The singing Tesla coil is a form of plasma speaker.

This is a variant of the plasma speaker, designed for public spectacle and sheer volume rather than fidelity.

In a plasma speaker, as member of the family of massless speakers, these limitations do not exist.

Plasmatronics produced a commercial plasma speaker that used a helium tank to provide the ionization gas.

Despite offering an aspect of ideal sound-reproduction, plasma speaker designs tend not to be used in practical musical systems nor any performing instruments.

"HVwiki, plasma speaker"

Plasma speakers are a form of loudspeaker which varies air pressure via a high-energy electrical plasma instead of a solid diaphragm.

Plasmatronics is a company, founded by former Air Force Weapons Laboratory (now Phillips Laboratory) scientist Dr. Alan E. Hill, which produced a plasma speaker design.

Connected to the output of an audio amplifier, plasma speakers vary the size of a plasma glow discharge, corona discharge or electric arc which then acts as a massless radiating element, creating the compression waves in air that listeners perceive as sound.