Larson Davis 831, User Manual

Page: 102 / 548

Model 831 Manual C-A and Impulsivity 5-23
Since community noise metrics are
based upon full day measurements,
they do not present valid data for
measurements less than 24 hours
duration. The Community Noise page displays the parameters L
DN
,
L
DEN,
L
Ceq
and L
Aeq
, commonly used to evaluate
community noise, and L
Ceq
-L
Aeq
, used to describe the low
frequency content of a sound and also as a parameter in the
selection of hearing protection devices. The parameter
L
AFTM5
will appear when “Takt Maximal Data” has been
selected on the Preferences Page as shown in "Takt Maximal
Data" on page 18-14. The definition is shown in
"Taktmaximal-5" on page D-21.
L
DEN
Although the standard ISO 1996-2:2007 specifies default
values for the parameters used in the calculation of L
DEN
, in
practice the time values defining the day, evening and night
periods may be changed, as permitted by Directive 2002/49/
EC of the European Parliament and of the Council of 25
June 2002 relating to the assessment and management of
environmental noise. It is important to verify prior to
measurement that the parameters have been properly defined
for your purposes. See Chapter 4 "Day/Night Tab” on page
4-13 for a detailed description of the setup procedure.
C-A and Impulsivity
FIGURE 5-24 Overall Tab: C-A Level and
Impulsivity