My PCB speaker is very simple and works just like any other speaker.
Its main components are the magnet and a coil, in this case a flexible printed traces. The vibrations created from the coil pushes the surrounding air to create sound waves. I also tried adding a diaphragm to amplify the music. It also worked with a 1.6mm rigid pcb, having the magnet connected to the diaphragm.
Check out the full video: