Larson Davis 831, User Manual

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Model 831 Manual Glossary D-3
Criterion Sound Exposure
(CSE)
The product of the Criterion Duration and the mean square
sound pressure associated with the Criterion Sound Level
when adjusted for the Exchange Rate. It is expressed in
Pascals-squared seconds when the exchange rate is 3 dB.
where q is the Exchange Rate Factor. See Exchange Rate.
Standard : ANSI S1.25
Criterion Sound Level (L
c
)
It is the sound level which if continually applied for the
Criterion Duration will produce a Noise Dose of 100%. The
current OSHA Criterion Level is 90 dB.
Standard : ANSI S12.19
Daily Personal Noise Exposure
(
LEP,d
)
It is the level of a constant sound over the Criterion Duration
that contains the same sound energy as the actual, unsteady
sound over a specific period. The period is generally shorter,
so the sound energy is spread out over the Criterion Duration
period.
Example : If the Criterion Duration = 8 hours and the specific
period is 4 hours and the average level during the 4 hours is
86 dB, then the L
EP,d
= 83 dB.
Day-Night Average Sound
Level (DNL, L
dn
)
A rating of community noise exposure to all sources of
sound that differentiates between daytime and nighttime
noise exposure. The equation for it is
The continuous equivalent sound level (See definition) is
generally calculated on an hourly basis and is shown in the
equation as L.
The values for the hourly periods from midnight to 7 a.m.
have 10 added to them to represent less tolerance for noise
CSE T
c
10
L
c
q

=
L
dn
10 Log
10
1
24
------
10
L
i
10 +
 
10

0000
0700

10
L
i
10

0700
2200

10
L
i
10 +
 
10

2200
2400

+ +
 
 
 
=