Noise pollution has been treated by the World Health Organization as the cause of several diseases, in addition to being the second largest environmental polluter, being surpassed only by air pollution. For schools, excessive noise, in addition to causing illness, is responsible for low levels of cognition and low productivity for both students and teachers. In general, Brazilian public schools are built on land provided by the government, in places that are not suitable for their siting. Thus, in Brazilian schools, students are exposed to noise from the surroundings, as well as noise generated indoors, which is not negligible, reaching levels that can be harmful to health and incompatible with educational activities. This study shows the evaluation of the level of indoor and outdoor noise in classrooms of five primary schools in the city of São Paulo, in the pre-pandemic period of COVID-19, comparing the results with those established by legislation, in addition to evaluating other descriptors such as LAeq, L10, L90, and SIL. The results show that classroom users are exposed to noise levels that complicate the communication of the teacher's message to the student, disrupt concentration and can even be affecting their health