# Moore–Glasberg loudness of stationary sounds (ISO 532-2, ANSI S3.4)

> Part of [LISQM](https://zhenxianli.github.io/LISQM/) (List of Implementations of Sound Quality Metrics), a list of open-source implementations of psychoacoustic metrics. Data as of 2026-10-28. Web page: https://zhenxianli.github.io/LISQM/metrics/loudness-moore-glasberg.html

**Quantity:** Loudness · **Unit:** sone, phon · **Also known as:** ISO 532-2, ANSI S3.4, ANSI/ASA S3.4-2007, Moore-Glasberg method, Cambridge loudness model

Loudness of stationary sounds from the Moore–Glasberg model: the spectrum is turned into an excitation pattern on the ERB-number scale, then into specific loudness, which is summed. ANSI S3.4-2007 standardised the model of Moore, Glasberg & Baer (1997) with later modifications; ISO 532-2:2017 specifies the method for monaural and binaural listening.

The current edition is ISO 532-2:2017. In development: ISO/CD 532-2. Open-source implementations of it: [phonometry](https://zhenxianli.github.io/LISQM/projects/phonometry.html) (Python; newly released, not yet seen to be widely used; with binaural inhibition). So far, only newly released projects, not yet seen to be widely used in the community, have released an implementation of it. Check their validation before relying on them. Implementations of earlier editions or related models: [AMT](https://zhenxianli.github.io/LISQM/projects/amt.html) (MATLAB, Octave; Chen et al. (2011)), [AMT](https://zhenxianli.github.io/LISQM/projects/amt.html) (MATLAB, Octave; Moore, Glasberg & Baer (1997)), [AARAE](https://zhenxianli.github.io/LISQM/projects/aarae.html) (MATLAB; Moore, Glasberg & Baer (1997); one channel, or two channels for binaural loudness), [NumpyLibforPsychoAcoustic](https://zhenxianli.github.io/LISQM/projects/numpylib-psychoacoustic.html) (Python; newly released, not yet seen to be widely used; Moore, Glasberg & Baer (1997)), [deeuu/loudness](https://zhenxianli.github.io/LISQM/projects/deeuu-loudness.html) (C++, Python; legacy, no commit since 2019-08; Chen et al. (2011)), [deeuu/loudness](https://zhenxianli.github.io/LISQM/projects/deeuu-loudness.html) (C++, Python; legacy, no commit since 2019-08; ANSI/ASA S3.4-2007; with the binaural inhibition of Moore & Glasberg (2007) for two ears), [Swift & Gee codes](https://zhenxianli.github.io/LISQM/projects/rapid-loudness-sharpness.html) (MATLAB; legacy, no commit since 2020-01; ANSI/ASA S3.4-2007), and [PsySound3](https://zhenxianli.github.io/LISQM/projects/psysound3.html) (MATLAB; legacy, no commit since 2015-03; Moore, Glasberg & Baer (1997)).

## Editions and who implements them

| Date | Edition | Status | What changed | Implemented by |
|---|---|---|---|---|
| 2024-11 | [ISO/CD 532-2](https://www.iso.org/standard/90812.html) | in development | Second edition at committee-draft stage since November 2024. | — |
| 2017-06 | [ISO 532-2:2017](https://www.iso.org/standard/63078.html) | current; Under revision; the 2nd edition has been at committee-draft stage since 2024-11-01. | Monaural and binaural loudness of stationary sounds; source code supplied with the standard. | [phonometry](https://zhenxianli.github.io/LISQM/projects/phonometry.html) |
| 2011 | [Chen et al. (2011)](https://doi.org/10.1016/j.heares.2011.08.001) | published | Faster excitation-pattern calculation, also for hearing loss (not standardised). | [AMT](https://zhenxianli.github.io/LISQM/projects/amt.html), [deeuu/loudness](https://zhenxianli.github.io/LISQM/projects/deeuu-loudness.html) |
| 2007 | [ANSI/ASA S3.4-2007](https://webstore.ansi.org/standards/asa/ANSIASAS32007R2020) | current | American standard based on the 1997 model with later modifications. | [deeuu/loudness](https://zhenxianli.github.io/LISQM/projects/deeuu-loudness.html), [Swift & Gee codes](https://zhenxianli.github.io/LISQM/projects/rapid-loudness-sharpness.html) |
| 1997 | [Moore, Glasberg & Baer (1997)](https://aes2.org/publications/elibrary-page/?id=10272) | published | Model paper (thresholds, loudness and partial loudness). | [AMT](https://zhenxianli.github.io/LISQM/projects/amt.html), [AARAE](https://zhenxianli.github.io/LISQM/projects/aarae.html), [NumpyLibforPsychoAcoustic](https://zhenxianli.github.io/LISQM/projects/numpylib-psychoacoustic.html), [PsySound3](https://zhenxianli.github.io/LISQM/projects/psysound3.html) |

## Project map

The lines of the project map for Moore–Glasberg loudness only, between the projects listed for it (the whole map: https://zhenxianli.github.io/LISQM/projects/map.md). Agreement between a project and the code it was ported or adapted from only checks the port.

