Voice recording
If you will forgive a non-professional intervening.
There are obvious benefits to having long term voice and other audio recordings. There are also obvious dangers, especially in an era of management by surveillance.
Understanding that what is suggested is a non-survivable recording, and given that 12 hours of CD quality audio will fit on about 12GB, would the solution be recording onto an SD card in some non-rugged outboard of the CVR system, with the SD card being the property of the captain, to be removed at the end of the flight unless there's a need of the recording?