Well-known sounds from a dying hard drive:http://www.pcworld.com/downloads/file/fid,22373-order,1-page,1-c,alldownloads/description.html
but remember a 250GB Sata is too recent to have ball bearings.
Also, run HdTune or HdTach. At the point where they observe the access time, you will hear the arm's movement.
On HdTune's diagram for access time, points are grouped in a band which is the platter's rotation time. 10 points outside this band are normal, 1000 are not.