Speech intelligibility – STIPA

Nor140The speech transmission index, STI, has shown to be a valuable tool for objective assessment of the speech intelligibility. The basis for the STI-index is that speech intelligibility is to a large extent is based on the slow amplitude modulation of octave band sound levels due to the acoustic environment in the test area. A simplified version of the STI-metric, known as STIPA, is an option in the Nor140 instrument.

  • Calculates the STIPA speech transmission index
  • Fulfils the requirements of the IEC 60268-16 Standard for STIPA
  • Includes signal excitation CD (Nor1034) for use through separate public address loudspeaker system or portable CD/MP3-player
  • Background noise correction





Option13 Stiparesults

Adding STIPA option to Nor140 turns the analyser into a powerful tool for analysing the Speech Transmission quality in public areas. The method can be used to compare the speech trans-mission quality at various positions and under various conditions within the same listening space. STIPA replaces the former used RASTI method as a more accurate method compared to RASTI.

A measurement in one listening position takes about 13 sec. Unlike many other STIPA measurement systems, the Nor140 can also correct the results for the background noise. In addition all calculated indexes are displayed, not only the single STIPA value. This feature is valuable for engineers optimising the room acoustics in public spaces or other areas where the speech quality is important.