Still no luck getting the sounds working?

Windows 10 is famous for not supporting many old games, and with each next update it seems like it's getting even worse..
There are many possible reasons behind it, so it's hard to say what is the cause. I have looked through similar problems our users have ever encountered, maybe you can find something helpful here:
https://www.helloclan.eu/threads/6957/
https://www.helloclan.eu/threads/7130/
https://www.helloclan.eu/threads/7014/
You can also try next method. Not sure if it would work for you, but let's try!
Go to settings folder inside your Battlefield Vietnam directory (for example,
C:\Program Files\EA GAMES\Battlefield Vietnam\Mods\BfVietnam\settings) and open
Default.con. Inside you will see something like this:
Code:
rem *** for BC
rem Game.GameLevelPath BFVietnam/Levels/Operation_Irving/
Game.useMenu 1
Game.useHud 1
Game.menuMain BattlefieldMenu
Game.menuInGame InGame
Game.menuMap Map
Game.DebugCallbackDisabled 0
run AliasedCommands.con
softRun ../../../Tools/Editors/Editors.con
You will need to add after
Game.DebugCallbackDisabled 0 one of the following lines:
Game.soundbuffersize 400
Game.soundbuffersize 1000
Sound.soundBufferCacheSize 400
Sound.soundBufferCacheSize 1000
So it would look something like this:
Try each of these 4 configurations one by one, you will also need to re-launch the game every time you apply changes to Default.con file.
If nothing works, you can also experiment with values between 1~1000 (200, 500, 700, etc).