Scope
IEC 60268-16:2011
Speech Transmission Index Measurement
This test method provides an objective measure of speech intelligibility in acoustic environments using the Speech Transmission Index (STI) method. STI quantifies how well speech is transmitted through an acoustic space, accounting for noise, reverberation, and frequency distortion. The measurement is critical for evaluating communication effectiveness in public address systems, conference rooms, classrooms, and other speech-critical environments. Venues with high standards for speech clarity use this method to verify system performance and acoustic suitability. ISO 17025 accreditation ensures reliable assessment of speech intelligibility compliance with design standards.
What it measures
- Speech Transmission Index (STI) value (0-1 scale)
- Modulation transfer function across frequency bands
- Speech intelligibility rating and quality assessment
- Impact of noise and reverberation on speech clarity
- Communication effectiveness and auditory conditions
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DIN EN ISO 3382-2
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BS EN ISO 3382-2
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NF EN ISO 3382-2
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UNI EN ISO 3382-2
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UNE EN ISO 3382-2
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NEN EN ISO 3382-2
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DIN EN ISO 1996-2
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BS EN ISO 1996-2
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NF EN ISO 1996-2
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UNI EN ISO 1996-2
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UNE EN ISO 1996-2
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NEN EN ISO 1996-2
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tungsten carbide)
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Microtech Services (Wessex)
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ISO 7251
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ISO 6888-3
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Moorcroft Controls
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DC CURRENT
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NSF Wales Limited
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BS EN ISO 7686:2005
DIN EN 997
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DIN ISO 10381-7
DIN EN 14622
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Nature’s Consultancy
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(HSG 248) – 2021
(PCM) based on HSG 248
DOC/002 based on HSG 248)
Normec DETS
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BS 1377: Part 2: 1990
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No DETSC 5012 based on BS EN
staining based on HSG 248.
(HSG 248) – 2021
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North Star Environmental
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(HSG 248) – 2021
NSDOC 47 based on HSG 248
staining based on HSG 248.
(PCM) based on HSG 248
Not One Iota
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(HSG 248) – 2021
SOP-12, based on HSG 248
staining based on HSG 248
(PCM) based on HSG 248
Nuclear Restoration Services
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AIR KERMA RATE
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O.C. Consulting (UK)
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(HSG 264, 2012)
Appendix 5 of HSG 227 (2004)
(HSG 248) – 2021
(PCM) based on HSG 248
IEC 61400-23
ASTM G73 (2012)
IEC 60885-3, 2.4.1
IEC 60502-2
IEC 60840
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IEC 60519-11
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DIN EN 13126-19
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