hard drive churning noise

My hard drive is making a noise on my 2009 2.66ghz core 2 duo. It makes a churning noise (like its working or something--the usualy noise it would make when working) every 1-2 seconds, and last for less than a second. It honestly sounds like a second hand on a clock ticking (but the noise is not a ticking, its the hard drive chruning). Verify hard disk came back ok, as did the permissions. My cpu useage did not show much at all. What could be going on?

Thanks