Perceived noise level, PNLT and EPNL (ICAO Annex 16, 14 CFR Part 36)
Effective perceived noise level for aircraft noise certification: perceived noisiness in noy, the tone-corrected perceived noise level (PNLT) and a duration correction. Defined in ICAO Annex 16, Volume I, and in the US regulation 14 CFR Part 36.
The current edition is ICAO Annex 16, Vol. I and 14 CFR Part 36. Open-source implementations of it:
- Python phonometry new, pySQAT developing, SUAVE legacy
- MATLAB SQAT
Editions and who implements them
| Date | Edition | Status | What changed | Implemented by |
|---|---|---|---|---|
| 2017-07 | ICAO Annex 16, Vol. I | current Amendment 15 was adopted on 2026-03-27 and applies from 2027-01-01 (new noise limits and supersonic aeroplanes); whether it changes the EPNL procedure itself has not been confirmed. | International standard for aircraft noise certification. | phonometry new, SUAVE legacy, Zhen-Ni/epnl legacy partial |
| 2002-07 | 14 CFR Part 36 | current | US regulation (Appendices A and B). | SQAT, pySQAT developing |
Project map
The project map, with only the lines for perceived noise level and EPNL 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
- SQAT SQAT, MoSQITo, and sottek-hearing-model
- legacy legacy project
Implementations
| Project | Edition | Functions | Validation (as stated) | Notes |
|---|---|---|---|---|
| SQAT MATLAB | 14 CFR Part 36 since v1.1 | EPNL_FAR_Part36, get_PNL, get_PNLT, get_Duration_Correction | compared with published EPNL values (Rizzi et al., 2020) | Follows Amendment 36-26 (2005). |
| phonometry Python | ICAO Annex 16, Vol. I PNL, PNLT and EPNL, in the phonometry.aircraft namespace | — | standard or paper data | new |
| pySQAT Python | 14 CFR Part 36 | EPNL_FAR_Part36 | compared with SQAT (its source) | developing no licence |
| SUAVE Python | ICAO Annex 16, Vol. I PNL, PNLT and EPNL; the code cites no edition | pnl_noise, noise_tone_correction, epnl_noise | not stated | legacy EPNL is computed from a PNLT time history. The noise tools cite neither ICAO Annex 16 nor 14 CFR Part 36, nor an edition; their docstrings give "Source: None". |
| Zhen-Ni/epnl Rust | ICAO Annex 16, Vol. I PNL and PNLT only; no duration correction to EPNL | SPL, Noy, PNL, PNLT | not stated | legacy no licence partial Code comments cite "Annex 16 - Volume I, APP 2-16 / 2-17" and number the 24 bands "consistent with ICAO ANNEX 16". The quantities are Rust types converted into each other with From. |
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.
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 · 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.
- phonometry new · ICAO Annex 16, Vol. I
standard or paper data
- Tested with the EPNL example of ICAO Doc 9501 (Environmental Technical Manual).
- pySQAT developing · 14 CFR Part 36
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.
- Compared with SQAT v1.3, run in MATLAB, by
validation/FINAL_VAL.py; the generated reports are not committed.
- Compared with SQAT v1.3, run in MATLAB, by
Not stated by SUAVE and Zhen-Ni/epnl.
References
- 14 CFR Part 36. Noise standards: aircraft type and airworthiness certification (Appendix A: EPNL). https://www.ecfr.gov/current/title-14/chapter-I/subchapter-C/part-36
- ICAO Annex 16, Vol. I. Annex 16 to the Convention on International Civil Aviation — Environmental Protection — Volume I: Aircraft Noise. https://store.icao.int/en/annex-16-environmental-protection-volume-i-aircraft-noise