ISO 3745-2012 PDF

Full title and description

ISO 3745:2012 — Acoustics — Determination of sound power levels and sound energy levels of noise sources using sound pressure — Precision methods for anechoic rooms and hemi-anechoic rooms. This International Standard specifies precision (grade 1) methods for determining the sound power and sound energy emitted by noise sources from measurements of sound pressure in qualified anechoic and hemi-anechoic test rooms, including requirements for the test environment, instrumentation, measurement surfaces and procedures, and reporting.

Abstract

ISO 3745:2012 defines laboratory procedures and acceptance criteria for performing surface-based sound pressure measurements in anechoic and hemi-anechoic rooms to calculate sound power levels (and, for transient or impulsive emissions, sound energy levels) in octave and one-third-octave bands or as A-weighted levels. The standard covers room qualification, microphone arrays and measurement surfaces, reference conditions and corrections, uncertainty considerations for grade 1 (precision) results, and reporting requirements. An amendment to the 2012 edition was published in 2017 to clarify and update certain requirements.

General information

• Status: Published (current edition confirmed following periodic review)
• Publication date: March 2012 (Edition 3)
• Publisher: International Organization for Standardization (ISO)
• ICS / categories: 17.140.01 (Acoustics)
• Edition / version: Edition 3 (ISO 3745:2012); amendment ISO 3745:2012/Amd 1:2017
• Number of pages: 63

Scope

This standard specifies precision methods for the determination of sound power levels and sound energy levels of noise sources from sound pressure measurements performed in purpose-built anechoic and hemi-anechoic rooms. It defines the test environment and instrumentation requirements, measurement-surface geometries and microphone arrangements, procedures for steady and transient noise, frequency-band reporting (typically one-third-octave and octave bands, commonly covering approximately 100 Hz to 10 kHz though the applicable range depends on room qualification), correction factors and treatment of meteorological differences, and requirements for uncertainty evaluation and test reporting. ISO 3745 is intended for tests requiring high accuracy (grade 1) values of sound power or sound energy.

Key topics and requirements

• Qualification criteria and acceptance tests for anechoic and hemi-anechoic rooms used for precision measurements.
• Definition of measurement surfaces (spherical, hemispherical, parallelepiped or other allowed shapes) that enclose the noise source and terminate appropriately on reflecting planes.
• Microphone placement, array layouts and number of measurement positions to achieve grade 1 accuracy.
• Instrument calibration and traceability requirements (sound level meters, microphones, calibrators).
• Procedures for steady, fluctuating and transient/impulsive noise; calculation of sound power and sound energy from measured surface sound pressure.
• Required corrections for reference acoustic impedance and environmental conditions (temperature, pressure, humidity) and their effect on calculated levels.
• Uncertainty assessment consistent with metrological practice and assignment of accuracy grade 1 to results.
• Reporting content: test room qualification data, instrumentation and calibration details, measurement surface geometry, raw and corrected results, uncertainty statement and test conditions.

Typical use and users

ISO 3745:2012 is used by accredited acoustical laboratories, national metrology institutes, manufacturers and R&D facilities performing high-accuracy sound power and sound energy measurements for product development, verification, certification and compliance. Typical users include test engineers, acoustics consultants, product compliance teams, manufacturers of machines and appliances, and researchers requiring laboratory-grade acoustic emission data.

Related standards

ISO 3745 complements other ISO acoustics standards in the ISO 374x and ISO 9614 series. Commonly referenced related standards include ISO 3744 and ISO 3746 (engineering and survey methods using sound pressure), ISO 3743 (methods for small movable sources in reverberant fields), the ISO 9614 series (sound intensity methods), and ISO/IEC and IEC references for instrumentation (for example sound level meter and calibrator standards). ISO 12001 and other guides on measurement uncertainty and reporting are also relevant for uncertainty evaluation and conformity assessment.

Keywords

acoustics; sound power level; sound energy level; sound pressure; anechoic room; hemi-anechoic room; precision measurement; grade 1; microphone array; measurement surface; room qualification; uncertainty; ISO 3745; amendment 2017

FAQ

Q: What is this standard?

A: ISO 3745:2012 is an international standard that specifies precision laboratory methods (grade 1) for determining sound power and sound energy levels of noise sources from sound pressure measurements made in anechoic and hemi-anechoic rooms.

Q: What does it cover?

A: It covers requirements for the test environment and room qualification, measurement-surface geometries and microphone layouts, instrumentation and calibration, measurement procedures for steady and transient noise, corrections for environmental conditions, uncertainty evaluation, and reporting requirements to produce high-accuracy sound power/energy values.

Q: Who typically uses it?

A: Accredited acoustics laboratories, manufacturers, product test and compliance teams, acoustical consultants, and researchers who need laboratory-grade sound power or sound energy determinations use ISO 3745.

Q: Is it current or superseded?

A: ISO 3745:2012 (Edition 3) is the current edition published in March 2012; an amendment was released in 2017. The standard is subject to periodic ISO review; users should check with their national standards body or ISO for any more recent revisions or confirmations.

Q: Is it part of a series?

A: Yes. ISO 3745 is part of a family of acoustics standards for determining sound power and sound energy (the ISO 374x series) and is often used alongside ISO 3744, ISO 3746, ISO 3743 and the ISO 9614 sound intensity standards, each addressing different test environments and accuracy grades.

Q: What are the key keywords?

A: Key keywords include: sound power level, sound energy level, sound pressure, anechoic room, hemi-anechoic room, measurement surface, grade 1 precision, room qualification, microphone array, uncertainty, ISO 3745.