When my infant daughter is screaming loud enough to wake Godzilla in his watery home (despite the fact that we live in Minnesota and he lives in the Pacific Ocean), one of the most effective methods for calming her down is simply to keep saying “shhh” to her over and over.

I'm not sure why this is, really, but I've heard two theories on the matter. One is just that it's white noise, and all people tend to find white noise calming, whether infants or adults. The other is that it somehow mimics what the baby would have heard in the womb for nine long months, and because of this the baby finds it deeply calming.

It's true that she gets this calm and almost wistful expression on her face when I make that sound. I don't know enough about infant brain development to know if this is plausible or not, but I have to wonder if she's actually remembering the way life used to be for her- white noise and darkness and strange lights, before she came out into a much louder and more confusing world. Is it only familiarity that makes that sound so calming to her, or was she actually happier in that earlier life? Does she remember it, even vaguely, as “the good old days”? Or does she just react to the sound itself without ever knowing why, soothed and comforted by something that just feels right to her, but without even a hint of memory?