# Time-varying loudness, Moore–Glasberg–Schlittenlacher (ISO 532-3)

> 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-time-varying.html

**Quantity:** Loudness · **Unit:** sone, phon · **Also known as:** ISO 532-3, TVL, time-varying loudness, Glasberg and Moore 2002, Moore-Glasberg-Schlittenlacher method, short-term loudness, long-term loudness

Loudness of time-varying sounds as instantaneous, short-term and long-term loudness. It starts from the Glasberg & Moore (2002) model; Moore et al. (2016) added binaural inhibition and Moore et al. (2018) revised the time constants. ISO 532-3:2023 standardises the resulting Moore–Glasberg–Schlittenlacher method for stationary and time-varying sounds.

The current edition is ISO 532-3:2023. In development: ISO/CD 532-3. Open-source implementations of it: [iso532-3 (tv2018.m)](https://zhenxianli.github.io/LISQM/projects/js2251-iso532-3.html) (MATLAB; reference MATLAB code referred to in ISO 532-3, per its readme) and [phonometry](https://zhenxianli.github.io/LISQM/projects/phonometry.html) (Python; newly released, not yet seen to be widely used). Implementations of earlier editions or related models: [AMT](https://zhenxianli.github.io/LISQM/projects/amt.html) (MATLAB, Octave; Moore et al. (2016); binaural), [AMT](https://zhenxianli.github.io/LISQM/projects/amt.html) (MATLAB, Octave; Glasberg & Moore (2002)), [AARAE](https://zhenxianli.github.io/LISQM/projects/aarae.html) (MATLAB; Glasberg & Moore (2002); time-varying; one channel, or two channels for binaural loudness), [torch_amt](https://zhenxianli.github.io/LISQM/projects/torch-amt.html) (Python; newly released, not yet seen to be widely used; Moore et al. (2016); binaural), [NumpyLibforPsychoAcoustic](https://zhenxianli.github.io/LISQM/projects/numpylib-psychoacoustic.html) (Python; newly released, not yet seen to be widely used; Glasberg & Moore (2002)), [torch_amt](https://zhenxianli.github.io/LISQM/projects/torch-amt.html) (Python; newly released, not yet seen to be widely used; Glasberg & Moore (2002); short-term and long-term loudness), [LoudnessModel](https://zhenxianli.github.io/LISQM/projects/loudnessmodel.html) (Python; developing; Moore et al. (2018); instantaneous, short-term and long-term loudness; binaural), [deeuu/loudness](https://zhenxianli.github.io/LISQM/projects/deeuu-loudness.html) (C++, Python; legacy, no commit since 2019-08; Glasberg & Moore (2002)), [HAW loudness tool](https://zhenxianli.github.io/LISQM/projects/haw-specific-loudness.html) (MATLAB; legacy, no commit since 2022-12; Glasberg & Moore (2002); specific loudness over time on ERB bands; three temporal models), [PsySound3](https://zhenxianli.github.io/LISQM/projects/psysound3.html) (MATLAB; legacy, no commit since 2015-03; Glasberg & Moore (2002); time-varying and binaural), and [Swift & Gee codes](https://zhenxianli.github.io/LISQM/projects/rapid-loudness-sharpness.html) (MATLAB; legacy, no commit since 2020-01; Glasberg & Moore (2002)).

