Svantek SV 973, User Manual

Page: 204 / 212

SVAN 973 User Manual
– Appendixes
204
E The E result (Exposition) represents the
amount of the acoustical energy received by
the worker.
 
10
LEQ
2
o
10 p
3600
s T
E
 =
E_8h The E_8h result (Exposition in 8 hours)
represents the amount of the acoustical
energy
received
by the worker during 8 hours. The E_8h result
is expressed in the linear units [Pa
2
h].
 
10
LEQ
2
o
10 p h 8 h 8 _ E
  =
PTC
The PTC result (Peak Threshold Counter)
– the number of the overpasses of the
Threshold Level by Lpeak result. This result is incremented in 100 ms intervals.
PTP The PTP result is the PTC result expressed
in percent.
ULT Upper Limit Time -
time that SPL exceeded the “ULT Threshold Level” set during
configuration.
TWA The Time Weighted Average is the average
A-weighted sound level for a nominal 8-hour
workday with Time Weighting S and
Exchange Rate 5.
TWA is usually measured
with A-weighting and Slow response detector
type. TWA is calculated from the measured
LAV (taking Threshold Level into account)
and a Reference time of 8 h. Mainly used in
the USA for assessing the noise exposure for
a worker during a workday.
•
Sound levels at or above the
THRESHOLD LEVEL are averaged
into the calculations relating to noise
exposure.
TWA is calculated with no
threshold level, or with threshold level
(typically 80dB or 90dB)
•
In case the time period is below 8
hours, the
TWA is less than the LAV
In case the time period is more than 8
hours, the
TWA is greater than the
LAV
PrTWA The Projected Time Weighted Average is calculated from the measured LAV (taking
THRESHOLD LEVEL into account) and the exposure time.
Lc-a
The C-A measurement is an Leq that
enhances the low-frequency components of
the sound signal. It is the result of subtracting
an A-weighted LAeq from a simultaneously
collected C-weighted Leq
Lc-a = LCeq - LAeq
D.4 D
EFINITIONS AND FORMULAS OF THE ADDITIONAL
R
UNNING
LEQ
FUNCTION RESULTS
LR15 15-minutes running Leq is the rolling (sliding)
Leq window for the last 15 minutes of
measurement (900 seconds) moving with 1
second step
( )
( )








=

−
T
900 T
2
0
dt p t r
s 900
1
log 10 15 LR
Note: If the current time period of the measurement T is less then 15 minutes then LR15 result is
undefined.