Never heard of a "surface wave acoustical filter" before. I love it. Whoever came up with the first iteration of that was a genius, a real out-of-the-box thinker. https://www.everythingrf.com/community/what-is-a-saw-filter

Who gets handed the problem of how to filter some EM and think to themselves hey, let's try turning this into sound...?

A signal processing prof back in college had worked on radars in WWII, and he told us about using acoustic delay lines for various purposes. (Can't find a good reference in the couple minutes I have right now, unfortunately.)

The Wikipedia article on delay-line memory has a section on radar delay-lines and some references to go off of: https://en.m.wikipedia.org/wiki/Delay-line_memory

Nice. Although it has little to do with the "internet of things". It's an improvement in radio receiver filters, always useful but not a huge deal.

Better link for this. https://group.ntt/en/newsrelease/2024/07/22/240722b.html