3
Norsonic Nor140
Instruction Manual
3
Norsonic Nor140
Instruction Manual
Reverberation time.
A typical Nor140 application is
to serve as the acoustician’s little blue tool. This will
require the ability to calculate the reverberation time
in octaves and third-octaves. Units without filters will
calculate the broadband values (A- and C- or Z-
weighted values). As usual, this is an optional feature
so if you don’t need it, you won’t have to pay for it
either.
The reverberation time algorithm may be based on the
integrated impulse response
method or the
interrupted
noise
method. Hence, impulses are required as excita-
tion signals, or noise excitation from the internal signal
generator may be applied.
Noise monitoring and mapping.
The large memory
and the time synchronising capabilities of the Nor140
makes it well-suited as a front end in noise monitor-
ing systems – outdoors for community noise as well as
indoors in workshops etc.
The high dynamic range (120 dB) makes the setup
easy and ensures reliable measurements in all situations.
The Norsonic product range contains a wide range
of equipment and accessories for use with noise
monitoring and measurements. We supply enclosures
for permanent monitoring installations, environmental
cases for semi-permanent installations, microphones
for applications in tough environments, cables,
modems, weather stations and post-processing soft-
ware. A detailed presentation of this is available in a
separate leaflet and on www.norsonic.com.
Real time frequency analysis
Octave band or third-octave band measurements – the
choice is yours, depending on how you prefer to con-
figure your Nor140.
The octave band measurements span the range
8 Hz to 16 kHz, or from 0,5 Hz to 16 kHz dependent
on your set-up. An upgrade to option 3 will provide
you with third-octave band measurements in the range
6,3 Hz to 20 kHz or from 0,4Hz to 20 kHz.
The two bandwidths share the type of functions
measured. In a single frequency analysis the Nor140
measures:
• SPL The Instantaneous Sound Pressure Level
• L
MAX
The Maximum Sound Pressure Level
• L
MIN
The Minimum Sound Pressure Level
• L
eq
The Integrated Equivalent SPL
• L
E
The Sound Exposure Level
While the measurement is running the instantaneous
SPL is available for inspection, but as soon as the
measurement is terminated the SPL becomes mean-
ingless and therefore not listed in the result tables.
If your Nor140 is equipped with parallel time
constants (option 5), the list of functions measured
simultaneously can be expanded to include functions
with F, S and I time constants at the same time.
The frequency bands measured are all visible in
the display with no need for horizontal scrolling. The
f
↔
t
key lets you enter and exit the spectrum display.
Furthermore, the instrument measures the selected
full frequency range – every time! Given the high
dynamic range (120 dB), which eliminates the need for
adjusting the gain, there is very little to set up before a
frequency analysis can be made – successfully!
The measured functions are also available in
tabulated form as numerical values. By pressing the
TBL
key before, during or after a measurement you
have instant access to the numerical version. Another
push on the key will restore the graphical display.
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