Casella HB4056-01 dBadge2 User Manual

May 2015 Page 47 of 51
Figure 11 shows the 12 hour measurement
It is now possible to calculate the value normalised to 8 hours, i.e. TWA(8h). This is
effectively achieved by keeping the measured energy (represented by the blue line)
constant, but changing the duration from 12 hours to 8 hours. This will have the effect of the
TWA(8h) value being higher than the 12 hour Lavg value.
Therefore, a 12 hour Lavg of 88.0 dB is equivalent to an 8 hour Lavg of 90.9 dB.
Figure 12 shows the 12 hour measurement (blue line); the TWA(8h) is shown by the red line. The
measured energy represented by the blue line is equal to the measured energy represented by the red
line.
Scenario 4: Criterion duration (Tc) = 8 hours; measurement duration (Tm) = 10 hours;
shift duration (Ts) = 12 hours
The noise which the worker is exposed to is measured for 10 hours, which is the entire shift
duration. However, the worker is exposed to the same noise levels for the remainder of the
shift (such that the worker is exposed to this noise level for the entire 12 hours).
Figure 13 shows the 10 hour measurement

Casella HB4056-01 dBadge2 Specifications

General

Brand	Casella
Model	HB4056-01 dBadge2
Category	Measuring Instruments
Language	English