<s>
The	O
process	O
of	O
weighting	B-General_Concept
involves	O
emphasizing	O
the	O
contribution	O
of	O
particular	O
aspects	O
of	O
a	O
phenomenon	O
(	O
or	O
of	O
a	O
set	O
of	O
data	O
)	O
over	O
others	O
to	O
an	O
outcome	O
or	O
result	O
;	O
thereby	O
highlighting	O
those	O
aspects	O
in	O
comparison	O
to	O
others	O
in	O
the	O
analysis	O
.	O
</s>
<s>
While	O
weighting	B-General_Concept
may	O
be	O
applied	O
to	O
a	O
set	O
of	O
data	O
,	O
such	O
as	O
epidemiological	O
data	O
,	O
it	O
is	O
more	O
commonly	O
applied	O
to	O
measurements	O
of	O
light	O
,	O
heat	O
,	O
sound	O
,	O
gamma	O
radiation	O
,	O
and	O
in	O
fact	O
any	O
stimulus	O
that	O
is	O
spread	O
over	O
a	O
spectrum	O
of	O
frequencies	O
.	O
</s>
<s>
In	O
the	O
measurement	O
of	O
loudness	B-Algorithm
,	O
for	O
example	O
,	O
a	O
weighting	B-General_Concept
filter	O
is	O
commonly	O
used	O
to	O
emphasise	O
frequencies	O
around	O
3	O
to	O
6kHz	O
where	O
the	O
human	O
ear	O
is	O
most	O
sensitive	O
,	O
while	O
attenuating	O
very	O
high	O
and	O
very	O
low	O
frequencies	O
to	O
which	O
the	O
ear	O
is	O
insensitive	O
.	O
</s>
<s>
A	O
commonly	O
used	O
weighting	B-General_Concept
is	O
the	O
A-weighting	O
curve	O
,	O
which	O
results	O
in	O
units	O
of	O
dBA	O
sound	O
pressure	O
level	O
.	O
</s>
<s>
Because	O
the	O
frequency	O
response	O
of	O
human	O
hearing	O
varies	O
with	O
loudness	B-Algorithm
,	O
the	O
A-weighting	O
curve	O
is	O
correct	O
only	O
at	O
a	O
level	O
of	O
40-phon	O
and	O
other	O
curves	O
known	O
as	O
B-	O
,	O
C	O
-	O
and	O
D-weighting	O
are	O
also	O
used	O
,	O
the	O
latter	O
being	O
particularly	O
intended	O
for	O
the	O
measurement	O
of	O
aircraft	O
noise	O
.	O
</s>
<s>
In	O
broadcasting	O
and	O
audio	O
equipment	O
measurements	O
468-weighting	O
is	O
the	O
preferred	O
weighting	B-General_Concept
to	O
use	O
because	O
it	O
was	O
specifically	O
devised	O
to	O
allow	O
subjectively	O
valid	O
measurements	O
on	O
noise	O
,	O
rather	O
than	O
pure	O
tones	O
.	O
</s>
<s>
It	O
is	O
often	O
not	O
realised	O
that	O
equal	O
loudness	B-Algorithm
curves	O
,	O
and	O
hence	O
A-weighting	O
,	O
really	O
apply	O
only	O
to	O
tones	O
,	O
as	O
tests	O
with	O
noise	O
bands	O
show	O
increased	O
sensitivity	O
in	O
the	O
5	O
to	O
7kHz	O
region	O
on	O
noise	O
compared	O
to	O
tones	O
.	O
</s>
<s>
Other	O
weighting	B-General_Concept
curves	O
are	O
used	O
in	O
rumble	O
measurement	O
and	O
flutter	O
measurement	O
to	O
properly	O
assess	O
subjective	O
effect	O
.	O
</s>
<s>
In	O
each	O
field	O
of	O
measurement	O
,	O
special	O
units	O
are	O
used	O
to	O
indicate	O
a	O
weighted	B-Algorithm
measurement	O
as	O
opposed	O
to	O
a	O
basic	O
physical	O
measurement	O
of	O
energy	O
level	O
.	O
</s>
<s>
In	O
the	O
fields	O
of	O
acoustics	O
and	O
audio	O
engineering	O
,	O
it	O
is	O
common	O
to	O
use	O
a	O
standard	O
curve	O
referred	O
to	O
as	O
A-weighting	O
,	O
one	O
of	O
a	O
set	O
that	O
are	O
said	O
to	O
be	O
derived	O
from	O
equal-loudness	O
contours	O
.	O
</s>
<s>
Another	O
use	O
of	O
weighting	B-General_Concept
is	O
in	O
television	O
,	O
in	O
which	O
the	O
red	O
,	O
green	O
and	O
blue	O
components	O
of	O
the	O
signal	O
are	O
weighted	B-Algorithm
according	O
to	O
their	O
perceived	O
brightness	O
.	O
</s>
<s>
In	O
the	O
calculation	O
of	O
UV	O
Index	O
,	O
a	O
weighting	B-General_Concept
curve	O
is	O
used	O
which	O
is	O
known	O
as	O
the	O
McKinlay-Diffey	O
Erythema	O
action	O
spectrum	O
.	O
</s>
