ISO 9614-3:2002

Overview

ISO 9614-3:2002 - Acoustics: Determination of sound power levels using sound intensity - Part 3 specifies a precision method for measurement by scanning. The standard defines how to measure the component of sound intensity normal to a measurement surface that encloses the source, by subdividing that surface into contiguous partial surfaces and scanning an intensity probe continuously across each partial surface. Measured one‑third‑octave band intensities are averaged over scans and combined to calculate octave‑band and band‑limited weighted sound power levels. The method applies where a physically stationary measurement surface and a stable acoustic environment can be defined.

Key topics and requirements

• Measurement principle: Surface integration of the normal sound intensity component via scanning probe paths over partial surfaces.
• Instrumentation: Requires calibrated sound intensity probes and instruments; conforming equipment (e.g., per IEC 61043) limits practical measurement to about 50 Hz–6.3 kHz for one‑third‑octave bands.
• Scanning procedure: Continuous manual or mechanical scan per partial surface; instrument outputs time‑averaged normal intensity and averaged squared sound pressure for each scan.
• Test environment: Criteria for adequacy include low and stationary extraneous noise, acceptable airflow/gas flows, stable temperature and atmospheric conditions, and controlled surroundings.
• Quality / uncertainty: Ancillary procedures (Annex C, normative) and field indicators (Annex B) assess measurement quality and define the grade of accuracy. Tests and corrective actions are specified if accuracy requirements are not met.
• Limitations: Not applicable to frequency bands where measured sound power is negative; unsuitable if extraneous noise or environmental variability exceed instrument dynamic capability or make intensity measurements unreliable.
• Data and reporting: Requirements for recording measurement surface definition, scanning paths, averaged intensities/pressures, and uncertainty indicators.

Applications and users

ISO 9614-3 is used by:

• Acoustic engineers and test laboratories performing sound power determinations for machinery and equipment.
• Product manufacturers needing accurate noise emission data for design, compliance, and noise control.
• R&D teams validating acoustic performance and directivity using sound intensity scanning.
• Certification bodies and compliance test facilities where higher precision than point methods is required.

Practical uses include determining radiated sound power of machines that cannot be tested in specialized ISO 3740–3747 facilities or where extraneous noise precludes pressure‑based methods.

Related standards

• ISO 9614-1: Measurement at discrete points
• ISO 9614-2: Measurement by scanning (general)
• ISO 3740–3747 series: Sound power determination using sound pressure
• IEC 61043: Instrumentation for sound intensity (equipment conformity)