sciencehabit writes: Biologists believe that sight, smell, and an internal compass all contribute to bird navigation. But none of these skills completely explains how the animals fly long distances or return home from places they've never been. A new study proposes that the animals use infrasound—low-level background noise in our atmosphere—to fly by "images" they hear. These acoustical maps may also explain how other creatures steer. (Sound clips included, which have been known to freak out people and animals. Check out "Earth").