08. July 2024

STIPA speech intelligibility measurement on the XL3 Acoustic Analyzer

STIPA speech intelligibility measurement on the XL3 Acoustic Analyzer

The XL3 Acoustic Analyzer now supports speech intelligibility measurements according to IEC60268-16. Together with the TalkBox (acoustic) and MR-PRO (electrical) signal sources, the XL3 is the ideal tool for efficient and reliable STIPA measurement tasks. The measured values can be conveniently visualized in a report.

STIPA (Speech Transmission Index for Public Address Systems) measurements are carried out to evaluate the speech intelligibility of public address systems in different environments. Typically, STIPA measurements are performed in conference rooms and classrooms, on public transport announcement systems, at theatres, sports stadiums, hospitals and many more. If a public address system is designed for safety-related emergency announcements, the minimum requirement for STIPA values must be demonstrated by measurement and documentation.

The Measurement

The STIPA test signal is fed, either acoustically or electrically, into the sound system. The STIPA values are then recorded with the XL3 at various points in the public area of interest. The measured values are displayed numerically and classified.

XL3 STIPA numerics   XL3 STIPA ambient noise   XL3 STIPA numerics with noise

Influence of background noise

A significant factor for speech intelligibility is the presence of background noise. As it is often not convenient to play the STIPA test signal during typical operating times (e.g. a theatre full of people), the XL3 Acoustic Analyzer allows background noise levels to be recorded while the location is full, and STIPA measurements to be recorded separately, when the location is vacated. These measurements can then be combined later.


The averaging of multiple measurements at one point is supported by a dedicated screen. Here the user retains the collected information about the individual measurements and the deviations between them. Invalid measurements can be disregarded immediately.

Measurement report

With the STIPA Reporting Tool, which is available free of charge, the measurements at several positions can be conveniently summarized in a measurement report.

   XL3 STIPA Summary Report
STI Summary Report 

You can find more information and numerous useful tips on how to carry out STIPA measurements on our STIPA application website.


The STIPA function is available on the XL3 from firmware V1.36. You also need:

600 000 712    XL3 STIPA option 

As an alternative to this permanent license, there is also a 365-day version

600 000 725    XL3 STIPA 365 Option 

(find this and other options for the XL3 Sound Level Meter here)


Firmware V1.36 is available to download free of charge for all XL3 devices.
A short video shows how it works.


Do you have any questions or would you like a non-binding offer?
Contact us at info@nti-audio.com