The cockpit voice recorder has been retrieved from an Air France jet which crashed into the ocean off the coast of Brazil two years ago.
The airliner's flight data recorder was retrieved from the ocean two days before.
The Airbus A330 was flying from Rio de Janeiro in Brazil to Paris when it went down on 1 June, 2009, killing all 228 people on board.
It had encountered an intense high-altitude thunderstorm, four hours following take-off from Rio de Janeiro.
The Bureau of Investigation abd Analysis hopes the recorder will explain what caused the plane to plunge into the Atlantic without any warning, killing all 228 people on board.
The BBC reports the wreckage was discovered in April after a long search of 10,000 square kilometres of sea floor.