disparity between their operating range and the ranges at which we're hearing them, seems to be uninterpretable for me. unless, the possibility, we know there are two boxes and the other possibility is that maybe it's not sitting on the sea floor. maybe it's somewhere in the water column and it's being moved by currents. >> it's drifting around? >> these are possibilities. >> another point that you raise which we found very interesting, you're saying the weakening of the signals from the black boxes, if that's what it is, it's not necessarily an indication that it's the weakening of the batteries. explain that to us. >> well, in the ocean, the propigation of sound can be very complicated. you know, there are different kinds of refractive indexes, indices that sounds have, if thear listening to something on the other side of a mountain, you wouldn't necessarily hear it. so if the thing is sitting on