<s>
A	O
horn	B-Device
loudspeaker	I-Device
is	O
a	O
loudspeaker	O
or	O
loudspeaker	O
element	O
which	O
uses	O
an	O
acoustic	O
horn	O
to	O
increase	O
the	O
overall	O
efficiency	O
of	O
the	O
driving	O
element(s )	O
.	O
</s>
<s>
A	O
common	O
form	O
(	O
right	O
)	O
consists	O
of	O
a	O
compression	B-Device
driver	I-Device
which	O
produces	O
sound	O
waves	O
with	O
a	O
small	O
metal	O
diaphragm	B-Device
vibrated	O
by	O
an	O
electromagnet	O
,	O
attached	O
to	O
a	O
horn	O
,	O
a	O
flaring	O
duct	O
to	O
conduct	O
the	O
sound	O
waves	O
to	O
the	O
open	O
air	O
.	O
</s>
<s>
Another	O
type	O
is	O
a	O
woofer	B-Device
driver	O
mounted	O
in	O
a	O
loudspeaker	B-Device
enclosure	I-Device
which	O
is	O
divided	O
by	O
internal	O
partitions	O
to	O
form	O
a	O
zigzag	O
flaring	O
duct	O
which	O
functions	O
as	O
a	O
horn	O
;	O
this	O
type	O
is	O
called	O
a	O
folded	B-Device
horn	I-Device
speaker	O
.	O
</s>
<s>
The	O
horn	O
serves	O
to	O
improve	O
the	O
coupling	O
efficiency	O
between	O
the	O
speaker	B-Device
driver	I-Device
and	O
the	O
air	O
.	O
</s>
<s>
The	O
horn	O
can	O
be	O
thought	O
of	O
as	O
an	O
"	O
acoustic	O
transformer	B-Algorithm
"	O
that	O
provides	O
impedance	O
matching	O
between	O
the	O
relatively	O
dense	O
diaphragm	B-Device
material	O
and	O
the	O
less-dense	O
air	O
.	O
</s>
<s>
The	O
angular	O
coverage	O
(	O
radiation	B-Device
pattern	I-Device
)	O
of	O
the	O
horn	O
is	O
determined	O
by	O
the	O
shape	O
and	O
flare	O
of	O
the	O
mouth	O
.	O
</s>
<s>
A	O
major	O
problem	O
of	O
horn	B-Device
speakers	I-Device
is	O
that	O
the	O
radiation	B-Device
pattern	I-Device
varies	O
with	O
frequency	O
;	O
high	O
frequency	O
sound	O
tends	O
to	O
be	O
emitted	O
in	O
narrow	O
beams	O
with	O
poor	O
off-axis	O
performance	O
.	O
</s>
<s>
The	O
main	O
advantage	O
of	O
horn	B-Device
loudspeakers	I-Device
is	O
they	O
are	O
more	O
efficient	O
;	O
they	O
can	O
typically	O
produce	O
approximately	O
3	O
times	O
(	O
10	O
dB	O
)	O
more	O
sound	O
than	O
a	O
cone	O
speaker	O
from	O
a	O
given	O
amplifier	O
output	O
.	O
</s>
<s>
Their	O
disadvantage	O
is	O
that	O
their	O
frequency	O
response	O
is	O
more	O
uneven	O
because	O
of	O
resonance	B-Application
peaks	O
,	O
and	O
horns	O
have	O
a	O
cutoff	O
frequency	O
below	O
which	O
their	O
response	O
drops	O
off	O
.	O
</s>
<s>
To	O
achieve	O
adequate	O
response	O
at	O
bass	O
frequencies	O
horn	B-Device
speakers	I-Device
must	O
be	O
very	O
large	O
and	O
cumbersome	O
,	O
so	O
they	O
are	O
more	O
often	O
used	O
for	O
midrange	O
and	O
high	O
frequencies	O
.	O
</s>
<s>
The	O
first	O
practical	O
loudspeakers	O
,	O
introduced	O
around	O
the	O
turn	O
of	O
the	O
20th	O
century	O
,	O
were	O
horn	B-Device
speakers	I-Device
.	O
</s>
<s>
Due	O
