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
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ENAC LE1703 Madrid, ES
ISO 11731 SM 5220 UNE-EN ISO 6222 UNE-EN ISO 20236 UNE EN 27888 + 3 more
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ENAC LC10.007 Torrejón de Ardoz, ES
ISO 16063-21 EN 55016-1-6 CEM EL-025 UNE-EN ISO 376 UNE-EN ISO 7500-1 + 3 more
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ENAC LE1285 Torrejón de Ardoz, ES
UNE-EN ISO 10704 UNE 73350-1 UNE 73311-5 ISO 11665-4 UNE 31010 + 1 more
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ENAC LE257 Zaragoza, ES
IEC 61000-4-13: 2002 DIN EN 50121-3-2 IEC 61000-3-2: 2014 DIN EN 60601-1-2 IEC 61000-3-3 + 3 more
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ENAC LE554 Paterna, ES
IEC 61000-3-2: 2014 UNE-EN IEC 61000-3-2 UNE-EN 61000-3-2 UNE-EN IEC 61000-6-4 IEC 61000-3-3 + 3 more
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ENAC LC10.149 Madrid, ES
(380 - 780 nm) 1 < R ≤ 100 0,01< DO ≤ 0,1 0,1 < DO ≤ 0,3 1,1 < DO <
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ENAC LE1286 Bétera, ES
DIN EN 1040 DIN EN 1656 DIN EN 14561 IEC 60127-6 DIN EN 13727 + 3 more
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ENAC LC10.164 Prat de Llobregat, ES
(500 ± 50) mPa · s (12500 ± 1250) mPa ·
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ENAC LC10.091 Cabrils, ES
2 · 10-6 mol/mol  C  100 · 10-6 mol/mo
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ENAC LE1754 Torrent, ES
UNE-EN ISO 16283-1 UNE-EN ISO 16283-3 UNE-EN ISO 16283-2
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ENAC LC10.259 Cartagena, ES
CEM EL-014 CEM EL CEM EL-001 CEM ME
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ENAC LE1644 Paterna, ES
UNE-EN ISO 16283-1 UNE-EN ISO 16283-3 UNE-EN ISO 16283-2
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ENAC LE2505 Granada, ES
UNE 320001 ISO/IEC 18045 ISO/IEC 15408 CEM ISO ISO/IEC 24759 + 2 more
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ENAC LC10.199 Hospitalet de Llobregat, ES
Caudal m3/h 0,010 m3/h  Q  250 m3/h 0, Caudal m3/h 0,16 m3/h  Q  2500 m3/h 0,
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LABACUSTIC

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ENAC LE1438 Vall d Uixó, ES
UNE-EN ISO 140-5 UNE-EN ISO 16283-3 UNE-EN ISO 16283-2 UNE-EN ISO 140-7 UNE-EN ISO 16283-1 + 1 more
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ENAC LE285 Alacant, ES
UNE-EN ISO 27888 SM 2540 UNE-EN ISO 8467 UNE-EN ISO 7027-1 UNE-EN ISO 10523 + 3 more
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ENAC LE1912 Colmenar Viejo, ES
AOAC 995.11 UNE EN ISO 6869 AOAC 985.35 UNE-EN 17298
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ENAC LE609 Abegondo, ES
UNE 77324 ISO 23318 UNE 77325 ISO 10390 UNE 77308 + 3 more
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ENAC LE390 Madrid, ES
UNE-EN ISO 663 UNE-EN ISO 662 UNE-EN 16328 UNE-EN 16618 UNE-EN 13368-1 + 3 more
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ENAC LE130 Madrid, ES
DIN EN 60335-2-51 DIN EN 60335-2-43 IEC 62054-21 IEC 60335-2-51 DIN EN 60335-2-99 + 3 more
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ENAC LE1892 León, ES
UNE-EN ISO 140-5 UNE-EN ISO 16283-3 UNE-EN ISO 16283-2 UNE-EN ISO 140-7 ISO 2631-2 + 3 more
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ENAC LC10.085 Madrid, ES
UNE-EN 60942 UNE-EN 61672-3 UNE-EN 60804 UNE-EN 60651 UNE-EN 61260-3 + 3 more
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LABENAC

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ENAC LE821 Madrid, ES
UNE-EN ISO 16283-1 UNE-EN ISO 16283-2 UNE-EN ISO 16283-3 UNE-EN ISO 140-7 UNE-EN ISO 140-4 + 1 more
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UPM

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ENAC LC10.086 Madrid, ES
- 40 ˚C a 85 ˚C > 85 ˚C a 200 ˚C - 25 ˚C a 85 ˚C
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ENAC LE1512 Donostia-San Sebastián, ES
UNE-EN ISO 140-5 UNE-EN ISO 16283-3 UNE-EN ISO 16283-2 UNE-EN ISO 140-7 UNE-EN ISO 16283-1 + 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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