The naming of massless transducers is often inaccurate, or at least not accurate enough, leading to confusion.
Examples
Massless speakers that are currently available:
Vaugn Loudspeakers’ Plasma Signature Lansche Audio Corona Acapella Ion TW-1
The plasma, corona and ion speakers in these designs are all the same type from the same root design – but with completely different names! They use a glow discharge plasma. Historically the naming is worse. Is a corona wind the same as an ion cloud? Could be, but maybe they are force fields as well. Is my Ionofone like your Plasmatronic? Perhaps they are both like a Waveion.
"Normal" Loudspeakers
Let’s start with some basics. An electroacoustic transducer, that which takes an electrical signal and converts it into sound waves, is called a loudspeaker. The word speaker is synonymous with loudspeaker – although older references may write ‘speaker as if shortening the word loudspeaker.
Any conventional loudspeaker can be considered electromechanical. The most common has a cone, coil and magnet and is known as a dynamic speaker. An electrodynamic loudspeaker to use its full name, also electromagnetic, but these names are less often used because everyone knows what a dynamic loudspeaker is. It is after all the most common type of speaker by far and as a result it is usually known simply as a speaker or loudspeaker.
There are a small variety of other speakers that might be put into a category of “moving mass”. These can be related to the dynamic speaker but have different names to distinguish them from the cone/coil/magnet construction. They are often electrodynamic but have names such as ribbon, balanced armature, air motion transformer (AMT), planar magnetic, orthodynamic, isodynamic, magnetostatic, distributed mode (DML), MEMS etc. In addition to dynamic moving mass speakers there are most notably the electrostatic, piezo ceramic and magnetostrictive types.
There has been little regulation or standardisation of naming as they typically get named by the inventors, related to marketing names, what they are made of or the physics employed. However, in general most of those names describe their specific technology fairly well.
When it comes to naming, the corona and glow discharge plasma speakers are a mess. They are both types of plasma and contain ions but they create sound using different physical principles. However the same names are used interchangeably and as a result people often misunderstand the underlying principle at work for a specific speaker. The terms are used for marketing but also in the scientific descriptions and by the inventors and designers of the speakers.
They have both been referred to as the following (at least), not even including most brand names:
Plasma Ion Arc Ionic Corona Ionophone Plasma arc Ion wind Ion cloud Corona wind Corona discharge Ion-plasma Singing arc Speaking arc Talking flame Blue flame Force field
The most commonly used term over all is plasma speaker and the most common type of that is a plasma tweeter. This can be extended to plasma arc loudspeaker. This is most often used to describe glow discharge, where there is a visible glow plasma, and this is by far the most common commercial design.
Even near its early conception, this type of speaker was described as ionic and called an ionophone (later Ionofone, Ionofane etc. used as brand names). The use of ions in the naming of a glow discharge is also common. Yes plasma is an ionised gas and so it is not inaccurate, but the mechanism creating the sound is the heating of the air by the plasma. In a way they are more thermal than ionic.
Then there is the corona discharge. This type has only once been seen in a commercial product, the Plasmasonic, otherwise in prototypes and demonstrations. It is rarely described as a plasma speaker, although it has and it is in the first commercial name. Early on the term corona wind was used but most often now it can be referred to as ion wind, ion cloud or just ionic or corona. Electrostatic has on occasion been used as a description, but the basic mode of operation does not involve a charge at rest even though there may be some static charge on or around the discharge points.
Further to that, testing has revealed that in the corona wind it is electrons that are the predominant cause of the air flow making it an electric speaker and only slightly ionic. Electric just seems to be too vague a description though, aren’t all loudspeakers electric in some way?
The use of the words corona and/or discharge nowadays has quite a different negative meaning to most people, so the corona discharge can have a harder time finding a name.
A Solution?
This doesn’t pose a problem in most peoples lives but it is in the remarkably narrow field of massless speakers. “That’s a nice ion speaker.”, “It’s not, I think you’ll find it’s a plasma arc wind transducer.”
So the following simple names could be used with their easily recognisable forms. Taking into account the historical usage, even though they may not be totally scientifically accurate.
If the plasma is too bright to look at, call it an arc speaker. Alternatives, plasma arc speaker. Physically a non-thermal arc discharge plasma electrohydrodynamic loudspeaker.
If you can see a steady plasma, call it a plasma speaker. Alternatives, ionophone. Physically a non-thermal glow discharge plasma electrohydrodynamic loudspeaker.
If the plasma looks like lightning call it a brush plasma speaker. Alternatives, zeusaphone. Physically a non-thermal brush discharge plasma electrohydrodynamic loudspeaker.
If you can’t see any plasma, call it an ionic speaker. Alternatives, ion or corona wind. Physically a non-thermal corona discharge plasma electrohydrodynamic loudspeaker.
If you set something on fire to make it then it’s a flame speaker. Alternatives, pyrophone. Physically a flame thermodynamic loudspeaker.
If you make something warm to make sound then it's a thermal speaker. Alternative thermodynamic speaker, thermophone. Physically a solid state thermodynamic loudspeaker.
