Though the voices are deactivated by default and need to be enabled

Good to know. I tried latest beta last night and didn't hear them.

For those that didn't read the release notes, the file to edit is located in "Cold Waters -> Cold Waters_Data -> StreamingAssets -> Default -> Hud." The file is called "Default.txt." Look for the the section titled [Message Log] and you will see a line called "LogVoiceVolume=0" and change the value of 0 to a value between 0 and 1. Save the change and you're good to go.

Keep in mind that the crew voices are a work in progress. Personally, I like them even in their raw form. One of them was recorded by FPSchazly who was an actual US Navy submarine crewman in his past life. His videos on YouTube are pretty interesting if you haven't seen Cold Waters in-game video and are wondering if you want to buy it.