no sound at all in Battlefield 4 PC.

Well fair enough fully your choice on all of this. But just to give you a heads up when I had issues in BF4 I had a issue in windows but had no clue on it as errors only showed up in BF4 😕mileysurprised:  I was not until I took a good hard look at my PC and windows was I able to fully fix the game. Yes it was a pain to do and it took me a long time to get my PC good to go as I hunted down a fix for every error in event viewer and fixed them all. 

Have you ever tried to talk with EA staff reg this as they may have a fix for this ...

I would contact an Electronic Arts Battlefield 4 technical support agent here:
http://help.ea.com/en/contact-us/new/?product=battlefield-4
Pick the device you need help with.
Select the topic your problem falls under, and provide some more information on the issue.
Select 'Live Chat' or 'Call Me' depending on what is available, and what you would prefer.
If you can use call me as it has always been fast when I had to use it.

Or use this

You can contact EA here: http://help.ea.com/en/contact-us/