ions loudspeaker
In all known loudspeakersexcept the ion loudspeaker, a mass is moved and the vibrations are transmitted as sound pressure. The ion loudspeaker, on the other hand, works masslessly by changing the air volume through temperature changes.
In the ion loudspeaker, the sound waves are transmitted by a brief change in volume as the air molecules transport this change in volume further.
Technically, an ion or plasma loudspeaker is an RF oscillator whose output power causes air ionization. This ionization is modulated with the audio signal, making it stronger and weaker. Stronger ionization produces a higher temperature and thus a higher sound pressure.
Because the ion loudspeaker is massless, it has no distortion and an extremely linear frequency response that extends from about 5 kHz well into the ultrasonic range, well beyond the human hearing limit. However, the ionization of air produces ozone, which is detrimental.