4-14 Setup Tabs Model 831 Manual
L
DN
The default day-night level L
DN
is defined by the following formula:
L
DEN
The default day-evening-night level L
DEN
is defined by the
following formula:
In the default form, the day has twelve hours, the evening
has four hours and the night has eight hours, as can be seen
in the equation. The default times for these periods are as
follows
• Day: 07.00 to 19.00
• Evening: 19.00 to 23.00
• Night: 23.00 to 07.00
Lday, Levening and Lnight are A-weighted long-term
average sound levels measured during the day, evening and
night, respectively.
To account for the increased impact of environmental noise
during the evening and night, penalties are added to the
measured level; 5 dB for evening and 10 dB for night, as can
be seen in the equation.
The Directive 2002/49/EC of the European Parliament and
of the Council of 25 June 2002, relating to the assessment of
environmental noise permits member states to shorten the
evening period by one or two hours and lengthen the day
L
dn
10Log
10
1
24
------
10
L
i
10+10
0000
0700
10
L
i
10
0700
2200
10
L
i
10+10
2200
2400
++
=
DEN
L =
10
10
10
5
10
10*810*410*12
24
1
lg10
LnightLeveningLday
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