 By taking the principles he found in Helmholtz's book, he expanded his tuning system until it allowed for a division of the octave into 43 tones based on ratios of small integers.Partch uses the terms Otonality and Utonality to describe chords whose pitch classes are the harmonics or subharmonics of a given fixed tone.These six-tone chords function in Partch's music much the same that the three-tone major and minor chords (or triads) do in classical music.