In music theory, an inversion is a type of change to intervals, chords, voices (in counterpoint), and melodies. In each of these cases, "inversion" has a distinct but related meaning. The concept of inversion also plays an important role in musical set theory.
An example of melodic inversion
from the fugue
in D minor from J. S. Bach
's The Well-Tempered Clavier
, Book 1.
Though they start on different pitches (A and E), the second highlighted melody is the upside-down version of the first highlighted melody. That is, when the first goes up
, the second goes down
the same number of diatonic steps
(with some chromatic
alteration); and when the first goes down
, the second goes up
the same number of steps.