# Aural detectability of sounds in background noise

> 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/aural-detectability.html

**Quantity:** Related quantities · **Unit:** d′ (detectability index), dB · **Also known as:** detectability, d-prime, signal detection, aural detection, audibility of aircraft

How likely a listener is to detect a sound in background noise, from signal-to-noise ratios in auditory filters and signal-detection theory. Used for aircraft, drone and urban air mobility noise. Not standardised.

There is no standard; the reference model is Fidell et al. (1974). Open-source implementations of it: [refmap-psychoacoustics](https://zhenxianli.github.io/LISQM/projects/refmap-psychoacoustics.html) (MATLAB, Python; MATLAB and Python). Implementations of earlier editions or related models: [refmap-psychoacoustics](https://zhenxianli.github.io/LISQM/projects/refmap-psychoacoustics.html) (MATLAB, Python; Rizzi et al. (2025); MATLAB and Python).

## Editions and who implements them

| Date | Edition | Status | What changed | Implemented by |
|---|---|---|---|---|
| 2025-07 | [Rizzi et al. (2025)](https://doi.org/10.2514/1.C038188) | published | NASA's use of the model in annoyance assessments of urban air mobility, with audibility as a factor. | [refmap-psychoacoustics](https://zhenxianli.github.io/LISQM/projects/refmap-psychoacoustics.html) |
| 1974 | [Fidell et al. (1974)](https://doi.org/10.1177/001872087401600405) | published | Model paper. | [refmap-psychoacoustics](https://zhenxianli.github.io/LISQM/projects/refmap-psychoacoustics.html) |

## Implementations

| Project | Language | Edition | Functions | Validation (as stated) | Notes |
|---|---|---|---|---|---|
| [refmap-psychoacoustics](https://zhenxianli.github.io/LISQM/projects/refmap-psychoacoustics.html) | MATLAB, Python | [Rizzi et al. (2025)](https://doi.org/10.2514/1.C038188) (MATLAB and Python) | `auralDetectability`, `aural_detect` | not stated | The same functions; the README cites this paper for the NASA development of the model. |
| [refmap-psychoacoustics](https://zhenxianli.github.io/LISQM/projects/refmap-psychoacoustics.html) | MATLAB, Python | [Fidell et al. (1974)](https://doi.org/10.1177/001872087401600405) (MATLAB and Python) | `auralDetectability`, `auralDetectFromLeq`, `aural_detect`, `aural_detect_from_lzeqt` | not stated | Code headers describe the Fidell, Pearsons & Bennett (1974) model as "developed further by NASA" and cite "Rizzi, SA et al, 2024"; the README cites Rizzi et al. (2025), *Journal of Aircraft*, doi:10.2514/1.C038188. |

## 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. Fidell, S., Pearsons, K. S., & Bennett, R. (1974). Prediction of aural detectability of noise signals. *Human Factors*, 16(4), 373–383. https://doi.org/10.1177/001872087401600405
2. Rizzi, S. A., Christian, A. W., Letica, S. J., & Lympany, S. V. (2026). Annoyance model assessments of urban air mobility vehicle operations. *Journal of Aircraft*, 63(1). Published online 2025-07-02. https://doi.org/10.2514/1.C038188