Vox -01 Operating Manual page 25

• A spherical loudspeaker configuration playing pink or white noise is the
preferred source of measurement noise.
• If you are using a single, non-spherical loudspeaker, avoid placement of
the microphone on the loudspeaker axis. Even though the microphone is
omnidirectional, avoid pointing the microphone straight at the loudspeaker.
• Eliminate sources of background noise.
• The state of all doors, windows and other separations should be fixed (open
or closed) throughout the measurements. The opening of doors and win-
dows changes the reverberation time.
• Do not walk around when the measurement is running, especially not in
the immediate surroundings of the noise source.
• The signal-to-noise ratio requirements for RT60 measurements are some-
times difficult to meet. Especially for T30 measurements, it may be neces-
sary to play back the test stimulus (interrupted noise) at high sound pres-
sure levels.
• If your signal-to-noise ratio is insufficient for reliably measuring the higher
frequency bands, consider switching over to white noise (instead of the
commonly used pink noise) as a source stimulus.
If you are having trouble getting acceptable measurement data (green balls with check
marks next to your measurement data), it may help to study the exact reasons why your
measurement data is marked for rejection.
Along with each measurement value, the reliabily status is display (acceptable, warning,
error). The stored data for each measurement (downloadable via USB) contains more de-
tails on the exact motivation for the indicated reliability status. This is indicated with the
following letter codes:
- d: no data was present (error)
- r: not enough range (warning)
- b: bandwidth-time product too low (error)
- n: snr too low (warning)
- s: start time before knee point of the decay curve (warning)
- c: correlation of the decay curve fit is low (warning or acceptable, depending on value)
Multiple letter codes may be stored with a single measurement value.
VOX-01 Operating Manual
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