Comparing temperaments (tunings)

Here is a sound file that shows why something like equal temperament became an imperative. These examples demonstrate the difference between equal temperament and the keyboard tuned so that all the notes of the C major scale are tuned so as to make the C, F and G major triads perfectly in tune in accordance with the harmonic series. That is to say, for example, that the frequencies of the notes C, E & G in the C  triad would be in the ratio 4:5:6.