Norsonic nor140, Instructional Manual

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117
Norsonic Nor140
Instruction Manual
Press
SETUP > 2
and move the cursor filed to exci-
tation type (Ex.type) and select “IMP” by the use of
the
INC
or the
DEC
key. Then select the swept sine
method (“ImpResp: ON”) in a similar way, as shown
in the picture.
There are two storing options for reverberation time
measurements. The result table will always be stored,
of course, but in this menu you may also turn on or
off the storage of the decay curve and the audio re-
cording of the impulse. Please note that both of these
alternatives takes a lot of the available memory so do
not use it unless it is needed for further investigations
and analysis. Set both “Decay” and “Audio” to “OFF”
to save memory. Press
ENTER
twice to leave the menu
and enter reverberation ready mode.
The letter
R
in the upper left corner of the display
indicates that the instrument now is in reverberation
time mode.
Press the
START
key. The instruments start send-
ing out the swept sine sequence and at the same time
start the logging the response. A special picture ap-
pears on the screen.
Reverberation Table
Reverberation Running
Once you have pressed the
START
key then you have
to wait for this sequence to finish and it takes about
one minute.
The calculation of the reverberation times is auto-
matically performed and the result values are shown
in a table. The table shows the calculated reverbera-
tion time for each frequency band and for the spectral
weighting networks (A- and C- or Z-weighting). If the
signal-to-noise ratio is insufficient for calculating the
reverberation time, the sign “-.-“ will be displayed in-
stead of a value. An overload is marked by “*”.
Press
FUNC
for displaying T20 or T30 as appropriate.
To store the values of reverberation time, press
STORE
and the result are stored and automatically as-
signed a file number displayed at the top of the dis-
play. The values may later be retrieved by pressing
RECALL
.