Failing hard disk drives will often (but not always) make distinctive noises. Here's an excellent compilation of the sounds they make.
This is a great list of the various kinds of sounds that hard disk drives make when they are failing.
The sounds are grouped by manufacturer, with the sounds that you really don't want to hear listed for each vendor - Western Digital, Seagate, Samsung, Hitachi/IBM, Maxtor, Fujitsu, Toshiba, and Quantum.
Just click on the circle with the triangle inside next to the link to hear the sound for that manufacturer.
You can listen to stuck spindles, bad heads, bad bearings, failing heads, and seized spindles.
Many of the sounds appear to be somewhat amplified so they can be easily heard.
If you hear noises coming from your hard disk drive, back up everything you can as quickly as you can, provided the disk still has some life left in it. :)
The hard disks I've had over the years that failed usually failed without a sound or became so slow as to be almost unusable. One made a faint clicking when the disk drive spun up. Your mileage may vary. :)
The site with the sounds belongs to a professional data recovery service, with a link and a fast quote box. While it's a commercial site, listening to the various failing hard disk drives is free.
Off for now,