I've recently started to take interest in PDEs and how to solve them, and I'm wondering a bit about real life applications of the wave equation. So far I haven't found anything about practical applications, but on Wikipedia it says that the wave equation is an important PDE that arises in fields like acoustics, electromagnetics and fluid dynamics. Since I know how to solve it I'd like to know how to apply it to something.
Maybe I should clarify something. I know about areas where the wave equation is used and how a simple solution like sin(x-ct) + sin(x+ct) describes a standing wave. What I'm asking about is examples of real, practical situations where solving the wave equation with appropriate boundary conditions is necessary.