NTi Audio Acoustilyzer AL1 - Manual (Page 37)

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Reverberation Time RT60
The Acoustilyzer supports reverberation time measurements in octave
band resolution according to ISO3382 with auto trigger, auto ranging and
averaging functionality.
What is Reverberation Time RT60
Reverberation time RT60 is the time required for the sound pressure level
to decrease by 60 dB after a sound stimulus signal is stopped. In practice,
since ambient noise often defeats measurements of 60dB level decrease,
the RT60 results are based on T20 measurements. This requires only a
35 dB level decrease within each octave band. The RT60 test result is the
extrapolation of the measured 20 dB decay.
Test Signal
It is recommended to use a gated pink noise signal as the test signal. Various
test tracks with different on/off time are included on the accompanying AL1
Test CD. Alternatively the Minirator features the required gated pink noise
signal.
a. Bargraph display
Octave Bands
Start Pause Measurement
Status
Individual Octave
Band Spectrum
RT60 Upper Mark
Indicator
RT60 Lower Mark
Indicator
X-Axis,
level with
10 dBSPL
marks
Number
of Test
Results
taken for
automatic
averaging
Ranging,
initial record of
environmental
noise prior
measurement
Octave
bands scroll
63Hz - 8kHz