Posted on

Day Night Average Sound Level (DNL): The Descriptor of Choice for Airport Noise Assessment

Document Library
Noise

This 1990 FAA document explains why the Day Night Average Sound Level (DNL) was chosen as the standard metric for measuring airport noise. DNL averages noise exposure over a full 24-hour period, applying a penalty for nighttime flights, and has been adopted by multiple federal agencies—including the EPA, DOT, HUD, and DOD—as the most reliable way to assess how aircraft noise affects surrounding communities. The FAA formally incorporated DNL into federal regulation through FAR Part 150, Airport Noise Compatibility Planning, in 1981.

Open full document

Notes

FAA Office of Environment and Energy report dated March 16, 1990 explaining the adoption of DNL (Day Night Average Sound Level) as the standard aircraft noise descriptor under FAR Part 150, Airport Noise Compatibility Planning. Covers EPA’s 1976 formal recommendation of DNL, the Federal Interagency Committee on Urban Noise (1980), ANSI S3.23-1980, the Aviation Safety and Noise Abatement Act, and the scientific basis for DNL as an indicator of community annoyance. Discusses EPA Levels Document (550/9-74-004), single-event noise levels vs. cumulative exposure, and land use compatibility planning. Participating agencies include EPA, DOT, HUD, DOD, and the Veterans Administration.

Sidebar On/Off
V V