User manual

133
STIPA
Hints: German Standard VDE 0833-4 Requirements
STI > 0.63 One single measurement is sufficient.
STI < 0.63 Perform three subsequent measurements at this
measurement position.
If the maximum result deviation of these three •
measurements is > 0.03 then a further three
measurements shall be performed.
If the maximum result deviation of these mea-•
surements is > 0.05 then the cause of this in-
stability shall be evaluated and removed.
The arithmetic average of the performed three •
or six measurements has to be reported.
Utilize the STIPA Reporting Tool for the documentation of your
measurements according the standard.
An STI > 0.63 implies that the speech intelligibility is higher
than 0.5 with a confidence level of 95%.
Hints: CD-Player
Only high-quality CD-Players should be used to reproduce •
the STIPA test signal as only limited time-shifts (+/- 20 ppm)
ensure reliable test results. Pitch control and shock protec-
tion should be disabled. We recommend that only profes-
sional CD-Players be used. You can verify the time shift of the
CD-Player using a 1 kHz test signal:
Insert the NTi Audio Test CD into the CD-Player and start
-
track 1, which is the 1 kHz test signal.
Connect the XL2 directly to the audio output of the CD-
-
Player and measure the signal frequency in RMS/THD+N
mode. The displayed frequency should be in the range
from 0.99998 kHz to 1.00002 kHz
STIPA test signals from other test system manufacturers •
may sound similar but are not compatible. Only the NTi Au-
dio STIPA test signal CD V1.1 or higher should be used in
combination with the XL2.