to	O
the	O
development	O
in	O
recent	O
decades	O
of	O
cone	O
loudspeakers	O
which	O
sometimes	O
have	O
a	O
flatter	O
frequency	O
response	O
,	O
and	O
the	O
availability	O
of	O
inexpensive	O
amplifier	O
power	O
,	O
the	O
use	O
of	O
horn	B-Device
speakers	I-Device
in	O
high	O
fidelity	O
audio	O
systems	O
over	O
the	O
last	O
decades	O
has	O
declined	O
.	O
</s>
<s>
The	O
most	O
well	O
known	O
early	O
horn	B-Device
loudspeakers	I-Device
were	O
those	O
on	O
mechanical	O
phonographs	O
,	O
where	O
the	O
record	O
moved	O
a	O
heavy	O
metal	O
needle	O
that	O
excited	O
vibrations	O
in	O
a	O
small	O
metal	O
diaphragm	B-Device
that	O
acted	O
as	O
the	O
driver	O
for	O
a	O
horn	O
.	O
</s>
<s>
The	O
horn	O
improves	O
the	O
loading	O
and	O
thus	O
gets	O
a	O
better	O
"	O
coupling	O
"	O
of	O
energy	O
from	O
the	O
diaphragm	B-Device
into	O
the	O
air	O
,	O
and	O
the	O
pressure	O
variations	O
therefore	O
get	O
smaller	O
as	O
the	O
volume	O
expands	O
and	O
the	O
sound	O
travels	O
up	O
the	O
horn	O
.	O
</s>
<s>
The	O
exponential	O
horn	O
has	O
an	O
acoustic	O
loading	O
property	O
that	O
allows	O
the	O
speaker	B-Device
driver	I-Device
to	O
remain	O
evenly	O
balanced	O
in	O
output	O
level	O
over	O
its	O
frequency	O
range	O
.	O
</s>
<s>
A	O
major	O
drawback	O
is	O
that	O
the	O
exponential	O
horn	O
allows	O
for	O
a	O
narrowing	O
of	O
the	O
radiation	B-Device
pattern	I-Device
as	O
frequency	O
increases	O
,	O
making	O
for	O
high	O
frequency	O
'	O
beaming	O
 '	O
on	O
axis	O
and	O
dull	O
sound	O
off	O
axis	O
.	O
</s>
<s>
The	O
revolutionary	O
coaxial	O
driver	O
,	O
the	O
Altec	B-Device
Lansing	I-Device
Duplex	I-Device
601	O
and	O
604	O
,	O
used	O
a	O
multicell	O
horn	O
for	O
its	O
high	O
frequency	O
component	O
from	O
1943	O
to	O
1998	O
.	O
</s>
<s>
For	O
ease	O
in	O
mounting	O
to	O
loudspeaker	B-Device
cabinets	I-Device
,	O
flat	O
front	O
radial	O
horns	O
have	O
been	O
used	O
,	O
for	O
instance	O
by	O
in	O
their	O
SQ	O
90	O
high-frequency	O
horn	O
.	O
</s>
<s>
Most	O
manufacturers	O
of	O
active	O
electronic	O
audio	B-Algorithm
crossovers	I-Algorithm
responded	O
to	O
this	O
requirement	O
by	O
adding	O
an	O
optional	O
CD	O
EQ	O
boost	O
filter	O
or	O
high	O
frequency	O
shelf	O
filter	O
.	O
</s>
<s>
For	O
instance	O
,	O
such	O
circuitry	O
was	O
provided	O
via	O
internal	O
jumper	O
links	O
by	O
BSS	O
in	O
their	O
FDS-310	O
crossover	B-Algorithm
and	O
by	O
Rane	O
in	O
their	O
AC	O
22S	O
and	O
AC	O
23B	O
crossovers	B-Algorithm
.	O
</s>
<s>
Rane	O
allowed	O
for	O
greater	O
front	O
panel	O
control	O
of	O
two	O
bandpasses	O
(	O
"	O
hi-mid	O
"	O
and	O
"	O
high	O
"	O
)	O
using	O
CD	O
horn	O
equalization	O
including	O
sweepable	O
frequency	O
range	O
on	O
their	O
AC	O
