I recommend that you take a look at
It's a program that is specifically designed to automatically manage background immersion.
It extracts audio,
removes chunks where no one is speaking
and saves the files to your
mpd folder automatically.
Being able to increase immersion density is really useful,
and in practice such condensed audio files are up to 2 times shorter
than if you just extracted the original audio.
If you're a brainlet, subs2srs has a built-in tool to extract audio from video.
If you want more customization, learn how to use FFmpeg from the terminal. It's very versatile. You can take it further and write scripts in Bash that would use FFmpeg to automate the process.
FFmpeg can also record audio from your computer in case you're watching some DRMed trash that you're unable to download. dmenurecord is an example of a script that can automate recording of audio and screen with FFmpeg. Audacity is graphical program that can record audio coming out of your computer.