Larson Davis 831, User Manual

Page: 181 / 548

9-6 Data Display Model 831 Manual
Dosimeter 1 and 2
FIGURE 9-6 Dosimeter 1 Display
In this example, we can see that the measurement parameters
correspond to the setup named “OSHA-1”.
TWA(8.0)
The value of TWA(8.0) (Time Weighted Average for 8
hours) is based on data measured during the run time and
calculated for the user-defined Criterion Time, in this case 8
hours. The value of Criterion Time is set by selecting a
predefined setup as described in "Predefined Setups" on
page 9-2 or by entering a numerical value as described in
"Threshold and Criterion" on page 9-4.
As an example, suppose a measurement was performed over
a time period of ten minutes. The value of TWA(8.0) would
be the same as the TWA measured over an eight hour period
if there had been no sound exposure other than that which
occurred during that ten minute period.
ProjTWA
The ProjTWA (Projected Time Weighted Average) is
calculated from data measured during the measurement run