[comex]

It’s not a coincidence, but it is only an approximation. Fourier analysis of sound assumes a continuous field of air pressure at each point in space, which evolves according to a continuous function; in reality, air consists of a large number of discrete particles, and “pressure” approximates the result of a large number of discrete, random collisions. We can prove mathematically that the more particles are in the system, the closer its behavior gets (with overwhelming probability) to the continuous ideal; and sound happens to operate at a sufficiently large scale that the discrepancy is far too small to make a difference, so we - and evolution - can just use the continuous ideal for our calculations. But that doesn’t require it to have any physical meaning.

On the other hand, at a lower level of abstraction, the most fundamental theories of physics known do tend to involve real numbers and continuous functions – from my limited understanding, that applies even to quantum mechanics in many cases, even though it’s known for discretizing quantities that were continuous in classical mechanics. However, it’s unknown – unknowable, even, at some point – whether these infinities are “real”, or themselves approximations of even more fundamental laws.