Urban noise is a main component in the deterioration of life quality for people in urban areas. This problem mainly affects those who periodically travel through high traffic areas. The first step in reducing environmental noise is to characterize the urban setting with acoustic metrology for its diagnosis and control. This document exposes the design, construction and characterization of a wireless urban noise measurement module. The device works as a low-cost node with the capacity to be replicated for the deployment of a network of wireless acoustic sensors that allows the elaboration of dynamic urban noise maps. Each module consists of an electrical autonomy system, a single board computer and a MEMS microphone. The project also includes the design of a web portal to display measurement results in real time. The low-cost system was calibrated and compared with a class 1 sound level meter used to measure urban noise in the Autonomous City of Buenos Aires (CABA). Global differences of less than 1 dB were obtained. Urban noise was measured near the National University of Tres de Febrero following guidelines of ISO 1996-2 standard. The performance obtained in the evaluation instance and the results of the comparison were satisfactory.