New Sound at Idle and Low Speed

[kerrton]

This might be overly detailed-orientated of me, but I'm sure my Rogue's idle sounds different than it did when it was new. What I hear most but not all the time superimposed over the normal idle sound is a very fast "woo-woo-woo" vibration sound, and if I put it in drive and let it roll forward it almost always makes this sound. The moment I lightly step on the gas the "woo-woo" sound stops, and I never hear it any other time, just idling and when rolling forward in drive.

I'm not worried about this, just curious if anyone else has noticed this? I'm wondering if a) it could be a small vacuum air leak, or b) exhaust c) normal sound of the vehicle.

I'm pretty confident it's "c", but I'm bored this morning so I thought I'd throw it out there and see what you guys think. Thanks!

[Pescakl1]

Maybe a ghost... afraid of moving.