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-PL-17009-02-01 Mainz, DE
VDE 0113-201 VDE 0113-202 DIN EN 60204-1 EN 61508-1: VDE 0803-1 + 3 more
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DAkkS D-PL-17009-29-02 Langenhagen, DE
ID136 DIN EN 137 100 C>T, 124 G>A, 137_138 > 140 Amyloid β 1-42 + 3 more
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DAkkS D-PL-17009-01-01 Hamburg, DE
DIN EN ISO 15106-3 DIN EN ISO 1522 DIN 30720-1: 2016-02 DIN 30720-2: 2009-10 DIN 30722-1: 2021-12 + 3 more
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DAkkS D-PL-17009-08-00 Mannheim, DE
DIN EN ISO 11357-4 IEC 61037 DIN EN ISO 13850 DIN EN ISO 13855 ISO 14119 + 3 more
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DAkkS D-K-17009-01-00 Sankt Augustin, DE
Eigenrauschen −60 dB Frequenzbewertung mit akustischen Signalen elektrischen Signalen + 3 more
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DAkkS D-PL-17009-34-00 Sankt Augustin, DE
DIN 58620: 2007-02 DIN 58621: 2011-10 DIN 58647-7: 1997-12 ID136 > 140 + 3 more
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DAkkS D-PL-18020-01-01 Varel, 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-K-11170-01-00 Hamburg, DE
Railway brakes — conditions for homologa − Durchfluss von Flüssigkeiten − Strömungsgeschwindigkeit von Gasen − Widerstandsthermometer − Temperatur-Transmitter, Datenlogger + 3 more
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DAkkS D-ML-13068-01-00 Berlin, DE
ADP ASPI TRAP Amiodaron, Desethylamiodaron Mycophenolsäure + 3 more
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UKAS 0254 Plymouth, GB
Specific Values 1  RF Power RF Attenuation 10 MHz to 1 GHz Other values -20 dBm to +20 dBm
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UKAS 0687 Devonport, GB
BS 4206:1967 (superseded) ISO 5173 ISO 7438 BS EN ISO 9606-2:2004 BS 131-5:1965 + 3 more
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Diagenom

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DAkkS D-ML-18903-01-00 Rostock, DE
Chromosomensatz (angeboren) Chromosomensatz (erworben) Adrenogenitales Syndrom Angelman-Syndrom (15q11-Region, UBE3A) Mikrodeletionen; AZFa-c) + 3 more
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Diagnos MVZ

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DAkkS D-ML-21150-01-00 Berlin, DE
HbA1c Differentialblutbild, maschinell Retikulozyten, maschinell Kleines Blutbild Thrombozyten + 3 more
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UKAS 0798 Hamilton, GB
AUDIOMETRIC EQUIPMENT Attenuator linearity Microphones EAR SIMULATORS Class LS, 1 and 2
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DAkkS D-K-19516-01-00 Ansbach, DE
Volumen strömender 0,0005 m − Durchfluss von Flüssigkeiten 0,025 m Wasserzähler und 0,001 m Durchflusssensoren + 3 more
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ACCREDIA 01333 Napoli, IT
DIN EN ISO 7730 EPA 6020 DIN EN ISO 6888-1 ISO 14698-1 ISO 4832 + 3 more
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UKAS 0560 Bingley, GB
TIME INTERVAL TEMPERATURE parameters and ranges)
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DAkkS D-K-20015-01-01 Lahr, DE
Absolutdruck p * Vickers hardness test (ISO 6507) Flüssigkeitsvolumen * variablem Volumen aufnehmern sowie + 3 more
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DAkkS D-ML-13252-01-01 München, DE
Blutbild groß Thrombozyten Urinsediment Natrium Kalium + 3 more
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DAkkS D-ML-19642-02-00 Ronnenberg, DE
Aminosäureprofil Guanidinoacetat Kreatin Hämoglobinprofil Nitisinon (NTBC), Succinylaceton + 3 more
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Druck

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UKAS 0221 Groby, GB
Gas pressure (absolute) Hydraulic pressure (gauge) Gas pressure (gauge) (At low current) Specific values (continued) + 3 more
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DAkkS D-K-11250-01-00 Lübeck, DE
Druck * Negativer und positiver Überdruck -0,01 bar Positiver Überdruck p e > 0,015 bar + 3 more
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Duravit

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DAkkS D-PL-21217-01-00 Hornberg, DE
*6095991, BAG3 [OMIM *6038831 (-13910T>C) rs4988235 - PiM rs6647, PiZ rs28929474, rs17580 DIN EN 997 DIN EN 13407 + 3 more
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UKAS 29302 Lower Earley, GB
DIN EN 14791 IEC 60519-11 BS EN ISO 16911-1:2013 using DIN EN 14792 DIN EN 13126-19 + 3 more
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E C L (2000)

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UKAS 0709 Forest Hall, GB
(PCM) based on HSG 248) (HSG 248) – 2021
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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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