NTi Audio Acoustilyzer AL1 - Manual (Page 42)

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Uncertainty
Factor in %
Uncertainty Factor in %
(applicable for averaged test result)
Based on at least three individual test
results, the uncertainty factors are
calculated. This factor indicates the
statistical test result accuracy based on
the randomly created pink noise test signal
(typically 0 - 15% for reliable RT60 test
results). Please see the standard ISO 3382
for details.
Error Indications
Delete single
test results
Various error indications display
unsuccessful RT60 measurements, These
can be deleted individually. Non-valid results
are excluded from average calculations.
• LOW LEVL
This is the abbreviation of “low test
signal level” during the measurement
→ Increase the test signal level, verifying
that all levels exceed the upper marks
while the source signal is switched on
→ Use an RT60 test signal with longer
on/off times, ensuring sufficient time for
the lower level marks to be reached after
the source is switched off
• CORR<70%
The correlation factor is lower than 70%
indicating an unreliable measurement
result.
• T>18S
The measured reverberation time
exceeds the time limit of 18 seconds,
e.g. caused by a unsuitable ranging or
environmental noise.
In this case repeat the ranging and start
the measurement again.