And I always take a moment to enjoy the peace, just after I've shut the car doors with them inside and me outside!