Articles tagged “speech intelligibility

4 articles covering speech intelligibility in acoustic engineering and building design.

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GUIDES10 min readFeatured

Church Reverberation — The Impossible Balance Between Speech and Music

Churches need RT60 of 1.0s for speech and 3.0s for organ music — in the same room. Here are 4 solutions that actually work.

March 15, 2026
churchworship
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PILLAR14 min readFeatured

Speech Transmission Index (STI) — The Complete Technical Reference

The definitive technical reference for STI (Speech Transmission Index) covering MTF theory, the full 98-point calculation method per IEC 60268-16:2020, STIPA and RASTI simplified methods, the CIS intelligibility scale, measurement equipment and methodology, STI targets by room type, and the relationship between RT60, background noise, and speech intelligibility.

March 14, 2026
STI complete guidespeech transmission index
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TUTORIALS19 min read

What Is STI (Speech Transmission Index) — Can People Actually Understand Speech in Your Room?

STI measures how much a room degrades speech from source to listener, on a scale from 0 (unintelligible) to 1 (perfect). An STI below 0.50 means one in four words is lost. Here is how STI works, what scores you need, and why reverberation time alone is not enough.

March 14, 2026
STIspeech transmission index
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STANDARDS20 min read

IEC 60268-16 Complete Guide: Speech Transmission Index (STI) Standard

IEC 60268-16:2020 defines the Speech Transmission Index — the definitive metric for speech intelligibility in rooms. Here is every aspect of the standard explained: the STI calculation method, STIPA measurement procedure, quality scale, and how building codes worldwide use it.

March 14, 2026
IEC 60268-16STI