speech trasmission index

The sound level meters Nor140 and Nor131 can measure the Speech Transmission quality in public areas accorsing to the IEC 60268-16 Standard for STIPA. The method can be used to compare the speech transmission index (STI) 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 and Nor131 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.