ISO 3744

Sound power — enveloping surface engineering method

ISO 3744 specifies the engineering method for determining sound power and sound energy levels using sound pressure measurements obtained on an imaginary surface (hemispherical or parallelepiped) surrounding a noise source. This method is widely used for in-situ testing of machinery, industrial equipment, and large installations where reverberation room testing is impractical. It provides a practical balance between accuracy and field applicability, making it suitable for machinery compliance testing, environmental noise assessments, and product CE marking requirements across the EU. ISO 17025 accreditation confirms laboratory proficiency in sound field measurement, environmental parameter correction, and uncertainty quantification for this complex measurement method.

What it measures

  • Sound power level (Lw) using enveloping surface pressure data
  • A-weighted and frequency-weighted sound power
  • Octave and one-third-octave band sound power (63 Hz to 8 kHz)
  • Environmental and measurement corrections
  • Sound power directivity and spatial variability
🇩🇪 DIN EN ISO 3740 🇬🇧 BS EN ISO 3740 🇫🇷 NF EN ISO 3740 🇮🇹 UNI EN ISO 3740 🇪🇸 UNE EN ISO 3740 🇳🇱 NEN EN ISO 3740 🇩🇪 DIN EN ISO 3743-1 🇬🇧 BS EN ISO 3743-1 🇫🇷 NF EN ISO 3743-1 🇮🇹 UNI EN ISO 3743-1 🇪🇸 UNE EN ISO 3743-1 🇳🇱 NEN EN ISO 3743-1
1,868 Accredited labs
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DAkkS D-K-19566-01-00 Hilden, DE
Druck * > –0,12 bar bis negativer und positiver Überdruck p e > –0,01 bar bis > 0,03 bar bis + 3 more
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COFRAC 1-7246 Cherbourg-En-Cotentin, FR
NF EN ISO 6892-1 (méthode DIN EN ISO 9016 DIN EN ISO 5178 ISO 11148-1
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CETEP

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COFRAC 1-2262 Mainvilliers, FR
DIN EN 12469 NF S 90-351 BS EN ISO 14644-1:2015 ISO 14644-3
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CEcert

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DAkkS D-PL-12049-01-02 Wismar, DE
IEC 61000-4-2: 2008 EN IEC 61000-4 IEC 61000-4-3: 2006 IEC 61000-4-4: 2012 IEC 61000-4-5: 2005 + 3 more
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ACCREDIA 00228 Monopoli, IT
DIN EN 17892 NEN-EN 16618 (incl EN 62366-1: 2015 +A1: BS EN 15662 ISO 12966-2 + 3 more
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ACCREDIA 00392 Menfi, IT
DIN EN ISO 14402 EPA 3630 EPA 1613 ISO 14189 ISO 11731 + 3 more
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ACCREDIA 00618 Vicenza, IT
DIN EN 1186-3 IEC 62321-3-1 DIN EN 13727 EPA 6020 DIN EN 12457-2 + 3 more
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COFRAC 1-2263 Arnage, FR
NF X 43-269 NF X 43-269 - Annexe K NF X 43-298 NF X 43-259 ISO 22262-1 + 3 more
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ENAC LE2097 Castellón de la Plana, ES
UNE-EN ISO 140-5 UNE-EN ISO 16283-3 UNE-EN ISO 140-7 UNE-EN ISO 16283-1 UNE-EN ISO 140-4
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ENAC LE2384 Leganés, ES
ISO/IEC 15408-3 ISO/IEC 15408-1 ISO/IEC 15408-2 ISO/IEC 15408-4 ISO/IEC 15408-5 + 1 more
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COFRAC 1-0064 Saint-Marcel, FR
DIN EN 1254-2 DIN EN 1254-3 DIN EN 1254-5 DIN EN 12101-10 BS EN 50291-1:2018 + 3 more
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DAkkS D-ML-21581-01-00 Berlin, DE
Thrombozytenaggregationstest Blutbild mit Vordifferenzierung Calcium Natriumchlorid Kalium + 3 more
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ENAC LC10.255 Torrejón de Ardoz, ES
CEM EL-020 EURAMET cg-17 CEM EL CEM ME-004 EURAMET cg-11 + 3 more
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ENAC LE1009 Talayuela, ES
UNE 118019 UNE 118012 ISO 22980 UNE 118020 UNE 118021-2
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DAkkS D-K-19708-01-00 Paderborn, DE
- Gleichspannung Quellen > 0,10 V > 1 V > 10 V - Gleichstromstärke + 3 more
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ENAC LE2170 Olot, ES
SM 3111 B SM 3500-K B SM 3500-Na B SM 2330 B SM 3113 B UNE-EN ISO 8467 + 3 more
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ACCREDIA 00034 Scanzorosciate, IT
ISO 19250 EPA 7473 2007 EPA 5030 EPA 8260 DIN EN 1484 + 3 more
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COSMOB

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ACCREDIA 00215 Montelabbate, IT
ISO 16000-3 BS ISO 9227:2022 ISO 16000-6 ISO 16000-9 DIN EN 14749 + 3 more
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COFRAC 1-6553 Senlis, FR
NF X 43-264 NF X 43-267 ISO 16200-1 DIN EN 14385 NF X43-551 + 3 more
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COFRAC 1-0097 Charleville-Mezieres, FR
DIN EN ISO 6508-1 ASTM E8/E 8M DIN EN ISO 643 EN ISO 12624 ISO 4967 + 3 more
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COFRAC 1-1570 Chatellerault, FR
EN 13819-2:2020 DIN 53521 DIN EN 13522 DIN 45635-23 Sizing, Range of fitting, Resistance to + 3 more
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ACCREDIA 00841 Grugliasco, IT
EN ISO 16119-2 DIN EN ISO 28139 EN ISO 16119-3 EN ISO 19932-1 EN ISO 19932-2
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DAkkS D-PL-12030-01-02 Plattling, DE
DIN EN 55016-2 VDE 0877-16-2-1 VDE 0877-16-2-2 VDE 0877-16-2-3 EN IEC 61000-4 + 3 more
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CSI SpA

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ACCREDIA 00009 Bollate, IT
BS 1363-1 BS EN 15662 DIN EN ISO 6888-1 DIN EN 60068-2-30 DIN EN 81-58 + 3 more
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ACCREDIA 00593 Rimini, IT
ISO 3745 DIN EN ISO 11202 DIN EN ISO 11203 UNI 9432 ISO 11204 + 1 more
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Industries

Industrial machinery manufacturers Construction equipment producers HVAC and ventilation systems Power generation and compressor suppliers Large transport and handling equipment makers

Related Standards

  • ISO 3740 Acoustics — Determination of sound power levels of noise sources — General guidelines
  • ISO 3743-1 Acoustics — Determination of sound power levels of noise sources — Part 1: Reverberation room method
  • ISO 3745 Acoustics — Determination of sound power levels of noise sources — Precision method using an enveloping surface

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