# HAW loudness tool

> 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/projects/haw-specific-loudness.html

**Legacy project.** Not maintained. Its last commit was in December 2022, more than three years ago. Kept here for reference. Its code may follow an older edition and may not run with current software.

MATLAB tool with a graphical interface, from HAW Hamburg, that shows the specific loudness of time-varying sounds: a Moore–Glasberg front end on ERB bands with temporal processing after Glasberg & Moore (2002), Chalupper & Fastl (2002) or Baumgarte (2000). Written in 2007 for a diploma thesis and published on Zenodo in 2022.

- **Full name:** Specific loudness of time-varying sounds (MATLAB tool)
- **Repository:** https://zenodo.org/records/7361480
- **Homepage:** https://reposit.haw-hamburg.de/handle/20.500.12738/14892
- **Language:** MATLAB
- **Kind:** Application (A program to run, with a graphical or command-line interface; no programming needed.)
- **Group:** legacy (Archived, or no commit for three years or more. Kept for reference. The code may follow an older edition and may not run with current software.)
- **Licence:** CC-BY-4.0 — Licence of the HAW Hamburg repository record; the archive itself has no licence file.
- **Latest release:** 1 (2022-12)
- **Last commit:** 2022-12-16 (inactive since 2022-12)
- **Maintainers:** Christian Sabrautzky, Robert Mores
- **AI assistance:** not stated
- **Paper:** Sabrautzky, C. (2007). *Erweiterung eines Lautheitsmodells von Moore und Glasberg zur Berechnung der spezifischen Lautheit dynamischer Audiosignale* [Diploma thesis, HAW Hamburg].
- **How to cite:** Cite the paper above. Software DOI: [10.5281/zenodo.7361480](https://doi.org/10.5281/zenodo.7361480). Name the version or commit you used.
- **Entry checked:** 2026-10-07

## What it implements

| Metric | Edition | Functions | Status | Validation (as stated) | Notes |
|---|---|---|---|---|---|
| [Time-varying loudness (Moore–Glasberg–Schlittenlacher)](https://zhenxianli.github.io/LISQM/metrics/loudness-moore-glasberg-time-varying.html) | [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` | available | reference code: LOUDAES and TVL (Glasberg & Moore's programs) | — |

## How it was validated

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

- [Time-varying loudness (Moore–Glasberg–Schlittenlacher)](https://zhenxianli.github.io/LISQM/metrics/loudness-moore-glasberg-time-varying.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.

## Before you compare numbers

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

- Input must be sampled at 32 kHz; the reference level is entered as the sound pressure level of a full-scale sine.


## Notes

- Code by Christian Sabrautzky (2007, revision 0.7), with changes by Robert Mores (2013) and a playback toolbar by Nico Schäfer. The Zenodo record (2022-12-16) includes an English overview of the models and the German thesis.
- Offers free-field and diffuse-field outer-ear filters and three spectral analyses: FFT with a Blackman–Harris or Hann window, and a Fourier-time transform.

## Before you rely on it

- Not an implementation of ANSI S3.4-2007 or ISO 532-2/-3. It follows Glasberg & Moore (2002) with the constants A, α and E_THRQ read from published graphs and interpolated, and its Chalupper–Fastl and Baumgarte options apply those models' temporal processing to Moore–Glasberg specific loudness.

## Sources

- https://zenodo.org/records/7361480
- https://reposit.haw-hamburg.de/handle/20.500.12738/14892