India, Dec. 24 -- The human body, I found out recently, is a heavy-metal concert, if you get the opportunity to really hear it.

One morning last June, an hour past sunrise, I visited one of the quietest places on earth. I was in Southern California, in Anza-Borrego Desert State Park, about 50 miles northeast of San Diego. I had wandered off the trail to climb a group of brown and red boulders. At the top, I lay down on my back, in what felt like complete silence. A few minutes later, I began to notice the sounds emanating from my own body. A cup of coffee sloshing around my stomach. The whoosh of blood circulating around my skull. After 15 minutes, what sounded like a helicopter flew over my shoulder. It turned out to be a hummingbird, w...