Single Event Noise Data

Installed in 1996, the Airport Noise Management System (ANMS) enables the Chicago Department of Aviation (CDA) to monitor the amount of noise generated over the communities surrounding O'Hare by the aircraft operating at the Airport. The ANMS collects, analyzes and processes data from a number of sources of information including a network of 43 noise monitors around O'Hare, Federal Aviation Administration (FAA) radar data, weather data and noise complaints. For more information on the system, click here.

The CDA’s noise monitors record noise events based on threshold exceedance. Each noise event starts at the time the noise level exceeds a decibel threshold, typically slightly above the background or ambient noise level, and ends at the time the noise level returns to the threshold. For every noise event (aircraft or community) recorded by the ANMS, the CDA is reporting three noise metrics.

These three noise metrics are industry standard metrics and are calculated at the noise monitor. The metrics include the Lmax (Maximum Sound Level), the Leq (Equivalent Sound Level), and the SEL (Sound Exposure Level). The Lmax is the peak noise event in decibels, the Leq is the average sound level for the event in decibels, and the SEL is the average sound level for the event in decibels accounting for both intensity and duration. SEL takes all of the energy under the line in a sound pressure level versus time graph and compresses it to a 1 second value.

The single event noise data is uploaded to this webpage on a weekly basis as a .txt file. Each file contains: the monitor Site ID, the start date and time of the event, the date and time of the peak noise for the event, the duration in seconds of the event, and the Lmax, the Leq, and the SEL of the noise event in decibels.

The following data is preliminary data and is subject to change. Preparation of the monthly noise data includes quality assurance and quality control procedures for the data and reports. The final data will be incorporated in the monthly ANMS Reports.

June 28, 2026 to July 4, 2026

June 21, 2026 to June 27, 2026

June 14, 2026 to June 20, 2026

June 7, 2026 to June 13, 2026

May 31, 2026 to June 6, 2026

May 24, 2026 to May 30, 2026

May 17, 2026 to May 23, 2026

May 10, 2026 to May 16, 2026

May 3, 2026 to May 9th, 2026

April 26, 2026 to May 2, 2026

April 19, 2026 to April 25, 2026

April 12, 2026 to April 18, 2026