Ordinary headphones have a cone shape diaphragm typically made out of paper, plastic or metal. The techies know these as electro-dynamic Transducers, and they work on electromagnetic principals and basically move Air which arrives at your ears as a sound Wave. Also, electro-dynamic speakers are a point source, meaning sound disperses radially from the speaker's center. Esl's use electrostatic principals to reproduce which are very different from the principals above. Instead of a magnet and cone diaphragm structure, esl's use a large, heavily biased (high voltage) ultra-thin plastic MEMBRANE 'hat' is sandwiched between two conductive stator plates to reproduce the sound. The ESL is a linear source and the music disperses evenly over the whole surface of the diaphragm. They are also dipole, meaning sound waves radiate from the front and rear, and the MEMBRANE is not usually enclosed in a cabinet, thus the thin speaker profiles and unique acoustic qualities.