Metrics › Tonality

Tonality from the Sottek Hearing Model (ECMA-418-2)

Unit: tu_HMS · Also known as ECMA-418-2 tonality, psychoacoustic tonality, tu_HMS, Sottek tonality, SHM tonality

Psychoacoustic tonality from the Sottek Hearing Model, Clause 6 of ECMA-418-2, with specific tonality and tonal frequency over time. The method came from ECMA-74 (17th edition, 2019) when ECMA-418-2 was first published in 2020.

Editions and who implements them

Project map

The project map, with only the lines for Sottek Hearing Model tonality between the projects listed for it. Agreement between a project and the code it was ported or adapted from only checks the port.

• ported or adapted from another project
• the author's own code
• used at run time
• same contributor
• SQAT SQAT, MoSQITo, and sottek-hearing-model

Scroll the picture sideways.

Implementations

Projects in bold and other established projects come first, then newly released, developing and legacy ones. Validation is what each project says about its own testing. The details are below, and the kinds of evidence are explained on the About page. The project map above shows which project was ported or adapted from which.

Also available through tools that call one of these implementations: rota-order (via sottek-hearing-model, ECMA-418-2:2025 (4th ed.)) and pySQAT (via sottek-hearing-model, ECMA-418-2:2025 (4th ed.)).

See also: Tonality, Aures/Terhardt model, Tone-to-noise ratio and prominence ratio (ECMA-418-1), Loudness from the Sottek Hearing Model (ECMA-418-2).

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. Kinds of evidence.

SQAT · 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Annex B.2 (PR #79) was merged and reverted on 2026-09-21 because the Annex B values of the 2025 edition appear to be out of date.

SQAT · 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.

sottek-hearing-model · ECMA-418-2:2025 (4th ed.)

standard or paper data (reference signal and one recording) also compared with ArtemiS SUITE (HEAD acoustics)

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

• Unit tests check the standard's reference signal, which should give 1 tu_HMS, at 48 and 44.1 kHz.
• RefMap's verification against ArtemiS v17.1, as for loudness.

Checked by the maintainer of LISQM: In personal use, Zhenxian LI found its results in very good agreement with those of HEAD acoustics ArtemiS SUITE. This is a personal check, not a published comparison.

refmap-psychoacoustics · ECMA-418-2:2025 (4th ed.)

compared with ArtemiS SUITE (HEAD acoustics)

• Verified against HEAD acoustics ArtemiS v17.1 with the same three signals as loudness.

MetaSona new · ECMA-418-2:2025 (4th ed.)

compared with SQAT (its source)

Ported or adapted from SQAT. It was compared with the code it was ported from, which checks the port only.

• The project says that detailed validation and reference comparisons are kept outside the repository; the results are not published.

phonometry new · ECMA-418-2:2025 (4th ed.)

standard or paper data (calibration signal only)

• Checked at the calibration signal only.

rota-order new via sottek-hearing-model · ECMA-418-2:2025 (4th ed.) (through sottek-hearing-model's shm_tonality_ecma)

own tests only

• Tests, which run only where sottek-hearing-model is installed (the project's continuous integration does not install it), check that the wrappers return what direct calls of the package give, that one speed bin reproduces the package's single values, and that the dominant tonal frequency of a tone in noise maps to its order.

rota-order new via SQAT · ECMA-418-2:2025 (4th ed.) (through SQAT v2.0's Tonality_ECMA418_2 in MATLAB)

own tests only

• Tests with a stub engine check the call passed to SQAT and the conversion of its output; the comparison with a direct SQAT call runs only where MATLAB and SQAT v2.0 are installed.

pySQAT developing via sottek-hearing-model · ECMA-418-2:2025 (4th ed.)

compared with SQAT (also ported from refmap-psychoacoustics)

Code ported from the same source is expected to agree, so that comparison is not an independent check.

• Compared by validation/FINAL_VAL.py with the bundled SQAT v1.3 MATLAB code, which follows ECMA-418-2:2024 (3rd edition), so the comparison crosses editions.

Before you compare numbers

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

• Edition and start. Compare implementations of the same edition; overall values leave out the first 304 ms, where the filters settle.
• Tonal annoyance weighting. RefMap and sottek-hearing-model offer an optional weighting after Sottek & Becker (2019), which is not part of ECMA-418-2; leave it off when comparing with other implementations.

What the projects state:

SQAT

• 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).

sottek-hearing-model

• Input at other sample rates is resampled to 48 kHz.

MetaSona new

• Expects calibrated sound pressure in pascals.
• The C functions require 48 kHz input; the Python interface resamples other rates to 48 kHz (SciPy resample_poly).
• time_skip_s (default 0 s) leaves out the start of the signal from the reported frames; the computation still runs over the whole signal. Time-varying results include every complete frame, labelled at frame centres, which differs from SQAT's handling of the last frame and of time stamps.

rota-order new

• For the ECMA-418-2 metrics, vs_rpm takes by default the mean of the loudness and the tonality in each speed bin, the tonality only above 0.02 tu_HMS, and the 90th percentile of the roughness, after about 0.3 s (0.6 s for SQAT's tonality).
• Input in any unit is turned into sound pressure in Pa by an explicit calibration factor and resampled to 48 kHz.

References

1. ECMA-74:2019 (17th ed.). Measurement of airborne noise emitted by information technology and telecommunications equipment. https://ecma-international.org/publications-and-standards/standards/ecma-74/
2. ECMA-418-2:2020 (1st ed.). Psychoacoustic metrics for ITT equipment — Part 2 (models based on human perception). https://ecma-international.org/wp-content/uploads/ECMA-418-2_1st_edition_december_2020.pdf
3. ECMA-418-2:2022 (2nd ed.). Psychoacoustic metrics for ITT equipment — Part 2 (models based on human perception). https://ecma-international.org/wp-content/uploads/ECMA-418-2_2nd_edition_december_2022.pdf
4. ECMA-418-2:2024 (3rd ed.). Psychoacoustic metrics for ITT equipment — Part 2 (methods for describing human perception based on the Sottek Hearing Model). https://ecma-international.org/wp-content/uploads/ECMA-418-2_3rd_edition_december_2024.pdf
5. ECMA-418-2:2025 (4th ed.). Psychoacoustic metrics for ITT equipment — Part 2 (methods for describing human perception based on the Sottek Hearing Model). https://ecma-international.org/wp-content/uploads/ECMA-418-2_4th_edition_june_2025.pdf