Rubens tube

Physics apparatus for demonstrating acoustic standing waves in a tube

A Rubens tube, also known as a standing wave flame tube, or simply flame tube, is a physics apparatus for demonstrating acoustic standing waves in a tube. Invented by German physicist Heinrich Rubens in 1905, it graphically shows the relationship between sound waves and sound pressure, as a primitive oscilloscope. Today, it is used only occasionally, typically as a demonstration in physics education.

This keyword could refer to multiple things. Here are some suggestions: