It's not just you - but it's not constant. I find that in some (but only some) U.S. commercials, it's like one of the audio tracks (the one with the voice) has been dropped: All you hear are the background noises. It's actually a kinda nice change!
I'm guessing that - because there's probably a fair amount of Olympic coverage on CNBC America right now, and NBC does not have the Olympic rights in Canada (that's the CBC) - CNBC America is blocked during the Olympics.
