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
20 Countries

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DAkkS D-ML-13258-03-00 Mainz, DE
5-Hydroxyindolessigsäure Amitriptylin/Nortriptylin Cyclosporin A Gesamt-Itraconazol Metanephrine, Normetanephrine + 3 more
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COFRAC 1-6561 Sainte-Florine, FR
ISO 16750-3 IEC 60068-2-80) IEC 60068-2-53 limitée à : IEC 60068-2-14 fait IEC 60068-2-1 et + 3 more
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DAkkS D-PL-12061-01-01 Offenbach am Main, DE
IEC 60061-1 IEC 60061-2 IEC 60238 IEC 61184 IEC 60400 + 3 more
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UKAS 1634 Whitley Bay, GB
(HSG 248) – 2021 ASB/10 based on HSG 248 (PCM) based on HSG 248 ASB/6 based on HSG 248 BS EN ISO 14644-1:2015 + 3 more
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ENAC LC10.112 Sevilla, ES
UNE-EN 60942 UNE-EN 61672-3 UNE 82503 UNE-EN 60804 UNE 20942 + 3 more
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ENAC LE2110 Castellón de la Plana, ES
UNE-EN ISO 16283-1 UNE-EN ISO 16283-3
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ENAC LC10.251 Hospitalet de Llobregat, ES
CEM ME009
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DAkkS D-PL-19465-01-00 Darmstadt, DE
Myopathie, Nemaline (TyP1, 3-10: ASTM E 23-18 ASTM D 1322 Toxizität UGT1A1-Gen rs3064744, rs414832 DIN EN 1789 + 3 more
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DAkkS D-PL-21133-01-00 Versmold, DE
DIN SPEC 91323 DIN EN 1815 DIN 8959 DIN 8959 Ber. 1
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VSL

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RvA K999 Delft, NL
HCS LF 1 1 HCS LF 2 1 HCS LF 1 3 HCS LF 12 HCS LF 22 + 3 more
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UKAS 0593 Lutterworth, GB
TEMPERATURE parameters and ranges) indicators or recorders WEIGHING INSTRUMENTS
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Vantify

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UKAS 7892 Stoke Prior, GB
Appendix 5 of HSG 227 (2004) (HSG 264, 2012)
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DAkkS D-PL-11149-01-01 Köln, DE
DIN EN 61466-1 DIN EN 61466-2 DIN 14678 DIN EN 54-2/A1 DIN EN 543 + 3 more
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Vectoflow

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DAkkS D-K-21643-02-00 Gilching, DE
am Standort Vectoflow Windtunnel A, Frie Strömungsgeschwindigkeit von Gasen 15 m/s bis > 38 m/s
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DAkkS D-ML-13393-01-00 Karlsruhe, DE
Blutbild, kleines (Erythrozyten, Leukozy Erythrozyten Leukozyten Retikulozyten Thrombozyten + 3 more
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UKAS 10213 Bishops Stortford, GB
(HSG 264:2012) 5 of HSG 227 (2004))
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UKAS 1249 Garston, GB
(HSG 248) – 2021 (PCM) based on HSG 248 P052 based on HSG 248
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DAkkS D-K-18737-01-01 Jena, DE
− Permanentes Laboratorium Positionen und Abstände gleichgerichteter Kanten positionen von Strukturen (Hartschichtmasken) + 3 more
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W H Stephens

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UKAS 7855 Belfast, GB
(HSG 264, 2012)
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DAkkS D-K-17723-01-00 Wiesthal, DE
Koordinatenmessgeräte von <7000 mm under-Edge, UK INCA3D, Software von Inspect 3D, Cholet, F + 3 more
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DAkkS D-K-15105-01-00 Klingenberg, DE
Positiver und −1 bar bis −0,03 bar Positiver und negativer (ein- oder mehrgängige > −0,03 bar bis > 0,15 bar bis + 3 more
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DAkkS D-K-17410-01-01 Korbußen, DE
− Parallelendmaße − Längenmessmittel − Durchmesser − Formabweichung − Gewinde + 3 more
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DAkkS D-PL-11098-01-01 Admannshagen-Bargeshagen, DE
IEC 61400-12 IEC 61400-12-1 IEC 61400-12-2 IEC 61400-12-3 IEC 61400-12-5 + 3 more
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DAkkS D-PL-11233-01-01 Grevenbroich, DE
IEC 61400-12-1 IEC 61400-12-2 IEC 61400-12-3 IEC 61400-12-5 IEC 61400-12-6 + 3 more
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WSP UK

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UKAS 2538 London, GB
(HSG 248) – 2021 AFC based on HSG 248 (PCM) based on HSG 248 SSA based on HSG 248
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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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