ISO 3743-2:2018

Overview

ISO 3743-2:2018 - "Acoustics - Determination of sound power levels of noise sources using sound pressure - Engineering methods for small, movable sources in reverberant fields - Part 2: Methods for special reverberation test rooms" - defines a practical engineering method to determine sound power levels of small, portable noise sources using sound pressure measurements in special reverberation test rooms. It is part of the ISO 3743 series and is intended for engineering‑grade acoustic measurements (A‑weighted and octave‑band) for machines, devices and sub‑assemblies that can be moved into a test room. The standard excludes isolated impulsive noise (see ISO 3744 / ISO 3745) and refers to classification guidance in ISO 12001.

Key Topics and Requirements

• Principle and scope: Measurement of spatially averaged sound pressure to calculate sound power levels (direct and comparison methods).
• Special reverberation test room criteria: Requirements and evaluation for room volume, reverberation time, surface treatment and environmental conditions (temperature, humidity), plus background noise limits.
• Instrumentation: Specifications for microphones, cabling, amplifiers, weighting networks, octave‑band filters, averaging/squaring circuits and calibration procedures.
• Measurement procedures:
  • Fixed microphone arrays and moving‑microphone traverses.
  • Prescribed microphone positions, path lengths, traverse speeds and averaging techniques.
  • Corrections for background sound pressure and checks for spectral irregularities.
• Calculation methods: Procedures for deriving mean band pressure levels and converting these to octave‑band and A‑weighted sound power levels (direct and comparison methods).
• Uncertainty and reporting: Methodology for estimating measurement uncertainty, guidance on σ values, and required information to record and report results.
• Annexes: Normative and informative annexes include reference source calibration, guidelines for room design, example instrumentation systems and uncertainty guidance.

Applications and Users

ISO 3743-2 is used wherever practical, repeatable sound power data are needed for small, movable equipment:

• Acoustic consultants and test laboratories performing sound power testing in reverberant fields.
• Manufacturers of hand‑held tools, small appliances, and portable equipment seeking product noise data for design, conformity, or labeling.
• R&D and QA teams validating noise control measures or comparing prototype performance.
• Facilities designing or qualifying special reverberation test rooms.

Related Standards

• ISO 3743-1 (other engineering methods)
• ISO 3740 (selection guidance for methods)
• ISO 3744, ISO 3745 (laboratory and precision methods; impulsive noise)
• ISO 12001 (noise classification)

Keywords: ISO 3743-2, sound power levels, reverberant test room, sound pressure, octave bands, A-weighted, acoustics measurement, measurement uncertainty.