# Metrics

> 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/

22 metrics in 8 groups: for each, the edition that an up-to-date implementation should follow and the projects that implement it.

## Loudness

How loud a sound is perceived, in sone (loudness) and phon (loudness level). Four models are standardised: Zwicker (ISO 532-1), Moore–Glasberg (ISO 532-2), Moore–Glasberg–Schlittenlacher (ISO 532-3) and the Sottek Hearing Model (ECMA-418-2).

| Metric | Unit | Current edition | Implementations of it |
|---|---|---|---|
| [Zwicker loudness](https://zhenxianli.github.io/LISQM/metrics/loudness-zwicker.html) | sone, phon | ISO 532-1:2017 | **[SQAT](https://zhenxianli.github.io/LISQM/projects/sqat.html)**, **[MoSQITo](https://zhenxianli.github.io/LISQM/projects/mosqito.html)**, [AARAE](https://zhenxianli.github.io/LISQM/projects/aarae.html), [MetaSona](https://zhenxianli.github.io/LISQM/projects/metasona.html) (newly released), [iso532-1-rs](https://zhenxianli.github.io/LISQM/projects/iso532-1-rs.html) (newly released), [Kirin Hypha](https://zhenxianli.github.io/LISQM/projects/kirin-hypha.html) (newly released), [Mosqito.NET](https://zhenxianli.github.io/LISQM/projects/mosqito-net.html) (newly released), [phonometry](https://zhenxianli.github.io/LISQM/projects/phonometry.html) (newly released), [SoundPalette](https://zhenxianli.github.io/LISQM/projects/soundpalette.html) (newly released), [ZwickerLoudness.jl](https://zhenxianli.github.io/LISQM/projects/zwickerloudness-jl.html) (newly released), [pySQAT](https://zhenxianli.github.io/LISQM/projects/pysqat.html) (developing), [PsychoacousticParametersMeasurer](https://zhenxianli.github.io/LISQM/projects/psychoacoustic-parameters-measurer.html) (legacy) |
| [Moore–Glasberg loudness](https://zhenxianli.github.io/LISQM/metrics/loudness-moore-glasberg.html) | sone, phon | ISO 532-2:2017 | [phonometry](https://zhenxianli.github.io/LISQM/projects/phonometry.html) (newly released) |
| [Time-varying loudness (Moore–Glasberg–Schlittenlacher)](https://zhenxianli.github.io/LISQM/metrics/loudness-moore-glasberg-time-varying.html) | sone, phon | ISO 532-3:2023 | [iso532-3 (tv2018.m)](https://zhenxianli.github.io/LISQM/projects/js2251-iso532-3.html), [phonometry](https://zhenxianli.github.io/LISQM/projects/phonometry.html) (newly released) |
| [Sottek Hearing Model loudness](https://zhenxianli.github.io/LISQM/metrics/loudness-ecma-418-2.html) | sone_HMS | ECMA-418-2:2025 (4th ed.) | **[SQAT](https://zhenxianli.github.io/LISQM/projects/sqat.html)**, **[sottek-hearing-model](https://zhenxianli.github.io/LISQM/projects/sottek-hearing-model.html)**, [refmap-psychoacoustics](https://zhenxianli.github.io/LISQM/projects/refmap-psychoacoustics.html), [MetaSona](https://zhenxianli.github.io/LISQM/projects/metasona.html) (newly released), [phonometry](https://zhenxianli.github.io/LISQM/projects/phonometry.html) (newly released) |

## Sharpness

The sensation produced by high-frequency content, in acum. Standardised in DIN 45692 on top of Zwicker loudness; ECMA-418-2 does not define sharpness.

| Metric | Unit | Current edition | Implementations of it |
|---|---|---|---|
| [Sharpness](https://zhenxianli.github.io/LISQM/metrics/sharpness.html) | acum | DIN 45692:2009 | **[SQAT](https://zhenxianli.github.io/LISQM/projects/sqat.html)**, **[MoSQITo](https://zhenxianli.github.io/LISQM/projects/mosqito.html)**, [refmap-psychoacoustics](https://zhenxianli.github.io/LISQM/projects/refmap-psychoacoustics.html), [MetaSona](https://zhenxianli.github.io/LISQM/projects/metasona.html) (newly released), [Kirin Hypha](https://zhenxianli.github.io/LISQM/projects/kirin-hypha.html) (newly released), [Mosqito.NET](https://zhenxianli.github.io/LISQM/projects/mosqito-net.html) (newly released), [phonometry](https://zhenxianli.github.io/LISQM/projects/phonometry.html) (newly released), [PsychoacousticMetrics.jl](https://zhenxianli.github.io/LISQM/projects/psychoacousticmetrics-jl.html) (newly released), [SoundPalette](https://zhenxianli.github.io/LISQM/projects/soundpalette.html) (newly released), [pySQAT](https://zhenxianli.github.io/LISQM/projects/pysqat.html) (developing), [PsychoacousticParametersMeasurer](https://zhenxianli.github.io/LISQM/projects/psychoacoustic-parameters-measurer.html) (legacy) |

