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SQAT

MATLAB · library/toolbox · established active

MATLAB toolbox for sound quality analysis that bundles most psychoacoustic metrics in one place: ISO 532-1 and ECMA-418-2 loudness, DIN 45692 sharpness, Daniel & Weber and ECMA-418-2 roughness, Osses fluctuation strength, Aures and ECMA-418-2 tonality, three psychoacoustic annoyance models (Widmann's, which SQAT also offers under its common attribution to Zwicker & Fastl; More; Di et al.) and EPNL. Every metric except the annoyance models has its own verification routine. Since v2.0 it also has a graphical interface.

What it implements

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. Kinds of evidence.

Zwicker loudness · ISO 532-1:2017

standard or paper data

Ported or adapted from AARAE.

• Checked with the 25 test signals of Annex B.2–B.5 against the standard's tolerances.
• For v2.0, the validation notes say that the maximum loudness and N5 of the time-varying test signals are close to the reference values, apart from offsets in the N5 of test signals 12 and 13 that they trace to the standard's reference spreadsheet. In v1.3, test signal 10 deviated by 18.14 % (PR #48).

Sottek Hearing Model loudness · ECMA-418-2:2025 (4th ed.)

compared with ArtemiS SUITE (HEAD acoustics)

Ported or adapted from refmap-psychoacoustics (the author's own code).

• Checked for the 4th edition against the ISO 226:2003 equal-loudness contours and against reference results from HEAD acoustics ArtemiS SUITE 17.1 (named in the source of SQAT's validation page) for a binaural recording of a train station (last checked in November 2025).

Sottek Hearing Model loudness · ECMA-418-2:2024 (3rd ed.)

compared with ArtemiS SUITE (HEAD acoustics)

Ported or adapted from refmap-psychoacoustics (the author's own code).

• Checked against the ISO 226:2003 equal-loudness contours and against reference results from HEAD acoustics ArtemiS SUITE 15.7 (named in the source of SQAT's validation page) for a binaural recording of a train station.

Sharpness · DIN 45692:2009

standard or paper data

• Checked with the narrowband and broadband test signals of DIN 45692.

Roughness (Daniel & Weber) · Daniel & Weber (1997)

standard or paper data

Ported or adapted from AARAE.

• Checked against amplitude- and frequency-modulation dependences from the literature.

Sottek Hearing Model roughness · ECMA-418-2:2025 (4th ed.)

compared with ArtemiS SUITE (HEAD acoustics)

Ported or adapted from refmap-psychoacoustics (the author's own code).

• Checked for the 4th edition for the dependence of the roughness of AM tones on modulation frequency, and against reference results from HEAD acoustics ArtemiS SUITE 17.1 (named in the source of SQAT's validation page) for a binaural recording of a train station.

Sottek Hearing Model roughness · ECMA-418-2:2024 (3rd ed.)

compared with ArtemiS SUITE (HEAD acoustics)

Ported or adapted from refmap-psychoacoustics (the author's own code).

• Checked for the dependence of the roughness of AM tones on modulation frequency, and against reference results from HEAD acoustics ArtemiS SUITE 15.7 (named in the source of SQAT's validation page) for a binaural recording of a train station.

Fluctuation strength (Osses et al.) · Osses et al. (2016)

standard or paper data

Ported or adapted from fluctuation-strength-TUe (the author's own code).

• Checked against amplitude- and frequency-modulation dependences from the literature.

Tonality (Aures) · Aures (1985b)

standard or paper data

• v2.0 has five validation scripts: a tone emerging from noise, compared with Fig. 1(a) of Hastings et al. (2003) (root mean square deviation 0.0129 t.u. over nine points); the extraction of tonal components and the level excess, compared with the intermediate values of an independent implementation (Zhang & Shrestha, 2003); the weightings of bandwidth and frequency, compared with Aures's Figs. 6 and 5; and the dependence on bandwidth, compared with Hastings's subjective data.
• v1.3 is checked with one signal-to-noise comparison.

Sottek Hearing Model tonality · ECMA-418-2:2025 (4th ed.)

compared with ArtemiS SUITE (HEAD acoustics)

Ported or adapted from refmap-psychoacoustics (the author's own code).

• Checked for the 4th edition against reference results from HEAD acoustics ArtemiS SUITE 17.1 (named in the source of SQAT's validation page) for a binaural recording of a train station.
• A verification against Annex B.2 (PR #79) was merged and reverted on 2026-09-21 because the Annex B values of the 2025 edition appear to be out of date.

Sottek Hearing Model tonality · ECMA-418-2:2024 (3rd ed.)

compared with ArtemiS SUITE (HEAD acoustics)

Ported or adapted from refmap-psychoacoustics (the author's own code).

• Checked against reference results from HEAD acoustics ArtemiS SUITE 15.7 (named in the source of SQAT's validation page) for a binaural recording of a train station.

Psychoacoustic annoyance · Di et al. (2016)

Psychoacoustic annoyance · More (2010)

not stated

• No verification routine (README).

