There are several modifications that can be applied to a melodic phrase. Three of the common mods of an original phrase are:
When using the inversion technique the intervals of the melodic phrase are inverted so that a melodic motion up becomes a melodic motion down instead (and vice-versa). A scale context can be provided so that the notes can be constrained to a specific scale if desired. If no scale context is provided the default is the chromatic scale.
When you enter a phrase and scale context using the lilypond format, the original phrase followed by each of the three mods will be played. On the retrograde and retrograde/inversion mods the rhythm of the original phrase is also reversed, while on the inversion the rhythm of the original phrase is maintained. If you want the original rhythm to be played on all of mods you can check the 'use original rhythms' box.
Sometimes it is interesting to have the inversion and retrograde/inversion played an octave higher. Use the 'Transpose inversion up one octave' checkbox to hear that result.
After you have played it, you can click the lower buttons to hear each mod by itself. The lilypond output at the bottom of the page can be loaded into lilypond to see the notation of the phrase and its three modifications.
There are four examples using different scale contexts and feel free to enter your own phrases for experimentation.