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 LC10.010 Madrid, ES
8 mT/A ≤ B/I < 500 mT/A 80 mT ≤ B ≤ 1,1 T 0,2 mT ≤ B < 1,1 T 0 mT ≤ B < 80 mT 10 Wb <   0,2 Wb + 2 more
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ENAC LC10.110 Vilanova i la Geltrú, ES
CEM DI-021 CEM DI-008 EURAMET CG-10 CEM DI-005 EURAMET CG-6 + 2 more
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TERMOCAL

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ENAC LC10.063 Valladolid, ES
3,5 kPa  P  70 kPa 70 kPa < P  700 kP 3,5 kPa  P  2,0 MPa 2,0 MPa < P  7,0 3,5 kPa  P  20 kPa 20 kPa < P  70 kPa 100 kPa  P  6,1 MPa 6,1 MPa < P  100 100 kPa  P 70 MPa + 3 more
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ENAC LC10.002 Madrid, ES
nach DIN EN ISO 3650:1999 EURAMET CG-6 ISO 5436-1 CEM DI-013 CEM DI-012 + 3 more
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LARUEX

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ENAC LE1260 Cáceres, ES
UNE-EN ISO 10704 UNE-EN ISO 10703 EPA 903.0 EPA 909.0 ISO 13161 + 3 more
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ENAC LC10.052 San Cibrao das Viñas, ES
CEM DI-025 CEM DI-018 UNE-EN ISO 21920-3 CEM DI-009 CEM DI-003 + 3 more
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ENAC LE1340 San Ginés, ES
UNE-EN ISO 7887 UNE-EN ISO 17852 UNE-EN ISO 8467 ISO 7150-1 SM 2510 B + 3 more
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ENAC LC10.195 Paterna, ES
ISO 5-3 ISO 2813 UNE-EN ISO 9342-1 UNE-EN ISO 8598-1 ISO 3664 + 3 more
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ENAC LE670 Pilar de la Horadada, ES
ISO 11290-1 AOAC 991.43 UNE-EN ISO 15216-2 UNE-EN ISO 6579-1 UNE 77324 + 3 more
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ENAC LE1116 Fuenlabrada, ES
UNE 10523 UNE 27888 UNE 7027-1 ISO 23695 UNE-EN ISO 9308-1 + 3 more
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ENAC LE1782 Paterna, ES
SM 2540 F SM 2540 C UNE-EN ISO 7027 SM 2520 B SM 2510 B + 3 more
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ENAC LE1322 Burguillos, ES
UNE-EN 7027-1 UNE-EN ISO 10523 SM 2520 B UNE EN 27888 UNE-EN 872 + 3 more
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ENAC LE2494 Paterna, ES
ISO/IEC 18045 ISO/IEC 15408 UNE 320001
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ENAC LE894 Bellaterra, ES
UNE-EN 12015 UNE-EN 50065-1 UNE-EN IEC 61000-6-4 UNE-EN IEC 61000-6-3 UNE-EN 61000-6-3 + 3 more
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ENAC LC10.040 Rubí, ES
10 · 10-6 mol/mol  C  20 · 10-6 mol/mo 10 · 10-6 mol/mol  C  5000 · 10-6 mol/ 1 · 10-6 mol/mol  C  10 · 10-6 mol/mol 1 · 10-6 mol/mol  C  5 · 10-6 mol/mol 10 · 10-6 mol/mol  C  100 · 10-6 mol/m + 3 more
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Margarida

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ENAC LE441 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 + 2 more
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MCV

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ENAC LC10.124 Collbató, ES
0,005 l/min ≤ Q ≤ 50 l/min 0,5 m3/h≤ Q ≤ 2,8 m3/h 0,6 m3/h  Q  2,8 m3/h 20 m3/h  Q  30 m3/h 30 m3/h < Q  70 m3/h + 3 more
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ENAC LC10.163 Badalona, ES
Rangos de caudal (m3/h): 1 m3/h ≤ Q < 25
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ENAC LC10.236 San Ginés, ES
1 g 2 g 5 g 10 g 20 g 50 g 100 g 200 g 5 5 kg 10 kg 20 kg 100 kg 200 kg 500 kg 1000 kg 1 g 2 g 5 g 10 g 20 g 50 g 100 g 200 g 5 + 2 more
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ENAC LC10.077 Madrid, ES
2 · 10–6 mol/mol  C  100 · 10–6 mol/mo 0,1 · 10–2 mol/mol < C  2,5 · 10–2 mol/ 1 · 10–6 mol/mol  C  100 · 10–6 mol/mo 5 · 10–6 mol/mol  C  20 · 10–6 mol/mol 0,15 · 10–2 mol/mol  C  20 · 10–2 mol/ + 3 more
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OCA GLOBAL

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ENAC LE2316 Pozuelo de Alarcón, ES
UNE-EN 14385 UNE-EN 15259 UNE-EN 13211 BS ISO 9096:2017 UNE 77216 + 3 more
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ENAC LE1844 Valencia, ES
UNE-EN ISO 140-5 UNE-EN ISO 16283-3 UNE-EN ISO 16283-2 UNE-EN ISO 140-7 UNE-EN ISO 3382-2 + 2 more
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ENAC LE2092 Alcázar de San Juan, ES
UNE-EN ISO/IEC 17025
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QUACER

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ENAC LE1517 Onda, 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 LE2055 Nigrán, ES
UNE-EN 1789
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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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