## Editions and who implements them

| Date | Edition | Status | What changed | Implemented by |
|---|---|---|---|---|
| 2024-11 | [ISO/CD 532-3](https://www.iso.org/standard/90816.html) | in development | Second edition at committee-draft stage since November 2024. | — |
| 2023-07 | [ISO 532-3:2023](https://www.iso.org/standard/69856.html) | current; Under revision; the 2nd edition has been at committee-draft stage since 2024-11-01. | Standardised method; source code supplied with the standard. | [iso532-3 (tv2018.m)](https://zhenxianli.github.io/LISQM/projects/js2251-iso532-3.html), [phonometry](https://zhenxianli.github.io/LISQM/projects/phonometry.html) |
| 2018 | [Moore et al. (2018)](https://doi.org/10.1121/1.5027246) | published | Revised time constants. | [LoudnessModel](https://zhenxianli.github.io/LISQM/projects/loudnessmodel.html) |
| 2016 | [Moore et al. (2016)](https://doi.org/10.1177/2331216516682698) | published | Adds binaural inhibition. | [AMT](https://zhenxianli.github.io/LISQM/projects/amt.html), [torch_amt](https://zhenxianli.github.io/LISQM/projects/torch-amt.html) |
| 2002 | [Glasberg & Moore (2002)](https://aes2.org/publications/elibrary-page/?id=11081) | published | Time-varying loudness model (short-term and long-term 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), [torch_amt](https://zhenxianli.github.io/LISQM/projects/torch-amt.html), [deeuu/loudness](https://zhenxianli.github.io/LISQM/projects/deeuu-loudness.html), [HAW loudness tool](https://zhenxianli.github.io/LISQM/projects/haw-specific-loudness.html), [PsySound3](https://zhenxianli.github.io/LISQM/projects/psysound3.html), [Swift & Gee codes](https://zhenxianli.github.io/LISQM/projects/rapid-loudness-sharpness.html) |

## Project map

The lines of the project map for time-varying loudness (Moore–Glasberg–Schlittenlacher) 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) (Glasberg & Moore (2002)); [torch_amt](https://zhenxianli.github.io/LISQM/projects/torch-amt.html) (Moore et al. (2016) and Glasberg & Moore (2002))
- From [iso532-3 (tv2018.m)](https://zhenxianli.github.io/LISQM/projects/js2251-iso532-3.html): [LoudnessModel](https://zhenxianli.github.io/LISQM/projects/loudnessmodel.html) (Moore et al. (2018))

