it's the sound search teams have desperately been trying to find and now they just may have. the pinger locator towed behind the "ocean shield" detected distinct sounds that may be from the black boxes. >> the first detection was held for approximately 2:20. the ship then lost contact. the second detection on the return leg was held for approximately 13 minutes. >> reporter: the detections about a mile apart in water more than 14,000 feet deep. on one occasion, two separate pings were heard, which only heightened the excitement because the cockpit voice recorder and the flight data recorder ping separately. >> this is the most promising lead. >> reporter: but we've heard that before. >> the most promising lead. >> credible leads. >> credible leads. >> reporter: but this time it could be different. >> the audible signal sounds to