BRUEL & KJAER 2203 - Page 34

15
Free field corrections for
.....
dB
Types 4144,4145 and 4146
lL'
with protection grid
orl
/'
1\
v
h \
30° ..
_L
L
1
l !j
10
v
\ \1'
0_V
lLl
I
~
I\ .
!
_l
//
\ I
I
! I
#
l..--"v
~6~
\ i I I I
~v
,.......v
..... -
-- :S',
\.
!
i
I
~
v
v
.... -
1\ \ ~ \\ I
~
i
--
.... -
0
-
,.......
1-----
---
----
\ \ 1 j\.J
J
~ I
--------
-
to-.
......
r--...
goo
\
_i
_l_i
180°
1--
1-15~
1'
~ l
~
!
~
l"'""l
~ ~1
J
\
------
Random Incidence
120°
~\\
_i
I!
\..\\
~
I I
~
Th\
\
I j
\
-5
I
I
\ \\~
I
, I·
~--~
(( ~
~ao
1
0° Incidence
\\ .\
_11
I-
0
I
'~
~
I •
I I I
-10
~ \ \'
\ 1
1 kHz
3 4 5 6 7 8 9 10
15 20
30 40 50 70
158150
Fig. 5. 2. Free field corrections for 4145
Excellent omnidirectional characteristics are also achieved by using
the 2203 with Extension Rod UA 0196, and Microphone 4145 with the
Random Incidence Corrector UA 0055 (Fig.5.4), or by using the half-
Frequencies
Tolerances
Hz
dB
31,5- 1000
+ 1
-1
1000 -
2000
+ 1
-2
2000
-
4000
+ 1
-3
4000 -
8000
+ 1
-6
8000
- 12500
+ 1
-10
073015
Table 5. 1. IEC tolerances on microphone sensitivity over an angle of
±90°
32