australian agency coordinating the search calls the detection of the signals "an important and encouraging lead" but he urged caution saying there is much work to do in confirming it. he also talked about the difficulties of tracking down the source of the underwater sounds. >> we go through a similar process when we go underwater. underwater, the environment is quite difficult. there are lots of occasions when noises will be transmitted over long distances depending on the temperature layers in the water and so on. so there's a complexity about working underwater that makes the task quite complex. >> all right. let's talk about the conditions now in the indian ocean there. as the search crews try to determine further whether these pings, these pulses are indeed