ISO 3746:2010

Overview

ISO 3746:2010 - "Acoustics - Determination of sound power levels and sound energy levels of noise sources using sound pressure - Survey method using an enveloping measurement surface over a reflecting plane" - specifies a practical survey method to estimate sound power levels and sound energy levels from measured sound pressure on a surface that envelops the noise source. The method applies A-weighting and is suitable for steady, fluctuating, transient or burst noise sources in indoor or outdoor test environments where one or more reflecting planes are present. Results meet accuracy grade 3 (survey grade) in accordance with ISO 12001:1996.

Key topics and requirements

• Measurement principle: Derive sound power (or event sound energy) from energy-averaged sound pressure measured at multiple microphone positions on an enveloping measurement surface that terminates on the reflecting plane.
• Measurement surfaces: Supports hemispherical, half-hemispherical and parallelepiped surfaces; normative guidance for microphone arrays is given in annexes (e.g., hemispherical and parallelepiped arrays).
• Frequency range: Nominal octave bands from 125 Hz to 8 000 Hz (frequency A-weighting applied).
• Corrections:
  • Background noise correction (K1) to compensate for non-test-source noise.
  • Environmental correction (K2) to account for reflections/absorption in the test environment.
• Instrumentation and calibration: References IEC 61672-1 for sound level meters and IEC 60942 for calibrators.
• Uncertainty and accuracy: Uncertainty information is provided and conforms to ISO 12001:1996 (survey grade). Guidance on measurement uncertainty is included (Annex D informative).
• Test reporting: Requirements for documented test conditions, measurement positions, corrections applied and results.

Applications

• Factory acceptance tests and routine noise surveys for machinery and equipment.
• Product noise declaration and labelling where a survey-grade estimate of sound power is sufficient.
• Occupational health & safety assessments to identify high-noise equipment and prioritize controls.
• Design verification for machine manufacturers during development or production checks.

Who uses ISO 3746:2010

• Acoustical engineers and consultants conducting noise emissions testing.
• Test laboratories performing machinery noise surveys.
• Manufacturers specifying or declaring equipment noise emissions.
• Safety officers and compliance teams assessing plant noise.

Related standards

• ISO 3740 series (selection guide across ISO 3741–3747)
• ISO 3744, ISO 3745 (higher-accuracy engineering/precision methods)
• ISO 12001:1996 (test code drafting rules, accuracy grade reference)
• IEC 61672-1 (sound level meters), IEC 60942 (calibrators)
• ISO 9614 (alternative sound power measurement methods)

Keywords: ISO 3746:2010, acoustics, sound power level, sound energy level, survey method, enveloping measurement surface, reflecting plane, A-weighting, measurement uncertainty.