1. Theoretical basis of physical phenomena

Here, we present the main physical phenomena relating to the effect of boundaries (soil, obstacles, buildings, etc.) on acoustic propagation, whether in "open" half-space (i.e. free of obstacles) or in a more densely built-up environment (i.e. an urban setting). For more details on the physical processes and mathematical laws discussed in this article, please refer to the reference works and bibliographical references listed at the end of the document (Further reading).