The study describes people's reaction to environmental noise in Curitiba, a city of approximately 1.6 million inhabitants in Brazil. Data was collected using questionnaires randomly delivered to the city's residents. Out of 1,000 questionnaires, 860 (86%) were returned and assessed. The main noise sources found as disturbing were motor vehicle traffic (73%) and neighbors (38%), which were rated as producing the most disturbing noise. All respondents pointed out at least one of the following as noise sources: neighbors, animals, sirens, civil construction, religious worship temples, nightclubs, toys, and domestic electric appliances. The main reactions to noise exposure were: irritability (58%), difficulty to concentrate (42%), sleeping disorders (20%), and headaches (20%).