The experiment that first made sound visible still decides where we put a wall.
In 1787 Ernst Chladni, a lawyer who preferred physics, fixed a brass plate at its centre, scattered sand across it and drew a violin bow down the edge. The plate sang, and the sand ran away from the parts that shook and gathered along the parts that did not.
The lines it formed are called nodal lines. Change the note and the lines rearrange into a new figure. Chladni toured Europe with his plates, and Napoleon paid him to translate his book into French.
Why it still matters
Violin makers still tune the front and back of an instrument this way, with tea leaves in place of sand. A plate that draws a clean ring at the right pitch will make a good violin.
A room is a plate with air in it. At low frequencies the air stands in the same kind of figure, with loud zones and quiet lines, and the listener's seat is somewhere on that map. We named the studio after the lines where nothing moves, because finding them is the first thing we do.