Search officials said on Monday that the recorder was found buried in about 8 meters of mud in waters about 30 meters deep. The cockpit voice recorder is one of the two so-called black boxes crucial for the investigation of a plane crash.The other black box, the flight data recorder, was recovered three days after the crash. A preliminary report by Indonesia’s transport safety commissionfocused on airline maintenance and training, as well as the response of a Boeing anti-stall system and a recently replaced sensor, but did not give a cause for the crash.