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More on the US Navy's pick-up of 'implosion' sound
The US Navy detected “an acoustic anomaly consistent with an implosion” just hours after the Titan began its dive on Sunday.
The information was immediately shared with the US Coast Guard, which used it to narrow the scope of its search, an official told CBS News.
But it's not clear why this information was not made public earlier.
It's believed the implosion sound was picked
by the Navy's secretive long-range sonar listening system which has its origins in the Cold War.
The Sound Surveillance System was created in the 1950s to listen for Soviet submarines in the remote depths of the Atlantic Ocean.
Precise details of current operations
are classified, but a US Navy website describes them as performing “detection, localisation and tracking of submarines and the collection of acoustic and hydrographic information.”