Just got to Meresti Train Station to deal with Vance and the other Vampires. After walking around for a few moments (doesn't seem to matter whether i'm in combat or dialogue) the sound just stops working. Not all of the sound, just player and NPC generated sound (no footsteps, no gunshots,no VATS, but GNR still plays music and the Bonfires still make sound). Then the next time I quicksave once this bug occurs, the game freezes (will loop a second of music if GNR is playing), and then I have to terminate the process.
Still trying some stuff so if I find a fix I'll post it here, but it's not looking good atm.