Larson Davis SoundExpert LxT, Руководство пользователя

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LxT Manual Measurement Settings Tabs
4-17
• 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
and/or the night accordingly and also to choose the time for
the start of the day.
To accommodate these and other possible modifications, the
Day/Night tab permits the user to modify the times for the
beginning of the Day, Evening and Night periods and the
penalties to be utilized when calculating 24-hour integrated
values.
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
settings, the measured value represents CNEL.
CNEL
10log10
1
24
------
10
Li 10 +
 
10

0000
0700

10
Li 10

0700
1900

10
Li 5 +
 
10

1900
2200

10
Li 10 +
 
10

2200
2400

+ + +
 
 
 
=