Ionophone

An ionophone is a transducer for converting acoustic vibrations in plasma into an electrical signal, or for converting an electrical signal into acoustic vibrations in plasma:

It can be used for "generation of subsonic or ultrasonic waves as well as a microphone or loudspeaker" [http://www.roger-russell.com/ionovac/ionovac.htm Ionovac] .

Ionophones are to plasma what microphones and loudspeakers are to air.

Because the acoustic impedance of air and plasma are similar, an ionophone will work well as a microphone or loudspeaker when appropriately coupled to air.

Ionophones are more commonly used as loudspeakers than as microphones.

Unlike a loudspeaker having solid matter (cone) that moves to push air (or water in the case of an underwater speaker or hydrophone) sound is produced by plasma (ionized gas) in a spark gap.

Typically a high frequency (ultrasonic) electric arc is established, and then modulated by audio frequencies.

External links

* [http://www.ce-mag.com/archive/1999/mayjune/mrstatic.html Ions]
* [http://www.roger-russell.com/ionovac/ionovac.htm Ionovac]