You searched for: “ionic tweeter
ionic tweeter
A type of speaker in which a varying electrostatic field activates a mass of air ionized by a high-voltage radio-frequency field.

Ionic speakers are capable of extremely extended high-frequency response (up to 100 kHz or so) because of the extreme lightness of the ionic "diaphragm".

This entry is located in the following unit: ion, ion- + (page 6)