When I started a new game today everything went fine until the character woke up. The NPC starts talking to me and the audio cuts out. His lips are moving but no sound except for background music. Shortly thereafter the charcter gets to stand up. No sound for footfalls or jumping, and when I walk over to the NPC his lips start moving again, but I am not hearing him. I am running a dual core E8400 with 4GB RAM, GeForce 9800 GT, and Realtek HD audio. This PC has never had sound issues in previous games.

I'm having the same sound issues that you are having. I get no audio at all from NPC's. I don't get any sounds for footsteps, when I switch weapons, or use the Pipboy. I hear the music, gunshots, and most of the ambient sounds. I'm so frustrated that they released this game with so many problems.

Update: I have manually turned the hardware acceleration for the sound from full to basic, and the audio is working much better. I have never had to do that for any game before, but it seems to work. Now if only the game would stop blue-screening every 30 minutes or so (usually when I am exiting a building), I would be laughing!