Dito to that, I never noticed it in my first play through of Mass Effect 3 but now that I'm on my third Ive been noticing alot more problems with volume and dialogue. There have been several times where text will come up for dailogue on screen and no one will be talking or i can barely hear them. I noticed this in Dragon age as well. I'm not saying that EA or bioware are bad companies but if they are going to stand by there products you think they would do a better job the first time around catching bugs like this. Just doesnt seem like very proud work to me...but then again I'm not a game editer so I dont know what all goes into it. I just buy the damn things and play them.
I've experienced the problem in ME3, but not DA:O. For me it only occurs when I get dialogue over comms, where moving Shepard will cut the dialogue off, but then resumes from the next line.
Quick fix: don't move when comm dialogue starts, and keep the mouse where it is- sometimes even changing the view can cause the same problem.
Yeah, I have this exact problem, it occured in ME2 as well. Had a X-FI sound card for both, my guess is the positional audio does not function correctly in all situations. Kinda frustrating because positional audio is not exactly new, I remember positional audio in Half Life 1 back in the day.