24	O
crossover	B-Algorithm
.	O
</s>
<s>
Further	O
refinements	O
of	O
the	O
filtering	O
process	O
are	O
available	O
in	O
DSP-based	O
crossovers	B-Algorithm
.	O
</s>
<s>
The	O
synergy	O
horn	O
design	O
promises	O
greater	O
power	O
output	O
achieved	O
from	O
a	O
smaller	O
loudspeaker	B-Device
enclosure	I-Device
.	O
</s>
<s>
Because	O
the	O
design	O
retains	O
pattern	O
control	O
through	O
its	O
crossover	B-Algorithm
regions	O
and	O
over	O
a	O
large	O
range	O
of	O
its	O
total	O
bandwidth	O
,	O
and	O
because	O
the	O
acoustic	O
center	O
of	O
the	O
design	O
is	O
near	O
the	O
rear	O
of	O
the	O
enclosure	O
,	O
it	O
is	O
more	O
easily	O
combined	O
in	O
arrays	O
for	O
public	O
address	O
applications	O
.	O
</s>
<s>
These	O
are	O
designed	O
more	O
to	O
control	O
the	O
radiation	B-Device
pattern	I-Device
rather	O
than	O
to	O
gain	O
efficiency	O
via	O
improved	O
acoustic	O
loading	O
.	O
</s>
<s>
The	O
horn	O
was	O
basically	O
a	O
simple	O
conic	O
section	O
but	O
its	O
throat	O
was	O
curved	O
in	O
a	O
circular	O
arc	O
to	O
match	O
the	O
desired	O
throat	O
size	O
for	O
proper	O
mating	O
to	O
the	O
speaker	B-Device
driver	I-Device
.	O
</s>
<s>
Oblate	O
spheroid	O
waveguide	O
(	O
OSWG	O
)	O
horn	O
designs	O
improve	O
directivity	B-Device
pattern	I-Device
control	O
above	O
1kHz	O
,	O
provide	O
a	O
lower	O
frequency	O
of	O
directivity	O
to	O
better	O
match	O
the	O
mid-range	O
driver	O
,	O
and	O
,	O
as	O
claimed	O
by	O
inventor	O
Dr.	O
Earl	O
Geddes	O
,	O
mitigate	O
higher	O
order	O
modes	O
,	O
a	O
form	O
of	O
phase	O
and	O
amplitude	O
distortion	O
.	O
</s>
<s>
Horn	B-Device
loudspeakers	I-Device
are	O
used	O
in	O
many	O
audio	O
applications	O
.	O
</s>
<s>
The	O
drivers	O
in	O
horn	B-Device
loudspeakers	I-Device
can	O
be	O
very	O
small	O
,	O
even	O
for	O
bass	O
frequencies	O
where	O
conventional	O
loudspeakers	O
would	O
need	O
to	O
be	O
very	O
large	O
for	O
equivalent	O
performance	O
.	O
</s>
<s>
Horn	B-Device
loudspeakers	I-Device
can	O
be	O
designed	O
to	O
reproduce	O
a	O
wide	O
range	O
of	O
frequencies	O
using	O
a	O
single	O
,	O
small	O
driver	O
;	O
to	O
some	O
extent	O
these	O
can	O
be	O
designed	O
without	O
requiring	O
a	O
crossover	B-Algorithm
.	O
</s>
<s>
Horn	B-Device
loudspeakers	I-Device
can	O
also	O
be	O
used	O
to	O
provide	O
the	O
very	O
high	O
sound	O
pressure	O
levels	O
needed	O
for	O
sound	O
reinforcement	O
and	O
public	O
address	O
applications	O
,	O
although	O
in	O
these	O
high	O
sound	O
pressure	O
applications	O
,	O
high	O
fidelity	O
is	O
sometimes	O
compromised	O
for	O
the	O
sake	O
of	O
the	O
necessary	O
efficiency	O
,	O
and	O
also	O
for	O
the	O
controlled	O
dispersion	O
characteristics	O
which	O
are	O
generally	O
required	O
in	O