### 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) (Glasberg & Moore (2002))

On the map without a line, as no relation to another project listed for time-varying loudness (Moore–Glasberg–Schlittenlacher) is recorded for them: [phonometry](https://zhenxianli.github.io/LISQM/projects/phonometry.html), [deeuu/loudness](https://zhenxianli.github.io/LISQM/projects/deeuu-loudness.html), [HAW loudness tool](https://zhenxianli.github.io/LISQM/projects/haw-specific-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 |
|---|---|---|---|---|---|
| [iso532-3 (tv2018.m)](https://zhenxianli.github.io/LISQM/projects/js2251-iso532-3.html) | MATLAB | [ISO 532-3:2023](https://www.iso.org/standard/69856.html) (reference MATLAB code referred to in ISO 532-3, per its readme) | `tv2018` | not stated | No licence file: by default, copying, changing or sharing the code needs the author's permission. Written by the model's authors (per the readme PDF). |
| [AMT](https://zhenxianli.github.io/LISQM/projects/amt.html) | MATLAB, Octave | [Moore et al. (2016)](https://doi.org/10.1177/2331216516682698) (binaural) | `moore2016` | not stated | Listed as "MOORE2016 - Binaural loudness model". The header says Josef Schlittenlacher provided the original implementation for the AMT in 2018, from code written for ANSI S3.4-2007 and ISO 532-2:2017. |
| [AMT](https://zhenxianli.github.io/LISQM/projects/amt.html) | MATLAB, Octave | [Glasberg & Moore (2002)](https://aes2.org/publications/elibrary-page/?id=11081) | `glasberg2002` | standard or paper data | Listed as "GLASBERG2002 - Loudness model for time-variant signals". |
| [AARAE](https://zhenxianli.github.io/LISQM/projects/aarae.html) | MATLAB | [Glasberg & Moore (2002)](https://aes2.org/publications/elibrary-page/?id=11081) (time-varying; one channel, or two channels for binaural loudness) | `Loudness_MGB2b` | not stated | Same function as the stationary model; the binaural extension follows Moore & Glasberg (2007). |
| [phonometry](https://zhenxianli.github.io/LISQM/projects/phonometry.html) | Python | [ISO 532-3:2023](https://www.iso.org/standard/69856.html) (since 3.1.0) | `loudness_moore_glasberg_time` | standard or paper data | Newly released project, not yet seen to be widely used. |
| [torch_amt](https://zhenxianli.github.io/LISQM/projects/torch-amt.html) | Python | [Moore et al. (2016)](https://doi.org/10.1177/2331216516682698) (binaural) | `torch_amt.models.Moore2016` | compared with AMT (its source) | Newly released project, not yet seen to be widely used. Described as a "1:1 port" of AMT `moore2016`, with outer and middle ear per ANSI S3.4-2007 (docstring). |
| [NumpyLibforPsychoAcoustic](https://zhenxianli.github.io/LISQM/projects/numpylib-psychoacoustic.html) | Python | [Glasberg & Moore (2002)](https://aes2.org/publications/elibrary-page/?id=11081) | `model.glasberg2002` | not stated | 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. Present in the code but not described in the implementation document. |
| [torch_amt](https://zhenxianli.github.io/LISQM/projects/torch-amt.html) | Python | [Glasberg & Moore (2002)](https://aes2.org/publications/elibrary-page/?id=11081) (short-term and long-term loudness) | `torch_amt.models.Glasberg2002` | compared with AMT (its source) | Newly released project, not yet seen to be widely used. Ported from AMT `glasberg2002`. |
| [LoudnessModel](https://zhenxianli.github.io/LISQM/projects/loudnessmodel.html) | Python | [Moore et al. (2018)](https://doi.org/10.1121/1.5027246) (instantaneous, short-term and long-term loudness; binaural) | `tvl2018.compute_loudness`, `tvl2018_jax.compute_loudness` | own tests only | Developing project: no publication or documented use by others. |
| [deeuu/loudness](https://zhenxianli.github.io/LISQM/projects/deeuu-loudness.html) | C++, Python | [Glasberg & Moore (2002)](https://aes2.org/publications/elibrary-page/?id=11081) | `DynamicLoudnessGM2002` | own tests only | Legacy project, no longer maintained. Per the header, excitation patterns follow ANSI S3.4-2007, and parameter sets use the modified long-term time constants of Moore et al. (2003) and the ANSI S3.4-2007 equation for specific loudness at high levels. |
| [HAW loudness tool](https://zhenxianli.github.io/LISQM/projects/haw-specific-loudness.html) | MATLAB | [Glasberg & Moore (2002)](https://aes2.org/publications/elibrary-page/?id=11081) (specific loudness over time on ERB bands; three temporal models) | `loud_gui`, `matlab_loud` | reference code: LOUDAES and TVL (Glasberg & Moore's programs) | Legacy project, no longer maintained. |
| [PsySound3](https://zhenxianli.github.io/LISQM/projects/psysound3.html) | MATLAB | [Glasberg & Moore (2002)](https://aes2.org/publications/elibrary-page/?id=11081) (time-varying and binaural) | `@LoudnessMGB` | not stated | Legacy project, no longer maintained. No licence file: by default, copying, changing or sharing the code needs the author's permission. The same analyser as the stationary entry; its description cites Glasberg & Moore (2002). |
| [Swift & Gee codes](https://zhenxianli.github.io/LISQM/projects/rapid-loudness-sharpness.html) | MATLAB | [Glasberg & Moore (2002)](https://aes2.org/publications/elibrary-page/?id=11081) | `Glasberg_loudness` | not stated | Legacy project, no longer maintained. |

**See also:** [Moore–Glasberg loudness of stationary sounds (ISO 532-2, ANSI S3.4)](https://zhenxianli.github.io/LISQM/metrics/loudness-moore-glasberg.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.

