To demonstrate standing wave resonances in an open tube.
To produce resonant frequencies of the tube, hold the tube by one end, keeping that end free for flow of air, and swing it around your head. Increasing the speed of the rotation raises the harmonic produced. Up to seven harmonics can be produced, illustrating the notes of the overtone series. The fundamental can only be produced by blowing gently into one end.◙
Frank S. Crawford, Singing Corrugated Pipes, AJP 42, 278-288 (1974). ◙J. A. Soules and Michael Kanner, The Normal Modes of the "Hybrid Hummer, " AAPT Announcer, 129, (Dec. 1988). Louis H. Cadwell, Singing Corrugated Pipes: Using Video Cameras to Measure Air Flow, TPT 32, 42-43 (1994). Louis H. Cadwell, Singing corrugated pipes revisited, AJP 62, 224-227 (1994).