From the NTSB's website today:
"A CVR committee usually consisting of members from the NTSB, FAA, operator of the aircraft, manufacturer of the airplane, manufacturer of the engines, and the pilots union, is formed to listen to the recording. This committee creates a written transcript of the CVR audio to be used during the investigation. FAA air traffic control tapes with their associated time codes are used to help determine the local standard time of one or more events during the accident sequence. These times are applied to the transcript, providing a local time for every event on the transcript. More precise timing for critical events can be obtained using sound spectrum software. The transcript, containing all pertinent portions of the recording, can be released to the public at the time of the Safety Board's public hearing.
The CVR recordings are treated differently than the other factual information obtained in an accident investigation.
Due to the highly sensitive nature of the verbal communications inside the cockpit, Congress has required that the Safety Board not release any part of a CVR audio recording. Because of this sensitivity, a high degree of security is provided for the CVR audio and its transcript. The content and timing of release of the written transcript are strictly regulated: under federal law, transcripts of pertinent portions of cockpit voice recordings are released at a Safety Board public hearing on the accident or, if no hearing is held, when a majority of the factual reports are made public."
http://www.ntsb.gov/aviation/CVR_FDR.htm