<s>
A	O
stage	O
monitor	O
system	O
is	O
a	O
set	O
of	O
performer-facing	O
loudspeakers	O
called	O
monitor	O
speakers	O
,	O
stage	O
monitors	O
,	O
floor	O
monitors	O
,	O
wedges	O
,	O
or	O
foldbacks	B-Device
on	O
stage	O
during	O
live	O
music	O
performances	O
in	O
which	O
a	O
sound	O
reinforcement	O
system	O
is	O
used	O
to	O
amplify	O
a	O
performance	O
for	O
the	O
audience	O
.	O
</s>
<s>
For	O
live	O
sound	O
reproduction	O
during	O
popular	O
music	O
concerts	O
in	O
mid	O
-	O
to	O
large-size	O
venues	O
,	O
there	O
are	O
typically	O
two	O
complete	O
loudspeaker	O
systems	O
and	O
PA	O
systems	O
(	O
also	O
called	O
sound	O
reinforcement	O
systems	O
)	O
:	O
the	O
main	O
or	O
front-of-house	O
system	O
and	O
the	O
monitor	O
or	O
foldback	B-Device
system	O
.	O
</s>
<s>
Without	O
a	O
foldback	B-Device
system	O
,	O
the	O
sound	O
that	O
on-stage	O
performers	O
would	O
hear	O
from	O
front	O
of	O
house	O
would	O
be	O
the	O
reverberated	O
reflections	O
bouncing	O
from	O
the	O
rear	O
wall	O
of	O
the	O
venue	O
.	O
</s>
<s>
In	O
situations	O
with	O
poor	O
or	O
absent	O
foldback	B-Device
mixes	O
,	O
vocalists	O
may	O
end	O
up	O
singing	O
off-tune	O
or	O
out	O
of	O
time	O
with	O
the	O
band	O
.	O
</s>
<s>
A	O
separately	O
mixed	O
signal	O
is	O
often	O
routed	O
to	O
the	O
foldback	B-Device
speaker	O
to	O
allow	O
musicians	O
to	O
hear	O
their	O
performance	O
as	O
the	O
audience	O
hears	O
it	O
or	O
in	O
a	O
way	O
that	O
helps	O
improve	O
their	O
performance	O
.	O
</s>
<s>
More	O
frequently	O
,	O
major	O
professional	O
bands	O
and	O
singers	O
often	O
use	O
small	O
in-ear	B-Device
monitors	I-Device
rather	O
than	O
onstage	O
monitor	O
speakers	O
.	O
</s>
<s>
The	O
two	O
systems	O
usually	O
share	O
microphones	B-Application
and	O
direct	O
inputs	O
using	O
a	O
splitter	O
microphone	B-Application
snake	O
.	O
</s>
<s>
The	O
front-of-house	O
system	O
,	O
which	O
provides	O
the	O
amplified	O
sound	O
for	O
the	O
audience	O
,	O
will	O
typically	O
use	O
a	O
number	O
of	O
powerful	O
amplifiers	O
driving	O
a	O
range	O
of	O
large	O
,	O
heavy-duty	O
loudspeaker	O
cabinets	O
including	O
low-frequency	O
speaker	O
cabinets	O
called	O
subwoofers	B-Application
,	O
full-range	O
speaker	O
cabinets	O
,	O
and	O
high-range	O
horns	O
.	O
</s>
<s>
The	O
use	O
of	O
performer-facing	O
loudspeakers	O
for	O
foldback	B-Device
or	O
monitoring	O
may	O
have	O
been	O
developed	O
independently	O
by	O
sound	O
engineers	O
in	O
different	O
cities	O
who	O
were	O
trying	O
to	O
resolve	O
this	O
problem	O
.	O
</s>
<s>
The	O
earliest	O
recorded	O
instance	O
that	O
a	O
loudspeaker	O
was	O
used	O
for	O
foldback	B-Device
(	O
monitoring	O
)	O
was	O
for	O
Judy	O
Garland	O
at	O
the	O
San	O
Francisco	O
Civic	O
Auditorium	O
on	O
September	O
13	O
,	O
1961	O
;	O
provided	O
by	O
McCune	O
Sound	O
Service	O
.	O
</s>
<s>
"	O
Duke	O
"	O
Mewborn	O
of	O
Atlanta	O
's	O
Baker	O
Audio	O
used	O
left	O
and	O
right	O
arrays	O
of	O
Altec	O
loudspeakers	O
to	O
cover	O
the	O
audience	O
and	O
to	O
serve	O
sidefill	O
duties	O
for	O
the	B-Application
