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Traditionally, a voice coil is the inductor in a speaker driver through which a signal voltage is passed that vibrates the cone and thus produces sound.

The computer industry discovered it can also use the voice coil for very fast and precise linear positioning. Changes in voltage will correspond to a change in force or position, and thus (with some feedback control) can be used to control the position of a head in a hard disk.

Typically the control feedback used to calibrate the voice coil is magneticly stored data on the same platter with the regular disk data, which makes low level formatting the drive a bit tricky, and only possible at the factory.

This was brought to you by the Save Our Archaic Technical Terms Society. Thanks to TinCanFury for his excellent speaker nodes.