User manual

80
Reverberation Time RT60
19
Correlation Factor in %
The correlation factor is 100% for perfectly linear sound
pressure level decay after the sound source has ceased.
The natural deviation from this linearity results in lower
correlation values. The correlation factor is typically 80 -
100%.
20
Cycle Reverberation Time Test Result
Readout of cycle reverberation time and correlation factor
19
when selection
18
is CYC xx or Last.
Correlation Factor. Scale is on the right Y-axis. For
more details see
19
.
Reverberation time measurement result of individ-
ual displayed cycle. Scale is on the left Y-axis.
21
Y-Axis Correlation Factor
The right Y-axis shows the correlation factor in %. The cor-
relation factor Y-axis is displayed when test result selection
18
is CYC xx or Last.
22
Delete Cycle Results
Individual cycle results may be deleted, thereby excluding
them from the calculation of the AVRG result.
Test Signals
Use either an interrupted pink noise or an im-
pulse source as the test signal.
Interrupted pink noise •
Precision measurements require an omni-di-
rectional speaker with identical radiation char-
acteristic in all directions. Various interrupted
pink noise test signals with different on/off
times are offered on the NTi Audio Test CD
(included with the XL2) or the Minirator signal
generator. A minimum of three measurement
cycles shall be performed. The XL2 averages
these readings automatically.
Impulse •
The trigger signal is an impulse source, such
as a starter pistol, starter clap or bursting bal-
loon. Individual measurements, or test se-
quences with repeated trigger signals, can be
carried out.