I kind of remember that a once I did have an infant (or he could possibly have been a toddler) wake when his father upgraded the stereo to include the entire house with speakers. Of course, that was a long time ago, probably before any EPs or patches.
There is still just one child in the household, now a toddler, but the second should be in the works very soon. I've used fencing to attractively separate half the nursery into a sleeping area with a gate that can be locked against older siblings and guests. The rest of the room is open with toys. There are two cribs that are not currently separated from one another, but which are set up so that they easily can be. I'll have to see how it goes. m.sato, I hadn't thought of the possibility of a child with the light sleeper trait, but thanks for bringing that up. Randomizing the traits of 100 children should throw up at least one light sleeper.