weird noise

hey so i recently got my macbook air, I've only had it for a month and recently it has been making a weird noise you know when you login into your laptop like you put in your password and it logs you into your laptop and as its logging in it makes that weird "wooshing" sound, yea so thats the sound that keeps playing randomly and i have no clue why. if anyone can help me out that would be great cause its starting to drive me insane.