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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NF T 90-412 DIN EN ISO 21528-2 DIN EN ISO 7899-1 DIN EN ISO 10304-1 DIN ISO 16649-2 + 3 more

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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