User manual

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STIPA
Data Post-Processing
In the case when no ambient noise correction has been car-
ried out on-site with the XL2 Analyzer, you may post-process
your measurement data on the PC. The NTi Audio STI Report-
ing Tool combines the speech intelligibility measurement taken
with quiet conditions and the actual ambient noise caused by
the public, e.g. during day-time. This emulates the speech intel-
ligibility expected during real-life conditions.
STI Reporting Tool
The STI Reporting Tool creates measurement reports accord-
ing to the IEC 60268-16 and VDE0833 standards. Import the
data directly from your XL2 including the ambient noise mea-
surements. The corresponding speech intelligibility STI or CIS
values are shown.
The STI Reporting Tool is free to download on the XL2 Support
website https://my.nti-audio.com for all registered users. (En-
able all macros when opening the document.)
System Requirements:
PC running Windows OS•
Excel 2010 - 2016•
STI Measurement Hints
Hints: Ambient Noise
The ambient noise has to be sufficiently static during the •
measurement. A signal-noise ratio of 15 dB or higher is rec-
ommended to achieve best speech intelligibility. Impulsive
ambient noise during the measurement, such as speech,
causes severe measurement errors. The STIPA result is usu-
ally too high.
Fluctuating noise is detected by measuring the direct STI in •
the absence of the test signal. Carry out these measurements
at least at a representative set of locations. If the STI is too
high (e.g. STI > 0,2), the measurement results are likely to
be erroneous. In this case the speech intelligibility measure-
ment should be carried out without the presence of noise.
Utilize the ambient noise correction for such instances.
At locations with varying conditions (e.g., some public areas •
with few people and other areas with crowds) the worst-
case speech intelligibility should be measured. Consult the
local regulations (e.g. the NFPA code in the U.S.) for direc-
tives concerning measurement locations and number of re-
quired measurements under which circumstances.