ISO 532-2:2017

Overview

ISO 532-2:2017 - "Acoustics - Methods for calculating loudness - Part 2: Moore‑Glasberg method" specifies a standardized algorithm for estimating the loudness and loudness level of stationary sounds as perceived by otologically normal adults. Based on the Moore–Glasberg model, the method supports monaural and binaural calculations for signals captured with a single microphone, a head-and-torso simulator, or presented via earphones. The standard applies to tones, broadband noises and complex sounds with sharp spectral lines (e.g., transformer hum, fan noise). Informative source code is provided with the publication. Evaluation of harmful effects of sound events is outside its scope.

Keywords: ISO 532-2, Moore‑Glasberg, loudness calculation, acoustics standard, loudness level, binaural loudness, stationary sounds.

Key topics and technical requirements

• Signal specification: Defines allowed input types (complex tones, band-limited noise, mixtures, 1/3‑octave band representations) and measurement conditions.
• Instrumentation: Requirements and guidance for microphones, head-and-torso simulators and earphone presentations.
• Ear transfer and preprocessing: Procedures to determine the sound spectrum at the tympanic membrane and oval window for different capture methods.
• Spectral to perceptual transformation: Converts input spectrum to a series of sinusoidal components, then through four physiologically based transformations to produce an excitation pattern and specific loudness.
• Loudness computation: Rules for calculating monaural and binaural loudness and deriving loudness level.
• Uncertainty and reporting: Guidance on uncertainty of calculated loudness for stationary sounds and recommended data reporting.
• Annexes: Informative material on binaural calculations (Annex A), test results (Annex B), and downloadable software (Annex C).
• Normative references: Links to related electroacoustic standards (e.g., IEC 61260‑1, IEC 61672‑1, IEC/TS 60318‑7).

Applications

ISO 532-2:2017 is practical for:

• Acoustic consultants performing perceptual noise assessments and product noise characterization.
• Product designers and manufacturers evaluating perceived loudness of equipment (motors, HVAC, transformers).
• Audio engineers and researchers conducting loudness modelling and psychoacoustic studies.
• Hearing scientists and audiologists modelling perceived sound strength under controlled conditions.
• Test laboratories implementing reproducible loudness calculations for compliance and R&D.

This method is particularly useful when human listener tests are impractical or when a reproducible metric of perceived loudness is required.

Who should use this standard

• Acoustic engineers, test labs and manufacturers
• Product noise consultants and environmental acousticians
• Hearing science researchers and audiologists
• Standards developers and regulatory bodies

Related standards

• ISO 532-1 (Zwicker method)
• ISO 226:2003 (equal loudness contours)
• ISO 389‑7:2005 (reference threshold of hearing)
• IEC 61260‑1, IEC 61672‑1, IEC/TS 60318‑7

For implementation, users can review the informative source code supplied with ISO 532-2:2017 to reproduce the Moore‑Glasberg loudness algorithm.