Larson Davis 831 - Page 546

Model 831 Manual Glossary D-21
Taktmaximal-5 An integration of the five second maximum A frequency
weighted, fast time weighted sound pressure levels.
Where:
L
Amax 5s(n)
is the maximum A-weighted fast exponential
time weighted sound pressure level for each n 5-second time
period
and
n is the number of 5 second periods accumulated during the
measurement.
Threshold Sound Level (Lt) The A-weighted sound level below which the sound
produces little or no Noise Dose accumulation and may be
disregarded. It is used for hearing damage risk assessment.
Standard: ANSI S1.25
Time Weighted Average Sound
Level (TWA, L
TWA(TC)
)
It is the level of a constant sound over the Criterion
Duration, that would expose a person to the same Noise
Dose as the actual (unsteady) sound over the same period. If
the Exchange Rate is 3 dB then the TWA is equal to the L
eq
.
where T
c
=T
2
-T
1
and K is the Exchange Rate Factor. It is
used for hearing damage risk assessment.
Standard: ANSI S12.19
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n
L
nsAF
L
AFTM
10
5
)(5max
10
log10
L
TWA TC
Klog
10
1
T
---
10
L
p
tK
td
T
1
T
2
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=