Noise Exposure Forecast Calculator
Calculate the legacy U.S. Noise Exposure Forecast from an energy-averaged EPNL and caller-supplied daytime and nighttime operation counts, with the historical 16.7 night weighting and an 88 dB offset.
Description
Legacy U.S.
Legacy U.S. NEF aggregates an energy-averaged EPNL with weighted operation counts. It differs from modern U.S. DNL and from assuming every jurisdiction has abandoned NEF.1, 2
Calculate the legacy U.S. Noise Exposure Forecast from an energy-averaged EPNL and caller-supplied daytime and nighttime operation counts, with the historical 16.7 night weighting and an 88 dB offset.
When to use Noise Exposure Forecast Calculator
Use this tool to calculate the legacy U.S. Noise Exposure Forecast from an energy-averaged EPNL and caller-supplied daytime and nighttime operation counts, with the historical 16.7 night weighting and an 88 dB offset.
Choose a supported reference topic, run an input-free reference with an empty object, or prepare the measured values and caller-supplied test records requested. Keep acoustic metrics, frequency, units and test conditions consistent.
How to use Noise Exposure Forecast Calculator and understand its results
- Choose a supported reference topic, run an input-free reference with an empty object, or prepare the measured values and caller-supplied test records requested. Keep acoustic metrics, frequency, units and test conditions consistent.
- Enter daytimeOperations, effectivePerceivedNoiseLevelDecibels, method, nighttimeOperations using the field table and calculation rules, then run the tool.
- Read caveat, daytimeOperations, formula, method, nefDecibels, nightPenaltyDecibels, nightWeightingFactor, nighttimeOperations, sourceNote, weightedOperationTerm. The explanation below defines the units, signs, ordering and any flags or placeholder values.
- If the tool reports an input issue, correct the values and run it again. Apply the stated assumptions when interpreting a successfully returned result.
| Input field | Meaning | Value type; see rules below | Requirement |
|---|---|---|---|
| daytimeOperations | Average number of daytime operations in the legacy planning scenario, not a modern annual average. | number; minimum: 0 | Required |
| effectivePerceivedNoiseLevelDecibels | Energy-averaged effective perceived noise level for the supplied event set, in EPNdB. (EPNdB) | number | Required |
| method | Legacy NEF method variant. | string; one of "us-nef" | Required |
| nighttimeOperations | Average number of nighttime operations in the legacy planning scenario. | number; minimum: 0 | Required |
Select us-nef; enter finite EPNdB and nonnegative operation counts with positive weighted total. Return NEF, weighted term, 16.7 factor, 10log10(16.7) night penalty, inputs, formula and stored notes.
NEF=EPNL+10log10(day+16.7night)−88 Units, indexing, boundary conditions and exceptional cases are defined in the calculation rules above.
| Output field | Meaning | Value type |
|---|---|---|
| caveat | Limitations of the legacy metric and the supplied event aggregation. | string |
| daytimeOperations | daytimeOperations | number; minimum: 0 |
| formula | formula | string |
| method | method | string; one of "us-nef" |
| nefDecibels | NEF (NEF) | number |
| nightPenaltyDecibels | nightPenaltyDecibels | number |
| nightWeightingFactor | nightWeightingFactor | number |
| nighttimeOperations | nighttimeOperations | number; minimum: 0 |
| sourceNote | sourceNote | string |
| weightedOperationTerm | Weighted operation term | number; minimum: 0 |
{
"input": {
"daytimeOperations": 10,
"effectivePerceivedNoiseLevelDecibels": 100,
"method": "us-nef",
"nighttimeOperations": 1
},
"output": {
"caveat": "NEF is a legacy perceived-noise metric, not DNL. The input EPNL must already be energy-averaged over the represented event set, and the operation counts, flight paths, aircraft mix, and planning-day assumptions must be documented.",
"daytimeOperations": 10,
"formula": "NEF = EPNL + 10 log10(ND + 16.7 NN) - 88",
"method": "us-nef",
"nefDecibels": 26.265112613645755,
"nightPenaltyDecibels": 12.227164711475833,
"nightWeightingFactor": 16.7,
"nighttimeOperations": 1,
"sourceNote": "Legacy NEF method described by Bishop and Horonjeff; FAA and Canadian sources now use DNL for most current airport studies.",
"weightedOperationTerm": 26.7
}
}Limitations and assumptions
Counts may be fractional planning averages; no event averaging, aircraft mix or contours are computed. The returned sourceNote broadly says Canadian sources now use DNL; Transport Canada continues to describe a NEF system, so do not rely on that wording as Canadian policy.
Numeric inputs, where present, must be finite. Follow the calculation-specific rules for overflow, underflow and exceptional cases. Extremely large text inputs are rejected. Missing required fields, extra fields, wrong value types and violations of the calculation rules are input errors.
Alternative or Complementary methods
Use WHO Night-Noise Reference: Return the WHO Europe night-noise guideline and interim-target context. For a complementary task, use Ordinance Hours Screen: Check a same-day activity interval against caller-supplied ordinance hours, with an explicit variance override; it embeds no jurisdictional schedule.
Further background: Noise Exposure Forecast and Related Programs.
References
-
Noise Exposure Forecast Calculator — tool.io
-
Noise Exposure Forecast and Related Programs — Transport Canada
Similar or alternative tools
- WHO Night-Noise Reference
Return the WHO Europe night-noise guideline and interim-target context.
- Ordinance Hours Screen
Check a same-day activity interval against caller-supplied ordinance hours, with an explicit variance override; it embeds no jurisdictional schedule.