Beatles	I-Application
at	O
Atlanta	O
Stadium	O
on	O
August	O
18	O
,	O
1965	O
.	O
</s>
<s>
Bill	O
Hanley	O
working	O
with	O
Neil	O
Young	O
of	O
Buffalo	O
Springfield	O
pioneered	O
the	O
concept	O
of	O
a	O
speaker	O
on	O
the	O
floor	O
angled	O
up	O
at	O
the	O
performer	O
with	O
directional	O
microphones	B-Application
to	O
allow	O
louder	O
volumes	O
with	O
less	O
feedback	O
.	O
</s>
<s>
Microphones	B-Application
and	O
direct	O
inputs	O
are	O
shared	O
with	O
the	O
front-of-house	O
system	O
.	O
</s>
<s>
In	O
this	O
case	O
,	O
a	O
microphone	B-Application
splitter	O
is	O
used	O
to	O
split	O
the	O
signal	O
from	O
the	O
microphones	B-Application
and	O
direct	O
inputs	O
between	O
the	O
monitor	O
mixer	O
and	O
the	O
FOH	O
mixer	O
.	O
</s>
<s>
This	O
splitter	O
may	O
be	O
part	O
of	O
the	O
microphone	B-Application
snake	O
or	O
it	O
may	O
be	O
built	O
into	O
the	O
monitor	O
mixer	O
.	O
</s>
<s>
A	O
variation	O
on	O
this	O
is	O
to	O
add	O
an	O
additional	O
input	O
to	O
each	O
mixer	O
which	O
is	O
the	O
performer	O
's	O
instrument	O
or	O
vocal	O
microphone	B-Application
so	O
that	O
each	O
performer	O
can	O
add	O
more	O
of	O
their	O
performance	O
to	O
the	O
other	O
sub-mixes	O
.	O
</s>
<s>
With	O
advances	O
in	O
digital	O
technology	O
,	O
it	O
is	O
now	O
possible	O
to	O
transmit	O
multiple	O
audio	O
channels	O
over	B-Protocol
a	I-Protocol
single	I-Protocol
Ethernet	I-Protocol
cable	I-Protocol
.	O
</s>
<s>
Distributed	O
monitor	O
mixers	O
are	O
most	O
successful	O
with	O
headphones	B-Device
or	O
in-ear	B-Device
monitors	I-Device
.	O
</s>
<s>
If	O
monitor	O
speakers	O
are	O
used	O
,	O
feedback	O
problems	O
are	O
common	O
when	O
the	O
performer	O
turns	O
their	O
microphone	B-Application
up	O
too	O
loud	O
.	O
</s>
<s>
Monitor	O
speakers	O
often	O
include	O
a	O
single	O
full-range	O
loudspeaker	O
and	O
a	O
horn	B-Device
in	O
a	O
cabinet	O
.	O
</s>
<s>
There	O
are	O
two	O
types	O
of	O
monitors	O
:	O
passive	O
monitors	O
consist	O
of	O
a	O
loudspeaker	O
and	O
horn	B-Device
in	O
a	O
cabinet	O
and	O
must	O
be	O
plugged	O
into	O
an	O
external	O
power	O
amplifier	O
;	O
active	O
monitors	O
have	O
a	O
loudspeaker	O
,	O
horn	B-Device
and	O
a	O
power	O
amplifier	O
in	O
a	O
single	O
cabinet	O
,	O
which	O
means	O
the	O
signal	O
from	O
the	O
mixing	O
console	O
can	O
be	O
plugged	O
straight	O
into	O
the	O
monitor	O
speaker	O
.	O
</s>
<s>
Active	O
monitors	O
are	O
typically	O
bi-amped	O
and	O
have	O
an	O
active	B-Algorithm
crossover	I-Algorithm
with	O
custom	O
equalization	O
to	O
tune	O
the	O
monitor	O
to	O
have	O
a	O
flat	O
frequency	O
response	O
.	O
</s>
<s>
These	O
speakers	O
may	O
also	O
be	O
single	O
small	O
speakers	O
which	O
are	O
sometimes	O
mounted	O
on	O
a	O
microphone	B-Application
stand	O
to	O
get	O
them	O
closer	O
to	O
the	O
performers	O
 '	O
ears	O
.	O
</s>
<s>
More	O
often	O
they	O
are	O
heavy-duty	O
two-way	O
systems	O
with	O
a	O
woofer	B-Device
and	O
a	O
high-frequency	O
horn	B-Device
.	O
</s>
<s>
A	O
small	O
floor	O
monitor	O
might	O
use	O
a	O
12	O
"	O
woofer	B-Device
