Air sound when pressing brakes

[Lorgnon]

Hey guys, I just got a new 2008 a couple of weeks ago and I noticed this low-key sound whenever I press the brake while driving. It is like air is being let in or out, similar to the sound of a small air pump, but quieter. I understand it has something to do with the brake servo and possibly vacuum booster. I did not notice it before probably due to ambient noise and radio, but now I drive without those and it annoys the hell out of me.
What could it possibly be?

[GiveMeABreak]

When did you last have your vehicle properly serviced? The brake fluid has to be replaced every 2 years. There is also the correct dual bleeding procedure that has to be done with diagnostic tools to ensure both the primary and secondary circuits are bled correctly. If not, then this can mean you have air in the system which can lead to this sort of problem, which can be dangerous. It can lead to 'spongy' brakes and less braking efficiency if there is air in the brake lines and can damage the master cylinder.

I suggest you get it checked out by a proper garage familiar with the appropriate knowledge, or use your dealer if unsure.