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screen.
4. Check the SPL reading and measure the SPL to confirm that it meets the design
requirements Turn off your emergency message on your system.
5. Insert the STI-PA disk into the Talkbox CD player.
6. Connect the ¼ inch TEST TONE OUTPUT jack on the Talkbox to the LINE INPUT jack
on your system panel.
7. Set the VOLUME CONTROL on the Talkbox to 50% (12 noon).
8. Play the STI-PA tone through the Talkbox.
9. Go back to the same location that you made the previous SPL measurement with the
DSP2B/BP and check the SPL again.
10. Match the SPL level to your previous reading by either adjusting the Volume control on
the Talkbox or the channel input pot on your control panel.
NOTE:
Do not change the systems master volume as this is already set to code. Your test
procedure is now calibrated. To make an intelligibility test, place the analyzer
microphone in the location to be tested.
11. On the analyzer, press the MODE SWITCH until the display reads STI or CIS depending
on your job specifications.
12. On the computer screen press the EMPTY BUTTON (without the STI-PA TONE
playing) and press MEASURE to collect the AMBIENT SOUND in the room.
13. On the Talkbox, start the CD player with the STI-PA TONE.
14. On the computer press the MEASURE BUTTON again to collect information with the
STI-PA TONE.
15. The box on the left of the computer screen will show you your MODULATION
TRANSFER FUNCTIONS and your MEASURED STI SCORE.
NOTE:
In the event of an STI failure, possible reasons may include; An unfurnished room under
test will produce a significantly lower STI value since the large flat reflective surfaces
will add echoes and the lack of absorptive materials will also increase RT60 times and
reduce the STI value further. If the “BAT” symbol is shown, replace batteries.
INSTRUCTIONS TO MEASURE INTELLIGIBILITY (OPT STIcis):
USING TALKBOX WITH TEST TONE OUTPUT, WITH ADD NOISE FEATURE
USING COMPUTER
NOTE:
Using the ADD NOISE FEATURE requires that you take 3 separate measurements. Two
measurements will be taken with the room empty and one with the room occupied. The
order for empty or occupied does not make a difference as the ADJUST
ED ST
I SCORE
requires all three measurements.
1. Choose an initial room to check the SPL dBA level of your emergency voice evacuation
system.
2. Play the system's pre-recorded emergency message and take the DSP2B/BP to the room
that you previously chose.
3. Insert the microphone into the top of the analyzer and turn on the power switch at the
bottom of the analyzer.
