(1) A transformation of an interval which can occur in two ways. In intervallic inversion where two notes are played together, the lower note of the original is played an octave higher (or the upper note is played an octave lower). This causes an interval of a fifth to be come a fourth and vice versa, an interval of a third to become a sixth and vice versa, etc. It is an arithmetic phenomenon that the original interval and its inversion always sum to nine. In melodic inversion, the interval between one note in a melody and the next note is inverted, so if the melody originally rises by a third, the inverted melody will fall by a third.
(2) A transformation of a chord through intervallic inversion such that the original bass note no longer remains the lowest note of the chord. A major or minor triad can appear in three positions:
