The modern speaker uses an electromagneta device that turns electrical currents into magnetic forces and a diaphragma thin disc which moves to create vibrations to create and amplify sound. As the electromagnet responds to an electrical input, it pushes against the permanent magnet, creating up-and-down movement in the diaphragm and creating sound waves in the air.
The shape of the conical diaphragm and the qualities of the electromagnet can change the frequency range of the sound which is produced. Speakers include subwoofers (which create very low frequency sounds), woofers (low frequency sounds), mid-range speakers (frequencies which include the human voice and most instruments), and tweeters (high frequency sounds).*Normandin & Normandin, 2015