## Roughness

The sensation produced by fast amplitude or frequency modulation (roughly 15 to 300 Hz, strongest near 70 Hz), in asper.

| Metric | Unit | Current edition | Implementations of it |
|---|---|---|---|
| [Roughness (Daniel & Weber)](https://zhenxianli.github.io/LISQM/metrics/roughness-daniel-weber.html) | asper | Daniel & Weber (1997) | **[SQAT](https://zhenxianli.github.io/LISQM/projects/sqat.html)**, **[MoSQITo](https://zhenxianli.github.io/LISQM/projects/mosqito.html)**, [AARAE](https://zhenxianli.github.io/LISQM/projects/aarae.html), [ITA-Toolbox](https://zhenxianli.github.io/LISQM/projects/ita-toolbox.html), [MetaSona](https://zhenxianli.github.io/LISQM/projects/metasona.html) (newly released), [Mosqito.NET](https://zhenxianli.github.io/LISQM/projects/mosqito-net.html) (newly released), [PsychoacousticMetrics.jl](https://zhenxianli.github.io/LISQM/projects/psychoacousticmetrics-jl.html) (newly released), [SoundPalette](https://zhenxianli.github.io/LISQM/projects/soundpalette.html) (newly released), [pySQAT](https://zhenxianli.github.io/LISQM/projects/pysqat.html) (developing), [PsySound3](https://zhenxianli.github.io/LISQM/projects/psysound3.html) (legacy) |
| [Sottek Hearing Model roughness](https://zhenxianli.github.io/LISQM/metrics/roughness-ecma-418-2.html) | asper_HMS | ECMA-418-2:2025 (4th ed.) | **[SQAT](https://zhenxianli.github.io/LISQM/projects/sqat.html)**, **[sottek-hearing-model](https://zhenxianli.github.io/LISQM/projects/sottek-hearing-model.html)**, [refmap-psychoacoustics](https://zhenxianli.github.io/LISQM/projects/refmap-psychoacoustics.html), [MetaSona](https://zhenxianli.github.io/LISQM/projects/metasona.html) (newly released), [ecma418-torch](https://zhenxianli.github.io/LISQM/projects/ecma418-torch.html) (newly released), [phonometry](https://zhenxianli.github.io/LISQM/projects/phonometry.html) (newly released) |
| [Roughness (DIN 38455)](https://zhenxianli.github.io/LISQM/metrics/roughness-din-38455.html) | asper | DIN 38455:2024 | none found |

## Fluctuation strength

The sensation produced by slow modulation (below about 20 Hz, strongest near 4 Hz), in vacil.

| Metric | Unit | Current edition | Implementations of it |
|---|---|---|---|
| [Fluctuation strength (Osses et al.)](https://zhenxianli.github.io/LISQM/metrics/fluctuation-strength-osses.html) | vacil | Osses et al. (2016) | **[SQAT](https://zhenxianli.github.io/LISQM/projects/sqat.html)**, [phonometry](https://zhenxianli.github.io/LISQM/projects/phonometry.html) (newly released), [PsychoacousticMetrics.jl](https://zhenxianli.github.io/LISQM/projects/psychoacousticmetrics-jl.html) (newly released), [pySQAT](https://zhenxianli.github.io/LISQM/projects/pysqat.html) (developing), [fluctuation-strength-TUe](https://zhenxianli.github.io/LISQM/projects/fluctuation-strength-tue.html) (legacy) |
| [Sottek Hearing Model fluctuation strength](https://zhenxianli.github.io/LISQM/metrics/fluctuation-strength-ecma-418-2.html) | vacil_HMS | ECMA-418-2:2025 (4th ed.) | **[SQAT](https://zhenxianli.github.io/LISQM/projects/sqat.html)** (PR), **[sottek-hearing-model](https://zhenxianli.github.io/LISQM/projects/sottek-hearing-model.html)** (unreleased), [ecma418-torch](https://zhenxianli.github.io/LISQM/projects/ecma418-torch.html) (newly released), [phonometry](https://zhenxianli.github.io/LISQM/projects/phonometry.html) (newly released) |

## Tonality

How prominent tonal components are. Covers psychoacoustic tonality models (Aures, ECMA-418-2) and the engineering measures used for product noise (tone-to-noise ratio, prominence ratio) and for environmental noise (tonal audibility and tone adjustments).

