RT60 — Reverberation Time
RT60 is the time in seconds for a sound to decay 60 dB after the source stops — the primary acoustic measurement that determines whether a room is suited for speech, music, or neither.
glossaryaudioacousticsrt60speech-intelligibilityinstalled-sound
STI — Speech Transmission Index
STI is the standard objective measure of speech intelligibility in a room — a value from 0 to 1 that predicts how clearly spoken words will be understood by listeners, accounting for reverberation, noise, and system distortion.
glossaryaudioacousticsspeech-intelligibilityconferencinginstalled-sound