More info available here: http://www.megavolts.nl/en/projecten/...
A Hard Drive playing music (hard drive speaker). The sound comes from the vibrating arm. No other hidden speakers. In most harddrives the arm positioning works with a coil between two powerful magnets. When the coil is hooked up to an audio amplifier the arm will start vibrating on the music, this in turn vibrates the air around it which will make you hear the music. The internal resistance of the coil is 9.0 ohm so this is no problem for any normal amplifier. The coil will get hot so dont try it too long at a high volume.