# Prominence of impulsive sounds (ISO/PAS 1996-3, NT ACOU 112)

> 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/impulsiveness.html

**Quantity:** Impulsiveness · **Unit:** dB · **Also known as:** ISO/PAS 1996-3, NT ACOU 112, impulsiveness, impulse adjustment, impulsive sound prominence

Objective prominence of impulsive sounds and the corresponding adjustment of the equivalent level in environmental noise assessment: Nordtest method NT ACOU 112 and ISO/PAS 1996-3:2022 (adjustment of 0 to 9 dB). Hearing-model impulsiveness metrics are not standardised and no open implementation is listed.

The current edition is ISO/PAS 1996-3:2022. Open-source implementations of it: [phonometry](https://zhenxianli.github.io/LISQM/projects/phonometry.html) (Python; newly released, not yet seen to be widely used; 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: [phonometry](https://zhenxianli.github.io/LISQM/projects/phonometry.html) (Python; newly released, not yet seen to be widely used; NT ACOU 112; in the phonometry.environment namespace).

## Editions and who implements them

| Date | Edition | Status | What changed | Implemented by |
|---|---|---|---|---|
| 2022-07 | [ISO/PAS 1996-3:2022](https://www.iso.org/standard/77035.html) | current; ISO Open Data (2026-09-30) links it to a successor project (ISO 95221), which has not been published yet. | Publicly available specification. | [phonometry](https://zhenxianli.github.io/LISQM/projects/phonometry.html) |
| 2002-05 | [NT ACOU 112](http://www.nordtest.info/wp/2002/05/01/acoustics-prominence-of-impulsive-sounds-and-for-adjustment-of-laeq-nt-acou-112/) | current | Nordic test method. | [phonometry](https://zhenxianli.github.io/LISQM/projects/phonometry.html) |

## Implementations

| Project | Language | Edition | Functions | Validation (as stated) | Notes |
|---|---|---|---|---|---|
| [phonometry](https://zhenxianli.github.io/LISQM/projects/phonometry.html) | Python | [ISO/PAS 1996-3:2022](https://www.iso.org/standard/77035.html) (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 | [NT ACOU 112](http://www.nordtest.info/wp/2002/05/01/acoustics-prominence-of-impulsive-sounds-and-for-adjustment-of-laeq-nt-acou-112/) (in the phonometry.environment namespace) | — | not stated | Newly released project, not yet seen to be widely used. |

## 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.

None of these projects says how its code was validated.

## References

1. Nordtest (2002). *NT ACOU 112: Acoustics — Prominence of impulsive sounds and for adjustment of LAeq*. Nordtest, Taastrup. http://www.nordtest.info/wp/2002/05/01/acoustics-prominence-of-impulsive-sounds-and-for-adjustment-of-laeq-nt-acou-112/
2. ISO/PAS 1996-3:2022. Acoustics — Description, measurement and assessment of environmental noise — Part 3: Objective method for the measurement of prominence of impulsive sounds and for adjustment of LAeq. https://www.iso.org/standard/77035.html