A wire that has an electric current flowing through it, like our 500 turns of copper wire, becomes a magnet (an electromagnet). If near a permanent magnet, like the one glued onto the ice-cream container, it will be attract or repulse it, depending on which poles are close together.

This means the bottom of the container with the magnet glued on will move back-and-forth with the magnet, slapping into the air, creating sound waves.

Our walkman supplies the electric current, but it turns the electromagnet on and off very fast to creating a linear (back-and-forth) movement rather than a rotational one (like inside normal motors). The linear motion of the our speaker "cone" creates air pressure waves that we perceive as sound.