- [iso532-3 (tv2018.m)](https://zhenxianli.github.io/LISQM/projects/js2251-iso532-3.html), ISO 532-3:2023: not stated
  - The folder "code for tables" has scripts that compute Table 5 (sone to phon) and the values of Annexes B and C (AnnexC.m is headed "Signals numbered as in ISO 532-2 Annex B"); the scripts do not name ISO 532-3.
- [AMT](https://zhenxianli.github.io/LISQM/projects/amt.html), Moore et al. (2016): not stated
  - There is no `exp_moore2016` experiment script on the develop branch.
- [AMT](https://zhenxianli.github.io/LISQM/projects/amt.html), Glasberg & Moore (2002): standard or paper data
  - Has the experiment script `exp_glasberg2002`; AMT's experiment scripts reproduce the results of the publication they are named after.
- [AARAE](https://zhenxianli.github.io/LISQM/projects/aarae.html), Glasberg & Moore (2002): 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 532-3:2023: standard or paper data
  - A documented deviation: the Annex B WAV-file cases are not reproduced, and Annex C values are used instead.
- [torch_amt](https://zhenxianli.github.io/LISQM/projects/torch-amt.html), Moore et al. (2016); Glasberg & Moore (2002): 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.
  - Agreement with AMT is claimed in the documentation, without stored reference data.
- [LoudnessModel](https://zhenxianli.github.io/LISQM/projects/loudnessmodel.html), Moore et al. (2018): own tests only
  - Ported or adapted from [iso532-3 (tv2018.m)](https://zhenxianli.github.io/LISQM/projects/js2251-iso532-3.html).
  - Tests run in GitHub Actions compare overall loudness, the first five short-term and long-term values and selected intermediate stages for one input (1 kHz tone, 100 ms, 32 kHz) with hard-coded expected values.
  - The README calls this "a known accurate output", but neither it nor the tests say where the values come from.
- [deeuu/loudness](https://zhenxianli.github.io/LISQM/projects/deeuu-loudness.html), Glasberg & Moore (2002): own tests only
- [HAW loudness tool](https://zhenxianli.github.io/LISQM/projects/haw-specific-loudness.html), Glasberg & Moore (2002): reference code: LOUDAES and TVL (Glasberg & Moore's programs)
  - The thesis compares the total loudness of pure tones (30–100 dB) with LOUDAES, Glasberg & Moore's program for stationary sounds: mostly within 5 %, with larger deviations at low levels near 50 Hz and above 5 kHz (−9.3 % for 5 kHz at 30 dB).
  - For two equal-level tones at 1 and 2 kHz, the deviation from LOUDAES ranges from −4.4 % to +3.8 % with the Hann-window FFT and reaches +6.7 % with the Fourier-time transform.
  - For the stationary part of signals the thesis reports good agreement with TVL, Glasberg & Moore's program for time-varying sounds, without figures.

Not stated by NumpyLibforPsychoAcoustic, PsySound3, and Swift & Gee codes.

## Before you compare numbers

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

- **Sample rate.** The Cambridge programs and ISO 532-3 work at 32 kHz. Most implementations resample to it; phonometry runs at the native rate (a documented deviation), and the Swift & Gee code and the HAW tool expect 32 kHz input.
- **Which output.** The models give instantaneous, short-term and long-term loudness; compare like with like.

What the projects state:

- [phonometry](https://zhenxianli.github.io/LISQM/projects/phonometry.html): Documented deviation: it runs at the native sample rate instead of resampling to 32 kHz.
- [HAW loudness tool](https://zhenxianli.github.io/LISQM/projects/haw-specific-loudness.html): Input must be sampled at 32 kHz; the reference level is entered as the sound pressure level of a full-scale sine.
- [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. Glasberg, B. R., & Moore, B. C. J. (2002). A model of loudness applicable to time-varying sounds. *Journal of the Audio Engineering Society*, 50(5), 331–342. https://aes2.org/publications/elibrary-page/?id=11081
2. Moore, B. C. J., Glasberg, B. R., Varathanathan, A., & Schlittenlacher, J. (2016). A loudness model for time-varying sounds incorporating binaural inhibition. *Trends in Hearing*, 20, 2331216516682698. https://doi.org/10.1177/2331216516682698
3. Moore, B. C. J., Jervis, M., Harries, L., & Schlittenlacher, J. (2018). Testing and refining a loudness model for time-varying sounds incorporating binaural inhibition. *The Journal of the Acoustical Society of America*, 143(3), 1504–1513. https://doi.org/10.1121/1.5027246
4. ISO 532-3:2023. Acoustics — Methods for calculating loudness — Part 3: Moore-Glasberg-Schlittenlacher method. https://www.iso.org/standard/69856.html
5. ISO/CD 532-3. Acoustics — Methods for calculating loudness — Part 3: Moore-Glasberg-Schlittenlacher method (2nd edition). https://www.iso.org/standard/90816.html