It happens sporadically... mostly around towers or under trees (driving or sitting still... no difference). And, it doesn't happen with a CD playing. So, that is why I thought antenna...
As to the tweeters, when they replaced the radio (thinking THAT was the problem) about a month ago, that was the first time I knew those WERE tweeters! They didn't work previously...
The "sound" variance is subtle... but it drives ME crazy... obviously a woman thing! The male service advisor said he couldn't even HEAR the change!
As to how long... it is only a second or two, then reverts... not long enough to find out exactly WHAT is happening! But, I have driven with every possible configuration (left/front, right/front, etc) of the speakers to try to isolate the problem, and have decided it probably isn't a speaker issue.
I may be trading it in on an '05 model... pretty sad that I would trade just because the radio sucks!
But it is just about THAT BAD to me!