Larson Davis System 824, Reference Manual

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10-38 824 Reference Manual 11/8/00
The check menu offers the following options:
• Edit Note - Edit the note of this stored record.
• Locate - Locate a Spatial Avg history record
- First - The first Spatial Avg history record
- Last - The last Spatial Average history record
- Find - Finds the specified Spatial Average his-
tory record
If you are viewing an “Avg History”
record use the +average function to
average records which are already in
the average history together.
Remember that all records are
weighted equally. If you have an
average history record which was
comprised of 100 samples it will be
averaged as one record. • +Average - Add spectrum to spatial average
• Rooms - View Room Criteria for this spectrum
• View Back - Return to the previous display
• Graph - Adjusts the vertical graph scale and offset
Rooms Views
NCB and RC are calculated and dis-
played from any spectral display
including snapshot or Averaged
Spectrum and are accessed from
their individual check menus. The Rooms Views are accessed from the check menu of
every display that can show a spectrum.
The Rooms displays consist of RC, NCB and HTL. All these
measurements are based on ANSI S12.2-1995.
The NCB and RC Criteria for 1/1 octave data calculates the
following:
• SIL - speech interference level
• Pass/Fail on Rumble check
• Pass/Fail on Hiss check
• Mid-frequency average Lmf and RC
• Neutral, Hiss, Rumble or Vibration/Rumble check