### Ported or adapted from another project

- From [AMT](https://zhenxianli.github.io/LISQM/projects/amt.html): [NumpyLibforPsychoAcoustic](https://zhenxianli.github.io/LISQM/projects/numpylib-psychoacoustic.html) (Moore, Glasberg & Baer (1997))

### The author's own code

- From [PsySound3](https://zhenxianli.github.io/LISQM/projects/psysound3.html) (Densil Cabrera): [AARAE](https://zhenxianli.github.io/LISQM/projects/aarae.html) (Moore, Glasberg & Baer (1997))

On the map without a line, as no relation to another project listed for Moore–Glasberg loudness is recorded for them: [phonometry](https://zhenxianli.github.io/LISQM/projects/phonometry.html), [deeuu/loudness](https://zhenxianli.github.io/LISQM/projects/deeuu-loudness.html), and [Swift & Gee codes](https://zhenxianli.github.io/LISQM/projects/rapid-loudness-sharpness.html).

## Implementations

| Project | Language | Edition | Functions | Validation (as stated) | Notes |
|---|---|---|---|---|---|
| [AMT](https://zhenxianli.github.io/LISQM/projects/amt.html) | MATLAB, Octave | [Chen et al. (2011)](https://doi.org/10.1016/j.heares.2011.08.001) | `chen2011` | standard or paper data | Listed as "CHEN2011 - Fast excitation pattern estimation". |
| [AMT](https://zhenxianli.github.io/LISQM/projects/amt.html) | MATLAB, Octave | [Moore, Glasberg & Baer (1997)](https://aes2.org/publications/elibrary-page/?id=10272) | `moore1997` | standard or paper data | Listed as "MOORE1997 - Loudness model for stationary signals" in models/Contents.m. |
| [AARAE](https://zhenxianli.github.io/LISQM/projects/aarae.html) | MATLAB | [Moore, Glasberg & Baer (1997)](https://aes2.org/publications/elibrary-page/?id=10272) (one channel, or two channels for binaural loudness) | `Loudness_MGB2b` | not stated | A port and extension of PsySound3's code by Densil Cabrera and Doheon Lee, version 1.02 (27 October 2015). Two-channel input gives binaural loudness after Moore & Glasberg (2007). The audio is resampled to 32 kHz. |
| [phonometry](https://zhenxianli.github.io/LISQM/projects/phonometry.html) | Python | [ISO 532-2:2017](https://www.iso.org/standard/63078.html) (with binaural inhibition; since 3.1.0) | `loudness_moore_glasberg`, `loudness_moore_glasberg_from_spectrum`, `loudness_moore_glasberg_from_third_octave` | standard or paper data | Newly released project, not yet seen to be widely used. |
| [NumpyLibforPsychoAcoustic](https://zhenxianli.github.io/LISQM/projects/numpylib-psychoacoustic.html) | Python | [Moore, Glasberg & Baer (1997)](https://aes2.org/publications/elibrary-page/?id=10272) | `model.moore1997`, `equalSones.getEqualSones` | standard or paper data; also compared with AMT (its source) | Newly released project, not yet seen to be widely used. No licence file: by default, copying, changing or sharing the code needs the author's permission. |
| [deeuu/loudness](https://zhenxianli.github.io/LISQM/projects/deeuu-loudness.html) | C++, Python | [Chen et al. (2011)](https://doi.org/10.1016/j.heares.2011.08.001) | `StationaryLoudnessCHGM2011` | own tests only | Legacy project, no longer maintained. |
| [deeuu/loudness](https://zhenxianli.github.io/LISQM/projects/deeuu-loudness.html) | C++, Python | [ANSI/ASA S3.4-2007](https://webstore.ansi.org/standards/asa/ANSIASAS32007R2020) (with the binaural inhibition of Moore & Glasberg (2007) for two ears) | `StationaryLoudnessANSIS342007` | own tests only | Legacy project, no longer maintained. |
| [Swift & Gee codes](https://zhenxianli.github.io/LISQM/projects/rapid-loudness-sharpness.html) | MATLAB | [ANSI/ASA S3.4-2007](https://webstore.ansi.org/standards/asa/ANSIASAS32007R2020) | `stationaryLoudness` | not stated | Legacy project, no longer maintained. |
| [PsySound3](https://zhenxianli.github.io/LISQM/projects/psysound3.html) | MATLAB | [Moore, Glasberg & Baer (1997)](https://aes2.org/publications/elibrary-page/?id=10272) | `@LoudnessMGB` | not stated | Legacy project, no longer maintained. No licence file: by default, copying, changing or sharing the code needs the author's permission. Also cites Glasberg & Moore (1990) for the auditory filters. The analyser description says it covers time-varying and binaural loudness, and it also cites Glasberg & Moore (2002) and Moore & Glasberg (2007). |

