The Physikanten present a round “piano” and play a melody on it. They then bring a strange phenomenon to our ears: when they play a scale from beginning to end, they end at the first tone. This trick can be repeated again and again. You are given the impression that the tone increases each time. In fact one distinct scale is just being repeated.
How does it work?
What you hear is an acoustic illusion called the “Shepard Scale”. Several octaves of the same tone are superimposed in such a way that a seemingly higher tone actually consists of a larger share of lower tones of lower octaves.
