voice coil
Voice coil is the term used to describe the coil that is permanently connected to the diaphragm in electrodynamically operating plunger coil loudspeakers and is located in an air gap of a permanent magnet.
Magnetic fields are generated inthe voice coil by the current flowing through it, the lines of force of which are repelled or attracted by the permanent magnet of the speaker. This causes the voice coil to move, and with it the diaphragm from which the sound is released. The force with which the voice coil moves depends on the number of turns and the wire length as well as the magnetic flux density.
The voice coil has an inductance of a few milli-Henry (mH) and forms an impedance of ohmic resistance and reactance for the current flowing through it. The latter increases with increasing frequencies, which is reflected in the loudspeaker impedance.