Using the Cockpit Voice Recorder transcript is the usual practice. Any Voice recording you hear is from Air Traffic Control.
And now we know why...
https://www.ntsb.gov/news/Pages/cvr_fdr.aspx
“...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...”
Handy, that.
So much for transparency.