with	O
an	O
integrated	O
high-frequency	O
horn	B-Device
or	O
driver	O
combination	O
.	O
</s>
<s>
A	O
large	O
floor	O
monitor	O
might	O
use	O
one	O
or	O
two	O
15	O
"	O
woofers	B-Device
and	O
a	O
high-frequency	B-Device
driver	I-Device
attached	O
to	O
a	O
high-frequency	B-Device
horn	I-Device
.	O
</s>
<s>
The	O
speaker	O
might	O
use	O
a	O
passive	B-Algorithm
crossover	I-Algorithm
or	O
might	O
be	O
bi-amped	O
with	O
an	O
active	B-Algorithm
crossover	I-Algorithm
and	O
separate	O
amplifiers	O
for	O
the	O
woofer	B-Device
and	O
high-frequency	O
driver	O
.	O
</s>
<s>
Drum	O
fills	O
are	O
typically	O
large	O
2	O
-	O
or	O
3-way	O
speakers	O
with	O
one	O
or	O
more	O
large	O
woofers	B-Device
capable	O
of	O
extremely	O
high	O
volumes	O
to	O
help	O
drummers	O
hear	O
other	O
band	O
members	O
over	O
the	O
acoustic	O
sound	O
of	O
their	O
drums	O
.	O
</s>
<s>
Acoustic	O
feedback	O
occurs	O
when	O
the	O
time	O
delay	O
between	O
the	O
acoustic	O
input	O
of	O
a	O
microphone	B-Application
and	O
the	O
output	O
of	O
a	O
monitor	O
speaker	O
is	O
a	O
multiple	O
of	O
the	O
period	O
of	O
a	O
frequency	O
.	O
</s>
<s>
When	O
this	O
occurs	O
the	O
acoustic	O
output	O
of	O
the	O
speaker	O
is	O
picked	O
up	O
by	O
the	O
microphone	B-Application
and	O
amplified	O
again	O
by	O
the	O
monitor	O
speaker	O
.	O
</s>
<s>
The	O
bandwidth	B-Algorithm
or	O
Q	O
of	O
each	O
band	O
can	O
either	O
be	O
1/3	O
,	O
2/3	O
or	O
one	O
octave	O
,	O
giving	O
a	O
31-band	O
,	O
15-band	O
,	O
or	O
10-band	O
for	O
a	O
graphic	O
equalizer	O
that	O
covers	O
the	O
audio	O
frequency	O
range	O
.	O
</s>
<s>
The	O
bandwidth	B-Algorithm
of	O
each	O
band	O
can	O
be	O
adjusted	O
from	O
a	O
wide	O
Q	O
factor	O
affecting	O
several	O
octaves	O
to	O
a	O
narrow	O
Q	O
affecting	O
less	O
than	O
an	O
octave	O
,	O
and	O
the	O
level	O
of	O
the	O
band	O
can	O
be	O
adjusted	O
.	O
</s>
<s>
The	O
advantage	O
of	O
using	O
parametric	O
equalizers	O
in	O
a	O
monitor	O
system	O
is	O
that	O
the	O
filter	O
can	O
be	O
exactly	O
adjusted	O
to	O
the	O
specific	O
feedback	O
frequency	O
,	O
and	O
the	O
bandwidth	B-Algorithm
of	O
the	O
filter	O
can	O
be	O
set	O
to	O
be	O
very	O
narrow	O
so	O
the	O
adjustment	O
affects	O
as	O
little	O
of	O
the	O
frequency	O
band	O
as	O
possible	O
.	O
</s>
<s>
A	O
notch	O
filter	O
is	O
a	O
semi-parametric	O
equalizer	O
where	O
the	O
bandwidth	B-Algorithm
is	O
set	O
very	O
narrow	O
,	O
a	O
1/6	O
an	O
octave	O
or	O
less	O
and	O
is	O
a	O
cut-only	O
filter	O
.	O
</s>
<s>
Some	O
musicians	O
may	O
prefer	O
a	O
bespoke	O
in-ear	B-Device
monitor	I-Device
mix	O
.	O
</s>
<s>
Hardshell	O
headphones	B-Device
are	O
typically	O
used	O
by	O
the	O
audio	O
engineer	O
to	O
listen	O
to	O
specific	O
channels	O
or	O
to	O
listen	O
to	O
the	O
entire	O
mix	O
.	O
</s>
<s>
While	O
an	O
amplified	O
monitor	O
speaker	O
can	O
also	O
be	O
used	O
for	O
this	O
purpose	O
,	O
the	O
high	O
sound	O
volumes	O
in	O
many	O
club	O
settings	O
make	O
hardshell	O
headphones	B-Device
a	O
better	O
choice	O
because	O
the	O
hard	O
plastic	O
shell	O
and	O
foam	O
