How does it work? Whatever you are using to supply the audio input sends an electrical signal to the coil on the speaker. When this electrical current flows through the wires, it creates a magnetic field. This field interacts with the field of the magnet, making the coil move as it is attracted and repelled. Since the coil is glued to the cup, the cup is moved as well. The moving cup moves the air, which creates the sound. When we use the cup like this it is called a diaphragm.