As a sound receiver coils in electrical signal format changes as the electromagnetic signals. To push the fixed magnetic field Cause of coil, cone went on to speakers or wobbly diaphragms.
A transmitter coil in the form of electrical signals coming into electromagnetic signals. To push for a permanent magnetic field The shake Boys coil. To make the speaker cone Or vibrating diaphragm
A receiver coil in the form of voice communication over a electromagnetic frequencies. To push the permanent magnetic field. Cause the vibration of the voice coil to make cone speakers or diaphragm vibration.