6.1.3. Flexible Extension Rod
UA
0196
This
is
21
em (8.25 in) long and fits
between
the
input stage and
the
half
inch microphone
or
one
of
the
micro-
phone
or
one
of
the
microphone
adaptors.
6.1.4. Half
inch-
one
inch
Adaptor
DB
0375
.
This
is
necessary when
the
exten-
sion rod and a
one
inch microphone
are
to
be used.
6.1.5. Random
Incidence Corrector
UA
0055
This is intended
to
be used for all
normal measurements with a
one
inch
microphone Type 4145.
It replaces
the
normal protecting grid and consider-
ably improves
the
omnidirectivity of
the
system. The Free-field corrections
for
one
inch microphones and random
incidence corrector are shown
in
Fig.5.6 and a typical frequency
response
is
shown
in
Fig.5.
1.
6.1.6. Windscreen
UA
0207
Fig.6.4. VA 0196
Fig.6.5. DB 0375
Fig.6.6. VA 0055
When a microphone
is
exposed
to
wind, noise will be generated
due
to
the
variation
of
air pressure
on
the
diaphragm.
The
three
principal reasons
for this are: wind velocity variations,
the
turbulence created around
the
microphone when it
is
placed
in
the
wind, and
the
interference between
the
variation
in
air pressure caused by these. Extensive tests have been made
with various windscreens and it has been shown
that
wind gusts (i.e. variable
wind speeds) cause more noise
than
constant
wind speeds. Wind noise can
be reduced by
a spherical windscreen such as
the
UA
0207
which
is
recom-
71
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