cushions	O
help	O
to	O
block	O
the	O
room	O
noise	O
.	O
</s>
<s>
Some	O
performers	O
may	O
use	O
headphones	B-Device
as	O
monitors	O
,	O
such	O
as	O
drummers	O
in	O
pop	O
music	O
bands	O
.	O
</s>
<s>
In	O
the	O
2000s	O
,	O
some	O
bands	O
and	O
singers	O
,	O
typically	O
touring	O
professionals	O
,	O
began	O
using	O
small	O
in-ear-style	O
headphone	B-Device
monitors	O
.	O
</s>
<s>
These	O
in-ear	B-Device
monitors	I-Device
allow	O
musicians	O
to	O
hear	O
their	O
voice	O
and	O
the	O
other	O
instruments	O
with	O
a	O
clearer	O
,	O
more	O
intelligible	O
sound	O
because	O
the	O
molded	O
in-ear	O
headphone	B-Device
design	O
blocks	O
out	O
on-stage	O
noise	O
.	O
</s>
<s>
While	O
some	O
in-ear	B-Device
monitors	I-Device
are	O
universal	O
fit	O
designs	O
,	O
some	O
companies	O
also	O
sell	O
custom-made	O
in-ear	B-Device
monitors	I-Device
,	O
which	O
require	O
a	O
fitting	O
by	O
an	O
audiologist	O
.	O
</s>
<s>
Custom-made	O
in-ear	B-Device
monitors	I-Device
provide	O
an	O
exact	O
fit	O
for	O
a	O
performer	O
's	O
ear	O
.	O
</s>
<s>
In-ear	B-Device
monitors	I-Device
greatly	O
reduce	O
on-stage	O
volume	O
by	O
eliminating	O
the	O
need	O
for	O
on-stage	O
monitor	O
wedges	O
.	O
</s>
<s>
In-ear	B-Device
monitors	I-Device
also	O
make	O
audio	O
feedback	O
howls	O
much	O
less	O
likely	O
since	O
there	O
are	O
no	O
monitor	O
speakers	O
.	O
</s>
<s>
One	O
drawback	O
of	O
in-ear	B-Device
monitors	I-Device
is	O
that	O
the	O
singers	O
and	O
musicians	O
cannot	O
hear	O
on-stage	O
comments	O
spoken	O
away	O
from	O
a	O
microphone	B-Application
(	O
e.g.	O
,	O
the	O
bandleader	O
turning	O
away	O
from	O
the	O
vocal	O
mic	O
and	O
looking	O
at	O
the	O
band	O
and	O
calling	O
for	O
an	O
impromptu	O
repetition	O
of	O
the	O
chorus	O
)	O
or	O
sounds	O
from	O
the	O
audience	O
.	O
</s>
<s>
This	O
issue	O
can	O
be	O
rectified	O
by	O
placing	O
microphones	B-Application
in	O
front	O
of	O
the	O
stage	O
and	O
mixing	O
those	O
into	O
the	O
monitor	O
mix	O
so	O
that	O
the	O
band	O
can	O
hear	O
the	O
audience	O
in	O
their	O
in-ear	B-Device
monitors	I-Device
.	O
</s>
<s>
Since	O
the	O
drums	O
are	O
already	O
very	O
loud	O
,	O
having	O
a	O
subwoofer	B-Application
producing	O
a	O
high	O
sound	O
pressure	O
level	O
can	O
raise	O
the	O
overall	O
stage	O
volumes	O
to	O
uncomfortable	O
levels	O
for	O
the	O
drummer	O
.	O
</s>
<s>
They	O
connect	O
to	O
an	O
amplifier	O
like	O
a	O
normal	O
subwoofer	B-Application
.	O
</s>
<s>
The	O
term	O
foldback	B-Device
is	O
sometimes	O
applied	O
to	O
in-ear	O
monitoring	O
systems	O
,	O
also	O
described	O
as	O
artist	O
's	O
cue-mixes	O
,	O
as	O
they	O
are	O
generally	O
set	O
up	O
for	O
individual	O
performers	O
.	O
</s>
<s>
Foldback	B-Device
may	O
less	O
frequently	O
refer	O
to	O
current	O
limiting	O
protection	O
in	O
audio	O
electronic	O
amplifiers	O
.	O
</s>
<s>
The	O
term	O
foldback	B-Device
has	O
been	O
used	O
when	O
referring	O
to	O
one	O
or	O
more	O
video	O
monitors	O
facing	O
a	O
stage	O
,	O
in	O
the	O
same	O
manner	O
as	O
an	O
audio	O
foldback	B-Device
monitor	O
.	O
</s>
