in perth, 3:00 in the morning there. will, the ping detected by the ocean shield was not the same frequency we would expect to hear from a black box. what are crews there saying about that? >> reporter: yeah, remember when we first got the word that those chinese ships that potentially heard a ping, and we heard the 37.5 kilo hertz, and then we're hearing that these pings were like 33, and 33.2. and so you're wondering, what gives, why is it not the same number? well, the manufacturer of the black boxes says that that -- it still makes this a credible lead. there's still a very good chance those frequencies would have come from an in-flight data recorder or cook about it voice recorder. two factors. battery life is one. if the battery is old or the frequency can change. also the depth at which the signal is being emitted, then the water pressure surrounding the device, that can also change the frequency that's detected on the surface. so they still feel very much that these two pings that were