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
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IMPELAB

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COFRAC 1-6403 Marrakech, MA
DIN EN ISO 7932 DIN EN ISO 6579-1 DIN EN ISO 7937 DIN EN ISO 11290-1 0.95) based on BS ISO 21527-2:2008 + 2 more
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Laboratoire Marocain de Métrologie Industrielle - L2MI

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COFRAC 1-6426 12 Et 14 Lot. Mauritania Q.I Sidi Bernoussi | - Casablanca | Maroc, MA
DIN EN 12469 NF S 90-351 BS EN ISO 14644-1:2015 ISO 14644-3
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PROCESS INSTRUMENTS (PI)

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COFRAC 1-5987 263, 3Eme Etage Zone Industrielle De Mohammedia | - Mohammedia | Maroc, MA
DIN EN 12469 NF S 90-351 BS EN ISO 14644-1:2015 ISO 14644-3
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REMINEX - CENTRE DE RECHERCHE

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COFRAC 1-0789 Reminex - Centre De Recherche - Bp 469 Marrakech Medina | - Marrakech | Maroc, MA
NF T 90-003 DIN EN 26777 DIN EN ISO 10523 DIN EN 846-7 DIN EN 25814 + 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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