Larson Davis SoundTrack LxT, Руководство пользователя

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C
-
2 Glossary and Formulas LxT Manual
Average Sound Level (L
avg
)
The logarithmic average of the sound during a Measurement
Duration (specific time period), using the chosen Exchange
Rate Factor. Exposure to sounds at this level over the
measurement duration result in the same noise dose as the
actual (unsteady) sound. If the Measurement Duration is the
same as the Criterion Duration, then L
avg
=L
TWA(LC)
where the Measurement Duration (specified time period) is
T=T
2
-T
1
and q is the Exchange Rate Factor. Only sound
levels above the Threshold Level are included in the
integral.
Standard : ANSI S12.19
CNEL
In the state of California, Community Noise Equivalent
Level (CNEL), a commonly used community noise
descriptor, is 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 will represent CNEL.
L
avg
qLog
10
1
T
--- 10
L
p
t
   
q

T
1
T
2

dt
 
 
 
 
=
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

+ + +
 
 
 
=