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
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COFRAC 1-0273 Dechy, FR
DIN EN 14385 NF X43-551 ETSI EN 301 489-1 V2.2.3 2019-11 DIN EN 13039 DIN EN ISO 21656 + 3 more
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ST GOBAIN GLASS France - Saint-Gobain Research Compiègne

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COFRAC 1-1374 Thourotte, FR
DIN EN ISO 10140-1 DIN EN ISO 717-1 DIN EN ISO 10140-2 DIN EN ISO 10140-4 DIN EN ISO 10140-5
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COFRAC 1-1202 Gellainville, FR
NF T90-111 DIN EN ISO 17294-2 DIN EN ISO 14403-2 DIN EN ISO 11357-3 DIN EN ISO 10304-1 + 3 more
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COFRAC 1-0576 Sedan, FR
DIN EN ISO 717-2 DIN EN ISO 10140-3 DIN EN 1081 DIN EN ISO 105-B02 DIN EN ISO 9239-1 + 3 more
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COFRAC 1-5598 Crolles, FR
DIN ISO 16000-6 DIN ISO 16000-3 DIN EN ISO 16017-2 DIN EN 16339 DIN ISO 16000-4 + 3 more
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COFRAC 1-6125 Aurillac Cedex, FR
DIN EN ISO 17294-2 DIN EN ISO 14403-2 NF U47-105 NF T 90-412 DIN EN ISO 7899-1 + 3 more
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COFRAC 1-7302 Valence Cedex 9, FR
DIN EN ISO 14403-2 VDE 414-9-11 DIN ISO 11465 DIN EN ISO 10304-1 NF-T 90-029 + 3 more
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COFRAC 1-6123 Le Puy En Velay Cedex, FR
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COFRAC 1-6949 Nevers Cedex, FR
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COFRAC 1-6120 Lempdes, FR
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COFRAC 1-1941 Nantes, FR
NF ISO 21438-3 NF X 43-264 NF ISO 21438-1 ISO 16200-2 NF ISO 21438-2 + 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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