Bit of a bump here...

My car started making a similar noise. It only happened a couple weeks ago and occurred at certain rpms - 1100, 1500, 1900rpm, but now happens all the way up to 2000rpm. I took it to Hanny's and they diagnosed it as a noisy alternator bearing. The didn't have anything available to replace it so I'm bringing it back this week to change the bearing. I hope that's all it is and will update when it's sorted.

Thought I'd add this for future searches.