Slight whistling Noise

[halla26]

Quick question not sure if anything serious, well hoping not..
When driving the car in first second, getting close to 2000-3000 rpm so getting round gear change, there is a slight whistling noise, barely noticable with music off but still.
Is that just normal engine noise or something else?

 

[Robclio98]

funny you say that mate, im having that trouble now aswel! was gona whack up a post asking what it could be, but i had my aux belt changed yday though.

 

[jack_davey]

do a search there's hundreds of threads about it, it's usually the aux belt tensioner