HUD Noise Site Reference

Return HUD environmental-noise site categories and procedural cautions.

Description

HUD identifies sites at or below 65 dB day-night average sound level as acceptable for noise assessment purposes.

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.^{[1, 2]}

The returned values include Source, Statement, Topic. The How section below explains the calculation, input rules and interpretation.

When to use HUD Noise Site Reference

Use HUD Noise Site Reference when you need to evaluate the supplied records under the calculation and evidence rules below. The reference does not measure, model or certify the supplied situation. This is an introductory excerpt, not the complete standard, a current compliance check or a project-specific calculation.

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 HUD Noise Site Reference 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 topic using the field table and calculation rules, then run the tool.
Read source, statement, topic. 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
topic	Reference topic to return.	string; one of "acceptable", "normally-unacceptable", "unacceptable"	Required

Choose one of the exact topic values in the table. The tool indexes a fixed, locally embedded reference entry and returns its source label, statement and unchanged topic. It does not fetch the source or update the wording. Topic meanings and all returned entries are shown below.

Selection	Returned reference entry
acceptable	source: 24 CFR Part 51 Subpart B; statement: HUD identifies sites at or below 65 dB day-night average sound level as acceptable for noise assessment purposes.; topic: acceptable
normally-unacceptable	source: 24 CFR Part 51 Subpart B; statement: Sites above 65 dB and not exceeding 75 dB are normally unacceptable and require the applicable mitigation and approval process.; topic: normally-unacceptable
unacceptable	source: 24 CFR Part 51 Subpart B; statement: Sites above 75 dB are unacceptable absent the exceptional approvals and protections specified by HUD rules.; topic: unacceptable

selected exact topic → embedded source label, explanatory statement and topic

Units, indexing, boundary conditions and exceptional cases are defined in the calculation rules above.

Output field	Meaning	Value type
source	Source used for the reference statement.	string
statement	Narrow reference statement for the selected topic.	string
topic	Selected reference topic.	string; one of "acceptable", "normally-unacceptable", "unacceptable"

json

{
  "input": {
    "topic": "acceptable"
  },
  "output": {
    "source": "24 CFR Part 51 Subpart B",
    "statement": "HUD identifies sites at or below 65 dB day-night average sound level as acceptable for noise assessment purposes.",
    "topic": "acceptable"
  }
}

Limitations and assumptions

The reference does not measure, model or certify the supplied situation. This is an introductory excerpt, not the complete standard, a current compliance check or a project-specific calculation.

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 DNL Segment Level Solver: 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. For a complementary task, use FAA Part 150 Land-Use Reference: Under 14 CFR Part 150 Appendix A, residential use is generally compatible below DNL 65 dB; determinations in higher bands depend on sound attenuation and local conditions. This reference explains the selected concept and the evidence needed to interpret it.

Further background: Site noise criteria, 24 CFR 51.103 (2025 edition).

References

HUD Noise Site Reference — tool.io
Site noise criteria, 24 CFR 51.103 (2025 edition) — US Government Publishing Office

Similar or alternative tools

DNL Segment Level Solver
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.
FAA Part 150 Land-Use Reference
Under 14 CFR Part 150 Appendix A, residential use is generally compatible below DNL 65 dB; determinations in higher bands depend on sound attenuation and local conditions. This reference explains the selected concept and the evidence needed to interpret it.