Low-pitched whistling noise on throttle

[voteforpedro]

I get a low-pitched, but not very loud, whistling noise when I rev at idle or slow speeds. Not sure if it's audible on the go because of the road/engine noise. I would guess so.

So, which belt is this? I believe the timing belt was done recently.

[EDIT] I meant high-pitched.

 

[richie_jones]

http://www.audiworld.com/tech/eng6.shtml

I have the same problem , but unsure how to fix