 Speaker drivers include a diaphragm that moves back and forth to create pressure waves in the air column in front, and depending on the application, at some angle to the sides.The diaphragm is typically in the shape of a cone for low and mid frequencies or a dome for higher frequencies, or less commonly, a ribbon, and is usually made of coated or uncoated paper or polypropylene plastic.More exotic materials are used on some drivers, such as woven fiberglass, carbon fiber, aluminum, titanium, pure cross carbon and a very few use PEI, polyimide, PET film plastic film as the cone, dome or radiator.