Initial wish: changing the fundamental tone during a piece of music In the preceding post, we saw that the just intonation is not pure any more when the fundamental tone is changed since certain intervals change. The further removed the key, the more tones fail to accord with the calculated, i.e. resonant tones. If the frequencies of the scale tones are very slightly shifted – i.e. tempered – then we can also change over into neighbouring keys, i.e. we can modulate. In the equal temperament, we can actually change over to any fundamental tone whatever, and this temperament has successfully