most	O
large	O
volume	O
spaces	O
.	O
</s>
<s>
EAW	O
horn-loaded	O
loudspeakers	O
that	O
have	O
been	O
processed	O
with	O
this	O
proprietary	O
system	O
show	O
reduced	O
compression	B-Device
driver	I-Device
diaphragm/phase	O
plug	O
time-smear	O
distortion	O
while	O
retaining	O
high	O
output	O
power	O
and	O
controlled	O
dispersion	O
.	O
</s>
<s>
Concert	O
venues	O
often	O
use	O
large	O
arrays	O
of	O
horn	B-Device
loudspeakers	I-Device
for	O
high-volume	O
bass	O
reproduction	O
(	O
"	O
bass	O
bins	O
"	O
or	O
subwoofers	B-Application
)	O
,	O
in	O
order	O
to	O
provide	O
bass	O
that	O
concertgoers	O
can	O
not	O
only	O
hear	O
but	O
feel	O
.	O
</s>
<s>
Combining	O
multiple	O
horn	B-Device
loudspeakers	I-Device
in	O
an	O
array	O
affords	O
the	O
same	O
benefits	O
as	O
having	O
a	O
single	O
horn	O
with	O
a	O
greater	O
mouth	O
area	O
:	O
the	O
low	O
frequency	O
cut-off	O
extends	O
lower	O
as	O
the	O
horn	O
mouth	O
gets	O
larger	O
,	O
and	O
the	O
array	O
has	O
the	O
greater	O
output	O
power	O
of	O
multiple	O
drivers	O
.	O
</s>
<s>
Consumer	O
audio	O
employs	O
horn	B-Device
loudspeakers	I-Device
for	O
controlled	O
directivity	O
(	O
to	O
limit	O
audio	O
reflections	O
from	O
room	O
surfaces	O
such	O
as	O
walls	O
,	O
floor	O
,	O
and	O
ceiling	O
)	O
and	O
for	O
greater	O
speaker	O
sensitivity	O
.	O
</s>
<s>
Horn	B-Device
loudspeakers	I-Device
can	O
provide	O
very	O
high	O
efficiencies	O
,	O
making	O
them	O
a	O
good	O
match	O
for	O
very	O
low-powered	O
amplifiers	O
,	O
such	O
as	O
single-ended	O
triode	O
amps	O
or	O
other	O
tube	O
amplifiers	O
.	O
</s>
<s>
Some	O
audiophiles	O
use	O
horn	B-Device
loudspeakers	I-Device
for	O
audio	O
reproduction	O
,	O
while	O
others	O
eschew	O
horn	O
systems	O
for	O
their	O
harmonic	O
resonances	B-Application
,	O
finding	O
in	O
them	O
an	O
unpleasant	O
form	O
of	O
distortion	O
.	O
</s>
<s>
Since	O
there	O
are	O
a	O
variety	O
of	O
horn	O
designs	O
(	O
of	O
differing	O
length	O
,	O
material	O
,	O
and	O
taper	O
)	O
,	O
as	O
well	O
as	O
different	O
drivers	O
,	O
it	O
is	O
,	O
to	O
some	O
extent	O
,	O
impossible	O
to	O
give	O
such	O
blanket	O
characterizations	O
to	O
horn	B-Device
loudspeakers	I-Device
.	O
</s>
<s>
Audiophiles	O
using	O
low	O
power	O
amplifiers	O
,	O
sometimes	O
in	O
the	O
5	O
to	O
25	O
watt	O
range	O
,	O
may	O
find	O
the	O
high	O
efficiency	O
of	O
horn	B-Device
loudspeakers	I-Device
an	O
especially	O
attractive	O
feature	O
.	O
</s>
<s>
The	O
high	O
sensitivity	O
of	O
horn	B-Device
loudspeakers	I-Device
aids	O
in	O
achieving	O
movie	O
theater	O
sound	O
levels	O
at	O
the	O
listening	O
position	O
with	O
typical	O
~	O
100	O
watts-per-channel	O
receiver/amplifiers	O
used	O
in	O
home	O
cinema	O
.	O
</s>
