Larson Davis System 824, Reference Manual

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9/12/00 A-1
C H A P T E R
A
Integrated Level Calculations
Basic Integrated Level Calculations
The Larson•Davis System 824 calculates all of its integrated
levels based on equations from IEC standard 804. IEC-804
Section 3.3 defines Leq as follows:
Equivalent continuous A-weighted sound pressure level
(also average A-weighted sound pressure level) is defined as
follows
where:
L
Aeq,T
is the equivalent continuous A-weighted sound pres-
sure level re 20 µPa, determined over a time interval T=t
2
-t
1
p
A
(t) is the instantaneous A-weighted sound pressure of the
sound signal
p
0
is the reference sound pressure of 20 µPa
When, a frequency weighting other than A is used, the fre-
quency weighting used shall be included explicitly in the
title and the formula of the quantity, for example equivalent
continuous C-weighted sound pressure level:
L
Aeq,T
10lg
1
T
--- p
A
2
t
1
t
2
∫
t
( )
dt
 
 
 
 
p
0
2
÷





dB





=