Larson Davis 831, User Manual

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Model 831 Manual Community Noise Descriptors C-11
the day, evening or night time periods then the number of
hours used in the formula is set to zero and the
corresponding Lday, Levening or Lnight will be shown as "-
- -". The Session Log and Run Time are used to qualify the
measurement periods.
CNEL
In the state of California, a commonly used community
noise descriptor is Community Noise Equivalent Level
(CNEL), defined by the following formula:
This is essentially the same as the L
DEN
using default
values, with the exception that the evening period begins at
22.00 instead of 23.00. Thus, by making this change in the
L
DEN
formula, the measured value will represent CNEL.
CNEL
10log
10
1
24
------
10
L
i
10 +
 
10

0000
0700

10
L
i
10

0700
1900

10
L
i
5 +
 
10

1900
2200

10
L
i
10 +
 
10

2200
2400

+ + +
 
 
 
=