electric signals (from a phone, an iPad, or any other device capable of playing music) into sound by sending the electric signal through a cable (the long wire plus what plugs into the device) into a coil of metal wires that is placed near a permanent magnet.

The coil of wires produces a magnetic field (the area around a magnetic object that can attract or repel another magnetic object) as it receives the electric signal continuously, and this magnetic field from the wires interacts with the magnetic field of the magnet. The magnetic field of the wires changes rapidly, resulting in its attraction and repulsion in turn to the permanent magnet. The wires are allowed to move, and vibrations due to the magnetic attraction and repulsion move the wires, which then transfer the movement to a flexible object such as a plastic cone. The flexible object increases the vibrations and moves the surrounding air, producing sound waves that reach our ears.

A loudspeaker is a machine that makes noise. Loudspeakers are found in TVs, radios, and the system that makes announcements at school. Headphones are small loudspeakers that produce the sound directly into your ear, so that only you can hear them.

Loudspeakers work by turning electricity into sound. To understand how this works, we have to understand how sound works. Sound is a type of vibration. Just like when a large truck passes by and you feel the rumble, sounds are vibrations that your ears are sensitive enough to feel. So, to produce sound, a loudspeaker (including headphones) needs to produce vibrations. To do this, the loudspeaker takes an electrical signal, and converts the signal into magnetism. This magnetism causes a portion of the loudspeaker to move back and forth quickly, creating vibrations: sound waves that you can hear!