How do i prevent my macbook from making this noise ?

So I got a macbook yesterday. Everytime I turn it on, it makes this weird noise – like a cd spinning really fast on the drive. But i have no cds on the optical drive. Also it makes the same sound when I wake up the macbook from its sleep state. So how do I fix this issue ?

(and i know its sad that an ex-apple employee would ask such a question)