Annual Noise Level Reports

The data presented summarizes the Day Night Average Noise Levels (DNL). DNL is a 24-hour time-averaged sound exposure level with a 10 db nighttime (10PM to 7AM) weighting.

The data displays the measured aircraft DNL for each month, each quarter, and the year-to-date measurement. Aircraft noise is noise associated with known aircraft operations at O'Hare. The quarterly noise levels for each site are displayed on the Aircraft DNL Chart.

The daily aircraft DNL noise level varies from day to day. This is primarily because different runways are used under different wind conditions that affect where the aircraft fly. The Aircraft DNL Chart plots the monthly aircraft DNL measured at each site.

	Aircraft DNL Table	Aircraft DNL Chart
	January 2006	January 2006
	February 2006	February 2006
	March 2006	March 2006
	April 2006	April 2006
	May 2006	May 2006
	June 2006	June 2006
	July 2006	July 2006
	August 2006	August 2006
	September 2006	September 2006
	October 2006	October 2006
	November 2006	November 2006
	December 2006	December 2006