DNL Segment Level Solver
Solve the standard 15-hour day or 9-hour night Leq from DNL and the other segment, retaining the 10 dB night penalty.
Description
Day-night average sound level (DNL) energetically combines 15 day hours and 9 night hours with a 10 dB night penalty.
Day-night average sound level (DNL) energetically combines 15 day hours and 9 night hours with a 10 dB night penalty. One segment can be solved when the other and total are known.1
The returned values include Solved segment Leq, Solved segment. The How section below explains the calculation, input rules and interpretation.
When to use DNL Segment Level Solver
Use DNL Segment Level Solver when you need to evaluate the supplied records under the calculation and evidence rules below. This assumes fixed 15/9-hour periods and energy averaging. It does not derive measured segment levels or local regulatory applicability.
Choose the measured quantities, units, weighting and measurement basis before entering values. For a reference, select the exact topic. For a catalog lookup, prepare complete source-backed records; for a screen, select an applicable caller limit.
How to use DNL Segment Level Solver and understand its results
- Choose the measured quantities, units, weighting and measurement basis before entering values. For a reference, select the exact topic. For a catalog lookup, prepare complete source-backed records; for a screen, select an applicable caller limit.
- Enter dayNightLevelDecibels, knownSegmentLevelDecibels, solveFor using the field table and calculation rules, then run the tool.
- Read solvedSegmentLevelDecibels, solvedSegment. 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 |
|---|---|---|---|
| dayNightLevelDecibels | DNL (dB) | number | Required |
| knownSegmentLevelDecibels | Known segment Leq (dB) | number | Required |
| solveFor | Segment to solve | string; one of "day", "night" | Required |
Enter finite target DNL and known segment level, and select the exact missing segment day or night. Subtract the known segment's weighted energy from the daily total and invert the remaining segment energy. Reject a known contribution at least as large as the total. Use a logarithmic fallback when direct energy arithmetic overflows or underflows; return the finite solution and segment.
24×10^(DNL/10)=15×10^(day/10)+9×10^((night+10)/10) Units, indexing, boundary conditions and exceptional cases are defined in the calculation rules above.
| Output field | Meaning | Value type |
|---|---|---|
| solvedSegmentLevelDecibels | Solved segment Leq (dB) | number |
| solvedSegment | Solved segment | string; one of "day", "night" |
{
"input": {
"dayNightLevelDecibels": 60,
"knownSegmentLevelDecibels": 60,
"solveFor": "night"
},
"output": {
"solvedSegmentLevelDecibels": 50,
"solvedSegment": "night"
}
}Limitations and assumptions
This assumes fixed 15/9-hour periods and energy averaging. It does not derive measured segment levels or local regulatory applicability.
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 fields without a declared default, extra fields, wrong value types and violations of the calculation rules are input errors.
Alternative or Complementary methods
Use Day-Evening-Night Level: Day-evening-night level (Lden) combines duration-weighted sound energy with evening and night penalties. Averaging the decibel numbers directly gives a different quantity. For a complementary task, use HUD Noise Site Reference: HUD identifies sites at or below 65 dB day-night average sound level as acceptable for noise assessment purposes. This reference explains the selected concept and the evidence needed to interpret it.
References
-
DNL Segment Level Solver — tool.io
Similar or alternative tools
- Day-Evening-Night Level
Day-evening-night level (Lden) combines duration-weighted sound energy with evening and night penalties. Averaging the decibel numbers directly gives a different quantity.
- HUD Noise Site Reference
HUD identifies sites at or below 65 dB day-night average sound level as acceptable for noise assessment purposes. This reference explains the selected concept and the evidence needed to interpret it.