The electrostatic earphone has a light and thin diaphragm and is polarized by a high DC voltage. The power required for polarization is converted from alternating current and is also supplied by batteries. The diaphragm is suspended in the electrostatic field formed by two fixed metal plates (stators).
Special amplifiers must be used to convert the audio signal into voltage signals of hundreds of volts. Electrostatic earphones are expensive, not easy to drive, and the sound pressure level they can reach is not as large as that of moving coil earphones. However, it has fast response speed, can replay all kinds of tiny details and has very low distortion.