Overview
EN ISO 9614-1:2009 - "Acoustics - Determination of sound power levels of noise sources using sound intensity - Part 1: Measurement at discrete points" specifies a sound-intensity-based method to determine the sound power radiated by a noise source. The procedure measures the normal component of sound intensity on a physically stationary surface that encloses the source, samples the intensity field at discrete points, and calculates one-octave, one-third-octave or band-limited weighted sound power levels. The method is applicable in situ or in special test environments where the source and measurement surface are stationary and the source noise is time‑stationary.
Key Topics
- Measurement principle: Determination of sound power by integrating the scalar product of the sound intensity vector and elemental area over an enclosing surface sampled at discrete points.
- Discrete-point sampling: Sampling strategy and its effect on sampling error (depends on source directivity, surface choice and point distribution).
- Frequency bands: Results are produced in one-octave or one-third-octave bands; band‑limited A‑weighted levels are derived from band data (not by direct A‑weighted intensity measurements).
- Instrument and environment requirements: Guidance on intensity probes, calibrators and acceptable acoustic environments (limits on airflow, extraneous noise and field variability).
- Installation & operation: Positioning of source, measurement surface definition, and precautions to avoid absorbing materials inside the surface that could bias results.
- Accuracy grading: Classification of uncertainty and grade of accuracy based on ancillary tests and calculations included in the standard.
- Annexes: Practical guidance on field indicators, procedures to achieve desired accuracy, airflow effects, and absorption effects within the measurement surface.
Applications
- Acoustic engineers & consultants: Field measurement of machinery, equipment and plant noise where laboratory conditions are impractical.
- Manufacturers & test labs: In‑situ verification of machine sound power for product development, quality control and compliance.
- Occupational and environmental noise assessment: Estimating emitted sound power for noise mapping, risk assessment and mitigation planning.
- Regulatory conformity: Useful where a presumption of conformity with machinery directives is required; the European adoption (CEN) links this standard to EU Directives (e.g., 98/37/EC, 2006/42/EC) through informative annexes.
Related Standards (if applicable)
- ISO 9614-2 (Measurement by scanning) - complementary method.
- ISO 3740–3747 series - sound power determination by pressure-based procedures (complementary methods).
- ISO 5725, IEC 942 - referenced for measurement precision and calibrators.
- Use keywords: EN ISO 9614-1:2009, sound intensity measurement, sound power level, discrete points, in situ acoustic measurement, one-third-octave.