First one "ping", then another.
A Chinese ship searching for missing Malayasi Airlines Flight 370 detected a second fleeting "ping" on Sunday.
Both sounds came from near where investigators think the plane went down on March 8 in the Indian Ocean.
Also on Sunday, the Australian defense ship Ocean Field detected a separate acoustic signal.
But that one came from a different part of the vast search area, some 300 nautical miles away.
Both vessels are trying to verify if the sounds came from the missing plane's black box recorder.
The Chinese say the two pings had the same unique frequency reserved specifically for black box recorders.
But they caution, too, that time to locate the plane's black box is running out.
(SOUNDBITE) (Mandarin) SURVEY CAPTAIN FROM THE SHANGHAI MARITIME CENTRE OF SURVEYING AND MAPPING, ZHANG LIANG, SAYING:
"These few days are crucial for locating the black box. The main problem is the battery of the underwater