ISO 3744-2010 PDF

Full title and description

ISO 3744:2010 — Acoustics — Determination of sound power levels and sound energy levels of noise sources using sound pressure — Engineering methods for an essentially free field over a reflecting plane. This International Standard specifies engineering-grade (grade 2) methods to determine sound power or sound energy levels of machinery and other noise sources from sound pressure measurements made on a surface surrounding the source in an environment approximating a free field over one or more reflecting planes.

Abstract

ISO 3744:2010 defines procedures for measuring sound pressure on a measurement surface enveloping a noise source and computing the sound power level (or sound energy level for transient events). It gives requirements for the test environment, instrumentation, measurement surface geometry and microphone positions, corrections for non-ideal environments, frequency-band and A-weighted results, and treatment of measurement uncertainty (engineering-grade/ISO 12001 guidance).

General information

• Status: Withdrawn / superseded (see Notes).
• Publication date: October 1, 2010.
• Publisher: International Organization for Standardization (ISO).
• ICS / categories: 17.140.01 (Acoustic measurements and noise abatement in general); commonly referenced with 13.110 (Safety of machinery) in adoptions.
• Edition / version: 3rd edition (2010).
• Number of pages: 78.

Scope

This standard applies to measurement situations where the noise source is situated in an environment that approximates an acoustic free field near one or more reflecting planes (for example an open field over a reflecting plane or a qualified hemi-anechoic chamber). It is intended for determining the sound power level or sound energy level of stationary or slowly moving machinery, plant, components and similar sources, in octave or fractional-octave bands or with A-weighting, provided the measurement conditions specified can be met. Procedures are provided to estimate and correct for non-ideal test environments within prescribed limits.

Key topics and requirements

• Definition and selection of measurement surfaces enveloping the source (rectangular, hemispherical, cuboidal surfaces depending on test setup).
• Requirements for test environment approximating a free field over a reflecting plane and guidance on acceptable deviations and corrections.
• Instrumentation requirements: microphones, calibrators, measurement equipment and spatial averaging procedures.
• Microphone grid layout and sampling positions to obtain surface sound pressure levels with engineering (grade 2) accuracy.
• Calculation methods for converting surface sound pressure measurements into sound power levels and sound energy levels (for transient/noise-burst events).
• Frequency-band reporting (octave and preferred fractional-octave bands) and optional A-weighted results.
• Estimation and reporting of measurement uncertainty consistent with ISO 12001 (engineering-grade uncertainty guidance).
• Specification of test conditions, mounting, operating conditions and information to be included in reports and noise test codes.

Typical use and users

Used by acoustic test laboratories, equipment manufacturers, acoustic consultants, research organizations and regulatory/standards bodies for product noise assessment, design verification, conformity testing, and in the development of noise test codes. Typical applications include machinery noise declaration, comparative product testing, and engineering assessments where a free-field-over-reflecting-plane method is appropriate.

Related standards

Commonly associated standards include the ISO 3740 series (ISO 3740, ISO 3741, ISO 3743, ISO 3745, ISO 3746, ISO 3747) which cover alternative methods and precision grades; ISO 3740:2019 (guidance for selecting basic standards); ISO 12001 (rules for drafting noise test codes); ISO 9614 (sound intensity methods); ISO 11200 / ISO 11201 / ISO 11202 (emitted noise of machinery and measurement methods); ISO 4871 (declaration of noise emission); and other machine- or product-specific noise test codes that reference ISO 3744 measurement principles.

Keywords

sound power level, sound energy level, sound pressure, acoustics, free field, reflecting plane, measurement surface, microphone grid, A-weighting, measurement uncertainty, engineering methods, noise emission, ISO 3744

FAQ

Q: What is this standard?

A: ISO 3744:2010 is an international standard that specifies engineering methods for determining the sound power level and sound energy level of noise sources from sound pressure measurements made on a surface surrounding the source in a free-field-over-reflecting-plane environment.

Q: What does it cover?

A: It covers test environment and instrumentation requirements, selection and layout of measurement surfaces and microphone positions, calculation procedures for sound power and sound energy, band and A-weighted reporting, uncertainty estimation (engineering/grade 2), and guidance for correcting non-ideal environments.

Q: Who typically uses it?

A: Acoustic test laboratories, manufacturers of machinery and equipment, acoustic consultants, standards developers and regulators use ISO 3744 for product noise testing, comparative measurements, and for noise test codes where a free-field-over-reflecting-plane method is appropriate.

Q: Is it current or superseded?

A: ISO 3744:2010 has been withdrawn and superseded by a later edition. The revised standard ISO 3744:2025 was published in December 2025 (corrected versions issued January 2026). For new testing and formal citations, refer to the 2025 edition; ISO 3744:2010 should be treated as superseded.

Q: Is it part of a series?

A: Yes. ISO 3744 is one of the ISO 3740 series of acoustics standards covering various methods and precision grades for determining sound power levels (ISO 3740–3747). It is also used together with ISO 3740:2019 guidance and with noise test codes guided by ISO 12001.

Q: What are the key keywords?

A: Key keywords include sound power level, sound energy level, sound pressure, free field, reflecting plane, measurement surface, microphone grid, A-weighting, measurement uncertainty, engineering methods, noise emission.