The current research proposal is situated in the field of urban sound propagation, and aims for an open-source software development of the Pseudo-Spectral Time-Domain method (openPSTD). Regardless of our location, we are at all times immersed by a sound environment, which may affect us both positively or negatively. The detailed reproduction of the urban sound environment is essential for analyzing and optimizing it. To date, there is a lack of a detailed 3D acoustic propagation method for this purpose, both due to the computational burden as well as due to the absence of an easy accessible software interface. The openPSTD project aims to provide a full-fledged software tool, accessible for academic research purposes, which enables to efficiently and in detail compute urban sound propagation. To achieve this, the computational method behind the tool will be further developed. Within the project, the software tool will also be implemented and applied to studying both reduction of urban noise as well as to support the positive sound environment, the latter especially directed to train the blind in the auditory perception of the environment through auralization.