So I've got Surround sound speakers set up to my TV via Optical to anolog and it's 5.1. However somethign I've found with only Fallout 4 (from what I can tell) is that voices are super quite from the middle front speaker. Like I honestly can't hear anything, even though everything else is really. I don't have this issue with The Division or Battlefront or any other game.

anyone else have this issue?

All I know is optical cables don't carry HD audio formats.. Could have something to do with that maybe but that doesn't really explain why other games would work properly. Have you messed around with all of the ps4 audio settings.. linear, bitstream, etc? Maybe something got switched around in there. I don't even know what those do.. I have mine set to linear. I have surround sound but everything is hooked up through hdmi. I haven't had any audio problems.

Maybe... I mean the surround sound works, like playing Battlefront you can hear directions as to where things are, same goes for Fallout 4 where if I just turn so the person talking is to the left of me I hear him uber clearly out of the left front speaker but for some reason teh center one doesn't work in Fallout...

Had this happen to me after I freaked out over how loud something was at 3am and thought my wife was going to get woken up. I changed a sound setting on the tv to make it quieter and suddenly couldn't hear things directly to my left. First thing I noticed was the roller door at Red Rocket, couldn't hear the opening/closing sound if I was turned sideways. Same with people talking to me. Eventually played around with the sound settings and fixed it straight away. If this sounds a bit like your problem(?) check all your Tv menu settings too as there didn't appear to be anything wrong with my surround set up either.