A survey of city noise in the Chicago area was initiated in 1947. This report describes traffic, industrial, and residential area noise which was investigated as a part of the work. Levels of traffic noise were 35 to 45 db, 45 to 65 db, and 65 to 75 db in the 400–800‐cps band for light, average, and heavy traffic conditions, respectively. Industrial noise ranged from 50 to 60 db in the same band for fifty percent of the cases measured. Ninety percent were below 65 db. A limiting spectrum for noise which is considered not objectionable is presented. Residential area noise ranged from 38 to 47 db in the mentioned band for fifty percent of the cases measured. At night and for winter conditions, traffic noise was 10 db lower in the mentioned band than in the daytime. At night, industrial area noise dropped to levels of existing traffic conditions, and in winter it was lower by about 5 db in octave bands mainly because factory windows were closed. At night, residential area noise was 5 to 10 db less in octave bands than during the day, and for winter conditions there was a drop of 6 to 8 db in octave bands due to the modified character of distant traffic.