The British Open on TNT was like this as well. Golf seems worse than the regular shows. All are annoying though. I've also noticed this problem on NBC (Olympics today) and on all Directv commercials, and also when watching House on Fox.
There is a place to complain about this on TNT's web site. I did so during the British Open. They finally responded back just last week, wanting to know if the commercials were too loud or the the broadcast was too low (possible) . They wanted to know who my provider was and if I had contacted them. Of course, I had provided all of that info in my initial complaint, so I just deleted the e-mail.
I guess it could be a Directv problem. Not sure...