9
L
dn
applies a 10 dB penalty for nighttime levels, while L
den
in addition has a 5 dB penalty for
evening levels.
A typical setup for 24 hours of unattended monitoring might be:
• Continuous measurement
• Hourly periodic reports
• Level triggered marker for events above L
AF
= 60dB(A)
• Sound Recording of events (please refer to the Sound Recording Option)
• Logging of other parameters as required (please refer to the Logging Software)
After the measurement, you can check L
dn
or L
den
, the Total and the periodic reports, and
then browse the events and sound recordings to verify the quality of your measurements.
Sound Recording Option – BZ 7226
Sound Recording BZ 7226 is an option that works with all other software modules. In all cases
it allows you to make recordings of the actual measured signal, that is, the microphone signal
used for measurements (this must not be confused with recorded voice annotations, which
uses the commentary microphone). However, its detailed working is dependent upon which
other software module is enabled and running. In any case, recordings are automatically
attached to the measurement and kept with it, even after transfer of the data to a PC.
The purpose of the Sound Recording Option is to let you record the measurement signal in
order to identify and document sound sources, for example:
• The measured L
Aeq
at 57 dB, did it actually stem from the rather distant compressor, or
from other sources such as nearby birds or traffic? Not necessarily easy to evaluate on-site,
very difficult to document convincingly later. If the signal is recorded: No discussion
• Is it really true that this noise is impulsive and should be penalised accordingly? If the
signal is recorded: There may still be an argument, but it is based on facts
• Exceedances were identified while no operator was present. Did they originate from the
plant under investigation or from another source. If the signal is recorded: No discussion
With Sound Level Meter Software BZ 7222 and Frequency Analysis Software BZ 7223, the
Sound Recording Option BZ 7226 basically lets you do the following:
• Record all or parts of the measured signal giving rise to specific results, levels and spectra
• Set up your instrument so that recording can be set to start automatically when the meas-
urement is started, or you can initiate recordings manually
With Logging Software BZ 7224 and Enhanced Logging Software BZ 7225, additional options
are available:
• Recording of sound can be associated with the Event Marker. Use the Event key or set an
Event marker on the profile display: The sound during the event is recorded and attached
to the appropriate part of the profile
• Automatic detection of events – based on level exceedance is also possible, meaning that
recordings can also be initiated when no operator is present
In all of the above cases the maximum duration of recordings can be set (Type 2250 is only
limited by available storage on the memory card currently in use). Recording sound obviously
requires large amounts of storage, therefore Sound Recording Option BZ 7226 allows you to
decide on the trade-off between storage needed and recording quality (sampling rate).
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