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ISO/IEC

IEC 60268-16

Objective rating of speech intelligibility by Speech Transmission Index (STI / STIPA)

Publication
IEC 60268-16
Edition
current

What it requires

Defines the STI measurement method and its qualification bands. Common AV design practice targets the “Good” band (STI/STIPA ≥ 0.60) for conferencing and reinforcement; life-safety voice intelligibility is governed by NFPA 72, not by this document.