NTi Audio Acoustilyzer AL1 - Manual (Page 54)

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Speech Intelligibility STI-PA (optional)
The speech intelligibility measurement STI-PA is an optional sales package
for the Acoustilyzer AL1. Ask your local representative for purchasing
details.
The STI-PA analyzer option allows reliable measurement of the speech
transmission index within 15 seconds. Besides the single value STI or CIS
test result, a detailed view of the modulation indices and individual band
level results is provided. The STI-PA analyzer fulfills the latest 2003 IEC
60268-16 standard and is a TNO verified algorithm (dutch STI-PA research
institute).
Find more information about speech intelligibility basics and the historical
developments in the Appendix to this user manual.
a. STI-PA Measurement Screen
Actual
Sound
Pressure
Level
Measurement Progress Bar
(0..15 seconds)
Analogue STI-PA Bargraph
STI-PA
Test
Result
Start
Measurement
Measurement
Status
Indication
STI-PA Test Result: Single-value speech transmission index result in
STI (speech transmission index) or CIS (common intelligibility scale),
whereby CIS is calculated as CIS = 1 + log STI.
Sound Pressure Level: Shows actual SPL value in dBAS (A-weighting
frequency and Slow time weighting).