Larson Davis Spartan 821, Reference Manual

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Spartan 821/721 Manual Glossary C-12
OR
Noise Exposure
See Sound Exposure (E)
Peak
The maximum value of the instantaneous, frequency weighted (A, C, or Z), sound
pressure in a given time interval. For the dosimeter, a Peak value is recorded for 2
different time intervals. The first records the Peak for an entire record’s run time (Peak
Overall). The second records the Peak for each individual time history sample.
The peak level displays on the meter as L <frequency weight> peak; L
Apeak
is an example.
Peak Frequency Weighting
The frequency weighting of the peak detector. Possible selections are A, C, Z. Peak
weighting is independent of the RMS frequency weighting. For additional information,
see the entry for Frequency Weightings .
Preamplifier
A preamplifier is a part of a sound level meter that matches a particular model of
microphone to the meter. It must be chosen in conjunction with a microphone and a
cable that connects them.
Dose 100
T
T
C
------- 10
L
avg
L
C
–
q
----------------------
 
%
=
L
AS
= A-weighting frequency and slow-exponential
time weighting sound level in dB. If the sound
level is less than the user specified threshold level,
then L
AS
= –∞)
L
avg
= average sound level in dB, only records
values higher than the user specified threshold
level
L
C
= Criterion Level in dB
T = measurement period or Run Time (T = T
2
– T
1
)
T
C
= Criterion Duration in hours (8 hours)
q = exchange rate constant
• If exchange rate = 3, q = 10
• If exchange rate = 4, q = 4 / log
10
(2) ≈ 13.29
• If exchange rate = 5, q = 5 / log
10
(2) ≈ 16.61
• If exchange rate = 6, q = 20