For hearing a sound. It should be changed to electric signal and transmitted to a speaker through electric wire or electric wave. Then a diaphragm vibrates air and reproduces the original sound. In this course the conventional speakers occupied much space and had to keep fixed form like a cone shape or an oval in order to reproduce good sound with the help of resonance. There are many ceramic parts in conventional speaker and there are several steps containing high temperature process to form ceramic parts. But a film speaker has a very big advantage of simple process.