The Rubens Tube
The Rubens tube (also called a flame tube) is a popular physics demonstration that reveals characteristics of the standing wave behavior inside the tube. We have studied the irregular spacing of natural frequencies that lead to the standing wave patterns and published the results in the Journal of the Acoustical Society of America (see #16 in Publications). In addition, we've compiled an overview of the history and research to-date on the flame tube in a Proceedings of Meetings on Acoustics article (see #48 in Publications).
The Rubens tube is a key element of our Sounds to Astound outreach show.