Perceived noise level and EPNL · 14 CFR Part 36

compared with published EPNL values (Rizzi et al., 2020)

• The README says that no reference implementation or test signals exist, so the verification is partial.
• Perceived noisiness is checked at its definition (a third-octave band of noise at 1 kHz and 40 dB SPL gives 1 noy), and the tone correction factor against Table 3.7 of ICAO Doc 9501.
• EPNL is cross-checked with Table 4 of Rizzi et al. (2020), AIAA 2020-2582, for 15 flyover sounds (five cases auralised by three tools): the largest difference is about 0.6 EPNdB.

Not stated for Sottek Hearing Model fluctuation strength · ECMA-418-2:2025 (4th ed.); Psychoacoustic annoyance · Zwicker & Fastl (1999); Psychoacoustic annoyance · Widmann (1992).

Before you compare numbers

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

• Statistics such as N5 take the nearest rank of the sorted time series, without interpolation (get_exceeded_value), and leave out the first time_skip seconds of the signal.
• Statistics take the nearest rank of the sorted time series, without interpolation (get_exceeded_value), and leave out the first time_skip seconds; the code enforces at least 304 ms (it cites ECMA-418-2:2025, Section 8.1.4).
• The single value is the 90th percentile from MATLAB's prctile, which interpolates; the other statistics take the nearest rank (get_exceeded_value). The first time_skip seconds are left out; the code enforces at least 320 ms (it cites ECMA-418-2:2025, Section 7.1.8).

Notes

• The README lists 61 studies and theses that use SQAT.
• v2.0 (2026-10-15) came about 330 commits after v1.3 (2025-04-04); its release notes mark the changes to the sound level meter, ISO 532-1 loudness, Daniel & Weber roughness, Aures tonality and the annoyance models as not backward compatible. Most of the metric-correctness work of August–September 2026, and the graphical interface, came from an external contributor through about 20 pull requests.
• The ECMA-418-2 functions come from the RefMap MATLAB code by Lotinga and Torjussen (University of Salford); the ISO 532-1 loudness was adapted in 2023 from Ella Manor's 2015 MATLAB code for AARAE.
• v2.0 adds a graphical interface, SQAT_GUI.m (#84). It loads calibrated .wav files, plays them with waveform and spectrogram, runs the sound level meter and any SQAT metric, compares files in a table of single values and exports the results. The README says every value comes from the SQAT functions, so the interface gives the same results as the code; it recommends the interface for a few files and the functions for many. The header of SQAT_GUI.m and the commit that added it say that its layout follows the interface of pySQAT; the commit lists a dBFS calibration field, a channel selector, a results table and the Widmann (1992) annoyance model as going beyond pySQAT.
• Open pull request: #78 (ECMA-418-2 fluctuation strength).

Before you rely on it

• Releases up to and including v1.3 are licensed for non-commercial use only; v2.0 is under the GPL.
• v2.0 is not backward compatible with v1.x. It corrects six deviations in ISO 532-1 time-varying loudness (#48; test signal 10 deviated by 18.14 % in v1.3) and eight defects in Aures tonality (#67), rewrites Daniel & Weber roughness (#65), corrects the time weighting of the sound level meter (#51; tone bursts with a duty cycle of 0.02 were reported 17.6 dB too low up to v1.3) and makes the annoyance calculation faster (#42). Results from v1.x and v2.0 differ.
• The README warns that main may contain changes that are not yet fully verified and recommends using a release.

Sources

1. https://github.com/ggrecow/SQAT/blob/main/README.md
2. https://github.com/ggrecow/SQAT/blob/main/LICENSE
3. https://github.com/ggrecow/SQAT/blob/main/citation.cff
4. https://github.com/ggrecow/SQAT/releases
5. https://github.com/ggrecow/SQAT/releases/tag/v2.0
6. https://github.com/ggrecow/SQAT/issues/67
7. https://github.com/ggrecow/SQAT/pull/48
8. https://github.com/ggrecow/SQAT/pull/65
9. https://github.com/ggrecow/SQAT/pull/78
10. https://github.com/ggrecow/SQAT/pull/79
11. https://github.com/ggrecow/SQAT/tree/v2.0/validation
12. https://github.com/ggrecow/SQAT/blob/v2.0/validation/Loudness_ISO532_1/2_synthetic_signals_time_varying_loudness/README.md
13. https://github.com/ggrecow/SQAT/blob/v2.0/validation/Tonality_Aures1985/README.md
14. https://github.com/ggrecow/SQAT/blob/v2.0/validation/sound_level_meter/README.md
15. https://github.com/ggrecow/SQAT/tree/main/validation/EPNL_FAR_Part36
16. https://github.com/ggrecow/SQAT/tree/v1.3/validation
17. https://github.com/ggrecow/SQAT/blob/main/psychoacoustic_metrics/FluctuationStrength_Osses2016/FluctuationStrength_Osses2016.m
18. https://github.com/ggrecow/SQAT/blob/v2.0/psychoacoustic_metrics/Roughness_Daniel1997/Roughness_Daniel1997.m
19. https://github.com/ggrecow/SQAT/blob/v2.0/psychoacoustic_metrics/PsychoacousticAnnoyance_Zwicker1999/PsychoacousticAnnoyance_Zwicker1999.m
20. https://github.com/ggrecow/SQAT/blob/v2.0/gui/SQAT_GUI.m
21. https://github.com/ggrecow/SQAT/pull/84