Jungle Monkey Squeal??

[GNBU]

I have a 1999 Boxster with 125000 miles.
Just bought it, with the squealing sound.
If I can I'd like to work on this issue myself.


I have this jungle monkey sound that starts as soon as I start the car and does not disappear warm or cold.
It seems to be coming from left rear side of the car.

I hear the sound when I am at idle/neutral.
I don't hear the sound when I am in gear and off gas pedal, decelerating.
I hear the sound increase in frequency as RPM goes up,
After 2500 rpm, I cannot hear the sound.
It may be disappearing but I suspect it's frequency is too high for my years. (is this possible?)

I checked the drive belt. Tried replacing it but the belt in place was new.
I took the belt out and started the car for a very brief moment but the sound was still there. So, I guess it isn't the belt.

Any inputs?