<s>
A	O
dipole	B-Architecture
speaker	I-Architecture
enclosure	O
in	O
its	O
simplest	O
form	O
is	O
constructed	O
by	O
mounting	O
a	O
loudspeaker	O
driver	O
on	O
a	O
flat	O
panel	O
.	O
</s>
<s>
For	O
this	O
reason	O
dipole	B-Architecture
speakers	I-Architecture
are	O
often	O
used	O
as	O
surround	O
channel	O
speakers	O
,	O
where	O
a	O
diffuse	O
sound	O
is	O
desired	O
to	O
create	O
ambience	O
.	O
</s>
<s>
A	O
dipole	B-Architecture
speaker	I-Architecture
works	O
by	O
creating	O
air	O
movement	O
(	O
as	O
sound	O
pressure	O
waves	O
)	O
directly	O
from	O
the	O
front	O
and	O
back	O
surfaces	O
of	O
the	O
driver	O
,	O
rather	O
than	O
by	O
impedance	O
matching	O
one	O
or	O
both	O
outputs	O
to	O
the	O
air	O
.	O
</s>
<s>
Common	O
examples	O
include	O
electrostatic	O
or	O
ribbon	O
drivers	O
,	O
though	O
a	O
conventional	O
cone	O
driver	O
mounted	O
in	O
an	O
open	O
baffle	O
also	O
works	O
as	O
a	O
dipole	B-Architecture
loudspeaker	I-Architecture
.	O
</s>
<s>
Dipole	B-Architecture
speakers	I-Architecture
are	O
said	O
to	O
be	O
better	O
for	O
rear	O
speakers	O
in	O
surround-sound	O
systems	O
,	O
although	O
this	O
is	O
disputed	O
(	O
or	O
at	O
least	O
success	O
depends	O
on	O
factors	O
such	O
as	O
room	O
acoustics	O
,	O
type	O
of	O
music	O
,	O
and	O
so	O
on	O
)	O
.	O
</s>
<s>
However	O
,	O
these	O
enclosures	O
are	O
less	O
efficient	O
because	O
,	O
for	O
the	O
same	O
driver	O
,	O
a	O
dipole	O
results	O
in	O
less	O
sound	O
pressure	O
level	O
than	O
a	O
closed	O
or	O
ported	O
enclosure	O
,	O
and	O
certainly	O
far	O
less	O
than	O
a	O
properly	O
designed	O
horn	B-Device
.	O
</s>
