# Tonal audibility in environmental noise (ISO 1996-2)

> 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/tonal-audibility-iso-1996-2.html

**Quantity:** Tonality · **Unit:** dB · **Also known as:** ISO 1996-2 Annex C, ISO 1996-2 Annex J, ISO 1996-2 Annex K, tonal adjustment, environmental noise tonality

Objective tonal audibility and tone adjustment for environmental noise assessment. ISO 1996-2:2007 gave a method in Annex C; ISO 1996-2:2017 replaced it with an engineering method (Annex J) and a survey method (Annex K).

The current edition is ISO 1996-2:2017. Open-source implementations of it: **[MoSQITo](https://zhenxianli.github.io/LISQM/projects/mosqito.html)** (Python; Annex K prominent-tone detection; PR, not merged) and [phonometry](https://zhenxianli.github.io/LISQM/projects/phonometry.html) (Python; newly released, not yet seen to be widely used; Annex K survey method and Table J.1; in the phonometry.environment namespace). So far, only newly released projects, not yet seen to be widely used in the community, have released an implementation of it. Check their validation before relying on them. Implementations of earlier editions or related models: [acoustic-toolbox](https://zhenxianli.github.io/LISQM/projects/acoustic-toolbox.html) (Python; ISO 1996-2:2007; tonal audibility and tonal adjustment), [phonometry](https://zhenxianli.github.io/LISQM/projects/phonometry.html) (Python; newly released, not yet seen to be widely used; ISO 1996-2:2007; Annex C; in the phonometry.environment namespace), and [python-acoustics](https://zhenxianli.github.io/LISQM/projects/python-acoustics.html) (Python; legacy, archived; ISO 1996-2:2007; tonal audibility and tonal adjustment).

## Editions and who implements them

| Date | Edition | Status | What changed | Implemented by |
|---|---|---|---|---|
| 2017-07 | [ISO 1996-2:2017](https://www.iso.org/standard/59766.html) | current; ISO Open Data (2026-09-30) links it to a successor project (ISO 86954), which has not been published yet. | Annex J engineering method and Annex K survey method. | **[MoSQITo](https://zhenxianli.github.io/LISQM/projects/mosqito.html)** (PR), [phonometry](https://zhenxianli.github.io/LISQM/projects/phonometry.html) |
| 2007-03 | [ISO 1996-2:2007](https://www.iso.org/standard/41860.html) | withdrawn | Annex C tonal audibility. | [acoustic-toolbox](https://zhenxianli.github.io/LISQM/projects/acoustic-toolbox.html), [phonometry](https://zhenxianli.github.io/LISQM/projects/phonometry.html), [python-acoustics](https://zhenxianli.github.io/LISQM/projects/python-acoustics.html) |

## Project map

The lines of the project map for tonal audibility (ISO 1996-2) 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 [python-acoustics](https://zhenxianli.github.io/LISQM/projects/python-acoustics.html): [acoustic-toolbox](https://zhenxianli.github.io/LISQM/projects/acoustic-toolbox.html) (ISO 1996-2:2007)

On the map without a line, as no relation to another project listed for tonal audibility (ISO 1996-2) is recorded for them: **[MoSQITo](https://zhenxianli.github.io/LISQM/projects/mosqito.html)** and [phonometry](https://zhenxianli.github.io/LISQM/projects/phonometry.html).

## Implementations

| Project | Language | Edition | Functions | Validation (as stated) | Notes |
|---|---|---|---|---|---|
| **[MoSQITo](https://zhenxianli.github.io/LISQM/projects/mosqito.html)** | Python | [ISO 1996-2:2017](https://www.iso.org/standard/59766.html) (Annex K prominent-tone detection) | — | not stated | PR (https://github.com/Eomys/MoSQITo/pull/52). Pull request from May 2022; no maintainer reply. |
| [acoustic-toolbox](https://zhenxianli.github.io/LISQM/projects/acoustic-toolbox.html) | Python | [ISO 1996-2:2007](https://www.iso.org/standard/41860.html) (tonal audibility and tonal adjustment) | `Tonality`, `tonal_audibility`, `tonal_adjustment` | own tests only | Module `acoustic_toolbox.standards.iso_1996_2_2007`, the same code lineage as python-acoustics. |
| [phonometry](https://zhenxianli.github.io/LISQM/projects/phonometry.html) | Python | [ISO 1996-2:2017](https://www.iso.org/standard/59766.html) (Annex K survey method and Table J.1; in the phonometry.environment namespace) | — | not stated | Newly released project, not yet seen to be widely used. |
| [phonometry](https://zhenxianli.github.io/LISQM/projects/phonometry.html) | Python | [ISO 1996-2:2007](https://www.iso.org/standard/41860.html) (Annex C; in the phonometry.environment namespace) | — | not stated | Newly released project, not yet seen to be widely used. |
| [python-acoustics](https://zhenxianli.github.io/LISQM/projects/python-acoustics.html) | Python | [ISO 1996-2:2007](https://www.iso.org/standard/41860.html) (tonal audibility and tonal adjustment) | `Tonality`, `tonal_audibility`, `tonal_adjustment` | own tests only | Legacy project, no longer maintained. Module `acoustics.standards.iso_1996_2_2007`. The `Tonality` docstring uses the title of Annex C ("Objective method for assessing the audibility of tones in noise"), though the code does not name the annex. |

**See also:** [Audibility of tones in noise (ISO/TS 20065)](https://zhenxianli.github.io/LISQM/metrics/tonal-audibility-iso-20065.html), [Tonal audibility of wind turbine noise (IEC 61400-11)](https://zhenxianli.github.io/LISQM/metrics/tonal-audibility-iec-61400-11.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.

- [acoustic-toolbox](https://zhenxianli.github.io/LISQM/projects/acoustic-toolbox.html), ISO 1996-2:2007: own tests only
  - Ported or adapted from [python-acoustics](https://zhenxianli.github.io/LISQM/projects/python-acoustics.html).
  - As in python-acoustics, the test of the examples in the standard is commented out.
- [python-acoustics](https://zhenxianli.github.io/LISQM/projects/python-acoustics.html), ISO 1996-2:2007: own tests only
  - A test of the examples in the standard, using DELTA tone files, is commented out.

Not stated by MoSQITo; phonometry for ISO 1996-2:2017 and ISO 1996-2:2007.

## References

1. ISO 1996-2:2007. Acoustics — Description, measurement and assessment of environmental noise — Part 2: Determination of environmental noise levels. https://www.iso.org/standard/41860.html
2. ISO 1996-2:2017. Acoustics — Description, measurement and assessment of environmental noise — Part 2: Determination of sound pressure levels. https://www.iso.org/standard/59766.html