4-12 Setup Tabs Model 831 Manual
event might look as shown in FIGURE 4-11 "Exceedance
Event Example" .
FIGURE 4-11 Exceedance Event Example
For exceedance counters a noise event is initiated when the
sound level rises above the event trigger level. A noise event
ends when the sound level drops 2 dB below the trigger
level. This hysteresis is introduced to avoid the creation of
multiple events when the sound level is fluctuating about the
threshold level.
SPL Trigger Levels
There are two threshold levels, SPL Trigger Levels 1 and 2,
which can be set to initiate an exceedance event when the
measured SPL (Slow, Fast or Impulse) exceeds either of
these thresholds.
Peak Trigger Level
Three different Peak Trigger Levels can be set
independently from the SPL trigger levels. Since the peak
detector has a very fast response time compared to the SPL
detectors, exceedance events based on the peak trigger level
can identify impulsive noises produced by blasts and gun
fire which would not ordinarily produce an exceedance of
the SPL trigger levels.
dB
Time
Event Begins
Event Ends
2 dB
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