When a tone – say „g" is played on some musical instrument, it is not only „g" which sounds but in general also a whole series of „partials" or higher harmonics. Already the ancient Greeks as described by Pythagoras knew about this. The origin of the partials is particularly transparent in the case string instruments like guitars or violins and can be explained by the formation of standing wave oscillations with different numbers of nodes. The frequencies are given by the corresponding components of a Fourier analysis where the fundamental and the first harmonic in the present example correspond to "g". Surprisingly the listener still has the mental sensation "g" even if fundamental and first harmonic are cut off by an acoustic high pass filter.
In the 19th Century the German Physicist, H. v. Helmholtz found the relation between the harmonic character of an interval or a chord and the associated partials. This will be demonstrated for prominent intervals like octaves, quarts, and terces. The results of these considerations will be supported by live demonstrations with alpine folklore music German songs from the renaissance and Japanese traditional folk songs.