the debris has gone into a very different direction. much of the focus, especially early on in this search, has been about the debris moving eastward. moving toward the strait. now that these pings seem to be much further northward, much closer to malaysia and the plane maybe hasn't flown that far, it means the circulation actually would have driven the debris the other way around, much more toward madagascar, toward africa, even. >> colleen, here's a mystery that i'd like you to explain to our viewers. the pinging sound that's coming from those two black boxes, they're supposed to be, what, 37.5 kilohertz, but we're told it was slightly different the first four pings that were detected, this fifth suspected ping. not exactly 37.5. how -- if they believe they're coming from the black boxes, what would explain the slight change in the kilohertz? >> well, it could be the environment or it could be the