Whining sound

[bmwraw8482]

So everything is working just fine but an annoying whining sound has developed under the hood. It sounds like its coming from the drivers side of the engine compartment and the sound is directly proportional to the engine RPM, gets louder as it revs up.
I needed new tires anyway and the firestone shop I took it to says they believe its the power steering pump, so what I would like to know is exactly where is the power steering pump and could that be the problem even though the sound doesn't change while steering?

 

[Lawdawg101]

I would say if it isn't your power steering pump whenever you turn the wheel, I would check your idler pulley that is what went out on my Expedition and it made a squeeling noise too.