datacrime@lemmy.dbzer0.com pointed out that the testing device I posted yesterday resembles a theremin.
Here's a 1961 magazine article about how to build your own theremin. Theremins were developed by Leon Theremin in the 1920s. The instrument measures the position of your hands, which control frequency and amplitude. It has been used in various genres of music, in Hollywood films, and is sometimes used to stand in for soaring human vocals.
Thereminist Carolina Eyck invented one of the primary playing techniques used by skilled players. This is Eyck playing the Interstellar theme on a theremin accompanied by a piano. Also, Flight of the Bumblebee, making the theremin sound like a bee. And Carpenter's Halloween theme.

This proves that Isabella Rossellini is a vampire
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