Im on PS3 and I also experienced this sound problem. As a special treat the last time it happened was just as I entered Ul'dah via the airship during the main storyline quest. The sound cut out, the game froze for about 10s, then my PS3 froze up. I did a hard restart, and was able to get back into the game just fine, but now my 3month old PS3 controller is fried.
The controller stayed on throughout the entire hard reset, and continued to stay on for 20min(which is how long I have the auto-off feature set for). I switched controllers and tried to turn the broken one back on. No dice. Its not the end of the world, but it is odd. It doesn't respond or charge even when plugged in.
All in all, I enjoyed P4. I ran into the 9000 error, but managed to avoid the 3102 error. I also never had the sound cut off after the initial time.
Im with you Grandmomma in regards to the NA voices. Once Early-Access hits, its going to be JP all the way. It sounds like they're reading their lines off a cue card. I was hoping to keep it NA for the ambient dialogue that they dont have chat bubbles for. Oh well.