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
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DIN EN ISO 3740
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BS EN ISO 3740
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NF EN ISO 3740
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UNI EN ISO 3740
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UNE EN ISO 3740
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NEN EN ISO 3740
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DIN EN ISO 3743-1
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BS EN ISO 3743-1
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NF EN ISO 3743-1
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UNI EN ISO 3743-1
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UNE EN ISO 3743-1
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NEN EN ISO 3743-1
cartridges, based on HTM 20309.201 to 9.212 and BS EN ISO35 °C/3 days based on HTM 2030section 9.201 to 9.212, BS ENISO 15883-1:2009 6.4.2.3 and+ 3 more
Industrial machinery manufacturersConstruction equipment producersHVAC and ventilation systemsPower generation and compressor suppliersLarge transport and handling equipment makers
Related Standards
ISO 3740Acoustics — Determination of sound power levels of noise sources — General guidelines
ISO 3743-1Acoustics — Determination of sound power levels of noise sources — Part 1: Reverberation room method
ISO 3745Acoustics — Determination of sound power levels of noise sources — Precision method using an enveloping surface
Scope