Norsonic nor118, Instruction Manual

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24 Chapter 4
Simple sound measurements
25 Norsonic Nor118
User Guide
Frequency analysis
A
   , you may have your Nor
equipped with parallel octave band filters. By adding
the optional extension , third-octave band filters become
available as well. e frequency range, expressed as centre
frequencies, is –  Hz for the octave band filters and
.–  Hz for the third-octave band filters.
When you make a frequency analysis, this comes in
addition to the traditional sound level measurement as
described in the chapter Simple sound measurements.
Setting up
e frequency range is fixed and cannot be changed by
the user. Bearing in mind that the dynamic range of the
Nor118 is no less than 120 dB and that the instrument
measures a fixed set of functions (which cannot be altered
by you), there is not much left to set up before the instru-
ment is ready to make a frequency analysis.
Actually, the setup procedure boils down to specifying
the measurement duration, the time constant to be used
and the use of - or -weighting, ensuring that the fre-
quency mode has been activated and – in case of extension
 present – specifying the filter bandwidth.
Setting the duration
Your instrument may, or may not be equipped with the
optional extension 6, which is the time profile logging.
is affects the look of the Measurement duration setup
menu. To read more about optional extensions see e
principle of the optional extensions .
How the menu looks with and without the optional
extension  installed is shown below.
To produce the measurement duration setup menu:
• Press  > 2. To leave the menu press the 
key.
Measurement duration setup menu
Measurement duration setup menu when time profile
option is installed (left), and when it’s not (right).