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26
Sound Intensity Calibrator Type 4297 – User Manual
Fig.5.3
Error due to phase
mismatch for intensity
measurements
Phase corrected intensity can be calculated by certain measurement systems in accordance
with the following formulae:
2
p
m
I
I
------------ -
=
–
cor
m
2
p
0
or
2
p
sin
φ
m
e
I
I
----------------------
=
cor
m
r
ωρ
Δ
0
0
where:
I
cor
I
m
p
m
I
p
,
0
0
✐
The correction factor [sin φ
Please note:
gas density and microphone separation. Thus, the factor should be determined for those
values of the variables that are to be used for the measurements.
Error due to Phase Mismatch
dB
8
7
6
5
4
3
2
1
0
-
-5
-
-1
-
-2
-
-3
I
0
: phase corrected intensity
: measured intensity
: measured pressure
: measured intensity and pressure for equal pressure applied
to the microphones.
-
-10
r
/(ω ρ
)] is a function of the selected system variables for
Δ
e
0
0
-
-
(L
- L
) - (L
-L
)
pm
lm
p0
l0
-
-15dB
890651/2
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