Mexico City, with a population estimated in 19 millions, is part of one of the largest metropolitan areas in the world. Unfortunately, scientific work on urban noise in Mexico City is scarce. A study on people reaction to urban noise carried out in open public spaces of two different zones of Mexico City will be presented. A previous survey in those zones showed that the noise levels exceeded the values recommended by international organizations to protect public health and welfare. The general objective of the study to be presented was to identify the sound sources perceived by the pedestrians, and to evaluate their response to urban noise pollution in the two mentioned areas. The results show that for most of the people a) urban noise is not considered a relevant aspect to improve these zones of the city, although urban noise has a negative effect on the decision of using open public spaces; b) the people who believe that noise pollution has negative effects are more annoyed; c) vehicular traffic is the most annoying noise source, contributing significantly the public transportation; d) one of the principal strategies to confront urban noise is to get used to it.