>> ships are headed for an area where chinese searchers have now twice detected electronic pulse signals in the southern indian ocean, holding a microphone underneath the ocean. and one of our expert analysts said that he thought it was encouraging that they heard this signal twice. the second time, just two kilometer from where they heard it the first time. and they heard something every second for 90 seconds. we learned this from australian authorities who held a news conference to make this announcement. they also said the australian ship the ocean shield picked up some kind of acoustic noise in the region. here's the announcement made by the head of search operations. >> this morn, we were contacted by the chinese authorities and