**See also:** [Time-varying loudness, Moore–Glasberg–Schlittenlacher (ISO 532-3)](https://zhenxianli.github.io/LISQM/metrics/loudness-moore-glasberg-time-varying.html)

## How they were validated

As reported by each project; LISQM has not run the code. Two implementations that agree can still share the same error.

- [AMT](https://zhenxianli.github.io/LISQM/projects/amt.html), Chen et al. (2011): standard or paper data
  - Has the experiment script `exp_chen2011`; AMT's experiment scripts reproduce the results of the publication they are named after.
- [AMT](https://zhenxianli.github.io/LISQM/projects/amt.html), Moore, Glasberg & Baer (1997): standard or paper data
  - AMT's experiment scripts (`exp_…`) reproduce published results; this model has `exp_moore1997`.
- [AARAE](https://zhenxianli.github.io/LISQM/projects/aarae.html), Moore, Glasberg & Baer (1997): not stated
  - Ported or adapted from [PsySound3](https://zhenxianli.github.io/LISQM/projects/psysound3.html) (the author's own code).
- [phonometry](https://zhenxianli.github.io/LISQM/projects/phonometry.html), ISO 532-2:2017: standard or paper data
  - The documentation says it reproduces the Annex B tone and broadband cases to within a percent or two.
- [NumpyLibforPsychoAcoustic](https://zhenxianli.github.io/LISQM/projects/numpylib-psychoacoustic.html), Moore, Glasberg & Baer (1997): standard or paper data; also compared with [AMT](https://zhenxianli.github.io/LISQM/projects/amt.html) (its source)
  - Ported or adapted from [AMT](https://zhenxianli.github.io/LISQM/projects/amt.html). It was compared with the code it was ported from, which checks the port only.
  - The implementation document says the model is compared with the results shown in the original article (plots of its Fig. 8 and Fig. 12).
  - Numerical error reports (PDF) compare intermediate arrays, such as the outer- and middle-ear filter, with AMT's MATLAB output.
- [deeuu/loudness](https://zhenxianli.github.io/LISQM/projects/deeuu-loudness.html), Chen et al. (2011): own tests only
- [deeuu/loudness](https://zhenxianli.github.io/LISQM/projects/deeuu-loudness.html), ANSI/ASA S3.4-2007: own tests only
  - Unit tests cover each module and model.
  - A validation script writes computed and expected loudness of pure tones to CSV; the expected values are labelled "Table 7" and "Example 2" without naming their source.

Not stated by Swift & Gee codes and PsySound3.

## Before you compare numbers

Implementations of the same metric can give different numbers without either being wrong. Check these choices first.

What the projects state:

- [Swift & Gee codes](https://zhenxianli.github.io/LISQM/projects/rapid-loudness-sharpness.html): The code works at 32 kHz; other rates are resampled with the Signal Processing Toolbox's `resample`.

## References

1. Moore, B. C. J., Glasberg, B. R., & Baer, T. (1997). A model for the prediction of thresholds, loudness, and partial loudness. *Journal of the Audio Engineering Society*, 45(4), 224–240. https://aes2.org/publications/elibrary-page/?id=10272
2. ANSI/ASA S3.4-2007. Procedure for the Computation of Loudness of Steady Sounds. https://webstore.ansi.org/standards/asa/ANSIASAS32007R2020
3. Chen, Z., Hu, G., Glasberg, B. R., & Moore, B. C. J. (2011). A new method of calculating auditory excitation patterns and loudness for steady sounds. *Hearing Research*, 282(1–2), 204–215. https://doi.org/10.1016/j.heares.2011.08.001
4. ISO 532-2:2017. Acoustics — Methods for calculating loudness — Part 2: Moore-Glasberg method. https://www.iso.org/standard/63078.html
5. ISO/CD 532-2. Acoustics — Methods for calculating loudness — Part 2: Moore-Glasberg method (2nd edition). https://www.iso.org/standard/90812.html