I live out in the desert, although during the first few years after we moved in, it was MUCH more deserted than it is now. Now it's more like a suburb.
Several years ago (5? 6? 7? I can't remember) on a couple of occasions at night, while standing on a balcony, I heard this deep sound, quite loudly, seeming to come from the sky, although I could see no source for it. My husband said it was probably a fighter or spy plane breaking the sound barrier or something, since there is an military air force base somewhere nearby (don't ask me where -- all I know is it's close) but that's very unlikely: it was regular and rhythmic, slow and heavy sounding. Something like this:
It went on for a long time, like half an hour or even longer. Unlike the Costa Ricans, however, I never heard anybody else mention it, though we did have some neighbors. Then again, I never mentioned it to anybody else before, either.
"If you're not careful the newspapers will have you hating the oppressed and loving the people doing the oppressing." - Malcolm X