9/12/00 A-3
For example, the System 824’s Logging SLM Overall-a dis-
play shows the current SPL (Sound Pressure Level) in 1/
10
th
decibel (dB) resolution. The actual real-time resolution
is 1/32
nd
dB. The displayed SPL is followed by the text
“dB” and then the frequency weighting in effect—set to
A
in
this example.
The System 824’s Logging SLM Overall-e display shows
the overall measurement period and TWA. In this case the
measurement is L
eq
(because of the 3dB exchange rate).
The quantity is A-weighted and has a measurement elapsed
time of 11:43.1 (11 hours, 43 minutes, and 1 second).
The actual equations used within the analyzers are based on
that for IEC-804 and are implemented according to this
equation:
lapsed measurement time, shown as mm:ss.ss,
h:mm:ss or hhhhh:mm
Scrolling SPL history
Current SPL while running or at the time a stop
occurred
The currently-selected frequency weighting for
SPL
The currently-selected detector
Elapsed measurement time, shown as mm:ss.ss,
hh:mm:ss or hhhhh:mm
Overall time weighted average (L
eq
in this case)
Time-weighted average (TWA) descriptor for
the overall measurement
Overall sound exposure level (SEL)
Overall exchange rate
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