'04 Edge 3.0, auto

This is kinda hard to explain, but when I really get on the gas, around 3000 rpm I hear a faint noise that sounds similar to the sound of an oversized tire rubbing the inside of the wheelwell when you turn too hard.

But for me, this doesn't happen when I turn. I'm usually going straight when I hear it, and its only at around 3000 rpm. Also it doesn't happen even single time I hit 3000 rpm, only maybe 50% of the time. It isn't very loud. In fact I don't even notice it when the radio is turned on.

I hope it isn't transmission related. Tranny fluid is still red and doesn't smell burnt. Fluid level is where it should be. Any ideas?

Edit: i should also note that i never hear it if i accelerate slowly. Its only under moderate/hard acceleration

 

is it coming from a general side? or just up front altogether?

 

it sounds like its coming from the passenger side, possibly even from behind me, but its hard to pinpoint. I guess the tranny is more in the front/middle, so maybe thats not it.

This one just has me scratching my head.