Both Physics and Astronomy courses do a lot of work with waves, and while light is one of the most important types for study, sound is exceptionally handy for demonstrations. There’s an immediacy, a feel, that can make sonic demos feel more intuitive.
We have a few of these about, metal bars with supports at the nodes of a standing wave, seated over a wooden box. The string goes where the bar doesn’t vibrate, and hence doesn’t dampen the sound, while the box helps it resonate louder. Ka-bong! They’re quite fun.
And, yes, Carl J. Ulrich of Minneapolis, Minnesota did some fine work here.