Articles tagged “speech intelligibility”
19 articles covering speech intelligibility in acoustic engineering and building design.
ANSI S12.60: Classroom Acoustic Performance Requirements
Complete guide to ANSI S12.60-2010 classroom acoustics — RT60 limits, background noise criteria, room volume thresholds, and compliance strategies.
The Complete Guide to Classroom Acoustics
Complete guide to classroom acoustics covering BB93, ANSI S12.60, DIN 18041 standards, RT60 targets, and treatment strategies for better learning outcomes.
DIN 18041: German Acoustic Quality Classes A, B, C Explained
Complete guide to DIN 18041 acoustic quality classes — Class A (music), B (speech), C (communication). Room types, RT60 targets, and compliance.
IEC 60268-16: Measuring Speech Intelligibility (STI/STIPA)
A practical guide to IEC 60268-16 speech intelligibility measurement — STI and STIPA methods explained, equipment requirements, field measurement procedures, and common interpretation errors.
Meeting Room Acoustics for Video Conferencing
Meeting room acoustic design for video conferencing — RT60 targets, mic placement, echo cancellation, and why £50K AV systems fail in untreated rooms.
Speech Transmission Index (STI): What It Is and Why Your Building Might Fail
Learn how Speech Transmission Index (STI) is calculated per IEC 60268-16, why buildings fail speech intelligibility tests, and how to fix poor STI scores.
How is STI Measured?
STI (Speech Transmission Index) is measured using modulation transfer functions derived from impulse responses or STIPA test signals. Learn the full-band and STIPA methods per IEC 60268-16.
What Are Early Reflections? The First 50ms That Shape What You Hear
Early reflections are the first sound reflections arriving within 50-80ms of the direct sound. Learn how they affect clarity, spaciousness, and speech intelligibility in room acoustics.
What is the Cocktail Party Effect? How Your Brain Filters Sound
The cocktail party effect is your brain's ability to focus on one voice amid many competing sounds. Learn the auditory science, how room acoustics help or hinder it, and design implications.
What is Critical Distance? Where Direct Sound Meets Reverberant Sound
Critical distance is the point where direct sound from a source equals the reverberant field. Learn the formula, why it determines speech clarity, and how to design rooms around it.
What is Speech Intelligibility? The Science of Being Understood
Speech intelligibility measures how well listeners understand spoken words in a space. Learn about STI, STIPA, the factors that affect it, and the standards that define acceptable levels.
How to Calculate STI for a Classroom — IEC 60268-16 Step-by-Step
Full STI calculation for a 200 m³ classroom. Derive RT60 via Sabine, then compute speech transmission index using the modulation transfer function method per IEC 60268-16:2020.
Courtroom Acoustics — When Justice Depends on Whether the Jury Hears | AcousPlan
UK MoJ requires STI ≥ 0.75 in courtrooms. Historic courtroom Sabine calculation shows RT60 1.94s. Seating and carpet treatment path to compliance.
STI Measurement — The Speech Metric 90% of Architects Ignore | AcousPlan
Speech Transmission Index below 0.60 means poor intelligibility. IEC 60268-16 step-by-step calculation with classroom worked example. Free STI estimator.
Church Acoustics: When RT60 Goes From 'Cathedral' to 'Unusable'
Cathedral RT60 of 8+ seconds is acoustically magnificent and completely unintelligible. Here's how to design worship spaces that serve both organ music and the spoken word.
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.
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.
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.
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.