The Cmdr I know who does this on PS4 does it by ear I think. I.e. by listening to it. And some on pc do the same. Otherwise you need to record the audio somehow ...
I cant speak for PS4 but on XBox we can record directly to a USB HDD, upload to the cloud or use a game capture card to get the files on PC on analyse it there.
Thanks. I did the same on my PS4. Capture video, then go to Capture Gallery and dump to external USB. Then I used VLC Player to convert video to audio mp3 and did the rest with Audacity.