Svantek SVAN 971 - Definitions and Formulas of Additional Running LEQ Function Results

SVAN 971 User Manual – Appendixes
218
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 DEFINITIONS AND FORMULAS OF THE ADDITIONAL RUNNING 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
900T
2
0
dtptr
s900
1
log1015LR
Note: If the current time period of the measurement T is less then 15 minutes then LR15 result is
undefined.
LR60
60-minutes running Leq is the rolling (sliding)
Leq window for the last 60 minutes of
measurement (3600 seconds) moving with 1
second step
 
 











T
3600T
2
0
dtptr
s3600
1
log1060LR
Note: If the current time period of the measurement T is less then 60 minutes then LR60 result is
undefined.