Played for the first time in a new documentary, the sound has a regular, steady beat which caught the attention of experts - and sparked hopes that they could be SOS signals from those on board.
The search for the missing submersible on an expedition to view the wreckage of the Titanic neared the critical 96-hour mark Thursday when breathable air is expected to run out.
Pilot and 4 passengers of the Titan submersible are dead navhindtimes.in - get the latest breaking news, showbiz & celebrity photos, sport news & rumours, viral videos and top stories from navhindtimes.in Daily Mail and Mail on Sunday newspapers.
Get the top national stories of the week here, including full coverage of the Ocean Gate submersible that went missing near the wreckage of the Titanic.
Get the top national stories of the week here, including full coverage of the Ocean Gate submersible that went missing near the wreckage of the Titanic.