How does it work? The principle is simple. Every device with an electric motor is able to generate a sound. Scanners and floppy drives use stepper motors to move the head with sensors which scans the image or performs read/write operations on a magnetic disk. The sound generated by a motor depends on driving speed. The higher the frequency, the greater the pitch. Hard disks use a magnet and a coil to tilt the head. When voltage is supplied for long enough, the head speeds up and hits the bound making the "drum hit" sound. The disk head coil can also be used as a speaker to play tones or even music, but… that would be too easy and too obvious.