Overview
EN ISO 3743-2:2019 (adopted from ISO 3743-2:2018) is a CEN standard for acoustics that specifies an engineering method to determine sound power levels from sound pressure measurements. It is aimed at small, movable noise sources tested in special reverberation test rooms (reverberant fields). The standard provides practical procedures for measurement setup, instrumentation, and calculation of broadband and octave-band sound power levels. It does not apply to isolated impulsive noise bursts (see ISO 3744 and ISO 3745). ISO 12001 provides noise classification guidance referenced by this document.
Key topics and technical requirements
- Test room requirements
- Criteria for room volume, reverberation time and surface treatment specific to special reverberation test rooms.
- Methods to evaluate the suitability of a test room for accurate measurements.
- Instrumentation and calibration
- Specifications for microphones and associated cables, amplifiers, weighting networks, octave-band filters, and averaging/squaring circuits.
- Requirements for system frequency response and traceable calibration.
- Source installation and operation
- Guidance on source location, mounting, handling of auxiliary equipment and stable operation during tests.
- Measurement procedure
- Microphone positioning strategies: fixed arrays and moving-microphone traverses.
- Periods of observation and criteria to detect spectral irregularities.
- Correction methods for background sound pressure levels.
- Calculation and uncertainty
- Direct and comparison methods for computing sound power levels from measured sound pressure.
- A-weighted sound power procedures and formal measurement uncertainty assessment (standard deviation σ and expanded uncertainty U).
- Environmental criteria
- Criteria for acceptable background noise and limits on temperature and humidity during testing.
Applications and users
- Practical uses:
- Type-testing of small machinery and equipment in reverberant rooms.
- Product noise labeling, development testing, and compliance verification for acoustic performance.
- Data used for noise control engineering, sound power databases, and source noise modeling.
- Typical users:
- Acoustic consultants, test laboratories, R&D and product engineers, compliance officers, and certification bodies.
- Manufacturers needing repeatable sound power data for design or regulatory compliance (e.g., machinery directives).
Related standards
- ISO 3743 series (other parts) - alternative methods for different environments.
- ISO 3744 and ISO 3745 - methods for free-field and precision reverberation room measurements; cover impulsive noises.
- ISO 12001 - noise classification guidance.
- Directive 2006/42/EC - this standard supports conformity assessment for machinery noise requirements when cited in the Official Journal.
Keywords: EN ISO 3743-2:2019, ISO 3743-2:2018, sound power levels, sound pressure, reverberant fields, special reverberation test rooms, measurement uncertainty, acoustic testing.