| Metric | Unit | Current edition | Implementations of it |
|---|---|---|---|
| [Tonality (Aures)](https://zhenxianli.github.io/LISQM/metrics/tonality-aures.html) | t.u. | Aures (1985b) | **[SQAT](https://zhenxianli.github.io/LISQM/projects/sqat.html)**, **[MoSQITo](https://zhenxianli.github.io/LISQM/projects/mosqito.html)** (PR), [MetaSona](https://zhenxianli.github.io/LISQM/projects/metasona.html) (newly released), [pySQAT](https://zhenxianli.github.io/LISQM/projects/pysqat.html) (developing) |
| [Sottek Hearing Model tonality](https://zhenxianli.github.io/LISQM/metrics/tonality-ecma-418-2.html) | tu_HMS | ECMA-418-2:2025 (4th ed.) | **[SQAT](https://zhenxianli.github.io/LISQM/projects/sqat.html)**, **[sottek-hearing-model](https://zhenxianli.github.io/LISQM/projects/sottek-hearing-model.html)**, [refmap-psychoacoustics](https://zhenxianli.github.io/LISQM/projects/refmap-psychoacoustics.html), [MetaSona](https://zhenxianli.github.io/LISQM/projects/metasona.html) (newly released), [phonometry](https://zhenxianli.github.io/LISQM/projects/phonometry.html) (newly released) |
| [Tone-to-noise ratio and prominence ratio](https://zhenxianli.github.io/LISQM/metrics/tone-to-noise-prominence-ratio.html) | dB | ECMA-418-1:2024 (3rd ed.) | [phonometry](https://zhenxianli.github.io/LISQM/projects/phonometry.html) (newly released), [rota-order](https://zhenxianli.github.io/LISQM/projects/rota-order.html) (newly released) |
| [Tonal components (DIN 45681)](https://zhenxianli.github.io/LISQM/metrics/tonality-din-45681.html) | dB | DIN 45681:2005 | none found |
| [Audibility of tones in noise (ISO/TS 20065)](https://zhenxianli.github.io/LISQM/metrics/tonal-audibility-iso-20065.html) | dB | ISO/TS 20065:2022 | none found |
| [Tonal audibility (ISO 1996-2)](https://zhenxianli.github.io/LISQM/metrics/tonal-audibility-iso-1996-2.html) | dB | ISO 1996-2:2017 | **[MoSQITo](https://zhenxianli.github.io/LISQM/projects/mosqito.html)** (PR), [phonometry](https://zhenxianli.github.io/LISQM/projects/phonometry.html) (newly released) |
| [Tonal audibility of wind turbines (IEC 61400-11)](https://zhenxianli.github.io/LISQM/metrics/tonal-audibility-iec-61400-11.html) | dB | IEC 61400-11:2012+AMD1:2018 | [phonometry](https://zhenxianli.github.io/LISQM/projects/phonometry.html) (newly released) |

## Impulsiveness

How prominent impulsive sounds are, and the adjustment applied to them in environmental noise assessment.

| Metric | Unit | Current edition | Implementations of it |
|---|---|---|---|
| [Impulse prominence](https://zhenxianli.github.io/LISQM/metrics/impulsiveness.html) | dB | ISO/PAS 1996-3:2022 | [phonometry](https://zhenxianli.github.io/LISQM/projects/phonometry.html) (newly released) |

## Psychoacoustic annoyance

Single-number models that combine loudness, sharpness, roughness, fluctuation strength and, in later models, tonality into a predicted annoyance.

| Metric | Unit | Current edition | Implementations of it |
|---|---|---|---|
| [Psychoacoustic annoyance](https://zhenxianli.github.io/LISQM/metrics/psychoacoustic-annoyance.html) | dimensionless | Widmann (1992), Zwicker & Fastl (1999), More (2010), and Di et al. (2016) | **[SQAT](https://zhenxianli.github.io/LISQM/projects/sqat.html)**, [refmap-psychoacoustics](https://zhenxianli.github.io/LISQM/projects/refmap-psychoacoustics.html), [phonometry](https://zhenxianli.github.io/LISQM/projects/phonometry.html) (newly released), [PsychoacousticMetrics.jl](https://zhenxianli.github.io/LISQM/projects/psychoacousticmetrics-jl.html) (newly released), [pySQAT](https://zhenxianli.github.io/LISQM/projects/pysqat.html) (developing), [PsychoacousticParametersMeasurer](https://zhenxianli.github.io/LISQM/projects/psychoacoustic-parameters-measurer.html) (legacy) |

## Related quantities

Quantities that psychoacoustic tools often include and that are closely tied to the metrics above.

| Metric | Unit | Current edition | Implementations of it |
|---|---|---|---|
| [Equal-loudness contours](https://zhenxianli.github.io/LISQM/metrics/equal-loudness-contours.html) | dB SPL, phon | ISO 226:2023 | [phonometry](https://zhenxianli.github.io/LISQM/projects/phonometry.html) (newly released) |
| [Perceived noise level and EPNL](https://zhenxianli.github.io/LISQM/metrics/epnl.html) | PNdB, EPNdB | ICAO Annex 16, Vol. I and 14 CFR Part 36 | **[SQAT](https://zhenxianli.github.io/LISQM/projects/sqat.html)**, [phonometry](https://zhenxianli.github.io/LISQM/projects/phonometry.html) (newly released), [pySQAT](https://zhenxianli.github.io/LISQM/projects/pysqat.html) (developing), [SUAVE](https://zhenxianli.github.io/LISQM/projects/suave.html) (legacy) |
| [Aural detectability](https://zhenxianli.github.io/LISQM/metrics/aural-detectability.html) | d′ (detectability index), dB | Fidell et al. (1974) | [refmap-psychoacoustics](https://zhenxianli.github.io/LISQM/projects/refmap-psychoacoustics.html) |