in the southern indian ocean. malaysia, though, is so sure of this that it's called off the search in the northern corridor. the malaysians have all their confidence pinned on this british company inmarsat, which says it tracked that plane into the southern corridor with six handshakes, or pings. cnn has also learned, it's been verified by space agency experts and by boeing itself. if searchers can figure out where this plane went down, recovery teams will be using the super sensitive listening device, it's called a hydrophone, to try to locate all of those crucial data recorders. that will let them know what happened onboard this plane. so, here she is. stephanie elam is joining me from santa barbara out on a boat, giving us this really pretty incredible firsthand look as far as how this technology works. so, show me. >> yeah. it's true, brooke. it's really amazing. when you think about the indian ocean, the south indian ocean, you're talking about a massive