New noise while moving that changes when braking

In the last few days, my nearly new to me 2006 has started making a new noise while moving. The noise sounds to me like either a belt or possibly bearing noise. It kicks in somewhere between 5 to 15 MPH, and is pretty constant in both pitch and volume while I'm moving, regardless of whether I'm accelerating or coasting. Braking seems usually to cause the noise to go up in pitch, although sometimes it causes it to almost but not completely silent. The noise is never there while I'm stopped, and the state of the gas engine makes no difference either way.

I've poked around the forums, but haven't found any descriptions that line up with what I've started hearing. Any good suggestions before I take it to a dealer? Thanks!