Odd sound, with sound clip!

[epapp]

This funky sound/'whirring' comes from the engine area, and it wasn't always there.

'99 and when I bought the car last summer, this noise was not there. I began to notice it slowly develop. It is still there with the acc belt off. Its now been like this for about 5 months.

The sound is always there, clutch in, clutch out, all gears, it is just MOST noticeable in 5th at ~65 mph (2700-2900). I know it is suspect in that RPM range to be variocam. But the sound is also there at 800rpm as well as 5000rpm.

If I keep a constant speed, the noise will be 'faintly' there, and when I alternate between on the gas ~75% and 0% in 5th gear on the freeway (hear recording), you can hear it whines mostly under load. It will also faintly whine when decelerating.

I have suspected a few things, but dont know how to troubleshoot them (short of pulling them out to visually inspect):

-oil scavenge pumps (anyone know if they sound like this/ spin this fast)?
-tranny input shaft
-clutch throwout bearing (I think these cars are setup such that the TOB always contacts the clutch plate

I'm not really suspecting the IMSB, given I've checked the oil/filter a few days ago, and with 5000mi on the oil since last year when I bought the car/changed the oil there are no obvious metal chunks/dust. It also doesnt appear to ever have leaked out of the transmission and engine mate/isnt leaking now, all is pretty clean down there.

Anybody know what else rotates around this audible speed in the engine? Noise is definitely tied to RPM and not speed.


https://drive.google.com/file/d/0BzgVZQpuS7NdVmJmUmRoczJJM3liNGdnZDBiOGtEUWx6cmow/edit?usp=sharing