Hitachi Global Storage Technologies has released as of now six sound bits to help you recognize Hard Disk Drive (HDD) failures. Couldn't they have told me about it a bit earlier? Maybe it could have helped to avoid a certain HDD failure I had on my own. Well, the server is located 700km away from me, but I'm sure someone would be able to hear it before it crashed.
You can download the clips yourself at: hitachigst.com
The problem is that if the computer is loud enough you will never be able to distinguish the sound of a dead drive. Maybe it is time to add a mike or something and flash a red light or whatever.