Chennai has emerged as the noisiest city in the country followed by Hyderabad and Mumbai based on the noise levels and number of locations violating standard levels, according to the Central Pollution Control Board. The locations selected in Chennai for the study included Anna Nagar under the silence zone, T Nagar, Perambur, Washermanpet and Pallikarnai under the commercial zone, Guindy under the industrial and Triplicane, Velachery and Sowcarpet under the residential zones.