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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, 2026STI complete guidespeech transmission index