I noticed this shortly after I bought my '03 Vibe in October 2012. Our first road trip was in December -- returning from North Carolina on the freeway (first real freeway mileage) I noticed a weird "rubbing/hissing/swoosh!" sound whenever we hit a bump or I hit my brakes. My husband said he didn't hear it. The mechanic who saw it after that trip couldn't replicate it.
It doesn't ALWAYS happen on the highway but, when it happens, it's usually on the highway.
I've read a couple of things on this board, since, about shocks perhaps making a noise as they bounce, or the car being TOO low (I bought mine used -- how would I know?), and the wheels rubbing on the wheel wells.
Anything I need to worry about?
THANKS. This forum has saved my sanity a number of times, already...