The Ocean Shield, which is carrying high-tech sound detectors from the U.S. Navy, picked up two separate signals late Saturday night and early Sunday morning in seas far off the west Australian coast that search crews have been crisscrossing for weeks. The first signal lasted two hours and 20 minutes (2:20)before it was lost. The ship then turned around and picked up a signal again — this time recording two distinct 220;pinger returns” that lasted 13 minutes, Houston said.”Significantly, this would be consistent with transmissions from both the flight data recorder and the cockpit voice recorder,” Houston said. In the first major break in the month-long hunt for the missing Malaysia Airlines jet, search vessels on Monday detected two distinct underwater sounds experts say are very much like the pings associated with aircraft black boxes. Here, Australian Air Force Captain Benn Carroll keeps his eyes on a smoke buoy marking suspected crash debris on Sunday, April 6, 2014. 1 of 17Still, Houston cautioned that it was too early to say the transmissions were coming from the missing jet.”I would want more confirmation before we say this is it,” he said. “Without wreckage, we can’t say it’s definitely here. We’ve got to go down and have a look.”The ping locator is pulled behind the ship at a depth of 3 kilometres and is designed to detect signals at a range of 1.8  kilometres, meaning it would need to be almost on top of the black boxes to detect them if they were on the ocean floor, which is about 4.5  kilometres deep.