9 and 7 year old boys: Constantly throwing.kicking thing around the house, turning whatever they are doing into a game which, within five minutes, results in the 9 year old taunting the 7 year old to the verge of tears. Also cricket, recently.
3 year old girl: Any tablet, any animals, Pennywise the clown from the film It (2017 version) and those YouTube videos of, presumably, modded GTA where Spiderman is somehow driving a car on a road in the sky and inevitably crashes into the sea or something. Lots of them.
All three of them together: Just noise. Constant noise, all of the time 