Supersonic Child Detector

It's late in the evening.  Grown-up time has finally arrived.  You and your loved one have your snacks, the movie is on, the lights are dim, the surround is so good you feel like you're in a movie theater.

And then there's a tiny squeak. You drop your popcorn, spring off the couch, and in 2.2 seconds, you're in your child's room, just before he or she begins to cry.

How did you know just when to run? What causes this phenomenon?

It's your very own internal Supersonic Child Detector.

From canstockphoto.com