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
🇩🇪 DIN EN ISO 3382-2 🇬🇧 BS EN ISO 3382-2 🇫🇷 NF EN ISO 3382-2 🇮🇹 UNI EN ISO 3382-2 🇪🇸 UNE EN ISO 3382-2 🇳🇱 NEN EN ISO 3382-2 🇩🇪 DIN EN ISO 1996-2 🇬🇧 BS EN ISO 1996-2 🇫🇷 NF EN ISO 1996-2 🇮🇹 UNI EN ISO 1996-2 🇪🇸 UNE EN ISO 1996-2 🇳🇱 NEN EN ISO 1996-2
1,868 Accredited labs
20 Countries

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AN DIAG

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COFRAC 1-7298 Saint Etienne Du Rouvray, FR
NF X 43-269 NF X 43-269 - Annexe K NF X43-050 (parties utiles de ISO 22262-1 NF X 43-050 + 1 more
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COFRAC 1-0876 Nanterre, FR
NF X 31-615 DIN EN ISO 7027-2 DIN EN ISO 10523 DIN EN 27888 DIN ISO 17289 + 3 more
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COFRAC 1-7202 Courbevoie, FR
DIN EN 14385 ETSI EN 301 489-1 V2.2.3 2019-11 NF X43-551 IS EN 1948-1:2006 2006 DIN EN 14789 + 3 more
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ENAC LE1878 Madrid, ES
UNE-EN 14584 UNE-EN 13554 UNE-EN 12819 UNE-EN 12817 UNE-EN ISO 15614-1 + 3 more
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UKAS 2136 Hebburn, GB
QOP03 based on HSG 248 QOP01 based on HSG 248 (HSG 248) – 2021 (PCM) based on HSG 248
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UKAS 0347 Hebburn, GB
(HSG 264, 2012)
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ENAC LE1299 Barcelona, ES
UNE-EN ISO 16283-1 UNE-EN ISO 140-4
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ENAC LC10.017 Leganés, ES
CEM DI-002 EURAMET CG-2 CEM DI-014 CEM DI-006 CEM DI-016 + 3 more
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ENAC LE201 Sada, ES
ISO 6059 ASTM D 1209 UNE-EN ISO 8467 SM 4500-NH D 3 UNE 77048 + 3 more
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ENAC LE2307 Puertollano, ES
ISO/IEC 25010 ISO/IEC 25040 ISO/IEC 25012 ISO/IEC 5259-2
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AQRAT

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DAkkS D-K-15060-01-00 Dettingen unter Teck, DE
Messschieber für 0 mm Außen-, Innen- und > 500 mm > 1000 mm Tiefenmessschieber * 0 mm Sondermessschieber 0 mm + 3 more
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AQUABIO

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COFRAC 1-7428 Saint Germain Du Puch, FR
DIN ISO 17289 NF T 90-395 NF T 90-354 NF T 90-393 NF T 90-328 + 3 more
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COFRAC 1-2194 Plancy L'Abbaye, FR
NF T 90-412 DIN EN ISO 7899-1 DIN EN ISO 10304-1 DIN EN 12880 ISO 5815-1 + 3 more
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ARCO

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UKAS 8495 Hull, GB
BS EN ISO 20344::2011 Clause 5.1 ASTM D 1388 BS EN ISO 13997:1999 ISO 11611 DIN EN ISO 13997 + 3 more
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ACCREDIA 01923 Trieste, IT
DIN EN 13725:2003-07 und Berichtigung
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ENAC LE2071 Berriozar, ES
IEC 61400-11:2012/ AMD:2018 IEC 61400-12-1 IEC 61400-12-3 IEC 61400-13 IEC 61400-12-5
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UKAS 20835 Warmley, GB
(HSG 264, 2012)
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UKAS 9924 Netherton, GB
ISO 10469:2006) (Based on ISO 10258:2018)
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UKAS 4352 Liverpool, GB
ISO 5983-1:2005/Cor.1:2008, ISO20483:201 07L.1.07 based on ISO 6865:2001 ISO 712 07L.1.02 based on ISO 6496:1999, ISO 12966-2 + 3 more
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COFRAC 1-7441 Le Vesinet, FR
NF S92-501 (mars
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ENAC LC10.098 San Ginés, ES
EURAMET cg-18 CEM Ed CEM GUIA CEM TH-001 CEM TH-007 + 3 more
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ENAC LE1105 Valencia, ES
DIN EN 13864 DIN EN 14808 DIN EN 12235 ISO 2549 ISO 4919 + 3 more
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ENAC LE016 Ibi, ES
UNE-EN 71-1 ISO 8124-1 ISO 8124-2 ASTM F963-17 (NM_001718: c.1-c.500) + 3 more
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ENAC LE025 Alcoi, ES
DIN EN ISO 11612 DIN EN ISO 3175-2 ISO 17493 DIN EN ISO 17227 DIN EN ISO 6330 + 3 more
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ENAC LE004 Castellón de la Plana, ES
UNE-EN ISO 10545-2 UNE-EN ISO 10545-3 ASTM C373 UNE-EN ISO 10545-4 UNE-EN ISO 10545-5 + 3 more
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Industries

Audio and sound system design Public address and emergency systems Telecommunications and broadcasting Educational and institutional facilities Aviation and maritime communication

Related Standards

  • ISO 3382-2 Acoustics - Measurement of room acoustic parameters - Part 2: Reverberation time in ordinary rooms
  • ISO 1996-2 Acoustics - Description, measurement and assessment of environmental noise - Part 2: Determination of sound pressure levels
  • EN 60268-1 Sound system equipment - Part 1: General

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