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Package for speech intelligibility STI STIPA (Code: 30002)

Price: 1545.81 EUR
Incl. 19 % TAX plus shipping
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With this package you can measure speech intelligibility STI STIPA according to IEC 60268-16.

Our system supports measurements via impulse response and modulated noise.


Speech-intelligibility is the key feature to human communication. For evacuation systems, telecommunication, announcement systems (e.g. train stations) or rooms for education, poor speech-intelligibility will degrade their function or even become a security issue.

In many countries there exist limits for the speech-intelligibility. For new public buildings a certification measurement is required and the speech-intelligibility results must be documented. In most cases this must be performed according to IEC 60849 or ISO 7240-16.

The first orginal measurements were based on statistical analysis of listening tests. In contrast, the STI-method specified in DIN/IEC 60268-16 is an objective method. It uses special test signals (modulated noise) that simulate human voice and computes the influence of a transmission channel which degrades the speech-intelligibility.

The speech intelligibility of a transmission channel depends on:

  • the speech level
  • frequency response of the channel
  • non-linear distortions
  • background noise level
  • quality of the sound reproduction equipment
  • echos (reflections with delay > 100ms)
  • the reverberation time
  • psychoacoustic effects (masking effects)

The STI method uses 7 octave bands in the range of 125Hz to 8000Hz. It computes a single value, that reflects the speech-intelligibility.
This value can be in the range of  0 to 1.0. A value of 0 is equivalent to a very poor speech-intelligibility. 1.0 is an ideal channel with excellent speech transmission.

Features of our STIPA measurement system

  • Conforms to IEC 60268-16:2003 and 2011
  • Measures STI, STIPA
  • Very easy usage. Make your first STIPA measurement within 2 min.
  • Measurement via modulated noise and room impulse response. (direct and indirect method)
  • Background noise can be included via spectral values or .wav file. No spreadsheet calculation required.
  • Auditory masking conforms to IEC 60268-16 ED 3.0 (2003) and ED 4.0 (2011)
  • Displays modulation indices for each band
  • Octave analyzer
  • Speech level measurement according to IEC 60268-16:2011 Annex J.2
  • Easy export of data


You can find the quick guide here


This package includes

  • Software PRO EX
  • Plug-in  speech intelligibility (STI-STIPA)
  • USB-Dongle
  • 1/2" USB measurement microphone
  • Audio CD with STI-PA signals

A PC/Notebook is not included.


  • Active loudspeaker with 10cm diaphragma
  • Sound level calibrator
  • RASTI is available in the Akulap product line


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