Decided I wanted to turn up the volume of the working ATC voices, did so and now I have not ATC sound at all. Switched voice sound back to where it was before, still no ATC sound.  Any one know how to fix this?

Is your radio tuned correctly?

After posting, I couldn't sleep so I poked at this some more and found the problem.  Settings\Sound on my setup was at the default for 'default primary device' as I had never messed with sound other than the one time to change voice volume that started the problem.  Idly poking at things I selected that actual sound system I had and POOF everything worked as they should.  Seems strange to me, but a lesson learned.

I had the same issue, I have a wireless gaming headset and Prepar3D routes the game sound though my desktop speakers (a.k.a my "default device") and the voice sounds through my wireless headset, even if it's turned off.

Glad you got sorted, bud.