User manual

292
Appendix
Application example:
Display the moving Leq over 5 seconds in accor-•
dance with DIN15905
Measure the moving Leq over 60 minutes in ac-•
cordance with V-NISSG
Fast Time Weighting
Time constant t = 125 ms; the time weighting is
an exponential function of time, which defines
how changes of the instantaneous sound pressure
level are averaged for useful sound pressure level
results. The measurement results are shown accu-
rately for sound sources with a minimum length of
0.5 seconds. The decay rate is 34.7 dB/s. Fast time
weighting is typically used for common sound level
measurements.
Holding Maximum Level
For tracing of feedback frequencies in the RTA page.
The hold time can be set to 3, 5 or 10 seconds.
Impulse Time Weighting
Time constant attack t = 35 ms; time constant de-
cay t = 1500 ms; the time weighting is an exponen-
tial function of time, which defines how changes
of the instantaneous sound pressure level are av-
eraged for useful sound pressure level results. The
measurement results are shown accurately for
sound sources with a minimum length of 0.1 sec-
onds. Impulse time weighting is used for impulsive
sound sources.
Impulse Penalty ImpPenalty
Impulsive penalty in accordance with BS4142:2014
and NordTest ACOU 112. The LAF is sampled with
a time interval of 12 ms. The penalty is calculated
as follows:
Penalty KI= 1.8 * (Prominence P - 5) for P > 5
P=3*lg(onset rate[dBs]) + 2*lg(level difference[dB])
The Prominence P is designed to give a maximum
around 15; concluding the maximum impulse pen-
alty is 18 dB.