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
1,670 Accredited labs
18 Countries

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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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ENAC LE1474 San Sebastián de los Reyes, ES
UNE 73109 IEC 60780 (1998) UNE 73109 (2001) ISO 28218 ISO 27048
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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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WTLAB

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ACCREDIA 01077 Tribano, IT
IEC 62109-1 IEC 61400-21-1 IEC 62109-2 DIN EN 60598-2-4 DIN EN 60068-2-30 + 3 more
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DAkkS D-K-20130-01-00 Meissen, DE
Charpy impact test (ISO 148-1) Salt spray / neutral salt fog test (ISO elektronische Waagen verwendete Abkürzungen: 1) In den CMC sind die erweiterten Messu + 2 more
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Waagen-Jöhnk

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DAkkS D-K-19520-01-00 Dätgen, DE
Charpy impact test (ISO 148-1) Salt spray / neutral salt fog test (ISO Radiated emissions (CISPR 32) verwendete Abkürzungen:
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DAkkS D-K-19038-01-00 Rimbach, DE
Charpy impact test (ISO 148-1) Salt spray / neutral salt fog test (ISO Radiated emissions (CISPR 32) verwendete Abkürzungen:
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DAkkS D-K-17685-01-00 Hardegsen, DE
Charpy impact test (ISO 148-1) Salt spray / neutral salt fog test (ISO elektronische Waagen verwendete Abkürzungen:
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UKAS 1762 High Wycombe, GB
EN 13501-2 DIN 51363-2 BS 1363-1 BS 476: Part 21:1987 Section 5 ISO 834:1975:Sections 5, 6, 7 + 3 more
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DAkkS D-PL-14015-01-02 Erding, DE
DIN EN 2561 DIN EN ISO 14126 DIN EN ISO 14125 DIN EN 2563 DIN 53504 + 3 more
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DAkkS D-PL-17463-01-00 Ahaus, DE
DIN 45645-2 DIN EN ISO 11690-1 DIN EN ISO 11690-2
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UKAS 20481 Winterborne Zelston, GB
TEMPERATURE controllers, and recorders) RELATIVE HUMIDITY
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DAkkS D-PL-21876-01-01 Dortmund, DE
DIN IEC 60060-1 VDE 0432- 1 IEC 60270 VDE 0434 DIN EN 61243-1 + 3 more
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DAkkS D-K-14054-01-00 Hörstel, DE
Kohlenstoffmonoxid *) Kohlenstoffdioxid Propan *) Stickstoffmonoxid Distickstoffmonoxid + 3 more
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UKAS 21065 Cleckheaton, GB
Analysts’ Guide (HSG 248) (PCM) based on HSG 248 staining based on HSG 248
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UKAS 7567 Newcastle-Under-Lyme, GB
(HSG 248) – 2021 SOP 12 based on HSG 248 (PCM) based on HSG 248 SOP 11 based on HSG 248
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UKAS 1830 Callington, GB
ISO 21528-2 BS ISO 4832:2006 BS ISO 16649-2:2001 Method No 2.9 based on BS EN ISO Method No 2.12 based on BS EN + 3 more
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ACCREDIA 00165 Roncoferraro, IT
ISO 13720 DIN 3388-4 EPA 6020 EPA 3535 DIN EN ISO 6888-1 + 3 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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