IL SB0654

Deletes the definition of "Ldn" (day-night average sound level) from the Permanent Noise Monitoring Act and replaces it with "CNEL" (Community Noise Equivalent Level) as the standard metric for measuring airport noise.

Adds new definitions for CNEL, hourly noise level, noise exposure level, noise level, and sound pressure level with detailed technical specifications and calculation methods.

Requires permanent noise monitoring reports to include noise contour maps showing 65 CNEL, 70 CNEL, and 75 CNEL zones around airports instead of the previous Ldn zones.

Updates time period designations in noise contour maps from "7:00 a.m. to 10:00 p.m." and "10:00 p.m. to 7:00 a.m." to more specific periods: 7:00 a.m. through 6:59 p.m., 7:00 p.m. through 9:59 p.m., and 10:00 p.m. through 6:59 a.m.