ISO 11820:2019

In-Situ Sound Attenuation Measurement of Silencers

ISO 11820 specifies the in-situ measurement method for determining the acoustic attenuation performance of silencers installed in railway ventilation ducts, brake systems, and exhaust lines. This test is critical for validating noise control equipment on operating trains and stationary installations where laboratory testing is impractical. Railway manufacturers, maintenance operators, and acoustic engineers use these measurements to verify compliance with noise regulations and to optimize silencer design. Accreditation ensures that attenuation claims are reliable and that performance targets for noise reduction are consistently achieved in real-world applications.

What it measures

  • Sound pressure level reduction across silencer (dB)
  • Attenuation performance by frequency band
  • Insertion loss of silencer in situ
  • Acoustic performance under operating conditions
  • Noise transmission loss through silencer element
🇩🇪 DIN EN ISO 11821 🇬🇧 BS EN ISO 11821 🇫🇷 NF EN ISO 11821 🇮🇹 UNI EN ISO 11821 🇪🇸 UNE EN ISO 11821 🇳🇱 NEN EN ISO 11821 🇩🇪 DIN EN ISO 3095 🇬🇧 BS EN ISO 3095 🇫🇷 NF EN ISO 3095 🇮🇹 UNI EN ISO 3095 🇪🇸 UNE EN ISO 3095 🇳🇱 NEN EN ISO 3095
1,516 Accredited labs
17 Countries

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COFRAC 1-10029 Colomiers, FR
NF X 43-050 NF X43-050 (parties
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COFRAC 1-10041 Villebon-Sur-Yvette, FR
NF X 46-032 NF X 43-050 NF X43-050 (parties
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COFRAC 1-6388 Saint-Martin D'Heres, FR
DIN EN 12469 NF S 90-351 BS EN ISO 14644-1:2015 ISO 14644-3
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COFRAC 1-6491 Bruz, FR
NF X 43-269 - Annexe K NF X 43-050 (parties utiles NF X 46-032 NF X 43-269 – Annexe K NF X 43-050 + 1 more
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COFRAC 1-2416 La Ciotat, FR
DIN EN 12469 NF S 90-351 NF X 44-201 (Octobre 1984) pour PSM BS EN ISO 14644-1:2015 ISO 14644-3
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COFRAC 1-1147 Sainte-Croix-En-Plaine, FR
DIN EN ISO 6888-1 0.95) based on BS ISO 21527-2:2008 DIN EN ISO 6888-2 DIN ISO 16649-2 DIN EN ISO 19020 + 3 more
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COFRAC 1-1592 Bagneux, FR
NF X 43-269 NF X 43-050 NF X43-050 (parties utiles de la NF X 46-032 NF X46-031
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COFRAC 1-1593 Henin-Beaumont, FR
NF X 43-269 – Annexe K NF X 43-050 NF X43-050 (parties utiles de la
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COFRAC 1-5597 Nantes Cedex 03, FR
NF X43-050 (parties utiles de NF X 43-050 NF X 43-269 - Annexe K NF EN 14346 – NF X43-050 (parties utiles de la
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COFRAC 1-5922 Vergeze, FR
NF X 43-269 – Annexe K NF X 43-050 NF X 43-269 - Annexe K NF X43-050 (parties utiles de la
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COFRAC 1-1591 Saint Etienne, FR
NF X 43-269 - Annexe K NF X 43-269 – Annexe K NF X 43-050 NF X43-050 (parties utiles de la NF X43-050 (parties + 1 more
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COFRAC 1-5840 Gradignan, FR
NF X 43-269 - Annexe K NF X 43-269 – Annexe K NF X 43-050 NF X43-050 (parties utiles de la NF ISO 21363
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COFRAC 1-2202 Douai, FR
NF T90-111 DIN EN ISO 14403-2 NF T 90-412 DIN EN ISO 7899-1 NF-T 90-029 + 3 more
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COFRAC 1-2243 Vennecy, FR
DIN EN ISO 21528-2 DIN EN ISO 6888-1 0.95) based on BS ISO 21527-2:2008 DIN EN ISO 6888-2 DIN ISO 16649-2 + 3 more
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COFRAC 1-6881 Les Milles, FR
DIN ISO 11665-4 DIN EN ISO 7932 DIN 53483-2 DIN EN ISO 15213-2 NF V08-050 + 3 more
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COFRAC 1-2241 Douai Cedex, FR
DIN EN ISO 6888-1 DIN EN ISO 21528-2 DIN EN ISO 6888-2 DIN ISO 16649-2 NF V08-054 + 3 more
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COFRAC 1-1830 Nantes, FR
DIN EN ISO 21528-1 NF V08-401 DIN ISO 16649-1 DIN EN ISO 6888-1 DIN EN ISO 21528-2 + 3 more
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COFRAC 1-5943 Nantes, FR
NF X 43-269 NF X 43-050 ISO ISO 16000-7
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COFRAC 1-7268 Seichamps, FR
DIN ISO 17289 NF T 90-260 NF X 31-615 (Uniquement DIN EN ISO 10523 DIN EN 27888
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COFRAC 1-0201 Bordeaux, FR
DIN EN 947 ISO 24339 DIN CEN TS 15119-2 DIN EN ISO 3741 NF P 20-501 + 3 more
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COFRAC 1-6017 Marseille, FR
DIN 51750-3 NF X 43-269 – NF X 43-050 NF X43-050 (parties utiles de la DIN EN 15002
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COFRAC 1-1185 Capelle-La-Grande, FR
NF T90-111 DIN EN ISO 17294-2 DIN EN ISO 14403-2 NF EN ISO 19340 DIN EN ISO 10304-1 + 3 more
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COFRAC 1-5765 Illkirch-Graffenstaden, FR
NF X 43-269 NF X 43-050 NF X43-050 (parties utiles de
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COFRAC 1-5952 Longjumeau, FR
DIN EN 13001-1 NF X 43-269 NF X43-050 (parties utiles de NF X 43-275 NF X 43-257 + 3 more
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FLASHLAB NORD

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COFRAC 1-6979 Lezennes, FR
NF X 43-050 NF X 43-050 (parties utiles NF X 43-269 - Annexe
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Industries

Railway rolling stock manufacturing Train maintenance and depot operations Acoustic engineering and noise control HVAC and ventilation system design Brake system suppliers and integrators

Related Standards

  • ISO 11821 Acoustics — In-situ measurement of sound insulation of windows and façades
  • EN ISO 3095 Acoustics — Measurement of noise emitted by railbound vehicles
  • ISO 7235 Acoustics — Laboratory measurement of sound absorption coefficient of materials in impedance tubes

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