<s>
Plasma	B-Device
speakers	I-Device
or	O
ionophones	B-Device
are	O
a	O
form	O
of	O
loudspeaker	O
which	O
varies	O
air	O
pressure	O
via	O
an	O
electrical	O
plasma	O
instead	O
of	O
a	O
solid	O
diaphragm	B-Device
.	O
</s>
<s>
The	O
term	O
ionophone	B-Device
was	O
used	O
by	O
Dr.	O
Siegfried	O
Klein	O
who	O
developed	O
a	O
plasma	O
tweeter	B-Device
that	O
was	O
licensed	O
for	O
commercial	O
production	O
by	O
DuKane	O
with	O
the	O
Ionovac	O
and	O
Fane	O
Acoustics	O
with	O
the	O
Ionofane	O
in	O
the	O
late	O
1940s	O
and	O
1950s	O
.	O
</s>
<s>
Conventional	O
loudspeaker	O
transducer	B-Algorithm
designs	O
use	O
the	O
input	O
electrical	O
audio	O
frequency	O
signal	O
to	O
vibrate	O
a	O
significant	O
mass	O
:	O
In	O
a	O
dynamic	O
loudspeaker	O
this	O
driver	B-Algorithm
is	O
coupled	O
to	O
a	O
stiff	O
speaker	B-Device
cone	I-Device
—	O
a	O
diaphragm	B-Device
which	O
pushes	O
air	O
at	O
audio	O
frequencies	O
.	O
</s>
<s>
Additionally	O
,	O
speaker	B-Device
cones	I-Device
will	O
eventually	O
suffer	O
tensile	O
fatigue	O
from	O
the	O
repeated	O
shaking	O
of	O
sonic	O
vibration	O
.	O
</s>
<s>
To	O
a	O
lesser	O
extent	O
square	O
wave	O
characteristics	O
are	O
also	O
problematic	O
;	O
the	O
reproduction	O
of	O
square	O
waves	O
most	O
stress	O
a	O
speaker	B-Device
cone	I-Device
.	O
</s>
<s>
In	O
a	O
plasma	B-Device
speaker	I-Device
,	O
as	O
member	O
of	O
the	O
family	O
of	O
massless	O
speakers	O
,	O
these	O
limitations	O
do	O
not	O
exist	O
.	O
</s>
<s>
The	O
low-inertia	O
driver	B-Algorithm
has	O
exceptional	O
transient	O
response	O
compared	O
to	O
other	O
designs	O
.	O
</s>
<s>
So	O
these	O
designs	O
are	O
more	O
effective	O
as	O
tweeters	B-Device
.	O
</s>
<s>
Plasma	B-Device
speaker	I-Device
designs	O
ionize	O
ambient	O
air	O
which	O
contains	O
the	O
gases	O
nitrogen	O
and	O
oxygen	O
.	O
</s>
<s>
Plasmatronics	O
produced	O
a	O
commercial	O
plasma	B-Device
speaker	I-Device
that	O
used	O
a	O
helium	O
tank	O
to	O
provide	O
the	O
ionization	O
gas	O
.	O
</s>
<s>
In	O
1978	O
Alan	O
E	O
.	O
Hill	O
of	O
the	O
Air	O
Force	O
Weapons	O
Laboratory	O
in	O
Albuquerque	O
,	O
NM	O
,	O
designed	O
the	O
Plasmatronics	O
Hill	O
Type	O
I	O
,	O
a	O
commercial	O
helium-plasma	O
tweeter	B-Device
.	O
</s>
<s>
This	O
avoided	O
the	O
ozone	O
and	O
nitrogen	O
oxides	O
produced	O
by	O
radio	O
frequency	O
decomposition	O
of	O
air	O
in	O
earlier	O
generations	O
of	O
plasma	O
tweeters	B-Device
.	O
</s>
<s>
In	O
the	O
1950s	O
,	O
the	O
pioneering	O
DuKane	O
Corporation	O
produced	O
the	O
air-ionizing	O
Ionovac	O
,	O
marketed	O
in	O
the	O
UK	O
as	O
the	O
Ionophone	B-Device
.	O
</s>
<s>
To	O
make	O
the	O
plasma	B-Device
speaker	I-Device
a	O
more	O
widely	O
available	O
product	O
,	O
ExcelPhysics	O
,	O
a	O
Seattle-based	O
company	O
,	O
and	O
Images	O
Scientific	O
Instruments	O
,	O
a	O
New	O
York-based	O
company	O
,	O
both	O
offered	O
their	O
own	O
variant	O
of	O
the	O
plasma	B-Device
speaker	I-Device
as	O
a	O
DIY	O
kit	O
.	O
</s>
<s>
A	O
flame	B-Device
speaker	I-Device
uses	O
a	O
modulated	O
flame	O
for	O
the	O
driver	B-Algorithm
and	O
could	O
be	O
considered	O
related	O
to	O
the	O
plasma	O
loudspeaker	O
.	O
</s>
<s>
A	O
similar	O
effect	O
is	O
occasionally	O
observed	O
in	O
the	O
vicinity	O
of	O
high-power	O
amplitude-modulated	B-Device
radio	O
transmitters	O
when	O
a	O
corona	O
discharge	O
(	O
inadvertently	O
)	O
occurs	O
from	O
the	O
transmitting	O
antenna	O
,	O
where	O
voltages	O
in	O
the	O
tens	O
of	O
thousands	O
are	O
involved	O
.	O
</s>
